LEGUME FEEDING STUDY

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The working hypothesis for the beneficial effects of a high legume, low glycemic index diet is that the dietary fiber content of the food may reduce the rate of the absorption of the carbohydrates and lower the postprandial glycemic and insulinemic responses leading to a reduced level of C-peptide and other markers of insulin resistance. The high level of fermentable fibers in legumes will be degraded by colonic bacteria to short chain fatty acids, including butyrate, a molecule with demonstrated anti-inflammatory and anti-neoplastic properties. The lowering of insulin and the increase in butyrate will both lower CRP, and other biomarkers of inflammation, and will alter expression level of inflammatory and insulin related genes in fecal colonocytes. An additional hypothesis being investigated is that a high legume, high fiber diet will result in changes in circulating levels of cholecystokin (CCK), ghrelin, and leptin which will increase satiety and reduce body weight. Study Objectives: This is a randomized crossover controlled feeding study in which each participant will consume a high legume, low glycemic index diet for four weeks and a control American diet for four weeks, with a three week break between diets. These two diet periods will be weight stable. An additional diet period will be optional in which they will consume the same legume rich diet, but weight loss will be permitted. The study will have four groups of male participants: 1. previous history of adenomas and IR; 2. previous history of adenomas and not IR; 3. IR with no history of adenomas; and 4. non-IR and no history of adenomas. The primary objective is to assess an overall effect of diet on the two endpoints, C-reactive protein and C-peptide in this population. A secondary objective is to assess whether changes in these intervention-related endpoints will differ by IR status or a history of adenomas. In addition, fecal calprotectin and colonocyte RNA will be measured to assess changes in gastrointestinal inflammation.