Elevated fasting insulin concentrations and insulin resistance have been associated with non-insulin-dependent diabetes mellitus (NIDDM), obesity, atherosclerosis, and hypertension. Vitamin E supplementation in persons with and without NIDDM may be related to greater insulin sensitivity (SI). The cross-sectional associations of the intake of vitamins E and C with SI and insulin concentrations were evaluated among African American, Hispanic, and non-Hispanic white men and women with a wide spectrum of glucose tolerance included in the Insulin Resistance and Atherosclerosis Study (IRAS) (n = 1151). Insulin sensitivity was measured by minimal model analysis of a 12-sample, insulin-modified, frequently sampled intravenous glucose tolerance test. Nutrient intake (including vitamin supplement use) was assessed with a food-frequency questionnaire modified to include foods consumed by the three ethnic groups. Linear-regression models were used, including rank of SI and the log of fasting insulin as the outcome variables. Pearson correlation coefficients for vitamins E and C in relation to rank SI were r = 0.07 (P = 0.01) and r = 0.07 (P = 0.02), respectively. After adjustment for total energy and BMI these associations were no longer statistically significant and did not differ between ethnic groups. Results were similar when vitamins E and C were combined in categories of low and high antioxidant intake. Models replicated with log of fasting insulin as the outcome variable also did not produce significant associations with vitamins E or C. Thus, these cross-sectional analyses do not support the hypothesis of improved SI with increased intake of vitamins E and C.
The purpose of this feasibility study was to assist limited English proficiency women predominately from Mexico (N = 24) to lose weight postpartum and establish effect sizes to power a randomized controlled pilot study. At 3 months, a small (0.20) effect size was noted in the experimental group compared to the control group in exercise, stress, and both the subscales of the eating self-efficacy scales. There was a medium (0.50) effect size noted in the experimental group compared to the control group in body mass index (BMI), nutrition, and exercise self-efficacy. There was a large (0.80) effect size noted in the experimental group compared to the control group in subscapular skinfolds and health responsibility.
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