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1.  Evaluation of a Validated Food Frequency Questionnaire for Self-Defined Vegans in the United States 
Nutrients  2014;6(7):2523-2539.
This study aimed to develop and validate a de novo food frequency questionnaire for self-defined vegans in the United States. Diet histories from pilot samples of vegans and a modified ‘Block Method’ using seven selected nutrients of concern in vegan diet patterns, were employed to generate the questionnaire food list. Food frequency responses of 100 vegans from 19 different U.S. states were obtained via completed mailed questionnaires and compared to multiple telephone-conducted diet recall interviews. Computerized diet analyses were performed. Correlation coefficients, t-tests, rank, cross-tabulations, and probability tests were used to validate and compare intake estimates and dietary reference intake (DRI) assessment trends between the two methods. A 369-item vegan-specific questionnaire was developed with 252 listed food frequency items. Calorie-adjusted correlation coefficients ranged from r = 0.374 to 0.600 (p < 0.001) for all analyzed nutrients except calcium. Estimates, ranks, trends and higher-level participant percentile placements for Vitamin B12 were similar with both methods. Questionnaire intakes were higher than recalls for most other nutrients. Both methods demonstrated similar trends in DRI adequacy assessment (e.g., significantly inadequate vitamin D intake among vegans). This vegan-specific questionnaire can be a useful assessment tool for health screening initiatives in U.S. vegan communities.
PMCID: PMC4113754  PMID: 25006856
vegans; food frequency questionnaire; diet recalls; nutrient intake; Dietary Reference Intakes; vegan questionnaire; vegetarians; vitamin D; vitamin B12
2.  Effects of supplementing n-3 fatty acid enriched eggs and walnuts on cardiovascular disease risk markers in healthy free-living lacto-ovo-vegetarians: a randomized, crossover, free-living intervention study 
Nutrition Journal  2014;13:29.
Plant and marine n-3 fatty acids (FA) may favorably modify select markers of cardiovascular disease risk. Whether supplementing the habitual diet of lacto-ovo-vegetarians (LOV) with walnuts (containing α-linolenic acid, ALA) and n-3 FA enriched eggs (containing primarily docosahexaenoic acid, DHA and ALA) would have equivalent effects on CVD risk factors is explored in this study.
In this study, 20 healthy free-living LOVs following their habitual diet were randomly assigned in a crossover design to receive one of three supplements: n-3 FA enriched egg (6/week), walnuts (28.4 g, 6/week) or a standard egg, 6/week (control) for 8 weeks each with 4-wk washout between treatments. Erythrocyte membrane fatty acids, serum lipids and inflammatory markers were measured at the end of each treatment.
Dietary compliance was observed by an expected increase in erythrocyte membrane ALA following the walnut treatment and in DHA following the n-3 FA enriched egg treatment. Walnut treatment lowered serum triacylglycerol, total cholesterol and Apo B (p < 0.05) compared to the standard egg but not the n-3 FA enriched egg treatment. However, walnut treatment significantly reduced total: HDL cholesterol ratio compared to both egg treatments. There were no differences between treatments for any of the inflammatory markers.
For LOV, a direct source of DHA such as n-3 FA enriched eggs seems necessary to increase membrane levels of DHA. However for producing an overall favorable blood lipid profile, daily consumption of a handful of walnuts rich in ALA may be a preferred option for lacto-ovo vegetarian.
PMCID: PMC4001106  PMID: 24673793
Walnuts; n-3 fatty acid enriched eggs; Lacto-ovo vegetarians; Cardiovascular risk factors; Eggs; Inflammation markers; Blood lipids
3.  Effect of a walnut meal on postprandial oxidative stress and antioxidants in healthy individuals 
Nutrition Journal  2014;13:4.
In vitro studies rank walnuts (Juglans regia) among the plant foods high in antioxidant capacity, but whether the active constituents of walnuts are bioavailable to humans remains to be determined. The intention of this study was to examine the acute effects of consuming walnuts compared to refined fat on meal induced oxidative stress. At issue is whether the ellagitannins and tocopherols in walnuts are bioavailable and provide postprandial antioxidant protection.
A randomized, crossover, and controlled-feeding study was conducted to evaluate a walnut test meal compared to one composed of refined ingredients on postprandial serum antioxidants and biomarkers of oxidative status in healthy adults (n = 16) with at least 1 week between testing sessions. Following consumption of a low phenolic diet for one day and an overnight fast, blood was sampled prior to the test meals and at intervals up to 24 hours post ingestion and analyzed for total phenols, malondiadehyde (MDA), oxidized LDL, ferric reducing antioxidant power (FRAP), hydrophilic and lipophilic oxygen radical absorbance capacity (ORAC), uric acid, catechins and urinary excretion of phenylacetate metabolites and of urolithin A.
Mixed linear models demonstrated a diet effect (P < 0.001) for plasma γ-tocopherol but not for α-tocopherol with the walnut meal. Following the walnut test meal, the incremental 5 hour area under the curve (AUC0-5h) was reduced 7.4% for MDA, increased 7.5% for hydrophilic and 8.5% for lipophilic ORAC and comparable for total phenols, FRAP and uric acid. Oxidized LDL was reduced at 2 hours after the walnut meal. Plasma concentrations of gallocatechin gallate (GCG), epicatechin gallate (ECG) and epicallocatechin gallate (EGCG) increased significantly at 1 hour after the walnut test meal. Quantities of urolithin-A excreted in the urine were significantly higher following the walnut meal.
Compared to the refined control meal, the walnut meal acutely increased postprandial γ-tocopherol and catechins and attenuated some measures of oxidative stress.
PMCID: PMC3893411  PMID: 24410903
Walnuts; Oxidative stress; γ-tocopherol; Catechins; Urolithin A
4.  Tree Nuts Are Inversely Associated with Metabolic Syndrome and Obesity: The Adventist Health Study-2 
PLoS ONE  2014;9(1):e85133.
To examine the relationships of nut consumption, metabolic syndrome (MetS), and obesity in the Adventist Health Study-2, a relatively healthy population with a wide range of nut intake.
Research Design and Methods
Cross-sectional analysis was conducted on clinical, dietary, anthropometric, and demographic data of 803 adults. MetS was defined according to the American Heart Association and the National Heart, Lung, and Blood Institute diagnostic criteria. We assessed intake of total nuts, tree nuts and peanuts, and also classified subjects into low tree nut/low peanut (LT/LP), low tree/high peanut (LT/HP), high tree nut/high peanut (HT/HP), and high tree/low peanut (HT/LP) consumers. Odds ratios were estimated using multivariable logistic regression.
32% of subjects had MetS. Compared to LT/LP consumers, obesity was lower in LT/HP (OR = 0.89; 95% CI = 0.53, 1.48), HT/HP (OR = 0.63; 95% CI = 0.40, 0.99) and HT/LP (OR = 0.54; 95% CI = 0.34, 0.88) consumers, p for trend = 0.006. For MetS, odds ratios (95% CI) were 0.77 (0.47, 1.28), 0.65 (0.42, 1.00) and 0.68 (0.43, 1.07), respectively (p for trend = 0.056). Frequency of nut intake (once/week) had significant inverse associations with MetS (3% less for tree nuts and 2% less for total nuts) and obesity (7% less for tree nuts and 3% less for total nuts).
Tree nuts appear to have strong inverse association with obesity, and favorable though weaker association with MetS independent of demographic, lifestyle and dietary factors.
PMCID: PMC3885676  PMID: 24416351
5.  A randomized 3x3 crossover study to evaluate the effect of Hass avocado intake on post-ingestive satiety, glucose and insulin levels, and subsequent energy intake in overweight adults 
Nutrition Journal  2013;12:155.
The behavioral outcome of food ingestion is a complex process that involves psychological and biological factors. Avocados are nutrient dense with properties that may favorably impact energy balance. This study sought to evaluate if incorporating approximately one half of a Hass avocado by addition or inclusion into a lunch meal will influence post-ingestive satiety, glucose and insulin response, and subsequent energy intake among overweight adults.
This was a randomized 3x3 single-blind crossover design study with 26 healthy overweight adults (mean ±SD age 40.8±11.0 years and BMI 28.1±2.4 kg/m2). Participants consumed a standardized breakfast followed by 1 of 3 lunch test meals [Control (C), avocado-free; Avocado Inclusive (AI); and, Avocado Added (AA)]. Participants rated five appetite sensations using a visual analog scale (VAS) before lunch and at specific intervals over 5 hours following the start of the test meal. Blood glucose and insulin were measured before lunch and at specific intervals over 3 hours following the start of the test meal. Mixed models were used to compare differences among the 3 test meals, and the area under the curve (AUC0-xh) was computed for the VAS and biological measures.
There were significant differences in the AUC(0-5h) for the self-reported feelings of satisfaction (P=0.04) and desire to eat (P=0.05) in the mixed model analysis. Compared to the C test meal, the AA test meal increased satisfaction by 23% (P=0.05) and decreased the desire to eat by 28% (P=0.04) for the AUC(0-5h). For the AUC(0-3h), the AA test meal increased satisfaction by 26% (P=0.02) and decreased the desire to eat by 40% (P=0.01) as compared to the C test meal. Compared to the AI meal, the AUC(0-3h) for blood insulin was higher in the C and AA meals (P=0.04 and P=0.05, respectively).
The addition of approximately one half of a Hass avocado at a lunch meal can influence post-ingestive satiety over a subsequent 3 and 5 hour period in overweight adults. A caveat to these findings is that the avocado contained an additional 112 kcal, which may have accounted for the observed increase in satisfaction and decreased desire to eat. Future trials are warranted to evaluate the effects of avocado intake on weight management in adults of varying BMIs and among insulin resistant individuals.
PMCID: PMC4222592  PMID: 24279738
Avocado; Satiety; Overweight; Glucose; Insulin; Visual analog scale; Dietary compensation
6.  Race-specific validation of food intake obtained from a comprehensive FFQ: the Adventist Health Study-2 
Public health nutrition  2011;14(11):1988-1997.
To assess race-specific validity of food and food group intakes measured using an FFQ.
Calibration study participants were randomly selected from the Adventist Health Study-2 (AHS-2) cohort by church, and then by subject-within-church. Intakes of forty-seven foods and food groups were assessed using an FFQ and then compared with intake estimates measured using six 24 h dietary recalls (24HDR). We used two approaches to assess the validity of the questionnaire: (i) cross-classification by quartile and (ii) de-attenuated correlation coefficients.
Seventh-day Adventist church members geographically spread throughout the USA and Canada.
Members of the AHS-2 calibration study (550 whites and 461 blacks).
The proportion of participants with exact quartile agreement in the FFQ and 24HDR averaged 46% (range: 29–87%) in whites and 44% (range: 25–88%) in blacks. The proportion of quartile gross misclassification ranged from 1 % to 11 % in whites and from 1 % to 15% in blacks. De-attenuated validity correlations averaged 0·59 in whites and 0·48 in blacks. Of the forty-seven foods and food groups, forty-three in whites and thirty-three in blacks had validity correlations >0·4.
The AHS-2 questionnaire has good validity for most foods in both races; however, validity correlations tend to be higher in whites than in blacks.
PMCID: PMC3433053  PMID: 21557864
Epidemiological methods; Ethnic groups; Questionnaires; Validation studies
7.  Determinants of Inflammatory Markers in a Bi-ethnic Population 
Ethnicity & disease  2011;21(2):142-149.
Inflammation is a common pathophysiological pathway for a number of chronic diseases, and is strongly influenced by sociodemographic factors and lifestyle. Less is known about factors that may influence the inflammatory response in individuals of distinct ethnic backgrounds. Therefore, this study examined the relationship between ethnicity and blood levels of inflammatory markers in a sample of non-smoking church-goers.
In a cross-sectional investigation, 508 men and women (>35 years old, 62% White, 38% Black) participated in the Biopsy-chosocial Religion and Health substudy of the Adventist Health Study 2. The contribution of socioeconomic status (education level and difficulty meeting expenses for basic needs) and health covariates (exercise, vegetarian or other type of diet, body mass index, and presence of inflammatory conditions) toward serum levels of C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) was assessed with linear regression models. Levels of interleukin-10 (IL-10), an anti-inflammatory marker, were also assessed.
Blacks showed higher levels of CRP and IL-6 than Whites. Controlling for socio-demographic and health variables attenuated the ethnic difference in CRP while IL-6 levels remained higher in Blacks than in Whites (β=.118; 95% confidence interval=.014–.206; P=.025). Ethnic differences in IL-10 and TNF-α were not found. Vegetarian diet was associated with lower CRP levels while exercise frequency was associated with higher IL-10 levels.
Higher susceptibility of Blacks to inflammatory diseases may reflect higher IL-6, which could be important in assessing health disparities among Blacks and Whites. Vegetarian diet and exercise may counteract effects of disparities.
PMCID: PMC3427005  PMID: 21749016
Inflammatory Markers; Ethnicity; Health Behavior; Adventists
8.  Validation of nutrient intake using an FFQ and repeated 24 h recalls in black and white subjects of the Adventist Health Study-2 (AHS-2) 
Public health nutrition  2009;13(6):812-819.
To validate a 204-item quantitative FFQ for measurement of nutrient intake in the Adventist Health Study-2 (AHS-2).
Calibration study participants were randomly selected from the AHS-2 cohort by church, and then subject-within-church. Each participant provided two sets of three weighted 24 h dietary recalls and a 204-item FFQ. Race-specific correlation coefficients (r), corrected for attenuation from within-person variation in the recalls, were calculated for selected energy-adjusted macro- and micronutrients.
Adult members of the AHS-2 cohort geographically spread throughout the USA and Canada.
Calibration study participants included 461 blacks of American and Caribbean origin and 550 whites.
Calibration study subjects represented the total cohort very well with respect to demographic variables. Approximately 33 % were males. Whites were older, had higher education and lower BMI compared with blacks. Across fifty-one variables, average deattenuated energy-adjusted validity correlations were 0·60 in whites and 0·52 in blacks. Individual components of protein had validity ranging from 0·40 to 0·68 in blacks and from 0·63 to 0·85 in whites; for total fat and fatty acids, validity ranged from 0·43 to 0·75 in blacks and from 0·46 to 0·77 in whites. Of the eighteen micronutrients assessed, sixteen in blacks and sixteen in whites had deattenuated energy-adjusted correlations ≥0·4, averaging 0·60 and 0·53 in whites and blacks, respectively.
With few exceptions validity coefficients were moderate to high for macronutrients, fatty acids, vitamins, minerals and fibre. We expect to successfully use these data for measurement error correction in analyses of diet and disease risk.
PMCID: PMC3417357  PMID: 19968897
Epidemiological methods; Ethnic groups; Questionnaires; Validation studies
9.  Effect of Consumption of Dried California Mission Figs on Lipid Concentrations 
Annals of Nutrition & Metabolism  2011;58(3):232-238.
Figs are a rich source of soluble fiber. We evaluated the effect of consuming dried California Mission figs on serum lipids in hyperlipidemic adults.
In a crossover trial men and women aged 30–75 years with elevated low-density lipoprotein cholesterol (100–189 mg/dl) were randomized to add dried California Mission figs (120 g/day) to their usual diet for 5 weeks or eat their usual diet for 5 weeks, then crossed over to the other condition for another 5 weeks. Six 24-hour dietary recalls were obtained.
Low- and high-density lipoprotein cholesterol and triglyceride concentrations did not differ between usual and figs-added diets (Bonferroni-corrected p > 0.017), while total cholesterol tended to increase with fig consumption (p = 0.02). Total cholesterol increased in participants (n = 41) randomized to usual followed by figs-added diet (p = 0.01), but remained unchanged in subjects (n = 42) who started with figs-added followed by usual diet (p = 0.4). During the figs-added diet, soluble fiber intake was 12.6 ± 3.7 versus 8.2 ± 4.1 g/day in the usual diet (p < 0.0001). Sugar intake increased from 23.4 ± 6.5 to 32.2 ± 6.3% of kcal in the figs-added diet (p < 0.0001). Body weight did not change (p = 0.08).
Daily consumption of figs did not reduce low-density lipoprotein cholesterol. Triglyceride concentrations were not significantly changed despite an increase in sugar intake.
PMCID: PMC3169356  PMID: 21811062
Figs; Dietary fiber; Hypercholesterolemia; Dietary intake; Lipids

Results 1-9 (9)