Dietary patterns by reduced rank regression predicting changes in obesity indices in a cohort study: Tehran Lipid and Glucose Study.

OBJECTIVE: To examine the association between dietary patterns and obesity indices (BMI, WC, WHR) among Tehranian adults in a 6-year follow-up study. METHODS: Within frame of a cohort study in Tehran (mean follow up 6.6+/-0.9 years), 141 adults were recruited with: two 24 hour dietary recalls at the beginning, as well as obesity indices at the beginning and end of the study period. Dietary intakes were converted into grams of intakes of food items and categorized into 16 groups. Reduced rank regression analysis derived five patterns with total and polyunsaturated-to-saturated fat intake, cholesterol, fiber and calcium intake as response variables. Factors (dietary patterns) were generated retaining a corresponding factor loading > or = |0.17| on the food groups. Changes in obesity indices were scrutinized within quintiles of factor scores. RESULTS: There were high loadings on refined carbohydrates, whole grain, starchy vegetables, other vegetables, red and refined meat, saturated/trans fat, and egg for the first factor named "traditional". All obesity indices had increasing trend across quintiles of pattern score. The fifth pattern (namely egg pattern) had high loading for eggs, salty snacks, as well as fruits and dry fruits, and negative loadings for red and processed meat, saturated and trans fat, plant oils, and dairy products. This pattern showed increasing trends for WC and WHR after adjustment for potential confounders. Other patterns showed non-significant trends for obesity indices. CONCLUSIONS: The results were indicative of a traditional pattern which is dominated in the Tehran region and associated with increase in obesity indices.

Vitamin C prevents hyperbaric oxygen-induced growth retardation and lipid peroxidation and attenuates the oxidation-induced up-regulation of glutathione in guinea pigs.

Hyperbaric oxygen therapy is used to treat various clinical conditions, but it also causes oxidative damage. The objectives of this study are to determine if increased vitamin C intake can prevent hyperbaric oxygen-induced damage and to determine interactions among vitamin C, glutathione and vitamin E in response to oxidative stress. The growth rates of unexposed guinea pigs fed 1.25 mg vitamin C/day were indistinguishable from that of guinea pigs fed 50 mg vitamin C/day. In contrast, hyperbaric oxygen exposure resulted in growth retardation in guinea pigs fed 1.25 mg vitamin C/day, but it had little effect on the growth rates of guinea pigs fed 50 mg vitamin C/day. Increased vitamin C intake also prevented hyperbaric oxygen-induced lipid peroxidation in the liver. In guinea pigs not exposed to hyperbaric oxygen, levels of vitamin C in tissues were closely related to vitamin C intake, but tissue levels of glutathione and vitamin E were not related to vitamin C intake. However, interactions between vitamin C and glutathione were observed upon chronic hyperbaric oxygen exposure. Chronic hyperbaric oxygen exposure resulted in >2-fold increases in the levels of glutathione in liver and lung of guinea pigs fed 1.25 mg vitamin C/day. In comparison, the oxidation-induced increases in glutathione were significantly attenuated in guinea pigs fed 50 mg vitamin C/day. These data show that increased intake of vitamin C can prevent or alleviate the hyperbaric oxygen-induced damage. The interactions between vitamin C and glutathione upon hyperbaric oxygen exposure indicate that there is a homeostatic regulation of antioxidant capacity in guinea pig tissues.