LATITUDE WITHIN AN NCEP STEP 1 DIET--AN OPTIMAL DIET

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The broad and long-term objective of the study is to examine whether the potential impact on coronary heart disease (CHD) risk reduction of an NCEP/AHA Step one diet may currently be underestimated because of an overemphasis on the avoidance of fat and cholesterol and an underemphasis on the inclusion of plant-based foods. A large number of dietary factors in plant-based foods have been linked to the reduction of various CHD risk factors. However, the food industry's production of thousands of new "reduced-fat" food products over the last decade has now made it possible to follow a low-fat diet with a foundation in high- sugar commercial snack foods rather than plant-based foods. We will design two diets that both meet NCEP/AHA Step One Diet guidelines and are matched on total fat, saturated fat, monounsaturated fat, polyunsaturated fat, cholesterol, protein and total carbohydrate. One diet will include a large proportion of plant-based foods, and will be relatively higher in content of plant protein, arginine, complex carbohydrates, soluble and insoluble fiber, Vitamins E, C and folate, carotenoids, phytosterols, phytoestrogens, flavonoids, allicin and saponins (NCEP-Plus). The other diet will include a large proportion of commercially available reduced fat products with an emphasis on snack foods and will be relatively higher in animal protein, simple carbohydrates and trans fatty acids (NCEP-Low). In a clinical trial using a parallel design, seventy adults with moderately elevated LDL- cholesterol (LDL-C 130-190 mg/dL) will be randomized to one of the two diets for four weeks. All meals will be provided. The composition of the two study diets will be determined by chemical analysis. The primary study endpoints will include fasting serum levels of LDL-C, insulin and homocysteine, blood pressure, in vitro susceptibility of LDL to oxidative degradation, monocyte adhesion, and endothelial reactivity. Our intentions are to examine whether a focus on avoiding fat and cholesterol rather than including plant-based foods results in underestimating the potential health benefits of an NCEP/AHA Step One Diet, and to determine the magnitude of favorable changes in an overall CHD risk factor profile that can be achieved by using current nutrition knowledge to design a "best-possible" overall diet.