Faculty Bibliography

OBJECTIVE: To develop and evaluate a pictorial, web-based version of the NCI diet history questionnaire (Web-PDHQ). DESIGN: The Web-PDHQ and paper version of the DHQ (Paper-DHQ) were administered 4 weeks apart with 218 participants randomised to order. Dietary data from the Web-PDHQ and Paper-DHQ were validated using a randomly selected 4 d food record recording period (including a weekend day) and two randomly selected 24 h dietary recalls during the 4 weeks intervening between these two diet history administrations. SETTING: Research office in Reston, VA, USA. PARTICIPANTS: Computer-literate men and women recruited through newspaper advertisements. RESULTS: Mean correlation of energy and the twenty-five examined nutrients between the Web-PDHQ and Paper-DHQ was 0.71 and 0.51, unadjusted and energy-adjusted by the residual method, respectively. Moderate mean correlations (unadjusted 0.41 and 0.38; energy-adjusted 0.41 and 0.34) were obtained between both the Web-PDHQ and Paper-DHQ with the 4 d food record on energy and nutrients, but the correlations between the Web-PDHQ and Paper-DHQ with the 24 h recalls were modest (unadjusted 0.31 and 0.29; energy-adjusted 0.37 and 0.26). A subset of participants (n 48) completing the Web-PDHQ at the initial visit performed a retest on the same questionnaire 1 week later to determine repeatability, and the unadjusted mean correlation was 0.82. CONCLUSIONS: These data indicate that the Web-PDHQ has comparable repeatability and validity to the Paper-DHQ but did not improve the relationship of the DHQ to other food intake measures (e.g. food records, 24 h recall).

The authors compared effects of macronutrients on self-reported appetite and selected fasting hormone levels. The Optimal Macronutrient Intake Trial to Prevent Heart Disease (OMNI-Heart) (2003-2005) was a randomized, 3-period, crossover feeding trial (n = 164) comparing the effects of 3 diets, each rich in a different macronutrient. Percentages of kilocalories of carbohydrate, fat, and protein were 48, 27, and 25, respectively, for the protein-rich diet; 58, 27, and 15, for the carbohydrate-rich diet; and 48, 37, and 15 for the diet rich in unsaturated fat. Food and drink were provided for each isocaloric 6-week period. Appetite was measured by visual analog scales. Pairwise differences between diets were estimated using generalized estimating equations. Compared with the protein diet, premeal appetite was 14% higher on the carbohydrate (P = 0.01) and unsaturated-fat (P = 0.003) diets. Geometric mean leptin was 8% lower on the protein diet than on the carbohydrate diet (P = 0.003). Obestatin levels were 7% and 6% lower on the protein diet than on the carbohydrate (P = 0.02) and unsaturated-fat (P = 0.004) diets, respectively. There were no between-diet differences for ghrelin. A diet rich in protein from lean meat and vegetables reduces self-reported appetite compared with diets rich in carbohydrate and unsaturated fat and can be recommended in a weight-stable setting. The observed pattern of hormone changes does not explain the inverse association between protein intake and appetite.

Obestatin, derived from the same gene as the hunger hormone ghrelin, may reduce food intake in animals. The role of obestatin in human physiology is unclear. We evaluated cross-sectional associations between participant characteristics and fasting levels of obestatin as well two other hormones associated with energy balance, ghrelin and leptin. Data are from the baseline visit of the Optimal Macronutrient Intake Trial to Prevent Heart Disease (OMNI-Heart) Trial that enrolled adults with elevated blood pressure (systolic 120-159 mm Hg or a diastolic of 80-99 mm Hg) but who were otherwise healthy. Partial Spearman's correlations and linear regression models estimated the association between age, gender, BMI, physical activity, and smoking with fasting hormones. Obestatin was directly associated with ghrelin (r = 0.45, P < 0.05). On average, overweight (BMI 25-30) and obese (BMI > 30) individuals had obestatin concentrations that were 12.6 (s.d. 8.8) and 25.4 (s.d. 8.4) pg/ml lower compared to normal weight (BMI < 25) individuals, respectively (P for trend = 0.002). Overweight (BMI 25-30) and obese (BMI > 30) individuals had ghrelin concentrations that were 161.7 (s.d. 69.6) and 284.7 (s.d. 66.5) pg/ml lower compared to normal weight (BMI < 25) individuals, respectively (P for trend <0.0001). A 5 unit increase in BMI was associated with 41.3% (s.d. 4.3%) (P < 0.0001) higher leptin. Obestatin and ghrelin are directly correlated and share the same patterns of association with participant characteristics. Modifiable risk factors for chronic diseases, such as BMI, are associated with fasting levels of leptin, obestatin, and ghrelin.