Association between vegetarian diets and cardiovascular risk factors in non-Hispanic white participants of the Adventist Health Study-2.

The association between dietary patterns and CVD risk factors among non-Hispanic whites has not been fully studied. Data from 650 non-Hispanic white adults who participated in one of two clinical sub-studies (about 2 years after the baseline) of the Adventist Health Study-2 (AHS-2) were analysed. Four dietary patters were identified using a validated 204-item semi-quantitative FFQ completed at enrolment into AHS-2: vegans (8·3 %), lacto-ovo-vegetarians (44·3 %), pesco-vegetarians (10·6 %) and non-vegetarians (NV) (37·3 %). Dietary pattern-specific prevalence ratios (PR) of CVD risk factors were assessed adjusting for confounders with or without BMI as an additional covariable. The adjusted PR for hypertension, high total cholesterol and high LDL-cholesterol were lower in all three vegetarian groups. Among the lacto-ovo-vegetarians the PR were 0·57 (95 % CI 0·45, 0·73), 0·72 (95 % CI 0·59, 0·88) and 0·72 (95 % CI 0·58, 0·89), respectively, which remained significant after additionally adjusting for BMI. The vegans and the pesco-vegetarians had similar PR for hypertension at 0·46 (95 % CI 0·25, 0·83) and 0·62 (95 % CI 0·42, 0·91), respectively, but estimates were attenuated and marginally significant after adjustment for BMI. Compared with NV, the PR of obesity and abdominal adiposity, as well as other CVD risk factors, were significantly lower among the vegetarian groups. Similar results were found when limiting analyses to participants not being treated for CVD risk factors, with the vegans having the lowest mean BMI and waist circumference. Thus, compared with the diet of NV, vegetarian diets were associated with significantly lower levels of CVD risk factors among the non-Hispanic whites.

Effects of walnut consumption on cognitive performance in young adults.

Walnuts contain a number of potentially neuroprotective compounds like vitamin E, folate, melatonin, several antioxidative polyphenols and significant amounts of n-3 α-linolenic fatty acid. The present study sought to determine the effect of walnuts on verbal and non-verbal reasoning, memory and mood. A total of sixty-four college students were randomly assigned to two treatment sequences in a crossover fashion: walnuts-placebo or placebo-walnuts. Baseline data were collected for non-verbal reasoning, verbal reasoning, memory and mood states. Data were collected again after 8 weeks of intervention. After 6 weeks of washout, the intervention groups followed the diets in reverse order. Data were collected once more at the end of the 8-week intervention period. No significant increases were detected for mood, non-verbal reasoning or memory on the walnut-supplemented diet. However, inferential verbal reasoning increased significantly by 11.2 %, indicating a medium effect size (P = 0.009; d = 0.567). In young, healthy, normal adults, walnuts do not appear to improve memory, mood or non-verbal reasoning abilities. However, walnuts may have the ability to increase inferential reasoning.

Correlations between estimated and true dietary intakes.

PURPOSE: It is unclear how well questionnaire or so-called reference methods of dietary assessment correlate with true dietary intake. We develop a method to estimate such correlations. METHODS: An error model is described that uses data from a food frequency questionnaire (Q), a reference method (R), and a biological marker (M). The model does not assume the classical error model for either R or M, or that the correlation between errors in the questionnaire and reference data is zero. Credible intervals can be placed about correlations between R, Q, M and true dietary data (T), also about the correlations between errors in reference and questionnaire data. RESULTS: Application of this model to a validation data set mainly found correlations in the range 0.4 to 0.8, and that correlations (R,T) generally exceeded correlations (Q,T), providing evidence that R is more valid than Q. Estimated correlations between errors in R and Q were often far from zero suggesting that regression calibration to imperfect reference data is problematic unless these error correlations can be estimated. CONCLUSION: A biological marker in addition to dietary data, allows calculation of correlations between estimated and true dietary intakes under reasonable assumptions about errors. However, sensitivity analyses are necessary on one variable.

Comparison of adipose tissue fatty acids with dietary fatty acids as measured by 24-hour recall and food frequency questionnaire in Black and White Adventists: the Adventist Health Study.

PURPOSE: To calibrate and compare intake of different fats and individual fatty acids as assessed with a food frequency questionnaire (FFQ) against that estimated with (i) a series of dietary recalls and; (ii) the relative fat concentration in an adipose tissue biopsy. The FFQ was specially designed for use in a cohort of Seventh-day Adventists. In preparation for a large cohort study investigating the effect of diet on risk of colon, prostate and breast cancer. METHODS: The association of adipose tissue fatty acids and dietary fat intake was assessed in 49 black and 72 white Seventh-day Adventists subjects using 8 different 24-hour recalls, a 200-item food frequency questionnaire (FFQ) and adipose tissue biopsies from each subject. RESULTS: Pearson correlation between fatty acids in adipose tissue and dietary intake as assessed by multiple 24-hour recalls were as follows: Linoleic acid: 0.77 in black and 0.71 in white subjects, respectively; Linolenic acid: 0.68 (blacks) and 0.62 (whites); Total Polyunsaturated fat (PUFA): 0.78 (blacks) and 0.70 (whites); Total Monounsaturated fat (MUFA): 0.35 (blacks) and 0.03 (whites); Total Saturated fat (SFA): 0.46 (blacks) and 0.56 (whites). Correlations between fatty acids in adipose tissue and dietary intake as assessed by FFQ were: Linoleic acid: 0.61 (blacks) and 0.52 (whites), respectively; Linolenic acid: 0.29 (blacks) and 0.49 (whites); PUFA: 0.62 (blacks) and 0.53 (whites); MUFA: 0.07 (blacks) and 0.31 (whites), SFA: 0.21 (blacks) and 0.31 (whites). CONCLUSIONS: Our study confirms findings of others that 24-hour recalls are valid for assessing dietary intake of different types of fat. The FFQ we developed and used in this study gave reasonably valid measures of fatty acid intake in our population and is thus suitable for use in large cohort studies. It had validity comparable to that observed for other FFQs.