This clinical trial evaluates how propionate and butyrate supplementation alters intestinal health in healthy volunteers and whether it would be feasible to administer these supplements to patients undergoing allogeneic hematopoietic stem cell transplant in the future. Propionate and butyrate are short chain fatty acids naturally produced in the intestines during the fermentation of dietary fibers. Greater levels of propionate and butyrate may improve intestinal barrier function, and propionate specifically has been shown to modulate immunity, energy metabolism, and gut-brain communication. The protective effects of propionate and butyrate supplementation on intestinal health may be especially beneficial for patients undergoing donor stem cell transplant, as these patients can experience significant gastrointestinal injury during treatment. The results of this study may help researchers determine whether propionate and butyrate supplementation positively alters the gut microbiome and whether or not supplementation could be used in the future for patients undergoing a donor stem cell transplant.