Associations between dietary patterns and blood pressure in a sample of Australian adults

BACKGROUND

Investigating effects of whole diets on blood pressure (BP) can contribute to development of diet-based recommendations for health. Our aim was to assess the relationship between dietary patterns and BP in a sample of free-living Australian adults.

METHODS

Usual dietary patterns of participants recruited to dietary intervention studies were assessed using factor analysis (two 24-h recalls). The mean of seven days of daily, seated BP measurements were used.

RESULTS

Complete data from 251 participants (112 males; mean age 55.1(9.1) (SD) years; body mass index (BMI) 29.5(3.9) kg/m²) was included. Three dietary patterns were identified. Only Dietary Pattern 2 was positively associated with home systolic BP (β = 1.88, 95% CI 0.16, 3.60) after adjusting for age, sex, BMI, anti-hypertensive medication, smoking, education, physical activity and energy intake. This dietary pattern was characterised by high consumption of low-fibre bread, pasta, noodles and rice, meat dishes, poultry dishes and egg dishes, mixed cereal dishes, salted nuts and low consumption of milk and yoghurt (low-fat), vegetable juice, vegetables and high-fibre bread. Dietary Pattern 2 was also positively associated with intakes of energy (P = 0.002) and sodium (P = 0.005) and inversely associated with potassium intake (P = 0.002). After adjustment for energy, only the inverse association with potassium remained (P <  0.001).

CONCLUSIONS

In this sample of Australian adults, Dietary Pattern 2 was associated with higher BP and thus chronic disease risk, supporting the evidence that diets high in energy and sodium, and low in potassium from vegetables and dairy, are detrimental to cardiovascular health.

The association between perceived sweetness intensity and dietary intake in young adults

Individual differences in taste perception may influence dietary habits, nutritional status, and ultimately nutrition-related chronic disease risk. Individual differences in sweetness intensity perception and the relationship between perceived sweetness intensity, food behaviors, and dietary intake was investigated in 85 adults. Subjects (body mass index [BMI]= 21 ± 3, 21 ± 4 y) completed a food and diet questionnaire, food variety survey, 2 24-h food records, and a perceived sweetness intensity measurement using the general labeled magnitude scale (gLMS). There was interindividual variation in perceived sweetness intensity (0 to 34 gLMS units, mean 10 ± 7). One-way analysis of variance (ANOVA) revealed no difference between perceived sweetness intensity and degree of importance placed on not adding sugar to tea or coffee (P = 0.2) and the degree of importance placed on avoiding sugar-sweetened or fizzy drinks (P = 1.0). Independent t-test analysis revealed no significant association between perceived sweetness intensity and the food variety measure for sugar and confectionary intake (P = 0.6) and selected fruit and vegetable intake (P = 0.1 to 0.9). One-way ANOVA also demonstrated no difference between tertiles of sweetness intensity and BMI (P = 0.1), age (P = 0.3), and food variety score (P = 0.5). No correlation was observed with regards to perceived sweetness intensity and mean total energy (kJ) intake (r = 0.05, P = 0.7), percent energy from total fat, saturated fat, protein, carbohydrate, and grams of fiber (r =-0.1 to 0.1, P = 0.2 to 0.8) and also for intake of the micronutrients: folate, magnesium, calcium, iron, and zinc (r = 0.1 to 0.2, P = 0.1 to 0.4). Only modest correlations were observed between sodium (r = 0.3, P < 0.05), vitamin C (r = 0.3, P < 0.05), and potassium (r = 0.2, P < 0.0) intake and perceived sweetness intensity. Overall, perceived sweetness intensity does not appear to play a role in food behaviors relating to sugar consumption and dietary intake in adults.

The influence of caffeine on energy content of sugar-sweetened beverages: 'the caffeine-calorie effect'

BACKGROUND/OBJECTIVES

Caffeine is a mildly addictive psychoactive chemical and controversial additive to sugar-sweetened beverages (SSBs). The objective of this study is to assess if removal of caffeine from SSBs allows co-removal of sucrose (energy) without affecting flavour of SSBs, and if removal of caffeine could potentially affect population weight gain.

SUBJECTS/METHODS

The research comprised of three studies; study 1 used three-alternate forced choice and paired comparison tests to establish detection thresholds for caffeine in water and sucrose solution (subjects, n=63), and to determine if caffeine suppressed sweetness. Study 2 (subjects, n=30) examined the proportion of sucrose that could be co-removed with caffeine from SSBs without affecting the flavour of the SSBs. Study 3 applied validated coefficients to estimate the impact on the weight of the United States population if there was no caffeine in SSBs.

RESULTS

Detection threshold for caffeine in water was higher (1.09 ± 0.08  mM) than the detection threshold for caffeine in sucrose solution (0.49 ± 0.04  mM), and a paired comparison test revealed caffeine significantly reduced the sweetness of sucrose (P<0.001). Removing caffeine from SSBs allowed co-removal of 10.3% sucrose without affecting flavour of the SSBs, equating to 116 kJ per 500  ml serving. The effect of this on body weight in adults and children would be 0.600 and 0.142  kg, which are equivalent to 2.08 and 1.10 years of observed existing trends in weight gain, respectively.

CONCLUSION

These data suggest the extra energy in SSBs as a result of caffeine's effect on sweetness may be associated with adult and child weight gain.

The effect of training in reduced energy density eating and food self-monitoring accuracy on weight loss maintenance

BACKGROUND

Failure to maintain weight losses in lifestyle change programs continues to be a major problem and warrants investigation of innovative approaches to weight control.

OBJECTIVE

The goal of this study was to compare two novel group interventions, both aimed at improving weight loss maintenance, with a control group.

METHODS AND PROCEDURES

A total of 103 women lost weight on a meal replacement-supplemented diet and were then randomized to one of three conditions for the 14-week maintenance phase: cognitive-behavioral treatment (CBT); CBT with an enhanced food monitoring accuracy (EFMA) program; or these two interventions plus a reduced energy density eating (REDE) program. Assessments were conducted periodically through an 18-month postintervention. Outcome measures included weight and self-reported dietary intake. Data were analyzed using completers only as well as baseline-carried-forward imputation.

RESULTS

Participants lost an average of 7.6 +/- 2.6 kg during the weight loss phase and 1.8 +/- 2.3 kg during the maintenance phase. Results do not suggest that the EFMA intervention was successful in improving food monitoring accuracy. The REDE group decreased the energy density (ED) of their diets more so than the other two groups. However, neither the REDE nor the EFMA condition showed any advantage in weight loss maintenance. All groups regained weight between 6- and 18-month follow-ups.

DISCUSSION

Although no incremental weight maintenance benefit was observed in the EFMA or EFMA + REDE groups, the improvement in the ED of the REDE group's diet, if shown to be sustainable in future studies, could have weight maintenance benefits.

Body weight and weight loss: are health messages reaching their target?

OBJECTIVE

To investigate lay peoples' knowledge of health risks of overweight, accuracy of self-perception of body weight and perceived benefits of weight loss.

METHOD

A nine item questionnaire was administered to a cross sectional survey of adults in metropolitan shopping centres, height and weight were measured.

RESULTS

Two hundred and nine (57% female) adults completed the survey. Thirty eight percent had a healthy BMI (18.5-24.9), 38% were overweight (BMI 25-29.9) and a further 22% were obese (BMI > 30). However only 46% perceived themselves 'overweight', 50% considered themselves 'just about right' and 4% considered themselves 'underweight'. Of those with a BMI of 25 or greater 28% considered their weight 'just about right'. Over 80% thought 'being overweight' was 'likely' or 'very likely' to be a risk factor for cardiovascular disease, hypertension, diabetes and stroke; however 20% of overweight or obese individuals did not think their health would improve if they lost weight.

CONCLUSION

A significant proportion of overweight or obese individuals do not accurately perceive their body weight and do not recognise the health advantages of weight loss despite recognising excess body weight as a risk factor for chronic diseases.

IMPLICATIONS

Increasing the awareness of an individual's BMI and promoting the benefits of modest weight loss maybe two underutilized strategies for population level weight control.

Caffeine as a flavor additive in soft-drinks

Over 60% of soft-drinks sold in the United States contain caffeine, a mildly addictive psycho-active chemical, as a flavor additive. Using sweeteners as controls, we assessed whether caffeine has flavor activity in a cola soft-drink. A forced-choice triangle discrimination methodology was used to determine detection thresholds of caffeine in sweeteners and a cola beverage. The subjects (n=30, 28 female, 23+/-4 years old) were trained tasters and completed over 1600 discrimination tests during the study. The mean detection thresholds for caffeine in the sweet solutions were: 0.333+/-0.1mM sucrose; 0.467+/-0.29 mM aspartame; 0.462+/-0.3mM sucralose, well below the concentration in common cola beverages (0.55-0.67 mM). A fixed concentration of caffeine, corresponding to the concentration of caffeine in a common cola beverage (0.67 mM) was added to the sweeteners and a non-caffeinated cola beverage. Subjects could distinguish between caffeinated and non-caffeinated sweeteners (p<0.001), but all subjects failed to distinguish between caffeinated and non-caffeinated cola beverage (p=1.0). Caffeine has no flavor activity in soft-drinks yet will induce a physiologic and psychologic desire to consume the drink.

Dietary counseling to increase natural folate intake: a randomized, placebo-controlled trial in free-living subjects to assess effects on serum folate and plasma total homocysteine

BACKGROUND

The association between vascular disease and elevated plasma total homocysteine (tHcy) concentrations is caused, in part, by inadequate intakes of dietary folate. Increasing folate intake either through supplements or foods naturally rich in folates has been shown to decrease tHcy concentrations.

OBJECTIVE

The aim of this study was to determine whether a similar reduction in tHcy was possible in free-living persons receiving dietary counseling.

DESIGN

The study included a 4-wk placebo-controlled dietary intervention trial in which participants consumed either unfortified breakfast cereal (control group) or an extra 350 micro g folate derived from food/d (dietary group). Serum folate and tHcy concentrations in both groups were measured before and after the intervention period, and the concentrations in the dietary group were also measured 17 wk after the intervention period.

RESULTS

During the 4-wk intervention, mean dietary folate intake in the dietary group increased from 263 (95% CI: 225, 307) to 618 micro g/d (535, 714), resulting in a mean increase in serum folate of 37% (15%, 63%) and a decrease in tHcy from 12.0 (10.9, 13.3) to 11.3 micro mol/L (10.2, 12.5). A further decrease in tHcy occurred in the dietary group during follow-up, with a final tHcy concentration of 9.7 micro mol/L (8.8, 10.8).

CONCLUSIONS

Increasing natural folate intake improved folate status and decreased tHcy concentrations to an extent that may significantly reduce the risk of vascular disease. Dietary modification may have advantages over folic acid fortification because the altered food-consumption patterns lead to increased intakes of several vitamins and minerals and decreased intakes of saturated fatty acids.

Assessment of three levels of folic acid on serum folate and plasma homocysteine: a randomised placebo-controlled double-blind dietary intervention trial

OBJECTIVE

To determine the minimum effective dose of folic acid required to appreciably increase serum folate and to produce a significant reduction in plasma total homocysteine (tHcy).

DESIGN

Double-blind, randomised placebo-controlled intervention trial.

SETTING

Community-based project in a New Zealand city.

SUBJECTS

Seventy free living men and women with tHcy> or =10 micromol/l. Mean age (range) was 58 (29-90) y.

INTERVENTIONS

Daily consumption over 4 weeks of 20 g breakfast cereal either unfortified (placebo) or fortified with 100, 200 or 300 microg folic acid. Dietary intake was determined by weighed diet records and consumption of commercially fortified products was avoided.

MAIN OUTCOME MEASURES

Plasma tHcy and serum folate concentrations.

RESULTS

Average serum folate concentrations (95% CI) increased significantly in the treatment groups relative to the control group by 28(9-51)%, 60(37-87)% and 79(51-114)% for supplementation with 100, 200 and 300 microg folic acid, respectively. A reduction in tHcy was observed, being 16(8-22)%, 12(4-18)% and 17(9-24)% in the three treatment groups, respectively.

CONCLUSIONS

A regular intake of as little as 100 microg folic acid per day was sufficient to lower tHcy in persons at the upper end of the normal range for tHcy. Low-level fortification may also be appropriate for lowering the risk of neural tube defects given that, when aggregated from all sources, the total intake of folic acid may be sufficiently high to adequately improve the folate status of young women.

Dietary strategies for lowering homocysteine concentrations

BACKGROUND

Elevated plasma total homocysteine (tHcy) concentrations are associated with increased risk of vascular disease, and there is a strong inverse association between dietary and blood folate and blood tHcy concentrations. Increased folate consumption may lower the risk of tHcy-mediated cardiovascular disease.

OBJECTIVES

The objective was to determine the most appropriate means of increasing dietary folate to reduce plasma tHcy.

DESIGN

Sixty-five free-living subjects aged 36-71 y with tHcy concentrations >/=9 micromol/L participated in a randomized, controlled trial to compare 3 approaches for increasing dietary folate to approximately 600 microg/d: folic acid supplementation, consumption of folic acid-fortified breakfast cereals, and increased consumption of folate-rich foods.

RESULTS

An intake of 437 microg folic acid/d from supplements resulted in a 27-nmol/L increase in serum folate and a 21% reduction in tHcy, relative to the change in a control group. In subjects who consumed folic acid-fortified breakfast cereal, folate intake increased by an average of 298 microg, serum folate increased by 21 nmol/L, and tHcy concentrations decreased by 24%. Increased intakes of folate-rich foods resulted in a 418-microg increase in dietary folate, a 7-nmol/L increase in serum folate, and a 9% reduction in tHcy concentrations. The decrease in tHcy was negatively correlated (r = -0.66) with the increase in serum folate.

CONCLUSIONS

Daily consumption of folic acid-fortified breakfast cereals and the use of folic acid supplements appear to be the most effective means of reducing tHcy concentrations. The reduction in tHcy was significantly negatively correlated with the increase in serum folate, which may be a useful marker for measuring dietary change.

Homocysteine levels in healthy New Zealanders and those with vascular disease

AIMS

Levels of plasma homocysteine (tHcy) have been shown to vary between populations. The aim of the present study was to determine tHcy levels in a New Zealand population to facilitate interpretation of international reference ranges.

METHODS

Fasting tHcy levels were determined in 431 volunteer men and women, aged between 17 and 83 years, from the greater Otago region. Subjects with self-reported incidences of vascular disease (n=138) were compared with healthy control subjects (n=293).

RESULTS

Mean (SD) fasting tHcy level of the entire population was 8.3(3.5) micromol/L and men had significantly higher levels than women (9.0(3.4) and 7.8(3.5) micromol/L, respectively, p<0.05). Levels increased significantly with increasing age (0.5 micromol/L for every ten years). There was a small but non-significant difference in tHcy levels between subjects with and without vascular disease (difference after excluding two outliers and adjusting for age and gender; 0.63, 95% CI, -0.03,1.29). tHcy levels were not significantly correlated with lipid or lipoprotein levels.

CONCLUSION

Levels of tHcy in a group of volunteers from the greater Otago region were similar to those reported in other populations at high risk of cardiovascular disease. Reference ranges derived from these populations would appear to be applicable for New Zealanders. tHcy measurements should be made when assessing individuals at high risk of vascular disease and intervention strategies considered.