Verification of the Effect of Heat-Killed Saccharomyces cerevisiae PA YEAST SC-1 on the Gut Environment: A Culture Study Using Human Feces and a Randomized, Double-Blind, Placebo-Controlled Crossover Trial in Healthy Adults

Abstract

To test the efficacy of heat-killed Saccharomyces cerevisiae PA YEAST SC-1 (PA YEAST SC-1) in improving the gut environment, we conducted a culture study using feces from healthy adults and a randomized double-blind placebo-controlled crossover controlled trial in healthy adults. In human clinical trials, the gut microbiota was used as the primary endpoint and defecation status, fecal physicochemical tests, blood immune system tests, Constipation Assessment Scale–middle term (CAS-MT), and clinical laboratory values were measured as secondary endpoints. Culture tests showed that adding PA YEAST SC-1 substantially increased acetic acid and propionic acid levels. In a human clinical trial, PA YEAST SC-1 intake significantly increased the occupancy of short-chain fatty acid-producing bacteria (such as Parabacteroides genus), while propionic acid and the total amount of short-chain fatty acids tended to increase. Phenol, skatole, and fecal pH levels were significantly reduced. These studies indicate that PA YEAST SC-1 was utilized by the human gut bacteria and influenced the gut microbiota and metabolites, improving the gut environment.