Use of biological markers to validate self-reported dietary intake in a random sample of the European Prospective Investigation into Cancer United Kingdom Norfolk cohort

Three gram sodium intake is associated with longer event-free survival only in patients with advanced heart failure

BACKGROUND

There is limited evidence to support the recommendation that patients with heart failure (HF) restrict sodium intake. The purpose of this study was to compare differences in cardiac event-free survival between patients with sodium intake above and below 3 g.

METHODS

A total of 302 patients with HF (67% male, 62 ± 12 years, 54% New York Heart Association [NYHA] Class III/IV, ejection fraction 34 ± 14%) collected a 24-hour urine sodium (UNa) to indicate sodium intake. Patients were divided into 2 groups using a 3-g UNa cutpoint and stratified by NYHA Class (I/II vs. III/IV). Event-free survival for 12 months was determined by patient or family interviews and medical record review. Differences in cardiac event-free survival were determined by Kaplan-Meier survival curve with log-rank test and Cox hazard regression.

RESULTS

The Cox regression hazard ratio for 24-hour UNa ≥ 3 g in NYHA Class I/II was 0.44 (95% confidence interval [CI] = 0.20-0.97) and 2.54 (95% CI = 1.10-5.84) for NYHA III/IV after controlling for age, gender, HF etiology, body mass index, ejection fraction, and total comorbidity score.

CONCLUSIONS

These data suggest that 3 g dietary sodium restriction may be most appropriate for patients in NYHA functional Classes III and IV.

Predictors of measurement error in energy intake during pregnancy

Nutrition plays a critical role in maternal and fetal health; however, research on error in the measurement of energy intake during pregnancy is limited. The authors analyzed data on 998 women living in central North Carolina with singleton pregnancies during 2001-2005. Second-trimester diet was assessed by food frequency questionnaire. Estimated energy requirements were calculated using Institute of Medicine prediction equations, with adjustment for energy costs during the second trimester. Implausible values for daily energy intake were determined using confidence limits of agreement for energy intake/estimated energy requirements. Prevalences of low energy reporting (LER) and high energy reporting (HER) were 32.8% and 12.9%, respectively. In a multivariable analysis, pregravid body mass index was related to both LER and HER; LER was higher in both overweight (odds ratio = 1.96, 95% confidence interval: 1.26, 3.02; P = 0.031) and obese (odds ratio = 3.29, 95% confidence interval: 2.33, 4.65; P < 0.001) women than in normal-weight counterparts. Other predictors of LER included marriage and higher levels of physical activity. HER was higher among subjects who were underweight, African-American, and less educated and subjects who had higher depressive symptom scores. LER and HER are prevalent during pregnancy. Identifying their predictors may improve data collection and analytic methods for reducing systematic bias in the study of diet and reproductive outcomes.

Causal beliefs and behaviour change post-myocardial infarction: How are they related?

INTRODUCTION

Weinman, Petrie, Sharpe, and Walker (2000) showed that the causal attributions of a sample of first-time myocardial infarction (MI) patients and their spouses from Auckland, New Zealand, were associated with changes in health-related behaviour over the first 6 months post-MI. However, their analyses did not control for pre-MI health-related behaviour.

METHOD

This paper reports a re-analyses of the Auckland data, and a replication study conducted with 155 first-time MI patients in Brighton, United Kingdom (UK), to investigate whether baseline attributions for MI were related to health-related behaviour change at 6 months (N=132). Spouses (N=85) also completed the attribution questionnaire at baseline.

RESULTS

There was no consistent relationship between the causal attributions of patients and subsequent behaviour change in Auckland and Brighton. For both samples, causal attributions were associated with pre-MI behaviour.

CONCLUSIONS

The data from both samples suggest that the causal attributions of MI patients and their spouses may be realistic, but not predictive of subsequent changes in behaviour.

CHD risk in relation to alcohol intake from categorical and open-ended dietary instruments

OBJECTIVE

To examine the risk of CHD in relation to alcohol intake from three different instruments.

DESIGN

In the European Prospective Investigation into Cancer in Norfolk study, weekly alcohol intake was estimated from a single question in a mail-in health and lifestyle questionnaire (HLQ), a semi-quantitative FFQ, and a 7 d diet diary (7DD). Information on smoking status, physical activity, disease history, social class and medication use was reported in the HLQ. Height, weight, blood pressure and blood lipids were measured at a health check-up. The average length of follow-up was 11 years. The association between alcohol intake and incident fatal and non-fatal CHD in a nested case-control sample was calculated using logistic regression.

SETTING

Norfolk, England.

SUBJECTS

A total of 2151 cases of incident fatal and non-fatal CHD and 5354 controls.

RESULTS

The Spearman correlation values between the 7DD, FFQ and HLQ alcohol estimates ranged from r = 0·70 to 0·82 (P < 0·0001 for all r values). Alcohol intake from all instruments was inversely associated with the risk of CHD in age- and multivariate-adjusted models. The relationships between the risk of CHD and alcohol intake from the 7DD, HLQ or FFQ were not significantly different from each other (P >0·10). A marginal difference between men and women was detected for the risk of CHD in relation to HLQ alcohol intake (P = 0·065).

CONCLUSIONS

In conclusion, while the instruments were not uniform in their assessment of alcohol intake levels, the 7DD, HLQ and FFQ yielded similar inverse associations between alcohol intake and risk of CHD.

The Use of Mobile Devices in Aiding Dietary Assessment and Evaluation

There is a growing concern about chronic diseases and other health problems related to diet including obesity and cancer. The need to accurately measure diet (what foods a person consumes) becomes imperative. Dietary intake provides valuable insights for mounting intervention programs for prevention of chronic diseases. Measuring accurate dietary intake is considered to be an open research problem in the nutrition and health fields. In this paper, we describe a novel mobile telephone food record that will provide an accurate account of daily food and nutrient intake. Our approach includes the use of image analysis tools for identification and quantification of food that is consumed at a meal. Images obtained before and after foods are eaten are used to estimate the amount and type of food consumed. The mobile device provides a unique vehicle for collecting dietary information that reduces the burden on respondents that are obtained using more classical approaches for dietary assessment. We describe our approach to image analysis that includes the segmentation of food items, features used to identify foods, a method for automatic portion estimation, and our overall system architecture for collecting the food intake information.

Assessment of dietary intake: NuGO symposium report

Advances in genomics science and associated bioinformatics and technology mean that excellent tools are available for characterising human genotypes. At the same time, approaches for characterising individual phenotypes are developing rapidly. In contrast, there has been much less investment in novel methodology for measuring dietary exposures so that there is now a significant gap in the toolkit for those investigating how diet interacts with genotype to determine phenotype. This symposium reviewed the strengths and limitations of current tools used in assessment of dietary intake and the potential to improve these tools through, for example, the use of statistical techniques that combine information from different sources (such as modelling and calibration methods) to ameliorate measurement error and to provide validity checks. Speakers examined the use of approaches based on technologies such as mobile ‘phones, digital cameras and Web-based systems which offer the potential for more acceptable (for study participants) and less laborious (for researchers and participants) routes to more robust data collection. In addition, the application of omics, especially metabolomics, tools to biofluids to identify new biomarkers of intake offers great potential to provide objective measures of food consumption with the advantage that data may be collected in forms that can be integrated readily with other high throughput (nutrigenomic) technologies.

Dietary fiber and colorectal cancer risk: a nested case-control study using food diaries

BACKGROUND

Results of epidemiological studies of dietary fiber and colorectal cancer risk have not been consistent, possibly because of attenuation of associations due to measurement error in dietary exposure ascertainment.

METHODS

To examine the association between dietary fiber intake and colorectal cancer risk, we conducted a prospective case-control study nested within seven UK cohort studies, which included 579 case patients who developed incident colorectal cancer and 1996 matched control subjects. We used standardized dietary data obtained from 4- to 7-day food diaries that were completed by all participants to calculate the odds ratios for colorectal, colon, and rectal cancers with the use of conditional logistic regression models that adjusted for relevant covariates. We also calculated odds ratios for colorectal cancer by using dietary data obtained from food-frequency questionnaires that were completed by most participants. All statistical tests were two-sided.

RESULTS

Intakes of absolute fiber and of fiber intake density, ascertained by food diaries, were statistically significantly inversely associated with the risks of colorectal and colon cancers in both age-adjusted models and multivariable models that adjusted for age; anthropomorphic and socioeconomic factors; and dietary intakes of folate, alcohol, and energy. For example, the multivariable-adjusted odds ratio of colorectal cancer for highest vs the lowest quintile of fiber intake density was 0.66 (95% confidence interval = 0.45 to 0.96). However, no statistically significant association was observed when the same analysis was conducted using dietary data obtained by food-frequency questionnaire (multivariable odds ratio = 0.88, 95% confidence interval = 0.57 to 1.36).

CONCLUSIONS

Intake of dietary fiber is inversely associated with colorectal cancer risk. Methodological differences (ie, study design, dietary assessment instruments, definition of fiber) may account for the lack of convincing evidence for the inverse association between fiber intake and colorectal cancer risk in some previous studies.

Dietary assessment methods for micronutrient intake in infants, children and adolescents: a systematic review

A systematic literature search identified studies validating the methodology used for measuring the usual dietary intake in infants, children and adolescents. The quality of each validation study selected was assessed using a European micronutrient Recommendations Aligned-developed scoring system. The validation studies were categorised according to whether the study used a reference method that reflected short-term intake ( < 7 d), long-term intake ( ≥ 7 d) or used biomarkers. A correlation coefficient for each nutrient was calculated from the mean of the correlation coefficients from each study weighted by the quality of the study. Thirty-two articles were included in the present review: validation studies from infants (1–23 months); child preschool (2–5 years); children (6–12 years); adolescents (13–18 years). Validation of FFQ studies in infants and preschool children using a reference method that reflected short-term intake showed good correlations for niacin, thiamin, vitamins B6, D, C, E, riboflavin, Ca, K, Mg, Fe and Zn (with correlations ranging from 0·55 for vitamin E to 0·69 for niacin).Regarding the reference method reflecting short-term intake in children and adolescents, good correlations were seen only for vitamin C (r 0·61) and Ca (r 0·51). Using serum levels of micronutrient demonstrated that the 3 d weighed dietary records was superior to the FFQ as a tool to validate micronutrient intakes. Including supplement users generally improved the correlations between micronutrient intakes estimated by any of the dietary intake methods and respective biochemical indices.

An exploratory NMR nutri-metabonomic investigation reveals dimethyl sulfone as a dietary biomarker for onion intake

The metabolome following intake of onion by-products is evaluated. Thirty-two rats were fed a diet containing an onion by-product or one of the two derived onion by-product fractions: an ethanol extract and the residue. A 24 hour urine sample was analyzed using (1)H NMR spectroscopy in order to investigate the effects of onion intake on the rat metabolism. Application of interval extended canonical variates analysis (ECVA) proved to be able to distinguish between the metabolomic profiles from rats consuming normal feed and rats fed with an onion diet. Two dietary biomarkers for onion intake were identified as dimethyl sulfone and 3-hydroxyphenylacetic acid. The same two dietary biomarkers were subsequently revealed by interval partial least squares regression (PLS) to be perfect quantitative markers for onion intake. The best PLS calibration model yielded a root mean square error of cross-validation (RMSECV) of 0.97% (w/w) with only 1 latent variable and a squared correlation coefficient of 0.94. This indicates that urine from rats on the by-product diet, the extract diet, and the residue diet all contain the same dietary biomarkers and it is concluded that dimethyl sulfone and 3-hydroxyphenylacetic acid are dietary biomarkers for onion intake. Being able to detect specific dietary biomarkers is highly beneficial in the control of nutritionally enhanced functional foods.

Low dietary sodium intake is associated with enhanced vascular endothelial function in middle-aged and older adults with elevated systolic blood pressure

BACKGROUND

Age and increasing systolic blood pressure (BP) are associated with vascular endothelial dysfunction, but the factors involved are incompletely understood. We tested the hypothesis that vascular endothelial function is related to dietary sodium intake among middle-aged and older adults (MA and O) with elevated systolic BP.

METHODS

Data were analyzed on 25 otherwise healthy adults aged 48-73 years with high normal systolic BP or stage I systolic hypertension (130-159 mmHg). Self-reported sodium intake was <100 mmol/d in 12 (7 M) subjects (low sodium, 73+/-6 mmol/d) and between 100 and 200 mmol/d in 13 (9 M) subjects (normal sodium, 144+/-6 mmol/d).

RESULTS

Groups did not differ in other dietary factors, age, body weight and composition, BP, metabolic risk factors, physical activity and maximal aerobic capacity. Plasma concentrations of norepinephrine, endothelin-1, oxidized low-density lipoproteins (LDL), antioxidant status and inflammatory markers did not differ between groups. Brachial artery flow-mediated dilation (FMD) was 42% (mm Delta) to 52% (% Delta) higher in the low versus normal sodium group (p < 0.05). In all subjects, brachial artery FMD was inversely related to dietary sodium intake (FMD mm Delta r =-0.40, p < 0.05; %Delta r =-0.53, p < 0.01). Brachial artery FMD was not related to any other variable. In contrast, endothelium-independent dilation did not differ between groups (p >or= 0.24) and was not related to sodium intake in the overall group (p >or= 0.29).

CONCLUSIONS

Low sodium intake is associated with enhanced brachial artery FMD in MA and O with elevated systolic BP. These results suggest that dietary sodium restriction may be an effective intervention for improving vascular endothelial function in this high-risk group.

Prevalence of the female athlete triad in high school athletes and sedentary students

OBJECTIVE

To determine the prevalence of the female athlete triad (low energy availability, menstrual dysfunction, and low bone mineral density) in high school varsity athletes in a variety of sports compared with sedentary students/control subjects.

DESIGN

Prospective study.

SETTING

Academic medical center in the Midwest.

PARTICIPANTS

Eighty varsity athletes and 80 sedentary students/control subjects volunteered for this study.

INTERVENTION

Subjects completed questionnaires, had their blood drawn, and underwent bone mineral density testing.

MAIN OUTCOME MEASURES

Each participant completed screening questionnaires assessing eating behavior, menstrual status, and physical activity. Each subject completed a 3-day food diary. Serum hormonal, thyroid-stimulating hormone, and prolactin levels were determined. Bone mineral density and body composition were measured by dual-energy x-ray absorptiometry.

RESULTS

Low energy availability was present in similar numbers of athletes (36%) and sedentary/control subjects (39%; P = 0.74). Athletes had more menstrual abnormalities (54%) compared with sedentary students/control subjects (21%) (P < 0.001). Dual-energy x-ray absorptiometry revealed that 16% of the athletes and 30% of the sedentary/control subjects had low bone mineral density (P = 0.03). Risk factors for reduced bone mineral density include sedentary control student, low body mass index, and increased caffeine consumption.

CONCLUSIONS

A substantial number of high school athletes (78%) and a surprising number of sedentary students (65%) have 1 or more components of the triad. Given the high prevalence of triad characteristics in both groups, education in the formative elementary school years has the potential to prevent several of the components in both groups, therefore improving health and averting long-term complications.

Adherence to the low-sodium diet plays a role in the interaction between depressive symptoms and prognosis in patients with heart failure

BACKGROUND

Although a low-sodium diet (LSD) is important in self-management of patients with heart failure (HF), the impact of LSD on event-free survival has not been investigated. Depressive symptoms predict worse event-free survival, in part, by affecting adherence to self-management. However, there are few investigations of the relationship among depressive symptoms, adherence to the LSD, and event-free survival.

PURPOSE

The purpose of this study was to determine the relationships among adherence to the LSD, depressive symptoms, and event-free survival.

METHODS

A total of 254 patients (57% male, 62 ± 14 years, 52% New York Heart Association class III/IV, ejection fraction of 36% ± 14%) were recruited from outpatient HF clinics in Korea. Twenty-four-hour urinary sodium excretion was collected as an indicator of patient adherence to the LSD. Patients were grouped based on the cut point of 3 g of urinary sodium excretion. Depressive symptoms were assessed by the Korean version of Beck Depression Inventory, and patients were split into 2 groups at the cutoff of the Korean version of Beck Depression Inventory. Event-free survival for 12 months was determined by medical records. Hierarchical Cox proportional hazards regression was used to determine the association of depressive symptoms and adherence to 3-g sodium intake on event-free survival.

RESULTS

After controlling for age, sex, etiology of HF, body mass index, New York Heart Association class, ejection fraction, N-terminal B-type natriuretic peptide, and total comorbidity score, nonadherence to 3-g sodium intake (hazard ratio = 1.56, 95% confidence interval = 1.05-2.32) and depressive symptoms (hazard ratio = 2.21, 95% confidence interval = 1.47-3.33) independently predicted event-free survival. Patients with sodium intake higher than 3 g and with depressive symptoms demonstrated a 3.7 times higher risk for cardiac events compared with patients with sodium intake lower than 3 g and without depressive symptoms (P < .001).

CONCLUSION

Improvement of adherence to the LSD and treatment for depressive symptoms could improve event-free survival.

The effect of low-fat versus whole-fat dairy product intake on blood pressure and weight in young normotensive adults

BACKGROUND

Epidemiologic and experimental studies suggest that higher intake of dairy products could be associated with lower risk of hypertension and obesity. Differences in nutrient composition of distinct dairy products suggest that their effect on these outcomes might be heterogeneous. However, little experimental research has examined the potentially different effects of low- and whole-fat dairy products on blood pressure (BP) and weight change. The present study aimed to assess whether supplementing diets with low- or whole-fat dairy products would differentially affect BP levels and weight.

METHODS

A randomised crossover trial in 45 normotensive volunteers (18-24 years old, 49% female) was conducted. Participants alternatively received 3.5 servings/day of whole-fat or low-fat dairy products (milk and yogurt) in addition to their usual diet during two 8-week periods, with a 4-week washout period between both interventions. Weight and BP were measured at the beginning and end of each intervention.

RESULTS

Whole-fat dairy supplementation significantly increased systolic BP [2.1 mmHg, 95% confidence interval (CI) = 0.1-4.0, P = 0.04] and weight (1.0 kg, 95% CI = 0.5-1.5, P = 0.0002), but not diastolic BP (P = 0.34). Weight and BP did not change significantly after the low-fat dairy intervention (P > 0.10). There were no significant differences in the effect of low-fat or whole-fat dairy products on BP (P > 0.60), but whole-fat dairy increased weight significantly compared to low-fat dairy (1.2 kg, 95% CI = 0.5-1.8, P = 0.0007).

CONCLUSIONS

In a young nonhypertensive population, dietary supplementation with whole-fat dairy products, compared to low-fat dairy, was associated with weight gain. No differential effects were observed for levels of BP.

Comparison between dietary assessment methods for determining associations between nutrient intakes and bone mineral density in postmenopausal women

It is important to identify the role of nutrition in the treatment and prevention of osteoporosis. The goal of this study was to compare the equivalency of nutrient intakes assessed by diet records and the Arizona Food Frequency Questionnaire and the associations of these nutrients with bone mineral density (BMD). This is a secondary analysis of cross-sectional data that was analyzed from six cohorts (fall 1995 to fall 1997) of postmenopausal women (n=244; 55.7+/-4.6 years) participating in a 12-month, block-randomized, clinical trial. One-year dietary intakes were assessed using 8 days of diet records and the Arizona Food Frequency Questionnaire. Participants' BMD was measured at the lumbar spine (L2-L4), femur trochanter, femur neck, Ward's triangle, and total body using dual-energy x-ray absorptiometry. Linear regression analyses (P< or =0.05) were adjusted for the effects of exercise, hormone therapy use, body weight at 1 year, years post menopause, and total energy intake. Significant correlations (r=0.30 to 0.70, P< or =0.05) between dietary assessment methods were found with all dietary intake variables. Iron and magnesium were consistently and significantly positively associated with BMD at all bone sites regardless of the dietary assessment method. Zinc, dietary calcium, phosphorous, potassium, total calcium, and fiber intakes were positively associated with BMD at three or more of the same bone sites regardless of the dietary assessment method. Protein, alcohol, caffeine, sodium, and vitamin E did not have any similar BMD associations. Diet records and the Arizona Food Frequency Questionnaire are acceptable dietary tools used to determine the associations of particular nutrients and BMD sites in healthy postmenopausal women.

The effects of high potassium consumption on bone mineral density in a prospective cohort study of elderly postmenopausal women

Few studies have investigated the long-term effects of potassium intake on BMD. In a cohort of 266 elderly women, we found that baseline potassium intake as reflected by 24-hour urine potassium excretion had positive association with BMD measured at 1 and/or 5 years later, suggesting a role of dietary potassium on osteoporosis prevention.

INTRODUCTION

High dietary potassium intake has been suggested to be beneficial for bone structure, but few studies have investigated the long-term effects of potassium intake on BMD in elderly women. We examined the relationship between potassium intake as reflected by 24-hour urine potassium excretion and bone density in a cohort of elderly women.

METHODS

The study subjects were 266 elderly postmenopausal women aged 70-80 years. Twenty-four-hour urinary potassium excretion was determined at baseline. At one year hip DXA BMD was measured, at 5 years hip and total body DXA BMD and distal radius and tibia pQCT vBMD were measured. The effects of potassium were evaluated by ANCOVA according to the quartile of baseline urinary potassium excretion.

RESULTS

After adjustment for confounding factors, subjects in the highest quartile of urinary potassium excretion had significantly higher total hip BMD at 1 (5%) and 5 years (6%), and significantly higher total body BMD (4%) and 4% distal tibia total (7%) and trabecular vBMD (11%) at 5 years than those in the lowest quartile.

CONCLUSIONS

Potassium intake shows positive association with bone density in elderly women, suggesting that increasing consumption of food rich in potassium may play a role in osteoporosis prevention.

Blood pressure and interactions between the angiotensin polymorphism AGT M235T and sodium intake: a cross-sectional population study

BACKGROUND

Intervention studies have indicated an interaction between the blood pressure response to a low-sodium or a low-fat and high-fruit and -vegetable diet and the angiotensinogen gene (AGT) polymorphisms G-6A and M235T.

OBJECTIVE

We investigated whether this interaction is also present in a large free-living population.

DESIGN

Urinary sodium, potassium as biomarkers of intake, and blood pressure were measured in 11 384 men and women aged 45-79 y participating in the Norfolk arm of the European Prospective Investigation of Nutrition and Cancer (EPIC). The M235T polymorphism was assessed by pyrosequencing.

RESULTS

Highly significant associations between sodium and blood pressure were shown for all genotypes (P < 0.001), but the regression coefficient for systolic blood pressure associated with each unit of sodium for each of the MT and TT genotypes was approximately double that for the MM homozygotes (P < 0.001 for heterogeneity between genotypes). Differences were evident at high exposures to sodium but not at low exposures. There were no significant associations between blood pressure and dietary or urinary potassium.

CONCLUSIONS

This large cross-sectional study supports public health recommendations to reduce salt consumption in the population as a whole, and it confirms intervention trial data showing the greatest response to intervention in persons with the AA and TT genotype in the AGT G-6A and M235T polymorphisms. Genotype effects in populations at low exposure to sodium are not likely to be seen.

Effect of potassium citrate supplementation or increased fruit and vegetable intake on bone metabolism in healthy postmenopausal women: a randomized controlled trial

BACKGROUND

Alkali provision may explain why fruit and vegetables benefit bone health.

OBJECTIVE

We aimed to determine the effects of alkali-providing potassium citrate (double-blind) and fruit and vegetable intake (single-blind) on bone turnover over 2 y.

DESIGN

We conducted a randomized placebo-controlled trial in 276 postmenopausal women (aged 55-65 y). Women were randomly assigned to 4 groups: high-dose potassium citrate (55.5 mEq/d), low-dose potassium citrate (18.5 mEq/d), placebo, and 300 g additional fruit and vegetables/d (equivalent of 18.5 mEq alkali). Serum and fasted urine for bone markers were collected at baseline and at 3, 6, 12, 18, and 24 mo. An additional urine sample was collected at 4-6 wk. Bone mineral density (BMD) was measured at baseline and 2 y.

RESULTS

Repeated-measures ANOVA showed no difference between groups for urinary free deoxypyridinoline cross-links relative to creatinine (fDPD/Cr), serum N-terminal propeptide of type 1 collagen, or beta C-terminal telopeptide, although, at 4-6 wk, fDPD/Cr was lower in the high-dose potassium citrate group (P = 0.04). Mean +/- SD spine BMD loss in the placebo group (1.8 +/- 3.9%) did not differ significantly from that in the treatment groups (2.1 +/- 3.2%; P = 0.88). Hip BMD loss in the placebo and low-dose potassium citrate groups was 1.3 +/- 2.3% and 2.2 +/- 2.3%, respectively (P = 0.14).

CONCLUSIONS

Two-year potassium citrate supplementation does not reduce bone turnover or increase BMD in healthy postmenopausal women, which suggests that alkali provision does not explain any long-term benefit of fruit and vegetable intake on bone.

Daily ingestion of alginate reduces energy intake in free-living subjects

Sodium alginate is a seaweed-derived fibre that has previously been shown to moderate appetite in models of acute feeding. The mechanisms underlying this effect may include slowed gastric clearance and attenuated uptake from the small intestine. In order to assess whether alginate could be effective as a means of appetite control in free-living adults, 68 males and females (BMI range: 18.50-32.81 kg/m(2)) completed this randomised, controlled two-way crossover intervention to compare the effects of 7 day daily ingestion of a strong-gelling sodium alginate formulation against a control. A sodium alginate with a high-guluronate content was chosen because, upon ingestion, it forms a strong gel in the presence of calcium ions. Daily preprandial ingestion of the sodium alginate formulation produced a significant 134.8 kcal (7%) reduction in mean daily energy intake. This reduced energy intake was underwritten by significant reductions in mean daily carbohydrate, sugar, fat, saturated fat and protein intakes. The absence of any significant interaction effects between the main effect of preload type and those of gender, BMI classification and/or timing of preload delivery indicates the efficacy of this treatment for individuals in different settings. These findings suggest a possible role for a strong-gelling sodium alginate formulation in the future management of overweight and obesity.

Nutrition and cancer: essential elements for a roadmap

Personalizing nutrition for cancer prevention and therapy will require a comprehensive understanding of "genotypes/phenotypes" in order to identify, evaluate, and prioritize appropriate points for dietary intervention. This nutritional preemption roadmap must begin with accurately assessing intakes/exposures of which bioactive food component(s) is needed to bring about a desired response in critical cellular processes (carcinogen metabolism, DNA repair, cell proliferation, apoptosis, inflammation, immunity, differentiation, angiogenesis, hormonal regulation and cellular energetic) within an individual. Understanding this "individuality" through a better understanding of the "omics" is fundamental to arriving at the correct destination and thus interpreting biological variables which establish the magnitude or direction of a response to bioactive food components.

Patients differ in their ability to self-monitor adherence to a low-sodium diet versus medication

OBJECTIVE

Poor adherence to a low-sodium diet (LSD) and prescribed medications increases rehospitalization risk in patients with heart failure (HF). Clinicians have difficulty assessing adherence objectively, so they depend on patients' self-report. The degree to which self-reported adherence reflects actual adherence is unclear. We examined patients' ability to self-monitor adherence to an LSD and medications by comparing self-reported adherence with objective evidence of adherence.

METHODS

A total of 133 patients with HF (male 71%; ejection fraction 35% +/- 14%) completed the Medical Outcomes Study Specific Adherence Scale. Adherence to the LSD and medication were assessed objectively using 24-hour urinary sodium excretion and dose counting with an electronic monitoring device, respectively. On the basis of self-report, patients were divided into adherent and non-adherent groups and evaluated for differences according to objective adherence.

RESULTS

There were no differences in urinary sodium levels between the self-reported LSD adherent and non-adherent groups (4560 mg vs. 4333 mg; P = .59). Self-reported adherent and non-adherent medication groups took 92.4% and 80.4% of prescribed doses, respectively (P < .001).

CONCLUSION

Patients were able to accurately estimate adherence to medication, but they failed to estimate LSD adherence. This finding suggests that we need to improve our means of evaluating adherence to the LSD and of educating patients more thoroughly about following the LSD. We speculated that the inability to estimate LSD adherence may be the result of gaps in patients' knowledge that preclude accurate self-assessment.

Validity of a new food frequency questionnaire for pregnant women in the Norwegian Mother and Child Cohort Study (MoBa)

The aim of the present study was to examine the relative validity of foods and nutrients calculated by a new food frequency questionnaire (FFQ) in the Norwegian Mother and Child Cohort Study (MoBa). Reference measures were a 4-day weighed food diary (FD), a motion sensor for measuring total energy expenditure, one 24-h urine collection for analysis of nitrogen and iodine excretion, and a venous blood specimen for analysis of plasma 25-hydroxy-vitamin D and serum folate. A total of 119 women participated in the validation study, and 112 completed the motion sensor registration. Overall, the level of agreement between the FFQ and the FD was satisfactory, and significant correlations were found for all major food groups and for all nutrients except vitamin E. The average correlation coefficient between the FFQ and the FD for daily intake was 0.48 for foods and 0.36 for nutrients, and on average, 68% of the participants were classified into the same or adjacent quintiles by the two methods. Estimated total energy expenditure indicated that under-reporting of energy intake was more extensive with the FD than with the FFQ. The biological markers confirmed that the FFQ was able to distinguish between high and low intakes of nutrients, as measured by vitamin D, folate, protein and iodine. This validation study indicates that the MoBa FFQ produces reasonable valid intake estimates and is a valid tool to rank pregnant women according to low and high intakes of energy, nutrients and foods.

Technology-Assisted Dietary Assessment

Dietary intake provides valuable insights for mounting intervention programs for prevention of disease. With growing concern for adolescent obesity, the need to accurately measure diet becomes imperative. Assessment among adolescents is problematic as this group has irregular eating patterns and have less enthusiasm for recording food intake. Preliminary studies among adolescents suggest that innovative use of technology may improve the accuracy of diet information from young people. In this paper, we propose a novel food record method using a mobile device that will provide an accurate account of daily food and nutrient intake among adolescents. Our approach includes the use of image analysis tools for identification and quantification of food consumption. Images obtained before and after food is consumed can be used to estimate the diet of an individual. In this paper we describe our initial results and indicate the potential of the proposed system.

Relative validity and utility of a short food frequency questionnaire assessing the intake of legumes in Scottish women

OBJECTIVE

To validate a five-item, semi-quantitative, short food frequency questionnaire (SFFQ) designed to estimate daily legume consumption over a week, against results obtained from 7-day food diaries (7-day FD).

DESIGN

Participants completed a 7-day FD and at the end of this period completed the SFFQ, to indicate the number of times they ate five legume-containing dishes in the previous week and what size portion of each dish they consumed. Daily legume intake (g day(-1)) was calculated for both methods and participants were classified into tertiles of intake for each method.

SUBJECTS/SETTING

Fifty-one healthy females aged 25-55 years, employed at the University of Glasgow, Scotland, UK between May 2003 and December 2004.

RESULTS

The two methods produced a similar mean intake of legumes [SFFQ: 14.8 (95% CI: 9.9-19.8) versus 7-day FD: 14.9 (95% CI: 9.3-20.6) g day(-1)] and the Pearson's correlation coefficient was 0.353 (P = 0.038). Exact agreement within tertiles and gross misclassification were 54.9% and 9.8% respectively. The weighted kappa statistic indicated fair agreement between the two methods (kappa = 0.262).

CONCLUSIONS

The SFFQ is an acceptable instrument for estimating legume consumption over a week and can be used to rank individuals according to the intake of this food group in similar nutrition intervention studies.

Is plasma vitamin C an appropriate biomarker of vitamin C intake? A systematic review and meta-analysis

Background

As the primary source of dietary vitamin C is fruit and to some extent vegetables, the plasma level of vitamin C has been considered a good surrogate or predictor of vitamin C intake by fruit and vegetable consumption. The purpose of this systematic review was to investigate the relationship between dietary vitamin C intakes measured by different dietary methods and plasma levels of vitamin C.

Method

We searched the literature up to May 2006 through the OVID interface: MEDLINE (from 1960) and EMBASE (from 1988). We also reviewed the reference lists in the articles, reviews, and textbooks retrieved. A total of 26 studies were selected and their results were combined using meta-analytic techniques with random-effect model approach.

Results

The overall result of this study showed a positive correlation coefficient between Food Frequency Questionnaire (FFQ) and biomarker (r = 0.35 for "both" genders, 0.39 for females, and 0.46 for males). Also the correlation between Dietary Recalls (DR)/diary and biomarker was 0.46 for "both" genders, 0.44 for females, and 0.36 for males. An overall correlation of 0.39 was found when using the weight record method. Adjusting for energy intake improved the observed correlation for FFQ from 0.31 to 0.41. In addition, we compared the correlation for smokers and non-smokers for both genders (FFQ: for non-smoker r = 0.45, adjusted for smoking r = 0.33).

Conclusion

Our findings show that FFQ and DR/diary have a moderate relationship with plasma vitamin C. The correlation may be affected/influenced by the presence of external factors such as vitamin bioavailability, absorption condition, stress and food processing and storage time, or by error in reporting vitamin C intake.

Biological variability dominates and influences analytical variance in HPLC-ECD studies of the human plasma metabolome

Background

Biomarker-based assessments of biological samples are widespread in clinical, pre-clinical, and epidemiological investigations. We previously developed serum metabolomic profiles assessed by HPLC-separations coupled with coulometric array detection that can accurately identify ad libitum fed and caloric-restricted rats. These profiles are being adapted for human epidemiology studies, given the importance of energy balance in human disease.

Methods

Human plasma samples were biochemically analyzed using HPLC separations coupled with coulometric electrode array detection.

Results

We identified these markers/metabolites in human plasma, and then used them to determine which human samples represent blinded duplicates with 100% accuracy (N = 30 of 30). At least 47 of 61 metabolites tested were sufficiently stable for use even after 48 hours of exposure to shipping conditions. Stability of some metabolites differed between individuals (N = 10 at 0, 24, and 48 hours), suggesting the influence of some biological factors on parameters normally considered as analytical.

Conclusion

Overall analytical precision (mean median CV, ~9%) and total between-person variation (median CV, ~50–70%) appear well suited to enable use of metabolomics markers in human clinical trials and epidemiological studies, including studies of the effect of caloric intake and balance on long-term cancer risk.

A randomized trial of a hypocaloric high-protein diet, with and without exercise, on weight loss, fitness, and markers of the Metabolic Syndrome in overweight and obese women

The purpose of this study was to examine the effects of 3:1 and 1:1 carbohydrate to protein ratios, hypocaloric diets with and without exercise, and risk factors associated with the Metabolic Syndrome in overweight and obese Canadian women. Groups were designated as control diet (CON), control diet with exercise (CONEx), high-protein (HP), or high-protein with exercise (HPEx). Free-living women from the Guelph community were studied in a university health and fitness facility. The participants were 44 of 60 overweight and obese women who had been randomized to the 4 weight-loss programs. Habitual diets of the subjects were energy restricted and were to contain either a 1:1 or 3:1 ratio of carbohydrate to protein energy. Subjects either exercised 3 times/week or maintained their normal level of activity for 12 weeks. The main outcome measures were weight loss, blood lipids, blood pressure, insulin, body composition, nitrogen balance, fitness, and resting energy expenditure. All groups lost weight over the 12 week period: -2.1 kg for the CON group, -4.0 kg in the CONEx group, -4.6 kg in the HP group, and -7.0 kg in the HPEx. All participants exhibited improved body composition, decreased blood pressure, and decreased waist and hip circumference. Actual diets consumed by the subjects contained ratios of carbohydrate to protein of 3.0:1, 2.7:1, 1.5:1, and 0.96:1 for the CON, CONEx, HP, and HPEx groups, respectively. Cardiovascular fitness improved in both exercise groups. There were no changes in resting energy expenditure. No adverse events were reported. Significant changes in blood lipids included decreased total cholesterol in the HP and CONEx groups, decreased low-density lipoprotein cholesterol in the HP group only, and decreased blood triglycerides in the HPEx group only. High-density lipoprotein cholesterol, fasting blood glucose, and fasting insulin levels were unaltered by diet or exercise. A high-protein diet was superior to a low-fat, high-carbohydrate diet either alone or when combined with an aerobic/resistance-training program in promoting weight loss and nitrogen balance, while similarly improving body composition and risk factors for the Metabolic Syndrome in overweight and obese Canadian women.

Biomarkers for diet and cancer prevention research: potentials and challenges

As cancer incidence is projected to increase for decades there is a need for effective preventive strategies. Fortunately, evidence continues to mount that altering dietary habits is an effective and cost-efficient approach for reducing cancer risk and for modifying the biological behavior of tumors. Predictive, validated and sensitive biomarkers, including those that reliably evaluate "intake" or exposure to a specific food or bioactive component, that assess one or more specific biological "effects" that are linked to cancer, and that effectively predict individual "susceptibility" as a function of nutrient-nutrient interactions and genetics, are fundamental to evaluating who will benefit most from dietary interventions. These biomarkers must be readily accessible, easily and reliably assayed, and predictive of a key process(es) involved in cancer. The response to a food is determined not only by the effective concentration of the bioactive food component(s) reaching the target tissue, but also by the amount of the target requiring modification. Thus, this threshold response to foods and their components will vary from individual to individual. The key to understanding a personalized response is a greater knowledge of nutrigenomics, proteomics and metabolomics.

Twenty-four-hour urinary thiamine as a biomarker for the assessment of thiamine intake

OBJECTIVE

To investigate 24-h urinary thiamine as a potential biomarker for thiamine intake for use in validation studies to assess the validity of dietary intake data collected by self-reporting dietary methods.

SUBJECTS

Seven male and six female healthy participants living for 30 days in a metabolic suite under strictly controlled conditions consuming their usual diet as assessed beforehand from four consecutive 7-day food diaries kept at home. During the 30-day study, all 24-h urine specimens were collected, validated for their completeness and analysed for thiamine.

RESULTS

Thirty-day mean (+/-s.d.) calculated thiamine intake was 2.22+/-0.55 mg/day. Thirty-day mean (+/-s.d.) urinary excretion of thiamine was 526.5+/-193.0 microg/day (24.7+/-8.10% of intake). There was a highly significant correlation between individuals' 30-day means of thiamine intake and their mean excretion level (r=0.720; P=0.006), where 1 mg of thiamine intake predicted 268.2 microg of thiamine in urine. The correlations between intake and excretion remained significant when measurement from a single 24-h urine collection was used (r=0.56).

CONCLUSION

Twenty-four-hour urinary thiamine can be used as a concentration biomarker for thiamine intake in dietary validation studies.

Relative validity of a food frequency questionnaire used in the Inter99 study

OBJECTIVE

To evaluate the validity of the Inter99 food frequency questionnaire (FFQ) compared with a 28-days' diet history and biomarkers.

SUBJECTS

A random sample of 13 016 individuals were drawn from a general population and invited for a health screening programme. Participation rate was 52.5%. All high-risk individuals were re-invited for assessment after 1 and 3 years and completed a 198-item FFQ at all three occasions. Participants attending for 3 years follow-up were invited to participate in the validation study, including a 28-days' diet history, a 24-h urine collection and a fasting blood sample. Overall, 264 subjects participated.

RESULTS

Spearman's rank correlation coefficients between the two dietary methods ranged from 0.31(beta-carotene) to 0.64 (fruits) in men and from 0.31 (polyunsaturated fat and sodium) to 0.64 (fruits) for women. The proportion of individuals classified in the same or adjacent quintiles were, on average, 72% for men and 69% for women. Gross misclassification was found on average in 2%. The correlation coefficients of the residuals ranged from 0.27 (sodium) to 0.61 (fruits) for men and from 0.21 (sodium) to 0.62 (B12-vitamin) for women. Correlation coefficients between fruit and vegetable intake and carotenoids ranged from -0.08 (lycopene) to 0.44 (alpha-carotene). For the residuals the correlation coefficients ranged from -0.004 (lycopene) to 0.47 (alpha-carotene).

CONCLUSION

The Inter99 FFQ and the residuals of the intake provide acceptable classification of individuals according to their dietary intakes and the FFQ gives a good quantitative measurement of key dietary components.

Prevalence of Female Athlete Triad Characteristics in a Club Triathlon Team

OBJECTIVE

To determine the prevalence of the female athlete triad in club triathletes.

DESIGN

Cross-sectional.

SETTING

Academic medical center in the midwestern United States.

PARTICIPANTS

Fifteen women (mean age, 35+/-6 y).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Disordered eating and menstrual status were determined by questionnaires. Energy status was determined by a 3-day food record, resting energy expenditure, and exercise energy output. Bone mineral density (BMD) was measured in the total left hip and lumbar spine (L2-4) by dual-energy x-ray absorptiometry.

RESULTS

Sixty percent of the triathletes were found to be in calorie deficit, 53% had a carbohydrate deficit, 47% had a fat deficit, 40% had a protein deficit, and 33% had a calcium deficit. Forty percent of triathletes reported a history of amenorrhea. BMD was normal in the lumbar spine (L2-4) (1.3+/-0.1 g/cm(2)) and total left hip (1.1+/-0.1 g/cm(2)).

CONCLUSIONS

Triathletes are at risk for components of the female athlete triad. Continued efforts need to be directed at prevention through education of athletes, coaches, parents, and health care professionals.

Fruit and vegetable consumption and self-reported functional health in men and women in the European Prospective Investigation into Cancer-Norfolk (EPIC-Norfolk): a population-based cross-sectional study

OBJECTIVES

To investigate the association between fruit and vegetable consumption and self-reported physical and mental functional health measured by an anglicised short-form 36-item questionnaire (UK SF-36).

DESIGN

Population-based cross-sectional study.

SETTING

General community in Norfolk, UK.

SUBJECTS

A total of 16,792 men and women aged 40-79 years recruited from general practice population registers as part of the European Prospective Investigation into Cancer (EPIC)-Norfolk study, who completed food-frequency questionnaires in 1993-1997 and Health and Life Experiences Questionnaires 18 months later, were enrolled in the study.

RESULTS

Mean SF-36 physical component summary scores increased significantly with increasing total fruit and vegetable consumption in both men and women (P < 0.0001 for trend). Men and women in the top quartile of consumption compared with the bottom quartile had a significantly higher likelihood of reporting good physical health (defined as a score > or = 55); odds ratio (OR) 1.30, 95% confidence interval (CI) 1.11-1.53 for men and OR 1.28, 95% CI 1.11-1.48 for women, after controlling for age, body mass index, smoking, education, social class, prevalent illness and total energy intake. Exclusion of current smokers and people with prevalent illness did not alter the associations.

CONCLUSION

Higher fruit and vegetable consumption is associated with better self-reported physical functional health within a general population. Increasing daily intake by two portions of fruit and vegetables was associated with an 11% higher likelihood of good functional health. Since the current average consumption of fruit and vegetables in the UK is about three portions, the recommended 'five a day' strategy may have additional benefit for functional as well as other health outcomes in the population.

Dietary fish intake and plasma phospholipid n-3 polyunsaturated fatty acid concentrations in men and women in the European Prospective Investigation into Cancer-Norfolk United Kingdom cohort

BACKGROUND

The n-3 polyunsaturated fatty acids (n-3 PUFAs) docosahexaenoic acid and eicosapentaenoic acid, found in fish and fish-oil supplements and also formed by conversion of alpha-linolenic acid in soy and rapeseed (canola) oils, are thought to have cardioprotective effects.

OBJECTIVE

Because the relative feasibility and measurement error of dietary methods varies, this study compared fish and fish-oil intakes obtained from 4 dietary methods with plasma n-3 PUFAs in men and women in a general population.

DESIGN

The study participants were 4949 men and women aged 40-79 y from the European Prospective Investigation into Cancer-Norfolk United Kingdom cohort. Measurements of plasma phospholipid n-3 PUFA concentrations and fish intakes were made with the use of 4 dietary methods (food-frequency questionnaire, health and lifestyle questionnaire, 7-d diary, and first-day recall from the 7-d diary).

RESULTS

Amounts of fish consumed and relations with plasma phospholipid n-3 PUFAs were not substantially different between the 4 dietary methods. Plasma n-3 PUFA concentrations were significantly higher in women than in men, were 20% higher in fish-oil consumers than in non-fish-oil consumers, and were twice as high in fatty fish consumers as in total fish consumers. Only approximately 25% of the variation in plasma n-3 PUFA was explained by fish and fish-oil consumption.

CONCLUSIONS

This large study found no substantial differences between dietary methods and observed clear sex differences in plasma n-3 PUFAs. Because variation in n-3 PUFA was only partially determined by fish and fish-oil consumption, this could explain the inconsistent results of observational and intervention studies on coronary artery disease protection.

Gender differences in adherence to the sodium-restricted diet in patients with heart failure

BACKGROUND

Despite the importance of the sodium-restricted diet (SRD) to heart failure (HF) management, patient adherence is poor. Little is known about gender differences in adherence or factors that affect patients' ability to follow SRD recommendations. The purposes of this study were to determine whether there were gender differences in (1) adherence to the SRD; (2) knowledge about SRD and HF self-care; and (3) perceived barriers to following the SRD.

METHODS AND RESULTS

Forty-one men and 27 women completed the Heart Failure Attitudes and Barriers questionnaire that measured HF self-care, knowledge, and perceived barriers to follow an SRD. Diet adherence was measured by 24-hour urinary sodium excretion (UNa). Women were more adherent to the SRD than men as reflected by 24-hour urine excretion (2713 versus 3859 mg UNa, P = .01). Women recognized signs of excess sodium intake such as fluid buildup (P = .001) and edema (P = .01) more often than men and had better understanding of appropriate actions to take related to following an SRD. There were no gender differences in perceived barriers to follow an SRD.

CONCLUSIONS

Although men and women perceived similar barriers, women were more adherent to the SRD and had greater knowledge about following an SRD. Further investigation of this phenomenon is warranted to determine if better adherence contributes to improved outcomes in women.

How much might achievement of diabetes prevention behaviour goals reduce the incidence of diabetes if implemented at the population level?

AIMS/HYPOTHESIS

Randomised trials targeting high-risk people with impaired glucose tolerance have halved progression to diabetes using behavioural interventions aimed at achieving five goals related to weight, diet and physical activity. The number of people currently meeting these goals in the general population is unknown. The potential impact on the incidence of diabetes of increasing the proportion of people who meet these goals is also unclear. We quantified the association between the achievement of behavioural goals for the prevention of diabetes and the incidence of diabetes in a population-based cohort study.

SUBJECTS AND METHODS

European Prospective Investigation into Cancer (EPIC)-Norfolk is a prospective cohort of 24,155 participants aged 40-79 years who attended a baseline health check and completed validated diet and activity questionnaires. We assessed the association between achievement of five diabetes healthy behaviour prevention goals (BMI <25 kg/m(2), fat intake <30% of energy intake, saturated fat intake <10% of energy intake, fibre intake > or =15 g/4,184 kJ, physical activity >4 h/week) and risk of developing diabetes at follow-up (mean 4.6 years).

RESULTS

Only 20% of EPIC participants met three or more diabetes prevention goals. Diabetes incidence was inversely related to the number of goals achieved (p<0.001). None of the participants who met all five goals developed diabetes, whereas diabetes incidence was highest in those who did not meet any goals. If the entire population were able to meet one more goal, the total incidence of diabetes would be predicted to fall by 20%.

CONCLUSIONS/INTERPRETATION

In this population-based study, the risk of diabetes was inversely associated with the number of behaviour goals for diabetes prevention that were met. Interventions that promote achievement of these goals in the general population could significantly reduce the growing burden of diabetes-related morbidity and mortality.

Urinary potassium is as reliable as urinary nitrogen for use as a recovery biomarker in dietary studies of free living individuals

Twenty-four-hour urinary nitrogen (UN) is commonly used to validate dietary assessment methods. Potassium is more widespread in food than nitrogen, but the role of 24-h urinary potassium (UK) as a biomarker has been less studied and characterized. To investigate the performance of UK as a recovery biomarker compared with UN in subjects consuming their normal diet, 7 males and 6 females consumed known amounts of food based on their habitual varying diet (assessed beforehand from 4 consecutive 7-d food diaries) for 30 d in a metabolic suite. All daily urine samples and dietary duplicates were collected, and N and K were measured. Stool K was determined in 5-d pooled samples. Thirty-day mean analyzed K intake was 121.3 +/- 25.1 (mean +/- SD) mmol/d. Overall, 77 +/- 6.7% of K in the diet was excreted in urine and 18 +/- 5% in stool. Dietary K was correlated with UK (r = 0.89; P < 0.001). UN was 77.7 +/- 6.6% of N intake and was correlated with N in the diet (r = 0.87; P < 0.001). When 16 d of intake and 8 d of urine-collection measurements were randomly selected from the 30-d measurements, correlations were significant for both K (r = 0.86; P < 0.001) and N (r = 0.92; P < 0.001). The high correlations between UK and K in the diet show that UK is a reliable recovery biomarker for use in studies of dietary measurement error. Factors for use of urinary N as a recovery biomarker are also confirmed.

Sodium in the Finnish diet: II trends in dietary sodium intake and comparison between intake and 24-h excretion of sodium

OBJECTIVE

To estimate cross-sectional and long-term dietary sodium intakes and sources in Finland, and to evaluate the validity of 48-h recall to assess sodium intake.

DESIGN

Cross-sectional dietary surveys and food availability data (Food Balance Sheets).

SETTING

Dietary surveys were carried out in Finland in 1992, 1997 and 2002. Food availability data were collected from 1980 to 1999.

SUBJECTS

A stratified random sample was drawn from the population register. The total number of participants in the three dietary surveys was 6730. In the subsample for urine collection, the number of participants was 879.

INTERVENTIONS

Nutrient intakes were estimated on the basis of a 3-day food diary in 1992, a 24-h recall in 1997 and a 48-h recall in 2002. The 24-h urinary excretion of sodium was used to validate sodium intake. In addition, salt intake was estimated based on Food Balance Sheets.

RESULTS

Sodium intake has slowly decreased since the early 1980s. Reported daily sodium intake correlated significantly with sodium excretion.

CONCLUSIONS

Sodium intake has decreased during the last two decades, but is still higher than the recommended daily intake. Sodium intake estimation based on dietary surveys and food availability data is a valid method provided that the food composition database is up to date and of good quality.

SPONSORSHIP

All surveys were funded by the National Public Health Institute in Finland and the Ministry of Social Affairs and Health.

Dietary antioxidants and asthma in adults

BACKGROUND

Several antioxidant nutrients have been reported to be inversely associated with asthma. A study was undertaken to assess the independent associations of these nutrients with asthma in adults.

METHODS

A nested case-control study was performed in 515 adults with physician diagnosed asthma and 515 matched controls using dietary data obtained from 7 day food diaries. The main outcome measures were physician diagnosed asthma and current symptomatic asthma (diagnosed asthma and self-reported wheeze within the previous 12 months).

RESULTS

Cases were similar to controls in age, sex, social class, and daily energy intake but had a lower median intake of fruit (132.1 v 149.1 g/day, p< or =0.05). 51.5% of the population reported zero consumption of citrus fruit; relative to these individuals, people who consumed >46.3 g/day had a reduced risk of diagnosed and symptomatic asthma (OR adjusted for potential confounders 0.59 (95% CI 0.43 to 0.82) and 0.51 (95% CI 0.33 to 0.79), respectively). In nutrient analysis, dietary vitamin C and manganese were inversely and independently associated with symptomatic asthma (adjusted OR per quintile increase 0.88 (95% CI 0.77 to 1.00) for vitamin C and 0.85 (95% CI 0.74 to 0.98) for manganese), but only manganese was independently associated with diagnosed asthma (OR 0.86 (95% CI 0.77 to 0.95)). Adjusted plasma levels of vitamin C were significantly lower in symptomatic cases than in controls (54.3 v 58.2 micromol/l, p = 0.003).

CONCLUSIONS

Symptomatic asthma in adults is associated with a low dietary intake of fruit, the antioxidant nutrients vitamin C and manganese, and low plasma vitamin C levels. These findings suggest that diet may be a potentially modifiable risk factor for the development of asthma.

A practical method for collecting 3-day food records in a large cohort

BACKGROUND

Recent studies suggest that diet records are more valid measures of nutrient intake than are food-frequency questionnaires. However, food records are considered unsuitable for large studies due to the need to train participants and to review and correct completed records.

METHODS

We evaluated a self-administered 3-day food record protocol in Washington State. One hundred men and women age 50-76 years were mailed a food record and serving-size booklet. Sixty-five people returned a completed food record and were subsequently interviewed to obtain missing information. The food records were analyzed with and without added information from the interview.

RESULTS

The most common error was incomplete description, which affected 8% of recorded foods. Differences in mean nutrient intake between the uncorrected and corrected records were within 5%, and nutrient estimates from the 2 methods were highly correlated.

CONCLUSIONS

This streamlined protocol yielded data comparable to those collected by more burdensome protocols, suggesting that the use of food records may be feasible in large cohort studies.

Assessment of erythrocyte phospholipid fatty acid composition as a biomarker for dietary MUFA, PUFA or saturated fatty acid intake in a controlled cross-over intervention trial

Background

Dietary intervention trials rely on self-reported measures of intake for assessment of energy and macronutrient composition. Dietary fat intake is of particular interest due to strong associations with pathophysiology. In epidemiological trials phospholipid fatty acid composition may reflect composition of habitual diet, although strong correlations have been identified only for essential polyunsaturated fatty acids (PUFAs). Preliminary evidence shows that saturated fatty acids (SFA) C15:0 and C17:0 may be acceptable biomarkers. This study measured changes in erythrocyte membrane fatty acids during a period of strictly controlled fat feeding to investigate their use as a short-term marker of compliance, particularly for intake of SFAs.

Results

This was a randomised cross-over trial in which diet was provided and strictly controlled. 20 healthy, male subjects were given a 40 energy % (en%) fat diet, high in saturated (high-SFA, 20 en%) or unsaturated (high-USFA, 24 en%) fatty acids for 2 periods of 3 weeks. Subjects were residential during intervention with all food and beverages provided. Dietary composition was verified by direct chemical analysis. Blood samples were collected on days 1,7,14, 21 and analysed for red blood cell (RBC) membrane fatty acid composition. Pearson correlation showed RBC fatty acid composition to mimic dietary composition by 3 weeks, but the relationships were weak. Of the SFAs only RBC C16:0 decreased in response to decreased dietary content on high-USFA treatment (ANOVA, diet, P < 0.05). Of the USFAs, higher levels of C18:1 MUFA, C20:4 and C22:6 long chain PUFA on high-USFA diet lead to higher C18:1, C20:4 and C22:6 within RBCs (ANOVA, time*diet, P < 0.05). Pearson's correlation was significant between dietary and RBC fatty acids during the 21d dietary manipulation for C18:1, and C20:5, C22:6 only (P < 0.05).

Conclusion

RBC membrane fatty acids cannot reliably be used as an independent measure of compliance for dietary SFA intake in short-term studies. The MUFA oleic acid and PUFAs EPA and DHA may be more useful as markers of compliance during short term intervention trials.

Micronutrient intake and the risk of herpes zoster: a case–control study

BACKGROUND

Herpes zoster can seriously impair quality of life and may also be a marker for age-related immune decline (immunosenescence). Diets low in micronutrients may increase the risk of zoster by temporarily compromising cell-mediated immune function or by hastening immunosenescence.

METHODS

Primary objectives were to examine the association between risk of zoster and (i) dietary intake of vitamins A, B(6), C, E, folic acid, zinc, and iron, and (ii) fruit and vegetable consumption. We conducted a community-based case-control study. Cases were adults with incident zoster presenting to 22 general practices in London. Controls were individuals with no zoster history, matched to cases by age, sex, and general practice. Diet was ascertained for 243 cases and 483 controls using an interviewer-administered food-frequency questionnaire. We used conditional logistic regression to estimate odds ratios.

RESULTS

There was a strong graded association between lower fruit intake and increasing zoster risk; in adjusted analysis, individuals who ate less than one piece of fruit per week had more than three times the risk of zoster compared with individuals who ate more than three portions per day. None of the dietary intakes of the seven micronutrients examined had a statistically significant association with zoster risk when considered singly. However, amongst individuals aged >60 years, a measure of combined micronutrient intake and vegetable intake showed similar dose-related associations with zoster risk.

CONCLUSION

A cocktail of nutrients such as those found in fruit and vegetables may act together, particularly in older individuals, to maintain immune health and prevent zoster.

Plasma ascorbic acid concentrations and fat distribution in 19,068 British men and women in the European Prospective Investigation into Cancer and Nutrition Norfolk cohort study

BACKGROUND

Antioxidants, such as ascorbic acid, play a role in scavenging free radicals to protect against oxidative endothelial damage. Excess fat may promote fatty acid oxidation and increase free radical concentrations, which could result in increased antioxidant use. Whether plasma ascorbic acid concentrations are associated with fat distribution remains unclear.

OBJECTIVE

Our aim was to examine the association between abdominal obesity, as measured by the waist-to-hip ratio, and plasma ascorbic acid concentrations in the general population.

DESIGN

We examined the cross-sectional relation between anthropometric measurements of fat distribution and plasma ascorbic acid concentrations in 19 068 men and women aged 45-79 y without known chronic illness. Dietary ascorbic acid intake was estimated for a subgroup of 8178 men and women who kept 7-d food diaries coded for nutrient intake.

RESULTS

The waist-to-hip ratio was inversely related to plasma ascorbic acid concentrations in both men and women. This association was independent of body mass index, age, vitamin supplement use, cigarette smoking, and socioeconomic group. Waist and hip circumferences showed separate and opposite associations with plasma ascorbic acid concentrations, independent of body mass index and other covariates. Dietary ascorbic acid intake only partly explained the observed associations.

CONCLUSIONS

Plasma ascorbic acid was associated with fat distribution independent of body mass index. Differences in dietary intake and lifestyle habits, underlying systemic oxidative stress, or both may explain the inverse relation between fat distribution and plasma ascorbic acid concentrations. Additional studies are needed to determine the underlying explanation of these observations.