GLYCEMIC INDEX/GLYCEMIC LOAD AND BLOOD LIPIDS IN THE WHI

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DESCRIPTION (provided by applicant): Coronary heart disease (CHD) is the number one killer of postmenopausal women. Reduction in fat intake is typically recommended for the prevention and treatment of CHD. However, decreased fat intake is generally accompanied by an increase in carbohydrate intake, which may itself have undesirable effects on CHD risk factors. Recent evidence suggest that diets abundant in high-starch carbohydrates may have an adverse effect on blood glucose and insulin concentrations, resulting in alterations of blood lipids that may increase the risk of developing CHD. Glycemic index (GI) is a way of ranking carbohydrate-containing foods based on their postprandial blood glucose responses and is a measure of carbohydrate quality. Glycemic load (GL) is a measure that incorporates both the high dietary carbohydrates. There is mounting evidence from observational studies that high dietary GI and may adversely affect blood lipids, including increasing plasma triglyceride (TG) and reducing plasma high-density lipoprotein-cholesterol (HDL-C). The Women's Health Initiative (WHI) is a multi-faceted research program examining factors associated with disease risk in postmenopausal women. This study will utilize WHI participants to further investigate the associations of GI and GL with blood glucose, insulin, and lipids. The first aim of this study is to investigate the associations of dietary GI and GL with blood glucose, insulin, and lipid (total cholesterol, low-density lipopretein-cholesterol, HDL-C, and TG) concentrations in a cross-sectional analysis of 728 participants at baseline in the WHI Observational Study. The second aim is to quantify changes, over a one-year period, in dietary GI and GL in 973 participants randomized in the WHI low-fat Dietary Modification trial, and to determine the effects of those changes on blood glucose, insulin, and lipid concentrations. To meet these aims, the nutrient database of the WHI food frequency questionnaire (FFQ) will be expanded to include GI and GL, which are not currently reported. Existing WHI FFQs will then be reanalyzed to calculate each participant's mean dietary GI and GL. Existing blood glucose, insulin, and lipid data for these WHI participants will be used in the data analyses.