Elucidating the Effect of Dietary Stearic Acid on the Regional Heterogeneity of the Gut Microbiome and Metabolome: Focus on Bile Acid Metabolism
Tufts University
Summary
Stearic acid and palmitic acid are two common consumed saturated fatty acids found in foods. Palmitic acid is associated with increases in blood cholesterol, whereas stearic acid is generally considered neutral with respect to blood cholesterol. However, the mechanisms underlying these different effects are not fully understood. The goal of this clinical trial is to determine how replacing dietary palmitic acid with stearic acid affects microorganisms living in the gastrointestinal tract (gut microbiome) and the metabolites they produce, including secondary bile acids, and whether these changes influence heart and metabolic health in postmenopausal women. The main question it aims to answer is whether the cholesterol lowering effect of dietary stearic acid, compared to dietary palmitic acid is due to changes in the composition and function of the gut microbiome and bile acid metabolism. Participants will consume a controlled diet high in palmitic acid for a 10-day run-in period, followed by a controlled diet high in stearic acid for 28 days. During the study, participants will provide biological samples, including blood samples collected in both fasting and non-fasting states, for assessment of cardiometabolic outcomes. Participants will also swallow mini-pills designed to collect samples from different regions of the gastrointestinal tract to assess the gut microbiome and related metabolites. Results will contribute to understanding the relationship between stearic acid mediated microbiota effects on cardiometabolic heath.
Description
Stearic acid (18:0) is unique among saturated fatty acids (SFAs) as it does not increase cardiovascular disease (CVD) risk. Prior work by the study investigators suggests that gut microbiome-mediated alterations in secondary bile acid (BA) metabolism as a potential mechanism for the cholesterol-lowering effects of 18:0. However, to test this hypothesis the investigators were limited to traditional fecal sampling methods, which primarily reflect colonic microbes and do not capture regional heterogeneity in microbial communities or BA transformations which occur mainly in the small intestine. Us…