One of the many beneficial activities of the human gut microbiome is the fermentation of dietary fiber into short-chain fatty acids. Butyrate, in particular, is the preferred carbon source of colonocytes, has anti-inflammatory and anti-tumorigenic properties, promotes intestinal barrier function, and helps regulate satiety. Therefore, modulating butyrate levels could be useful for treating a variety of diseases and maintaining health. We attempted to increase fecal butyrate levels in healthy young adults by supplementing their diets with one of several resistant starches; potato starch (n=45), Hi-Maize (n=15), inulin (n=17), or psyllium (n=23). Only the potato starch supplement significantly increased fecal butyrate concentrations, but not in all individuals. Potato starch supplementation was associated with an increased abundance of primary resistant starch degraders. Some individuals responded with an increase in Bifidobacterium species, while the others responded with increased abundance of Ruminococcus bromii or other Ruminococcaceae. We observed similar increases in Bifidobacterium spp. among individuals consuming inulin and increases in R. bromii among individuals consuming Hi-Maize, but without an increase in butyrate. Using Random Forest regression analysis, we found that the genera Roseburia, Anaerostipes, Clostridium XIVa, and unclassified Lachnospiraceae were most indicative of increasing butyrate levels. These results demonstrate that only certain dietary fibers are capable of stimulating butyrate production, and even then, not all individuals will respond. Our findings also suggest that the bacterial populations responsible for butyrate production differ between individuals. Additional studies are needed to better understand what factors enable certain microbiomes to respond with increased butyrate production and how to leverage those factors to improve human health.
Sponsored by the Host Microbiome Initiative