The Women's Health Trial Feasibility Study in Minority Populations: design and baseline descriptions

Diet and Chronic Disease Research in the Women's Health Initiative

The Women's Health Initiative (WHI) has been a major contributor to diet and chronic disease research among postmenopausal US women over its 30+ year history (1993 to present). The WHI program included full-scale randomized trials of a low-fat dietary pattern high in fruits, vegetables, and grains, and of calcium and vitamin D supplementation, each with designated primary and secondary chronic disease outcomes. The history of these trials will be briefly reviewed here, along with principal findings that included evidence for breast cancer-related benefits for each of the 2 interventions. In recent years, WHI investigators have developed an active research program in nutritional biomarker development and in the application of these biomarkers in WHI cohorts, among various other nutritional epidemiology uses of WHI observational study resources. The intake biomarker work, which primarily relies on blood and urine metabolomics profiles, lends support to the low-fat dietary pattern trial results, and supports chronic disease benefits of higher carbohydrate diets more generally, especially through the fiber component of carbohydrate.

Effect of Low-Fat Dietary Modification on Incident Open-Angle Glaucoma

PURPOSE

We tested whether dietary modification (DM) altered the risk for incident primary open-angle glaucoma (POAG).

DESIGN

Secondary analysis of a randomized intervention trial.

PARTICIPANTS

We linked Medicare claims data to 45 203 women in the Women's Health Initiative Dietary Modification Trial, of which 23 776 participants were enrolled in fee-for-service Medicare Part B and had physician claims.

METHODS

Women were randomized to follow either DM (a low-fat diet, with increased vegetable, fruit, and grain intake) or their usual diet without modification. Nine thousand three hundred forty women were randomized to the DM intervention, whereas 13 877 women were randomized to the control group. Our analyses were based on an intention-to-treat design, with a follow-up to the end of continuous Medicare coverage, death, or the last clams date (12/31/2018), whichever occurred first. Primary open-angle glaucoma was defined as the first claim with the International Classification of Diseases, Ninth or Tenth Revision, codes. Dietary data were assessed using a food frequency questionnaire.

MAIN OUTCOME MEASURES

We used Cox proportional hazards models to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for risk of POAG. Subgroup analyses were performed with P values for interaction.

RESULTS

After exclusion of women with Medicare-derived glaucoma before randomization, the final analysis included 23 217 women (mean age, 64.4 ± 5.8 years). Baseline characteristics were balanced between the intervention and control groups. Primary open-angle glaucoma incidence was 11.1 per 1000 woman-years (mean follow-up, 11.6 ± 7.4 years; mean DM duration, 5.2 ± 3.2 years). We found no overall benefit of DM in reducing incident POAG (HR, 1.04; 95% CI, 0.96-1.12). Race and participant age did not modify this relation (P = 0.08 and P = 0.24 for interaction, respectively). In further analysis of baseline nutrient and food intake stratified by quartile groups, risk of open-angle glaucoma (OAG) in DM participants in the lowest quartile group for percentage calories (kilocalories) from total fat (33.8 or lower) was increased (HR, 1.22; 95% CI, 1.05-1.41; P = 0.007 for interaction).

CONCLUSIONS

Analysis suggests that DM in participants in the lowest quartile group for percentage calories from total fat at baseline increased the risk of incident OAG among women regardless of age or race.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Whole-diet interventions and cardiovascular risk factors in postmenopausal women: A systematic review of controlled clinical trials

OBJECTIVES

Menopause is accompanied by many metabolic changes, increasing the risk of cardiometabolic diseases. The impact of diet, as a modifiable lifestyle factor, on cardiovascular health in general populations has been well established. The purpose of this systematic review is to summarize the evidence on the effects of whole diet on lipid profile, glycemic indices, and blood pressure in postmenopausal women.

METHODS

Embase, Medline, Cochrane Central Register of Controlled Trials, and Google Scholar were searched from inception to February 2021. We included controlled clinical trials in postmenopausal women that assessed the effect of a whole-diet intervention on lipid profile, glycemic indices, and/or blood pressure. The risk of bias in individual studies was assessed using RoB 2 and ROBINS-I tools.

SUMMARY OF EVIDENCE

Among 2,134 references, 21 trials met all eligibility criteria. Overall, results were heterogenuous and inconsistent. Compared to control diets, some studies showed that participants experienced improvements in total cholesterol (TC), low-density lipoprotein cholesterol (LDL), systolic blood pressure (SBP), fasting blood sugar (FBS), and apolipoprotein A (Apo-A) after following fat-modified diets, but some adverse effects on triglycerides (TG), very low-density lipoprotein cholesterol (VLDL), lipoprotein(a) (Lp(a)), and high-density lipoprotein cholesterol (HDL) concentrations were also observed. A limited number of trials found some effects of the Paleolithic, weight-loss, plant-based, or energy-restricted diets, or of following American Heart Association recommendations on TG, TC, HDL, insulin, FBS, or insulin resistance.

CONCLUSION

Current evidence suggests that diet may affect levels of some lipid profile markers, glycemic indices, and blood pressure among postmenopausal women. However, due to the large heterogeneity in intervention diets, comparison groups, intervention durations, and population characteristics, findings are inconclusive. Further well-designed clinical trials are needed on dietary interventions to reduce cardiovascular risk in postmenopausal women.

Dietary sugar intake and risk of Alzheimer's disease in older women

BACKGROUND

Despite some reports of cardiometabolic disorders associated with the risk of Alzheimer's disease (AD), limited studies have been conducted to examine the association between excessive sugar intake (a risk factor for cardiometabolic disorders) and AD risk.

AIM

The purpose of our study was to evaluate if excessive sugar intake has a significant long-term effect on the risk of AD.

METHODS

A population sample of 37,689 participants, who enrolled in the United States (US) Women's Health Initiative - Dietary Modification Trial (WHI-DM) in 1993-2005 and its extended observational follow-up study through 1 March 2019, were analyzed. Dietary sugar intake was measured using food frequency questionnaires. AD was classified by reports using a standard questionnaire. A dietary pattern that explained the maxima variations in sugar intake was constructed using reduced rank regression (RRR) technique. Associations of RRR dietary pattern scores and sugar intake (g/day) by quartiles (Q1 through Q4) with AD risk were examined using Cox proportional hazards regression analysis with adjusting for key covariates.

RESULTS

During a mean follow-up of 18.7 years, 4586 participants reported having incident AD. The total incidence rate (95% confidence interval [CI]) of AD was 6.5 (6.3-6.7) per 1000 person-years (PYs). The incidence rates (95% CI) of AD by total sugar intake were 6.2 (5.8-6.6), 6.4 (6.0-6.8), 6.6 (6.3-7.0), and 6.9 (6.5-7.3) per 1000 PYs among those in quartiles (Q) 1 to Q4 (toward higher sugar consumption) of total sugar intake, respectively (test for trend of AD incident rates, p < 0.001). Individuals in Q4 of total sugar intake had a 1.19 higher risk of incident AD than those in Q1 (hazard ratio [HR] = 1.19, 95% CI: 1.05-1.34, p = 0.01). An estimated increase of 10 g/day in total sugar intake (about 2.4 teaspoons) was associated with an increased AD risk by 1.3-1.4%. Of six subtypes of sugar intake, lactose was significantly associated with AD risk.

CONCLUSIONS

Our study indicates that excessive total sugar intake was significantly associated with AD risk in women. Of six subtypes of sugar intake, lactose had a stronger impact on AD risk.

Nutritional epidemiology and the Women's Health Initiative: a review

The dietary modification (DM) clinical trial, within the Women's Health Initiative (WHI), studied a low-fat dietary pattern intervention that included guidance to increase vegetables, fruit, and grains. This study was motivated in part from uncertainty about the reliability of observational studies examining the association between dietary fat and chronic disease risk by using self-reported dietary data. In addition to this large trial, which had breast and colorectal cancer as its primary outcomes, a substantial biomarker research effort was initiated midway in the WHI program to contribute to nutritional epidemiology research more broadly. Here we review and update findings from the DM trial and from the WHI nutritional biomarker studies and examine implications for future nutritional epidemiology research. The WHI included the randomized controlled DM trial (n = 48,835) and a prospective cohort observational (OS) study (n = 93,676), both among postmenopausal US women, aged 50-79 y when enrolled during 1993-1998. Also reviewed is a nutrition and physical activity assessment study in a subset of 450 OS participants (2007-2009) and a related controlled feeding study among 153 WHI participants (2010-2014). Long-term follow-up in the DM trial provides evidence for intervention-related reductions in breast cancer mortality, diabetes requiring insulin, and coronary artery disease in the subset of normotensive healthy women, without observed adverse effects or changes in all-cause mortality. Studies of intake biomarkers, and of biomarker-calibrated intake, suggest important associations of total energy intake and macronutrient dietary composition with the risk for major chronic diseases among postmenopausal women. Collectively these studies argue for a nutrition epidemiology research agenda that includes major efforts in nutritional biomarker development, and in the application of biomarkers combined with self-reported dietary data in disease association analyses. We expect such efforts to yield novel disease association findings and to inform disease prevention approaches for potential testing in dietary intervention trials. This trial was registered at clinicaltrials.gov as NCT00000611.

Reduction in saturated fat intake for cardiovascular disease

BACKGROUND

Reducing saturated fat reduces serum cholesterol, but effects on other intermediate outcomes may be less clear. Additionally, it is unclear whether the energy from saturated fats eliminated from the diet are more helpfully replaced by polyunsaturated fats, monounsaturated fats, carbohydrate or protein.

OBJECTIVES

To assess the effect of reducing saturated fat intake and replacing it with carbohydrate (CHO), polyunsaturated (PUFA), monounsaturated fat (MUFA) and/or protein on mortality and cardiovascular morbidity, using all available randomised clinical trials.

SEARCH METHODS

We updated our searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid) and Embase (Ovid) on 15 October 2019, and searched Clinicaltrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) on 17 October 2019.

SELECTION CRITERIA

Included trials fulfilled the following criteria: 1) randomised; 2) intention to reduce saturated fat intake OR intention to alter dietary fats and achieving a reduction in saturated fat; 3) compared with higher saturated fat intake or usual diet; 4) not multifactorial; 5) in adult humans with or without cardiovascular disease (but not acutely ill, pregnant or breastfeeding); 6) intervention duration at least 24 months; 7) mortality or cardiovascular morbidity data available.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed inclusion, extracted study data and assessed risk of bias. We performed random-effects meta-analyses, meta-regression, subgrouping, sensitivity analyses, funnel plots and GRADE assessment.

MAIN RESULTS

We included 15 randomised controlled trials (RCTs) (16 comparisons, 56,675 participants), that used a variety of interventions from providing all food to advice on reducing saturated fat. The included long-term trials suggested that reducing dietary saturated fat reduced the risk of combined cardiovascular events by 17% (risk ratio (RR) 0.83; 95% confidence interval (CI) 0.70 to 0.98, 12 trials, 53,758 participants of whom 8% had a cardiovascular event, I² = 67%, GRADE moderate-quality evidence). Meta-regression suggested that greater reductions in saturated fat (reflected in greater reductions in serum cholesterol) resulted in greater reductions in risk of CVD events, explaining most heterogeneity between trials. The number needed to treat for an additional beneficial outcome (NNTB) was 56 in primary prevention trials, so 56 people need to reduce their saturated fat intake for ~four years for one person to avoid experiencing a CVD event. In secondary prevention trials, the NNTB was 53. Subgrouping did not suggest significant differences between replacement of saturated fat calories with polyunsaturated fat or carbohydrate, and data on replacement with monounsaturated fat and protein was very limited. We found little or no effect of reducing saturated fat on all-cause mortality (RR 0.96; 95% CI 0.90 to 1.03; 11 trials, 55,858 participants) or cardiovascular mortality (RR 0.95; 95% CI 0.80 to 1.12, 10 trials, 53,421 participants), both with GRADE moderate-quality evidence. There was little or no effect of reducing saturated fats on non-fatal myocardial infarction (RR 0.97, 95% CI 0.87 to 1.07) or CHD mortality (RR 0.97, 95% CI 0.82 to 1.16, both low-quality evidence), but effects on total (fatal or non-fatal) myocardial infarction, stroke and CHD events (fatal or non-fatal) were all unclear as the evidence was of very low quality. There was little or no effect on cancer mortality, cancer diagnoses, diabetes diagnosis, HDL cholesterol, serum triglycerides or blood pressure, and small reductions in weight, serum total cholesterol, LDL cholesterol and BMI. There was no evidence of harmful effects of reducing saturated fat intakes.

AUTHORS' CONCLUSIONS

The findings of this updated review suggest that reducing saturated fat intake for at least two years causes a potentially important reduction in combined cardiovascular events. Replacing the energy from saturated fat with polyunsaturated fat or carbohydrate appear to be useful strategies, while effects of replacement with monounsaturated fat are unclear. The reduction in combined cardiovascular events resulting from reducing saturated fat did not alter by study duration, sex or baseline level of cardiovascular risk, but greater reduction in saturated fat caused greater reductions in cardiovascular events.

Effects of total fat intake on body fatness in adults

BACKGROUND

The ideal proportion of energy from fat in our food and its relation to body weight is not clear. In order to prevent overweight and obesity in the general population, we need to understand the relationship between the proportion of energy from fat and resulting weight and body fatness in the general population.

OBJECTIVES

To assess the effects of proportion of energy intake from fat on measures of body fatness (including body weight, waist circumference, percentage body fat and body mass index) in people not aiming to lose weight, using all appropriate randomised controlled trials (RCTs) of at least six months duration.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, Clinicaltrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP) to October 2019. We did not limit the search by language.

SELECTION CRITERIA

Trials fulfilled the following criteria: 1) randomised intervention trial, 2) included adults aged at least 18 years, 3) randomised to a lower fat versus higher fat diet, without the intention to reduce weight in any participants, 4) not multifactorial and 5) assessed a measure of weight or body fatness after at least six months. We duplicated inclusion decisions and resolved disagreement by discussion or referral to a third party.

DATA COLLECTION AND ANALYSIS

We extracted data on the population, intervention, control and outcome measures in duplicate. We extracted measures of body fatness (body weight, BMI, percentage body fat and waist circumference) independently in duplicate at all available time points. We performed random-effects meta-analyses, meta-regression, subgrouping, sensitivity, funnel plot analyses and GRADE assessment.

MAIN RESULTS

We included 37 RCTs (57,079 participants). There is consistent high-quality evidence from RCTs that reducing total fat intake results in small reductions in body fatness; this was seen in almost all included studies and was highly resistant to sensitivity analyses (GRADE high-consistency evidence, not downgraded). The effect of eating less fat (compared with higher fat intake) is a mean body weight reduction of 1.4 kg (95% confidence interval (CI) -1.7 to -1.1 kg, in 53,875 participants from 26 RCTs, I² = 75%). The heterogeneity was explained in subgrouping and meta-regression. These suggested that greater weight loss results from greater fat reductions in people with lower fat intake at baseline, and people with higher body mass index (BMI) at baseline. The size of the effect on weight does not alter over time and is mirrored by reductions in BMI (MD -0.5 kg/m², 95% CI -0.6 to -0.3, 46,539 participants in 14 trials, I² = 21%), waist circumference (MD -0.5 cm, 95% CI -0.7 to -0.2, 16,620 participants in 3 trials; I² = 21%), and percentage body fat (MD -0.3% body fat, 95% CI -0.6 to 0.00, P = 0.05, in 2350 participants in 2 trials; I² = 0%). There was no suggestion of harms associated with low fat diets that might mitigate any benefits on body fatness. The reduction in body weight was reflected in small reductions in LDL (-0.13 mmol/L, 95% CI -0.21 to -0.05), and total cholesterol (-0.23 mmol/L, 95% CI -0.32 to -0.14), with little or no effect on HDL cholesterol (-0.02 mmol/L, 95% CI -0.03 to 0.00), triglycerides (0.01 mmol/L, 95% CI -0.05 to 0.07), systolic (-0.75 mmHg, 95% CI -1.42 to -0.07) or diastolic blood pressure(-0.52 mmHg, 95% CI -0.95 to -0.09), all GRADE high-consistency evidence or quality of life (0.04, 95% CI 0.01 to 0.07, on a scale of 0 to 10, GRADE low-consistency evidence).

AUTHORS' CONCLUSIONS

Trials where participants were randomised to a lower fat intake versus a higher fat intake, but with no intention to reduce weight, showed a consistent, stable but small effect of low fat intake on body fatness: slightly lower weight, BMI, waist circumference and percentage body fat compared with higher fat arms. Greater fat reduction, lower baseline fat intake and higher baseline BMI were all associated with greater reductions in weight. There was no evidence of harm to serum lipids, blood pressure or quality of life, but rather of small benefits or no effect.

Reduction in saturated fat intake for cardiovascular disease

BACKGROUND

Reducing saturated fat reduces serum cholesterol, but effects on other intermediate outcomes may be less clear. Additionally, it is unclear whether the energy from saturated fats eliminated from the diet are more helpfully replaced by polyunsaturated fats, monounsaturated fats, carbohydrate or protein.

OBJECTIVES

To assess the effect of reducing saturated fat intake and replacing it with carbohydrate (CHO), polyunsaturated (PUFA), monounsaturated fat (MUFA) and/or protein on mortality and cardiovascular morbidity, using all available randomised clinical trials.

SEARCH METHODS

We updated our searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid) and Embase (Ovid) on 15 October 2019, and searched Clinicaltrials.gov and WHO International Clinical Trials Registry Platform (ICTRP) on 17 October 2019.

SELECTION CRITERIA

Included trials fulfilled the following criteria: 1) randomised; 2) intention to reduce saturated fat intake OR intention to alter dietary fats and achieving a reduction in saturated fat; 3) compared with higher saturated fat intake or usual diet; 4) not multifactorial; 5) in adult humans with or without cardiovascular disease (but not acutely ill, pregnant or breastfeeding); 6) intervention duration at least 24 months; 7) mortality or cardiovascular morbidity data available.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed inclusion, extracted study data and assessed risk of bias. We performed random-effects meta-analyses, meta-regression, subgrouping, sensitivity analyses, funnel plots and GRADE assessment.

MAIN RESULTS

We included 15 randomised controlled trials (RCTs) (16 comparisons, ~59,000 participants), that used a variety of interventions from providing all food to advice on reducing saturated fat. The included long-term trials suggested that reducing dietary saturated fat reduced the risk of combined cardiovascular events by 21% (risk ratio (RR) 0.79; 95% confidence interval (CI) 0.66 to 0.93, 11 trials, 53,300 participants of whom 8% had a cardiovascular event, I² = 65%, GRADE moderate-quality evidence). Meta-regression suggested that greater reductions in saturated fat (reflected in greater reductions in serum cholesterol) resulted in greater reductions in risk of CVD events, explaining most heterogeneity between trials. The number needed to treat for an additional beneficial outcome (NNTB) was 56 in primary prevention trials, so 56 people need to reduce their saturated fat intake for ~four years for one person to avoid experiencing a CVD event. In secondary prevention trials, the NNTB was 32. Subgrouping did not suggest significant differences between replacement of saturated fat calories with polyunsaturated fat or carbohydrate, and data on replacement with monounsaturated fat and protein was very limited. We found little or no effect of reducing saturated fat on all-cause mortality (RR 0.96; 95% CI 0.90 to 1.03; 11 trials, 55,858 participants) or cardiovascular mortality (RR 0.95; 95% CI 0.80 to 1.12, 10 trials, 53,421 participants), both with GRADE moderate-quality evidence. There was little or no effect of reducing saturated fats on non-fatal myocardial infarction (RR 0.97, 95% CI 0.87 to 1.07) or CHD mortality (RR 0.97, 95% CI 0.82 to 1.16, both low-quality evidence), but effects on total (fatal or non-fatal) myocardial infarction, stroke and CHD events (fatal or non-fatal) were all unclear as the evidence was of very low quality. There was little or no effect on cancer mortality, cancer diagnoses, diabetes diagnosis, HDL cholesterol, serum triglycerides or blood pressure, and small reductions in weight, serum total cholesterol, LDL cholesterol and BMI. There was no evidence of harmful effects of reducing saturated fat intakes.

AUTHORS' CONCLUSIONS

The findings of this updated review suggest that reducing saturated fat intake for at least two years causes a potentially important reduction in combined cardiovascular events. Replacing the energy from saturated fat with polyunsaturated fat or carbohydrate appear to be useful strategies, while effects of replacement with monounsaturated fat are unclear. The reduction in combined cardiovascular events resulting from reducing saturated fat did not alter by study duration, sex or baseline level of cardiovascular risk, but greater reduction in saturated fat caused greater reductions in cardiovascular events.

Association of Diet Quality and Physical Activity on Obesity-Related Cancer Risk and Mortality in Black Women: Results from the Women's Health Initiative

BACKGROUND

Obesity-related cancers disproportionately affect the Black community. We assessed the relationship between diet quality, physical activity, and their combined effect on obesity-related cancer risk and mortality in Black women enrolled in the Women's Health Initiative (WHI).

METHODS

Data from postmenopausal (50-79 years of age) Black women enrolled in WHI clinical trials or observational studies were analyzed. Exposure variables included baseline physical activity [metabolic equivalent of tasks (MET)-hours/week of moderate-to-vigorous physical activity (MVPA)] and diet quality [Healthy Eating Index (HEI)-2015]. Outcomes included adjudicated obesity-related cancer incidence and mortality. Cox proportional hazard models were used to evaluate the association between MVPA and HEI-2015 and obesity-related cancer risk and mortality.

RESULTS

The analytical sample included 9,886 Black women, with a baseline mean body mass index (BMI) of 31.1 kg/m² (SD = 6.8); mean HEI-2015 score of 63.2 (SD = 11.0, possible range 0 to 100); and mean MVPA of 5.0 (SD = 9.4) MET-hours/week. Over an average of 13 years of follow-up, 950 (9.6%) obesity-related cancer cases were observed, with 313 (32.9%) resulting in death. Physical activity [HR, 1.05; 95% confidence interval (CI), 0.86-1.30], diet quality (HR, 0.99; 95% CI, 0.92-1.08), and their combination (HR, 1.05; 95% CI, 0.85-1.29) were not associated with risk for any or site-specific obesity-related cancers. Similarly, these health behaviors had no association with mortality.

CONCLUSIONS

Diet quality, physical activity and their combined effect, as measured, were not associated with obesity-related cancer risk and mortality in Black women enrolled in WHI.

IMPACT

Other social, behavioral, and biological factors may contribute to racial disparities observed in obesity-related cancer rates.

Effects of total fat intake on body weight

BACKGROUND

In order to prevent overweight and obesity in the general population we need to understand the relationship between the proportion of energy from fat and resulting weight and body fatness in the general population.

OBJECTIVES

To assess the effects of proportion of energy intake from fat on measures of weight and body fatness (including obesity, waist circumference and body mass index) in people not aiming to lose weight, using all appropriate randomised controlled trials (RCTs) and cohort studies in adults, children and young people

SEARCH METHODS

We searched CENTRAL to March 2014 and MEDLINE, EMBASE and CINAHL to November 2014. We did not limit the search by language. We also checked the references of relevant reviews.

SELECTION CRITERIA

Trials fulfilled the following criteria: 1) randomised intervention trial, 2) included children (aged ≥ 24 months), young people or adults, 3) randomised to a lower fat versus usual or moderate fat diet, without the intention to reduce weight in any participants, 4) not multifactorial and 5) assessed a measure of weight or body fatness after at least six months. We also included cohort studies in children, young people and adults that assessed the proportion of energy from fat at baseline and assessed the relationship with body weight or fatness after at least one year. We duplicated inclusion decisions and resolved disagreement by discussion or referral to a third party.

DATA COLLECTION AND ANALYSIS

We extracted data on the population, intervention, control and outcome measures in duplicate. We extracted measures of weight and body fatness independently in duplicate at all available time points. We performed random-effects meta-analyses, meta-regression, subgrouping, sensitivity and funnel plot analyses.

MAIN RESULTS

We included 32 RCTs (approximately 54,000 participants) and 30 sets of analyses of 25 cohorts. There is consistent evidence from RCTs in adults of a small weight-reducing effect of eating a smaller proportion of energy from fat; this was seen in almost all included studies and was highly resistant to sensitivity analyses. The effect of eating less fat (compared with usual diet) is a mean weight reduction of 1.5 kg (95% confidence interval (CI) -2.0 to -1.1 kg), but greater weight loss results from greater fat reductions. The size of the effect on weight does not alter over time and is mirrored by reductions in body mass index (BMI) (-0.5 kg/m(2), 95% CI -0.7 to -0.3) and waist circumference (-0.3 cm, 95% CI -0.6 to -0.02). Included cohort studies in children and adults most often do not suggest any relationship between total fat intake and later measures of weight, body fatness or change in body fatness. However, there was a suggestion that lower fat intake was associated with smaller increases in weight in middle-aged but not elderly adults, and in change in BMI in the highest validity child cohort.

AUTHORS' CONCLUSIONS

Trials where participants were randomised to a lower fat intake versus usual or moderate fat intake, but with no intention to reduce weight, showed a consistent, stable but small effect of low fat intake on body fatness: slightly lower weight, BMI and waist circumference compared with controls. Greater fat reduction and lower baseline fat intake were both associated with greater reductions in weight. This effect of reducing total fat was not consistently reflected in cohort studies assessing the relationship between total fat intake and later measures of body fatness or change in body fatness in studies of children, young people or adults.

Reduction in saturated fat intake for cardiovascular disease

BACKGROUND

Reducing saturated fat reduces serum cholesterol, but effects on other intermediate outcomes may be less clear. Additionally it is unclear whether the energy from saturated fats that are lost in the diet are more helpfully replaced by polyunsaturated fats, monounsaturated fats, carbohydrate or protein. This review is part of a series split from and updating an overarching review.

OBJECTIVES

To assess the effect of reducing saturated fat intake and replacing it with carbohydrate (CHO), polyunsaturated (PUFA) or monounsaturated fat (MUFA) and/or protein on mortality and cardiovascular morbidity, using all available randomised clinical trials.

SEARCH METHODS

We updated our searches of the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid) and EMBASE (Ovid) on 5 March 2014. We also checked references of included studies and reviews.

SELECTION CRITERIA

Trials fulfilled the following criteria: 1) randomised with appropriate control group; 2) intention to reduce saturated fat intake OR intention to alter dietary fats and achieving a reduction in saturated fat; 3) not multifactorial; 4) adult humans with or without cardiovascular disease (but not acutely ill, pregnant or breastfeeding); 5) intervention at least 24 months; 6) mortality or cardiovascular morbidity data available.

DATA COLLECTION AND ANALYSIS

Two review authors working independently extracted participant numbers experiencing health outcomes in each arm, and we performed random-effects meta-analyses, meta-regression, subgrouping, sensitivity analyses and funnel plots.

MAIN RESULTS

We include 15 randomised controlled trials (RCTs) (17 comparisons, ˜59,000 participants), which used a variety of interventions from providing all food to advice on how to reduce saturated fat. The included long-term trials suggested that reducing dietary saturated fat reduced the risk of cardiovascular events by 17% (risk ratio (RR) 0.83; 95% confidence interval (CI) 0.72 to 0.96, 13 comparisons, 53,300 participants of whom 8% had a cardiovascular event, I² 65%, GRADE moderate quality of evidence), but effects on all-cause mortality (RR 0.97; 95% CI 0.90 to 1.05; 12 trials, 55,858 participants) and cardiovascular mortality (RR 0.95; 95% CI 0.80 to 1.12, 12 trials, 53,421 participants) were less clear (both GRADE moderate quality of evidence). There was some evidence that reducing saturated fats reduced the risk of myocardial infarction (fatal and non-fatal, RR 0.90; 95% CI 0.80 to 1.01; 11 trials, 53,167 participants), but evidence for non-fatal myocardial infarction (RR 0.95; 95% CI 0.80 to 1.13; 9 trials, 52,834 participants) was unclear and there were no clear effects on stroke (any stroke, RR 1.00; 95% CI 0.89 to 1.12; 8 trials, 50,952 participants). These relationships did not alter with sensitivity analysis. Subgrouping suggested that the reduction in cardiovascular events was seen in studies that primarily replaced saturated fat calories with polyunsaturated fat, and no effects were seen in studies replacing saturated fat with carbohydrate or protein, but effects in studies replacing with monounsaturated fats were unclear (as we located only one small trial). Subgrouping and meta-regression suggested that the degree of reduction in cardiovascular events was related to the degree of reduction of serum total cholesterol, and there were suggestions of greater protection with greater saturated fat reduction or greater increase in polyunsaturated and monounsaturated fats. There was no evidence of harmful effects of reducing saturated fat intakes on cancer mortality, cancer diagnoses or blood pressure, while there was some evidence of improvements in weight and BMI.

AUTHORS' CONCLUSIONS

The findings of this updated review are suggestive of a small but potentially important reduction in cardiovascular risk on reduction of saturated fat intake. Replacing the energy from saturated fat with polyunsaturated fat appears to be a useful strategy, and replacement with carbohydrate appears less useful, but effects of replacement with monounsaturated fat were unclear due to inclusion of only one small trial. This effect did not appear to alter by study duration, sex or baseline level of cardiovascular risk. Lifestyle advice to all those at risk of cardiovascular disease and to lower risk population groups should continue to include permanent reduction of dietary saturated fat and partial replacement by unsaturated fats. The ideal type of unsaturated fat is unclear.

Dietary advice for reducing cardiovascular risk

BACKGROUND

Changes in population diet are likely to reduce cardiovascular disease and cancer, but the effect of dietary advice is uncertain. This review is an update of a previous review published in 2007.

OBJECTIVES

To assess the effects of providing dietary advice to achieve sustained dietary changes or improved cardiovascular risk profile among healthy adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials, the Database of Abstracts of Reviews of Effects (DARE) and the HTA database on The Cochrane Library (Issue 4, 2010). We searched MEDLINE (Ovid) (1950 to week 2 October 2010) and EMBASE (Ovid) (1980 to Week 42 2010). Additional searches were done on CAB Health (1972 to December 1999), CVRCT registry (2000), CCT (2000) and SIGLE (1980 to 2000). Dissertation abstracts and reference lists of articles were checked and researchers were contacted.

SELECTION CRITERIA

Randomised studies with no more than 20% loss to follow-up, lasting at least three months and involving healthy adults comparing dietary advice with no advice or minimal advice. Trials involving children, trials to reduce weight or those involving supplementation were excluded.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. Study authors were contacted for additional information.

MAIN RESULTS

Forty-four trials with 52 intervention arms (comparisons) comparing dietary advice with no advice were included in the review; 18,175 participants or clusters were randomised. Twenty-nine of the 44 included trials were conducted in the USA. Dietary advice reduced total serum cholesterol by 0.15 mmol/L (95% CI 0.06 to 0.23) and LDL cholesterol by 0.16 mmol/L (95% CI 0.08 to 0.24) after 3 to 24 months. Mean HDL cholesterol levels and triglyceride levels were unchanged. Dietary advice reduced blood pressure by 2.61 mm Hg systolic (95% CI 1.31 to 3.91) and 1.45 mm Hg diastolic (95% CI 0.68 to 2.22) and 24-hour urinary sodium excretion by 40.9 mmol (95% CI 25.3 to 56.5) after 3 to 36 months but there was heterogeneity between trials for the latter outcome. Three trials reported plasma antioxidants, where small increases were seen in lutein and β-cryptoxanthin, but there was heterogeneity in the trial effects. Self-reported dietary intake may be subject to reporting bias, and there was significant heterogeneity in all the following analyses. Compared to no advice, dietary advice increased fruit and vegetable intake by 1.18 servings/day (95% CI 0.65 to 1.71). Dietary fibre intake increased with advice by 6.5 g/day (95% CI 2.2 to 10.82), while total dietary fat as a percentage of total energy intake fell by 4.48% (95% CI 2.47 to 6.48) with dietary advice, and saturated fat intake fell by 2.39% (95% CI 1.4 to 3.37).Two trials analysed incident cardiovascular disease (CVD) events (TOHP I/II). Follow-up was 77% complete at 10 to 15 years after the end of the intervention period and estimates of event rates lacked precision but suggested that sodium restriction advice probably led to a reduction in cardiovascular events (combined fatal plus non-fatal events) plus revascularisation (TOHP I hazards ratio (HR) 0.59, 95% CI 0.33 to 1.08; TOHP II HR 0.81, 95% CI 0.59 to 1.12).

AUTHORS' CONCLUSIONS

Dietary advice appears to be effective in bringing about modest beneficial changes in diet and cardiovascular risk factors over approximately 12 months, but longer-term effects are not known.

Dietary advice for reducing cardiovascular risk

BACKGROUND

Changes in population diet are likely to reduce cardiovascular disease and cancer, but the effect of dietary advice is uncertain. This review is an update of a previous review published in 2007.

OBJECTIVES

To assess the effects of providing dietary advice to achieve sustained dietary changes or improved cardiovascular risk profile among healthy adults.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials, the Database of Abstracts of Reviews of Effects (DARE) and the HTA database on The Cochrane Library (Issue 4, 2010). We searched MEDLINE (Ovid) (1950 to week 2 October 2010) and EMBASE (Ovid) (1980 to Week 42 2010). Additional searches were done on CAB Health (1972 to December 1999), CVRCT registry (2000), CCT (2000) and SIGLE (1980 to 2000). Dissertation abstracts and reference lists of articles were checked and researchers were contacted.

SELECTION CRITERIA

Randomised studies with no more than 20% loss to follow-up, lasting at least three months and involving healthy adults comparing dietary advice with no advice or minimal advice. Trials involving children, trials to reduce weight or those involving supplementation were excluded.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. Study authors were contacted for additional information.

MAIN RESULTS

Forty-four trials with 52 intervention arms (comparisons) comparing dietary advice with no advice were included in the review; 18,175 participants or clusters were randomised. Twenty-nine of the 44 included trials were conducted in the USA. Dietary advice reduced total serum cholesterol by 0.15 mmol/L (95% CI 0.06 to 0.23) and LDL cholesterol by 0.16 mmol/L (95% CI 0.08 to 0.24) after 3 to 24 months. Mean HDL cholesterol levels and triglyceride levels were unchanged. Dietary advice reduced blood pressure by 2.61 mm Hg systolic (95% CI 1.31 to 3.91) and 1.45 mm Hg diastolic (95% CI 0.68 to 2.22) and 24-hour urinary sodium excretion by 40.9 mmol (95% CI 25.3 to 56.5) after 3 to 36 months but there was heterogeneity between trials for the latter outcome. Three trials reported plasma antioxidants, where small increases were seen in lutein and β-cryptoxanthin, but there was heterogeneity in the trial effects. Self-reported dietary intake may be subject to reporting bias, and there was significant heterogeneity in all the following analyses. Compared to no advice, dietary advice increased fruit and vegetable intake by 1.18 servings/day (95% CI 0.65 to 1.71). Dietary fibre intake increased with advice by 6.5 g/day (95% CI 2.2 to 10.82), while total dietary fat as a percentage of total energy intake fell by 4.48% (95% CI 2.47 to 6.48) with dietary advice, and saturated fat intake fell by 2.39% (95% CI 1.4 to 3.37).Two trials analysed incident cardiovascular disease (CVD) events (TOHP I/II). Follow-up was 77% complete at 10 to 15 years after the end of the intervention period and estimates of event rates lacked precision but suggested that sodium restriction advice probably led to a reduction in cardiovascular events (combined fatal plus non-fatal events) plus revascularisation (TOHP I hazards ratio (HR) 0.59, 95% CI 0.33 to 1.08; TOHP II HR 0.81, 95% CI 0.59 to 1.12).

AUTHORS' CONCLUSIONS

Dietary advice appears to be effective in bringing about modest beneficial changes in diet and cardiovascular risk factors over approximately 12 months, but longer-term effects are not known.

A comprehensive cardiovascular disease lifestyle treatment controlled trial among high-risk African Americans

Background

The purpose of this study was to assess the effects of a comprehensive lifestyle intervention on modifiable cardiovascular risk factors among high-risk African Americans.

Methods

The study included a randomized treatment/controlled intervention trial among 136 African Americans residing in Atlanta, GA who were overweight and had elevated blood pressure. The treatment group was exposed to 3-months of a multi-component intervention and the control to an abbreviated 6-week intervention after the completion of the treatment group’s intervention. The main outcomes included mean systolic blood pressure (SBP), mean diastolic blood pressure (DBP), mean waist circumference, mean body mass index (BMI), mean number of times exercise per week, mean number of servings of fruits and vegetables per day, and mean level of daily stress. Data were collected at baseline and at 6-month follow-up. Separate linear regressions were used with an established significance level of p < 0.05.

Results

Results revealed significant net improvement in treatment group when compared to controls in waist circumference, BMI, times weekly exercise, servings of fruit and vegetables per day (p < 0.001, 0.04, 0.02, 0.002, respectively). Diastolic blood pressure also significantly improved within the treatment group for overall hypertensives from baseline to 6-month follow-up (90.9 mmHg to 83.1 mmHg, p = 0.002).

Conclusion

These results show that a comprehensive lifestyle intervention can improve cardiovascular risk factor profile among high risk African Americans. Caregivers should encourage patients to participate in such programs and public health policymakers should allocate resources to community based health oriented organizations to implement comprehensive lifestyle program.

Ethnic Differences in Correlates of Obesity between Latin-American and Black Women

OBJECTIVE

To date, no studies have examined dietary intake, physical activity, and body image in a large sample of Latin-American and black women recruited using the same methodology. The aim of this study was to examine three potential correlates of obesity (dietary intake, body image, and physical activity) in a large sample of Latin-American and black women across the weight spectrum.

RESEARCH METHODS AND PROCEDURES

Participants were black (n = 271) and Latin-American (n = 234) adult women who completed a 24-hour dietary recall and physical activity and body image questionnaires.

RESULTS

After controlling for BMI, education, marital status, and number of children, black women consumed more kilocalories, dietary fat (grams), and percent calories from fat than Latin-American women, who consumed more carbohydrates (grams) and dietary fiber (total and soluble). Black women engaged in more sedentary behavior than Latin-American women. Although Latin-American women weighed less than black women, they perceived their current body image as heavier and reported greater body image dissatisfaction than black women. Black women also reported a higher ideal body image than Latin-American women.

DISCUSSION

The combined effect of a diet higher in calories and fat, increased sedentary behavior, and more accepting body image could account for higher rates of obesity among black women. Future studies should further explore cultural attitudes and beliefs related to weight that could provide information for the development of culturally competent obesity interventions.

Reduced or modified dietary fat for preventing cardiovascular disease

BACKGROUND

Reduction and modification of dietary fats have differing effects on cardiovascular risk factors (such as serum cholesterol), but their effects on important health outcomes are less clear.

OBJECTIVES

To assess the effect of reduction and/or modification of dietary fats on mortality, cardiovascular mortality, cardiovascular morbidity and individual outcomes including myocardial infarction, stroke and cancer diagnoses in randomised clinical trials of at least 6 months duration.

SEARCH METHODS

For this review update, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE, were searched through to June 2010. References of Included studies and reviews were also checked.

SELECTION CRITERIA

Trials fulfilled the following criteria: 1) randomised with appropriate control group, 2) intention to reduce or modify fat or cholesterol intake (excluding exclusively omega-3 fat interventions), 3) not multi factorial, 4) adult humans with or without cardiovascular disease, 5) intervention at least six months, 6) mortality or cardiovascular morbidity data available.

DATA COLLECTION AND ANALYSIS

Participant numbers experiencing health outcomes in each arm were extracted independently in duplicate and random effects meta-analyses, meta-regression, sub-grouping, sensitivity analyses and funnel plots were performed.

MAIN RESULTS

This updated review suggested that reducing saturated fat by reducing and/or modifying dietary fat reduced the risk of cardiovascular events by 14% (RR 0.86, 95% CI 0.77 to 0.96, 24 comparisons, 65,508 participants of whom 7% had a cardiovascular event, I(2) 50%). Subgrouping suggested that this reduction in cardiovascular events was seen in studies of fat modification (not reduction - which related directly to the degree of effect on serum total and LDL cholesterol and triglycerides), of at least two years duration and in studies of men (not of women). There were no clear effects of dietary fat changes on total mortality (RR 0.98, 95% CI 0.93 to 1.04, 71,790 participants) or cardiovascular mortality (RR 0.94, 95% CI 0.85 to 1.04, 65,978 participants). This did not alter with sub-grouping or sensitivity analysis.Few studies compared reduced with modified fat diets, so direct comparison was not possible.

AUTHORS' CONCLUSIONS

The findings are suggestive of a small but potentially important reduction in cardiovascular risk on modification of dietary fat, but not reduction of total fat, in longer trials. Lifestyle advice to all those at risk of cardiovascular disease and to lower risk population groups, should continue to include permanent reduction of dietary saturated fat and partial replacement by unsaturates. The ideal type of unsaturated fat is unclear.

A diet high in low-fat dairy products lowers diabetes risk in postmenopausal women

Some previous studies have suggested that consuming dairy products, particularly the low-fat variety, lowers the incidence of type 2 diabetes. However, no study to our knowledge has focused on an ethnically diverse group of postmenopausal women, a population with a high risk of this disease. We conducted a prospective cohort study of 82,076 postmenopausal women enrolled in the Women's Health Initiative Observational Study who did not report diabetes at enrollment. Total, low-fat, and high-fat dairy product and yogurt intakes were estimated from FFQ at baseline and 3 y of follow-up. Treated diabetes incidence was ascertained from annual follow-up questionnaires. During 8 y of follow-up, 3946 cases of incident treated diabetes were reported (annual incidence, 0.73%; cumulative incidence, 4.8%). After multivariable adjustment, low-fat dairy product consumption was inversely associated with the risk of type 2 diabetes. RR was roughly 0.5-0.6 in the upper quintiles compared with the lowest quintile (median servings/d, 2.8 in the 5th quintile and 1.5 in the 4th quintile vs. 0.05 in the first quintile; P-trend < 0.001). The inverse relationship was more pronounced in women with a higher BMI. High yogurt consumption was associated with a significant decrease in diabetes risk, whereas there was no relationship between high-fat dairy product consumption and diabetes risk. A diet high in low-fat dairy products is associated with lower diabetes risk in postmenopausal women, particularly those who are obese.

Reduced or modified dietary fat for preventing cardiovascular disease

BACKGROUND

Reduction and modification of dietary fats have differing effects on cardiovascular risk factors (such as serum cholesterol), but their effects on important health outcomes are less clear.

OBJECTIVES

To assess the effect of reduction and/or modification of dietary fats on mortality, cardiovascular mortality, cardiovascular morbidity and individual outcomes including myocardial infarction, stroke and cancer diagnoses in randomised clinical trials of at least 6 months duration.

SEARCH STRATEGY

For this review update, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE, were searched through to June 2010. References of Included studies and reviews were also checked.

SELECTION CRITERIA

Trials fulfilled the following criteria: 1) randomised with appropriate control group, 2) intention to reduce or modify fat or cholesterol intake (excluding exclusively omega-3 fat interventions), 3) not multi factorial, 4) adult humans with or without cardiovascular disease, 5) intervention at least six months, 6) mortality or cardiovascular morbidity data available.

DATA COLLECTION AND ANALYSIS

Participant numbers experiencing health outcomes in each arm were extracted independently in duplicate and random effects meta-analyses, meta-regression, sub-grouping, sensitivity analyses and funnel plots were performed.

MAIN RESULTS

This updated review suggested that reducing saturated fat by reducing and/or modifying dietary fat reduced the risk of cardiovascular events by 14% (RR 0.86, 95% CI 0.77 to 0.96, 24 comparisons, 65,508 participants of whom 7% had a cardiovascular event, I(2) 50%). Subgrouping suggested that this reduction in cardiovascular events was seen in studies of fat modification (not reduction - which related directly to the degree of effect on serum total and LDL cholesterol and triglycerides), of at least two years duration and in studies of men (not of women). There were no clear effects of dietary fat changes on total mortality (RR 0.98, 95% CI 0.93 to 1.04, 71,790 participants) or cardiovascular mortality (RR 0.94, 95% CI 0.85 to 1.04, 65,978 participants). This did not alter with sub-grouping or sensitivity analysis.Few studies compared reduced with modified fat diets, so direct comparison was not possible.

AUTHORS' CONCLUSIONS

The findings are suggestive of a small but potentially important reduction in cardiovascular risk on modification of dietary fat, but not reduction of total fat, in longer trials. Lifestyle advice to all those at risk of cardiovascular disease and to lower risk population groups, should continue to include permanent reduction of dietary saturated fat and partial replacement by unsaturates. The ideal type of unsaturated fat is unclear.

Low-fat diets for acquired hypercholesterolaemia

BACKGROUND

Hypercholesterolaemia, characterised by raised blood cholesterol levels, is not a disease itself but a metabolic derangement that often contributes to many diseases, notably cardiovascular disease. In most cases, elevated cholesterol levels are associated with high-fat diet, especially saturated fat, coupled with an inactive lifestyle. Less commonly, raised cholesterol may be related to an inherited disorder, familial hypercholesterolaemia. This systematic review is only concerned with acquired hypercholesterolaemia.

OBJECTIVES

To assess the effects of low-fat diets for acquired hypercholesterolaemia and to investigate the incidence of adverse effects from low-fat dietary interventions. We planned to compare the relative effectiveness of low-fat diets with calorie-restricted diets for acquired hypercholesterolaemia. We also wanted to look into the relative effectiveness of low-fat diets and pharmacological interventions for acquired hypercholesterolaemia.

SEARCH STRATEGY

Studies were obtained from computerised searches of The Cochrane Library, MEDLINE, EMBASE and databases of ongoing trials. Date of last search was February 2010.

SELECTION CRITERIA

Otherwise healthy adults (equal to or greater than 18 years) with acquired (not familial) hypercholesterolaemia. We defined hypercholesterolaemia as either total cholesterol greater than 5.2 mmol/L, LDL-cholesterol greater than 3.0 mmol/L, HDL-cholesterol less than 1.0 mmol/L or a combination thereof, although investigators' definitions were also accepted. We wanted to include any low-fat dietary intervention, like low-fat and low-saturated fat diets, intended to lower serum total and LDL-cholesterol or to raise HDL-cholesterol. A low-fat diet was considered as a fat calorie intake less than 20% of the total calories. The minimum duration of the intervention had to be six months. We excluded studies in unhealthy people.

DATA COLLECTION AND ANALYSIS

Two authors were planned to independently assess risk of bias and extract data.

MAIN RESULTS

No study met our inclusion criteria.

AUTHORS' CONCLUSIONS

Well designed, adequately powered randomised controlled trials investigating patient-relevant outcomes of low-fat diets for otherwise healthy people with hypercholesterolaemia are required.

The women's health initiative: lessons learned

The Women's Health Initiative (WHI) was initiated in 1992 as a major disease-prevention research program among postmenopausal women. The program includes a randomized controlled intervention trial involving 68,132 women and four distinct interventions: conjugated equine estrogens, alone or in combination with medroxyprogesterone acetate, for coronary heart disease prevention with breast cancer as an anticipated adverse effect; a low-fat eating pattern for breast and colorectal cancer prevention; and calcium and vitamin D supplementation for hip fracture prevention. Results from this multifaceted trial have made a substantial impact in clinical practice. A companion cohort study among 93,676 women serves as a source for new risk factor information and provides a comparative observational assessment of the clinical trial interventions. A specimen repository and quality-controlled outcome data for a range of diseases are among the resources that support the ongoing research program. WHI clinical trial contributions and challenges are reviewed and discussed.

Dietary advice for reducing cardiovascular risk

BACKGROUND

Changes in population diet are likely to reduce cardiovascular disease and cancer, but the effect of dietary advice is uncertain.

OBJECTIVES

To assess the effects of providing dietary advice to achieve sustained dietary changes or improved cardiovascular risk profile among healthy adults.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials, DARE and HTA databases on The Cochrane Library (Issue 4 2006), MEDLINE (1966 to December 2000, 2004 to November 2006) and EMBASE (1985 to December 2000, 2005 to November 2006). Additional searches were done on CAB Health (1972 to December 1999), CVRCT registry (2000), CCT (2000) and SIGLE (1980 to 2000). Dissertation abstracts and reference lists of articles were checked and researchers were contacted.

SELECTION CRITERIA

Randomised studies with no more than 20% loss to follow-up, lasting at least 3 months involving healthy adults comparing dietary advice with no advice or minimal advice. Trials involving children, trials to reduce weight or those involving supplementation were excluded.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information.

MAIN RESULTS

Thirty-eight trials with 46 intervention arms (comparisons) comparing dietary advice with no advice were included in the review. 17,871 participants/clusters were randomised. Twenty-six of the 38 included trials were conducted in the USA. Dietary advice reduced total serum cholesterol by 0.16 mmol/L (95% CI 0.06 to 0.25) and LDL cholesterol by 0.18 mmol/L (95% CI 0.1 to 0.27) after 3-24 months. Mean HDL cholesterol levels and triglyceride levels were unchanged. Dietary advice reduced blood pressure by 2.07 mmHg systolic (95% CI 0.95 to 3.19) and 1.15 mmHg diastolic (95% CI 0.48 to 1.85) and 24-hour urinary sodium excretion by 44.2 mmol (95% CI 33.6 to 54.7) after 3-36 months. Three trials reported plasma antioxidants where small increases were seen in lutein and beta-cryptoxanthin, but there was heterogeneity in the trial effects. Self-reported dietary intake may be subject to reporting bias, and there was significant heterogeneity in all the following analyses. Compared to no advice, dietary advice increased fruit and vegetable intake by 1.25 servings/day (95% CI 0.7 to 1.81). Dietary fibre intake increased with advice by 5.99 g/day (95% CI 1.12 to 10.86), while total dietary fat as a percentage of total energy intake fell by 4.49 % (95% CI 2.31 to 6.66) with dietary advice and saturated fat intake fell by 2.36 % (95% CI 1.32 to 3.39).

AUTHORS' CONCLUSIONS

Dietary advice appears to be effective in bringing about modest beneficial changes in diet and cardiovascular risk factors over approximately 10 months but longer term effects are not known.

Predictors of dietary change and maintenance in the Women's Health Initiative Dietary Modification Trial

OBJECTIVE

To identify predictors of dietary change to and maintenance of a low-fat eating pattern (<20% energy from fat, > or = 5 servings fruits/vegetables daily, and > or = 6 servings grains daily) among a cohort of postmenopausal women. Candidate predictors included intrapersonal, interpersonal, intervention program characteristics, and clinical center.

DESIGN

Longitudinal study within the Women's Health Initiative Dietary Modification Trial. Dietary change was evaluated after 1 year of participation in the Women's Health Initiative Dietary Modification Trial, and dietary maintenance after 3 years.

SUBJECTS

Postmenopausal women aged 50 to 79 years at baseline who were randomized to the intervention arm of the Women's Health Initiative Dietary Modification Trial (n=19,541).

STATISTICAL ANALYSIS

Univariate and multivariate linear regression analysis was performed and associations evaluated between candidate predictors and each of the three dietary goals: percent energy from fat, fruit/vegetable servings, and grain servings.

RESULTS

Year 1 (change) predictors of percent energy from fat (P<0.005) included being younger (beta=2.12; 70 to 79 years vs 50 to 59 years), more educated (beta=-.69; college vs high school), more optimistic (beta=-.07), attending more sessions (beta=-.69), and submitting more self-monitoring records (beta=-.74). At year 3 (maintenance), the predictors of percent energy from fat (P<0.005) included attending more sessions (beta=-.65) and submitting more self-monitoring scores (beta=-.71). The analytic model predicted 22% of the variance in fat intake at year 1 and 27% at year 3 (P<0.01).

CONCLUSIONS

The strongest predictors of dietary change and maintenance were attending intervention sessions and self-monitoring dietary intake. Novel was the finding that optimism predicted dietary change.

Fiber intakes and anthropometric measures are predictors of circulating hormone, triglyceride, and cholesterol concentrations in the women's health trial

The unhealthy eating patterns and obesity among women in the U.S. are indicated by changes in biomarkers, such as insulin, lipoproteins, and estradiol, that are risk factors for breast cancer and cardiovascular diseases. This article models the inter-relations among diet, serum insulin, estradiol, and sex hormone binding globulin (SHBG) concentrations, plasma LDL and HDL cholesterol, and net triglyceride concentrations, using the data at baseline and 12 mo on 379 and 615 postmenopausal women in the Control and Intervention groups, respectively, of the Women's Health Trial: Feasibility Study in Minority Populations. Subjects in the Intervention group received detailed advice over a period of 1 y for reducing fat intakes and increasing the consumption of whole grains and fruits and vegetables. The main findings were that there were significant differences between the Control and Intervention groups in the changes from baseline to 12 mo in LDL and HDL cholesterol and SHBG concentrations. Second, using a comprehensive random effects modeling framework, the ratio of fiber to energy intake was significantly associated (P < 0.05) with lower insulin and triglyceride levels, and with a higher HDL cholesterol concentration in the Intervention group. Third, the subjects' waist-to-hip ratio and BMI were significantly associated with insulin, SHBG, LDL and HDL cholesterol, and triglyceride concentrations. Fourth, insulin levels were significantly negatively associated with SHBG and HDL cholesterol, and positively associated with LDL cholesterol, triglyceride, and estradiol concentrations. Overall, weight loss, especially around the waist, and increased fiber intakes are likely to be beneficial for lipid, cholesterol, and hormone profiles of U.S. women.

Low-fat, high fruit and vegetable diets and weight loss do not affect biomarkers of cellular proliferation in Barrett esophagus

Risk factors for esophageal adenocarcinoma include obesity, high fat intake, and low consumption of fruits and vegetables. This trial tested whether an intervention to reduce these risk factors in patients with Barrett esophagus, a preneoplastic condition for esophageal adenocarcinoma, could reduce biomarkers of cellular proliferation and, by inference, the risk of neoplastic progression. Eighty-seven men and women with Barrett esophagus were randomized to an intensive dietary intervention or control group. At baseline, 18 and 36 months after intervention, biopsies were obtained at 2-cm intervals throughout the length of the Barrett segment. Ki67/DNA content flow cytometry was used to assess (a) % Ki67-positive proliferating diploid G(1) cells, (b) % total Ki67-positive proliferating cells, (c) presence of aneuploidy, and (d) presence of >6% of cells in the 4N (G(2)/tetraploid) fraction of the cell cycle. We also assessed re-epithelialization and length of the Barrett segment, reflux symptoms, and medication use. The intervention effects for energy, fat, fruits and vegetables, and weight were, respectively, -314 kcal, -12.2% energy, 1.8 servings/d, and -4.0 kg at 18 months (all P < 0.005) and were smaller but remained significant at 36 months. There were no significant effects of the intervention on any biomarker of cellular proliferation. The intervention effects +/- SE for mean %G(1) Ki67+ cells were 0.98 +/- 1.58 at 18 months and 1.79 +/- 1.31 at 36 months; the relative risks (95% confidence interval) for developing >6% of cells in 4N were 0.5 (0.1-2.6) at 18 months and 0.75 (0.2-3.1) at 36 months. A single control participant developed aneuploidy. There were no significant effects on re-epithelialization, segment length, or reflux medication use. We conclude that substantial dietary change has no short-term effects on biomarkers of cellular proliferation in Barrett esophagus or on clinical observations of the Barrrett segment.

Dietary advice for reducing cardiovascular risk

BACKGROUND

Changes in population diet are likely to reduce cardiovascular disease and cancer, but the effect of dietary advice is uncertain.

OBJECTIVES

To assess the effects of providing dietary advice to achieve sustained dietary changes or improved cardiovascular risk profile among healthy adults.

SEARCH STRATEGY

We searched the Cochrane Controlled Trials Register on The Cochrane Library (Issue 2 2000), MEDLINE (January 1966 to December 2000), EMBASE (January 1985 to December 2000), DARE (December 2000), CAB Health (December 1999), dissertation abstracts, and reference lists of articles. We contacted researchers in the field.

SELECTION CRITERIA

Randomised studies with no more than 20% loss to follow-up, lasting at least three months involving healthy adults comparing dietary advice with no advice or less intensive advice. Trials involving children, trials to reduce weight or those involving supplementation were excluded.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information.

MAIN RESULTS

Twenty-three trials with 29 intervention arms (comparisons) comparing dietary advice with no advice were included in the review. Dietary advice reduced total serum cholesterol by 0.13 mmol/l (95% CI 0.03 to 0.23) and LDL cholesterol by 0.13 mmol/l (95% CI 0.01 to 0.25) after 3-12 months. Mean HDL cholesterol levels were unchanged. Dietary advice reduced blood pressure by 2.10 mmHg systolic (95% CI 1.37 to 2.83) and 1.63 mmHg diastolic (95% CI 0.56 to 2.71) and 24-hour urinary sodium excretion by 44.2 mmol (95% CI 33.6 to 54.7) after 3-36 months. Plasma triglycerides, ss-carotene and red cell folate were each measured in one small study which suggested no significant effect. Self-reported dietary intake may be subject to reporting bias, and there was significant heterogeneity in all the following analyses. Compared to no advice, dietary advice increased fruit and vegetable intake by 1.24 servings/day (95% CI 0.43 to 2.05). Dietary fibre intake increased with advice by 7.22 g/day (95% CI 2.84 to 11.60), while total dietary fat as a percentage of total energy intake fell by 6.18 % (95% CI 4.00 to 8.36) with dietary advice and saturated fat intake fell by 3.28 % (95% CI 1.92 to 4.64).

AUTHORS' CONCLUSIONS

Dietary advice appears to be effective in bringing about modest beneficial changes in diet and cardiovascular risk factors over approximately 9 months but longer term effects are not known.

A combined breast health/weight loss intervention for Black women

BACKGROUND

Overall incidence of breast cancer is slightly lower, but mortality rates are higher, for Black women compared to White women. Higher body mass index (BMI), sedentary lifestyles, and lower compliance with recommended breast health behaviors may contribute to higher risk and mortality.

METHODS

A randomized pilot intervention trial was conducted to assess feasibility and efficacy of a combined breast health/weight loss intervention for 64 overweight or obese Black women, ages 35-65. The primary objectives were to determine whether a 20-week (twice weekly) intervention could decrease weight and dietary fat intake and increase physical activity and breast self-exam (BSE) proficiency.

RESULTS

The project was implemented in two cohorts and retention was high for both (96% and 89%, respectively). Both cohorts showed increased proficiency in BSE in the intervention versus the control group (2.4 vs. -0.4, P<0.05; 3.3 vs. -0.2, P<0.001, respectively), but only cohort 2 showed decreased percent body weight (4.0% decrease vs. 0.9% increase, P<0.01), increased physical activity frequency (2.4 vs. 0.1 times/week, P<0.05), and a trend for decreased dietary fat (-2.6% kcal vs. 0.0% kcal, P=0.07) in the intervention compared to the control group.

CONCLUSION

Few studies have documented weight loss among Black women, and no combined breast health/weight loss intervention has been conducted. This study documents the feasibility of recruiting, randomizing, and retaining women in a combined intervention and demonstrated weight loss and associated lifestyle changes.

Results of mujeres felices por ser saludables: a dietary/breast heafth randomized chnicail trial for latino women

BACKGROUND

Data are limited on the efficacy of health-focused interventions for young, low-acculturated Latino women. Because breast cancer is the most commonly diagnosed cancer and the most common cause of cancer mortality in this population, combined interventions that address both early detection and dietary patterns could help reduce both morbidity and mortality associated with breast cancer in this underserved population.

PURPOSE

Mujeres Felices por ser Saludables was randomized intervention study designed to assess the efficacy of an 8-month combined dietary and breast health intervention to reduce fat and increase fiber intake as well as to increase the frequency and proficiency of breast self-examination (BSE) and reduce anxiety related to BSE among Latinas.

METHODS

Blocked randomization in blocks of 6 was used to randomize 256 20- to 40-year-old Latinas to the intervention (n = 127) or control group (n = 129). The intervention group attended an 8-month multicomponent education program designed specifically for low-acculturated Latinas. The control group received mailed health education material on a schedule comparable to the intervention. A total of 195 women (76.2%) completed both the baseline and 8-month follow-up interviews.

RESULTS

The intervention and control groups were similar on baseline sociodemographic characteristics. At the 8-month follow up, the intervention group reported lower dietary fat (P < .001) and higher fiber intake (p = .06); a higher proportion reported practicing BSE at the recommended interval (p < .001) and showed improved BSE proficiency (p < .001) compared to the control group. BSE-related anxiety was low for both groups at baseline, and no difference in reduction was observed.

CONCLUSIONS

This project provides a successful model for achieving dietary change and improving breast health behavior in young, low-acculturated Latinas.

Behavioral variables and education are predictors of dietary change in the Women's Health Trial: Feasibility Study in Minority Populations

BACKGROUND

Reducing the intakes of fats and increasing consumption of fruits and vegetables are an important goal for improving population health. Analyzing the effects of nutrition education programs on subjects' dietary intakes incorporating factors such as habit persistence in diets, unhealthy eating habits, perceptions of health risks, participation motivation, and expectancies can yield useful insights.

METHODS

A Food Frequency Questionnaire (FFQ) was used to measure intakes at baseline, 6 and 12 months, by 318 and 548 postmenopausal women in, respectively, the Control and Intervention groups of the Women's Health Trial: Feasibility Study in Minority Populations (WHTFSMP). Information on background, behavioral, and anthropometric variables was collected. The Intervention group met in classes led by nutritionists. Dynamic random effects models were estimated for the two groups using the data at baseline, 6 and 12 months on the intakes of carbohydrate, saturated, monounsaturated, and polyunsaturated fats, fiber, beta-carotene, ascorbic acid, and calcium.

RESULTS

The nutrition education program lowered the intakes of fats while increasing fiber, beta-carotene, and ascorbic acid intakes especially in subjects scoring high on indices reflecting concerns about health, desirability of change, and participation motivation. In addition, subjects' education was a predictor of dietary intakes in the Intervention group.

CONCLUSIONS

Nutrition education can be an effective tool for improving diets, but behavioral characteristics deserve greater attention in helping to design the most effective approaches for various target groups.

Number of days, number of subjects, and sources of variation in longitudinal intervention or crossover feeding trials with multiple days of measurement

Dietary studies are often conducted as longitudinal intervention or crossover trials using multiple days of measurement on each subject during each of several measurement periods, and determining the required numbers of days and subjects is important in designing these studies. Linear mixed statistical models were used to derive equations for precision, statistical power and sample size (number of days and number of subjects) and to obtain estimates of between-subject, period-to-period, and day-to-day variation needed to apply the equations. Two cohorts of an on-going exercise intervention study, and a crossover study of Olestra, each with 14 d of measurement/subject per period, were used to obtain estimates of variability for energy and macronutrient intake. Numerical examples illustrate how the equations for calculating the number of days or number of subjects are applied in typical situations, and sample SAS code is given. It was found that between-subject, period-to-period, and day-to-day variation all contributed significantly to the variation in energy and macronutrient intake. The ratio of period-to-period and day-to-day standard deviations controls the trade-off between the number of days and the number of subjects, and this remained relatively stable across studies and energy and macronutrient intake variables. The greatest gains in precision were seen over the first few measurement days. Greater precision and fewer required days were noted in the study (Olestra) that exerted greater control over the subjects and diets during the feeding protocol.

Review of evaluation tools used to assess the impact of nutrition education on dietary intake and quality, weight management practices, and physical activity of low-income audiences

Nutrition education programs and social marketing campaigns frequently focus on low-income audiences with the goal of improving dietary intake and quality, weight management practices, and physical activity. The impact of nutrition education can be assessed by measuring change in relation to any or all of these broad variables. Unfortunately, little information is available concerning the reliability, validity, and sensitivity to change of measures used to assess these constructs with low-income audiences of adults and adolescents. This article reviews the literature and discusses the types of available measures that have been used and evaluated for the above audiences. It describes specific measures used to assess total diet, consumption of food groups from the Food Guide Pyramid, and behaviors related to weight management and physical activity. Overall, this review suggests that there is a critical need for additional development and evaluation of dietary quality measurement tools for low-income and minority audiences.

Mujeres felices por ser saludables: a breast cancer risk reduction program for Latino women

BACKGROUND

Breast cancer is the most commonly diagnosed cancer and the most common cause of cancer mortality among Latino women. Several behavioral factors such as early detection and dietary practices could help decrease morbidity and mortality associated with breast cancer in this population. Unfortunately, there are few data regarding the efficacy of health-related interventions for young Latino women.

METHODS

Mujeres Felices por ser Saludables is a randomized intervention project designed to assess breast cancer risk reduction behavior among Latino women ages 20-40 years. The primary objectives of the project were to determine whether an 8-month integrated dietary/breast health intervention could lead to a greater reduction in dietary fat, increase in dietary fiber, increase in the frequency and proficiency of breast self examination (BSE), and reduction in anxiety related to BSE compared to controls. Herein we describe the overall design of the project and present baseline characteristics of the 256 randomized women.

RESULTS

Our results suggest that the average daily intake of dietary fat (percentage of total energy) was slightly below 30% (percentage of total energy) among the women randomized. While over half of these women reported that they practice BSE, and few reported anxiety related to BSE, less than 27% of women were proficient in the recommended BSE technique.

CONCLUSIONS

There are few data on the dietary and breast health behaviors of young low-acculturated Latino women. This study documents the feasibility of recruiting, randomizing, and obtaining both baseline dietary and breast health data on this unique and underserved population.

Hip-Hop to Health Jr., an obesity prevention program for minority preschool children: baseline characteristics of participants

BACKGROUND

The prevalence of obesity in the United States is a significant public health problem. Many obesity-related risk factors are more prevalent in minority populations. Given the recalcitrant nature of weight loss interventions for adults, prevention of overweight and obesity has become a high priority. The present study reports baseline data from an obesity prevention intervention developed for minority preschool children.

METHODS

Hip-Hop to Health Jr. is a 5-year randomized controlled intervention that targets 3- to 5-year-old minority children enrolled in 24 Head Start programs. Our primary aim is to test the effect of the intervention on change in body mass index. Data were collected on sociodemographic, anthropometric, behavioral, and cognitive variables for the children and parents at baseline.

RESULTS

Participants included 416 black children, 337 black parents, 362 Latino children, and 309 Latino parents. Using body mass index for age and sex > or = the 95th percentile as the definition of overweight, 15% of the black children and 28% of the Latino children were overweight. More than 75% of the parents were either overweight or obese.

DISCUSSION

The development of interventions to effectively prevent or control obesity early in life is crucial. These data highlight the escalating problem of weight control in minority populations.

Effects of fat content on fat hedonics: cognition or taste?

Understanding and perhaps overriding preferences for fat is important, given the relationship between higher dietary fat consumption and poorer health. We have examined the roles of potential mechanisms for differences in fat preference: actual fat content and expected fat content. The subjects were women (n=192, ages=50-69) recruited to a study of low-fat dietary change. Subjects were randomized to one of the four cells: participants received either a high- or low-fat milkshake at baseline, and half of each group was told that their milkshake was low in fat and the other half high in fat. Women who received a high-fat milkshake consumed more grams than women who received a low-fat milkshake. Women who expected low-fat shakes reported liking them more than those who expected high-fat milkshakes. These data indicate that both physiology and cognition play a role in determining consumption of high- and low-fat foods.

Unhealthy eating habits, physical exercise and macronutrient intakes are predictors of anthropometric indicators in the Women's Health Trial: Feasibility Study in Minority Populations

The increasing prevalence of obesity in the USA, especially among minority populations, is a serious public health concern. This present study analysed repeated measurements at baseline and at 6 and 12 months on 351 women in the control group and 575 women in the intervention group of the Women's Health Trial: Feasibility Study in Minority Populations. Dynamic random effects models were estimated using the three repeated observations to explain the effects of energy and macronutrient intakes, physical exercise, unhealthy eating habits and socio-economic characteristics on the subjects' body weights and waist and hip circumferences. In both the control and intervention groups, physical exercise was negatively associated with body weight and with waist and hip circumferences, while an index of unhealthy eating habits was positively associated (P<0.05). The proportion of energy derived from carbohydrate and from saturated and monounsaturated fat were often significant predictors of body weight and of waist and hip circumferences in the two groups. The results indicated that nutrition education programmes for improving eating habits and increasing physical exercise can reduce obesity prevalence in the USA.

Selection and description of cancer clinical trials participants--science or happenstance?

BACKGROUND

The selection of clinical trials participants is a critical step in study design, because it affects the generalizability of recommendations made on the basis of trial results and public acceptance of medical research. The authors assessed the heterogeneity of subgroups in cancer treatment and prevention trials and the analysis of subgroups in the evaluation of trial outcomes.

METHODS

The authors reviewed published reports (1990-2000) of cancer prevention and treatment trials from 11 journals. They report here on all Phase III cancer treatment and prevention trials that had at least 100 participants and were conducted among adults in the United States. A structured abstract was developed and used to extract data from the 261 published reports. Descriptive summaries of the abstracted data provided the information included in this systematic review.

RESULTS

Age and gender of study participants were reported in more than 90% of these trials, whereas fewer than 30% of the trials reported race or ethnicity. Gender was reported as an explicit criterion for participant selection primarily in studies of gender specific malignancies. Race and ethnicity were reported as explicit selection criteria for participant selection for five of the prevention trials and for none of the cancer treatment trials. The 105 treatment trials that reported including both men and women had 42,355 participants, and 38.6% of those participants were women. The 26 prevention trials that reported including both men and women had 73,995 participants, and 34.7% of those participants were women. Fifty-seven treatment trials reported participant ethnic diversity: There were 45,815 participants, with 10.5% African-American participants and with less than 1% Hispanic, Asian, or Native American participants. Seventeen prevention trials reported participant ethnic diversity: There were 91,741 participants, with 5.5% African-American participants, 1.7% Hispanic participants, and less than 1% Asian or Native American participants.

CONCLUSIONS

Cancer treatment and prevention trial reports provide scant information about participant race and ethnicity. Such studies use participant selection criteria that do not define diverse subgroups, and few subgroup analyses are conducted. Improvements in the selection, reporting, and analysis of clinical trials participants are needed.

Oral hormone replacement therapy: factors that influence the estradiol concentrations achieved in a multiracial study population

The assumption that estradiol (E2) concentrations are reliably increased to therapeutic levels in postmenopausal women receiving hormone replacement therapy (HRT) has not been explicitly tested. Nor have factors that may modulate the E2 levels achieved been evaluated. The author examined E2 concentrations in a multiracial study population of 309 postmenopausal women treated with oral HRT and observed that 51.1% had achieved estradiol levels of at least 45 pg/ml (achievers). The odds of being an achiever were significantly elevated among non-Caucasian women by a HRT dose greater than 0.625 mg, current moderate drinking, and increasing duration of HRT use. The odds were significantly decreased by having a high school education or less and increasing time since last HRT dose. White postmenopausal women had significantly reduced odds of being an achiever, and both a dose of less than 0.625 mg and a dose equal to 0.625 mg significantly reduced the odds of being an achiever. Increasing body mass index and menopause duration were both associated with lower odds. This report demonstrates not only that women treated with HRTdo not all achieve therapeutic levels of estradiol but also that factors can be identified that modulate the E2 concentration achieved in response to HRT administration.

Measurement characteristics of 2 different self-monitoring tools used in a dietary intervention study

OBJECTIVE

To examine the measurement characteristics of 2 self-monitoring tools, a food diary and fat scan, used in the dietary intervention of the Women's Health Trial: Feasibility in Minority Populations study.

DESIGN

Comparison of fat intake reported on the self-monitoring tools to a criterion measure of fat intake, specifically the mean of a food frequency questionnaire and a 4-day food record. The main outcome measures were differences in fat grams and correlations between each of the self-monitoring tools and the criterion measure.

SUBJECTS/SETTING

Six-month postrandomization data from 313 women aged 50 to 79 years who participated in the intervention group of the Women's Health Trial: Feasibility in Minority Populations study.

RESULTS

Both self-monitoring tools underestimated fat intake compared to the criterion measure, the food diary by 9 g and the fat scan by 6 g. The self-monitoring instruments were better than chance at detecting a low-fat dietary pattern, however, and did not differ from each other in their ability to do so.

APPLICATIONS/CONCLUSIONS

The self-monitoring tools were modestly precise as measures of fat intake, but neither was sufficiently accurate to be reliable as a sole assessment of dietary adherence. Dietetics professionals are encouraged to assess the measurement properties of self-monitoring tools to use them appropriately in supporting dietary changes.

Reduced or modified dietary fat for preventing cardiovascular disease

BACKGROUND

Reduction or modification of dietary fat can improve total cholesterol levels, but may also have a variety of effects, both positive and negative, on other cardiovascular risk factors.

OBJECTIVES

The aim of this systematic review was to assess the effect of reduction or modification of dietary fats on total and cardiovascular mortality and cardiovascular morbidity over at least 6 months, using all available randomized clinical trials.

SEARCH STRATEGY

The Cochrane Library, MEDLINE, EMBASE, CAB Abstracts, CVRCT registry and related Cochrane Groups' trial registers were searched through spring 1998, SIGLE to January 1999. Trials known to experts in the field and biographies were included through May 1999.

SELECTION CRITERIA

Trials fulfilled the following criteria: 1) randomized with appropriate control group, 2) intention to reduce or modify fat or cholesterol intake (excluding exclusively omega-3 fat interventions), 3) not multi factorial, 4) healthy adult humans, 5) intervention at least six months, 6) mortality or cardiovascular morbidity data available. Inclusion decisions were duplicated, disagreement resolved by discussion or a third party.

DATA COLLECTION AND ANALYSIS

Rate data were extracted by two independent reviewers and meta-analysis performed using random effects methodology. Meta-regression and funnel plots were used.

MAIN RESULTS

Twenty seven studies were included (40 intervention arms, 30,901 person-years). There was no significant effect on total mortality (rate ratio 0.98, 95% CI 0.86 to 1.12), a trend towards protection form cardiovascular mortality (rate ratio 0.91, 95% CI 0.77 to 1.07), and significant protection from cardiovascular events (rate ratio 0.84, 95% CI 0.72 to 0.99). The latter became non-significant on sensitivity analysis. Trials where participants were involved for more than 2 years showed significant reductions in the rate of cardiovascular events and a suggestion of protection from total mortality. The degree of protection from cardiovascular events appeared similar in high and low risk groups, but was statistically significant only in the former.

REVIEWER'S CONCLUSIONS

The findings are suggestive of a small but potentially important reduction in cardiovascular risk in trials longer than two years. Lifestyle advice to all those at high risk of cardiovascular disease (especially where statins are unavailable or rationed), and to lower risk population groups, should continue to include permanent reduction of dietary saturated fat and partial replacement by unsaturates.

Dietary advice given by a dietitian versus other health professional or self-help resources to reduce blood cholesterol

BACKGROUND

The average level of blood cholesterol is an important determinant of the risk of coronary heart disease. Blood cholesterol can be reduced by dietary means. Although dietitians are trained to provide dietary advice, for practical reasons it is also given by other health professionals and occasionally through the use of self-help resources.

OBJECTIVES

To assess the effects of dietary advice given by a dietitian compared with another health professional, or the use of self-help resources, in reducing blood cholesterol in adults.

SEARCH STRATEGY

We searched The Cochrane Library (to Issue 2 1999), MEDLINE (1966 to January 1999), EMBASE (1980 to December 1998), Cinahl (1982 to December 1998), Human Nutrition (1991 to 1998), Science Citation Index, Social Sciences Citation Index, hand searched conference proceedings on nutrition and heart disease, and contacted experts in the field.

SELECTION CRITERIA

Randomised trials of dietary advice given by a dietitian compared with another health professional or self-help resources. The main outcome was difference in blood cholesterol between dietitian groups compared with other intervention groups.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed study quality.

MAIN RESULTS

Eleven studies with 12 comparisons were included, involving 704 people receiving advice from dietitians, 486 from other health professionals and 551 people using self-help leaflets. Four studies compared dietitian with doctor, seven with self-help resources, and one compared dietitian with nurse. Participants receiving advice from dietitians experienced a greater reduction in blood cholesterol than those receiving advice only from doctors (-0.25 mmol/L (95% CI -0.37, -0.12 mmol/L)). There was no statistically significant difference in change in blood cholesterol between dietitians and self-help resources (-0.10 mmol/L (95% CI -0.22, 0.03 mmol/L)). No statistically significant differences were detected for secondary outcome measures between any of the comparisons with the exception of dietitian versus nurse for HDLc, where the dietitian groups showed a greater reduction (-0.06 mmol/L (95% CI -0.11, -0.01)). No significant heterogeneity between the studies was detected.

REVIEWER'S CONCLUSIONS

Dietitians were better than doctors at lowering blood cholesterol in the short to medium term, but there was no evidence that they were better than self-help resources. The results should be interpreted with caution as the studies were not of good quality and the analysis was based on a limited number of trials. More evidence is required to assess whether change can be maintained in the longer term. There was no evidence that dietitians provided better outcomes than nurses.

Involving minority and underrepresented women in clinical trials: the National Centers of Excellence in Women's Health

Recent attention to reducing health disparities among population groups has focused on the need to include in clinical studies, especially clinical trials, participants who represent the diversity of the populations to which study results will be applied. While scientists generally applaud the goal of broadening the characteristics of participants in clinical trials, they are faced with multiple challenges as they seek to include historically underrepresented populations in their research. This article examines the historical and sociocultural context of participation by underrepresented groups, especially women and minorities, in clinical trials, identifies major barriers and challenges facing researchers, and suggests strategies for meeting these challenges. The article draws upon the experiences of the investigators affiliated with the National Centers of Excellence of Women's Health (CoEs).

Recruitment and retention of minority women in cancer screening, prevention, and treatment trials

Researchers are giving greater attention to the recruitment and retention of minority women in clinical studies because of their historical underrepresentation, despite their greater morbidity and mortality for many conditions. Using findings from four studies, this article examines documented barriers to the recruitment and retention of minority women to clinical cancer research and discusses effective recruitment strategies. Among the major barriers to recruitment were lack of awareness, lack of transportation, interference with work/family responsibilities, financial costs, negative side effects, and burdensome procedures. Effective recruitment strategies focused on using culturally targeted mass mailings and media presentations based on acquiring an understanding of the minority community. Recommendations are made for further study and implementation.

The prevalence and impact of 'atypical' days in 4-day food records

OBJECTIVE

To understand how days with atypical food intake affect estimates of usual nutrient intake from 4-day food records.

PARTICIPANTS/SETTING

Secondary analyses of 4-day food records (4DFRs) (n = 2,560) collected from 1,090 women, aged 50 to 79 years, who participated in the Women's Trial Feasibility Study in Minority Populations, a randomized dietary intervention trial.

DESIGN

Food records were classified as atypical if participants marked one or more day's food intake as "more than usual" or "less than usual." Total amounts and nutrient densities (percent of energy or grams per 1,000 kcal) were examined for all macronutrients, fiber, vitamin C, beta carotene, and calcium.

STATISTICAL ANALYSIS

Contingency tables were used to examine associations of demographic characteristics with the likelihood of completing a 4DFR with atypical intake days. Analysis of variance was used to test whether nutrient intake differed among records with and without atypical days. Student t tests were used to identify any differences in total energy and percent energy from fat among typical and atypical intake days.

RESULTS

Approximately 16% of records included at least 1 atypical day. Reporting less-than-usual intake was associated with younger age, higher income, and higher body mass index. Black women were less likely to report more-than-usual intake than whites and Hispanics. Records with less-than-usual intake had lower intakes of all nutrients analyzed except alcohol; however, there were no differences in nutrient densities. Records with more-than-usual intake had higher intakes of alcohol and all nutrients except beta carotene and vitamin C, with higher nutrient density measures of alcohol and decreased nutrient density measures of protein, vitamin C, and fiber.

CONCLUSIONS

Atypical intake days are common in 4DFRs and they have a large effect on mean total intakes of most nutrients.

APPLICATIONS

It is important for researchers to collect information on atypical intake days included in a 4-day food record. Strategies are needed to incorporate information on atypical intake days when analyzing and interpreting research results.

Individually randomized intervention trials for disease prevention and control

It is argued that randomized, controlled trials should fulfil a critical role in the identification of practical approaches to the prevention and control of chronic diseases. Because of the great public health potential of chemopreventive and behavioural approaches to chronic disease prevention there is need for a major interdisciplinary scientific effort aimed at intervention development. Because of the cost and duration of controlled trials to evaluate specific interventions there is a need for well-conducted feasibility, pilot and intermediate outcome trials, to inform and to justify corresponding full-scale trials having clinical disease outcomes. Compared to therapeutic trials, prevention trials need to have a greater emphasis on overall benefit versus risk assessment. Such trials need to be large enough, and of sufficient duration, to yield powerful tests of key hypotheses, and informative benefit versus risk summary statements. These requirements have a range of implications for intervention trial design, conduct, monitoring and reporting, which are reviewed and discussed. The clinical trial component of the ongoing Women's Health Initiative provides illustration throughout this discussion.

Differences in fat-related dietary patterns between black, Hispanic and White women: results from the Women's Health Trial Feasibility Study in Minority Populations

OBJECTIVE

This report examines how sources of fat and patterns of fat-related dietary habits differed between black, Hispanic and white women participating in a randomized trial of a low-fat diet intervention.

DESIGN

The intervention consisted of group sessions, which met weekly for 6 weeks, biweekly for 6 weeks and monthly for 9 months, and included didactic nutrition education and activities to provide motivation for sustained dietary change. Outcomes included total fat and fat from nine food groups from a food frequency questionnaire (FFQ), and a summary scale and five subscales that measure fat-related dietary habits.

SETTING/SUBJECTS

Data are from 1702 post-menopausal women, recruited from clinical centres in Atlanta, Birmingham and Miami, with dietary assessments at baseline and 6 months post-randomization.

RESULTS

Total fat intake was similar across race/ethnic groups at baseline, yet there were many differences in sources of fat and fat-related dietary habits. For example, blacks consumed less fat from dairy foods and more fat from meats than whites. Effects of the intervention on total fat intake or the summary fat-related dietary habits scale did not differ across race/ethnicity groups. There were, however, many differences in how the intervention affected sources of fat and fat-related dietary habits. For example, the intervention effect for added fats (e.g. butter and salad dressings) was -8.9 g for blacks and -12.0 g for whites (P<0.05). The intervention effect for adopting low-fat meat purchasing and preparation methods was larger for blacks than whites, and the intervention effect for replacing high-fat foods with fruits and vegetables was larger for Hispanics than whites.

CONCLUSIONS

This study demonstrates that, if properly designed, a single nutrition intervention programme can work well even in groups with culturally diverse dietary patterns.

The Oklahoma Postmenopausal Women's Health Study: recruitment and characteristics of American Indian, Asian, Black, Hispanic, and Caucasian women

Since 1994, the National Institutes of Health has required the inclusion of women and minorities in all of its sponsored clinical research. This study describes a workable recruitment strategy that embraces the National Institutes of Health requirement. We describe the recruitment pattern of the Oklahoma Postmenopausal Women's Study conducted in the general community of Oklahoma City and in surrounding areas that are both urban and rural. For the period 1994 through 1997, 491 postmenopausal women from all racial/ethnic groups in the community have participated in this study. Over 4 years of recruitment, the percentage of minority women in the study population has risen annually from 31% in 1994 to 81% in 1997. The overall percentage of minority women in the study population is currently 63.3%: American Indian, 21.8%; Asian, 3.7%; Black, 14.9%; Hispanic, 9.4%; White/American Indian Blend, 13.6%; and White, 36.7%. The recruitment approach described may be implemented in a variety of research settings. Specific recruitment approaches are described, as well as the distribution of sociodemographic and health behaviors across and within ethnic/racial groups.