Pinto bean consumption changes SCFA profiles in fecal fermentations, bacterial populations of the lower bowel, and lipid profiles in blood of humans

Accumulating data suggest that beans lower serum lipids in human subjects and lower the risk of colon cancer via greater short-chain fatty acid (SCFA) production. This USDA study examined the hypothesis that pinto bean consumption affects SCFA production, colonic bacterial populations, and serum lipids. The study used 40 adults with premetabolic syndrome (pre-MetSyn; metabolic syndrome is a cluster of metabolic conditions that signal risks for coronary heart disease and type 2 diabetes) and 40 controls. Subjects were randomly assigned to consume either a bean entrée [1/2 cup (130 g) of dried, cooked pinto beans] or a chicken soup entrée (equal calories to bean meal) daily for 12 weeks. Relative to baseline, propionate SCFA production from fecal material fermented in vitro with bean flour was greater in adults consuming beans relative to the soup group. The most robust effects were seen with bean consumption and lipid profiles. Specifically, beans lowered serum total cholesterol by approximately 8% in the controls and 4% in the pre-MetSyn group. Bean consumption lowered serum HDL-cholesterol and LDL-cholesterol in both groups without affecting serum triglycerides, VLDL cholesterol, or glucose. This study indicates that bean consumption can favorably affect lipid profiles associated with cardiovascular disease, however, the data do not indicate clear health benefits associated with colon cancer risk.

Finley JW, Burrell JB, and Reeves PG. -2007. Journal of Nutrition 137: 2391-2398

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The researchers demonstrated that daily consumption of pinto beans can have several cholesterol-lowering benefits (i.e., total and LDL-cholesterol) in both healthy subjects and in those preconditioned for metabolic syndrome. In fact, the authors stated that, “the treatment differences were of such magnitude that significance was found to be both statistical and physiological. This study adds to a growing and convincing body of evidence that adding dry beans to the diet in quantities of at least 100 g/d changes lipid profiles in a manner associated with decreased risk of cardiovascular disease.”