Pilot Study Shows Sake By-Product Sake Lees Alleviates Constipation

A recent pilot study conducted by researchers from Kanazawa University, the University of Fukui, and KAGAMI INC. has revealed that sake lees, the by-product of sake fermentation, may alleviate constipation in adults. The findings were published in the journal PLoS One on June 10, 2025, and indicate a potential health benefit of this traditional Japanese food product, widely consumed for its high dietary fiber content.

The study involved eight healthy participants, predominantly female, who suffered from chronic constipation. Over a six-week period, participants consumed either 25g or 50g of sake lees daily, prepared according to their personal preferences. The sake lees used in the study were sourced from the sake manufacturer “Kakuma no Sato” in Japan, which specified that every 100g of sake lees contained 7.2g of protein, 30.8g of carbohydrates, 5.2g of dietary fiber, and notable amounts of D-amino acids, including D-alanine and D-serine.

According to the researchers, "Sake lees is a fermented food that contains a variety of bacteria and may contribute to changes in the fecal microbiome." The constipation scoring system (CSS) indicated significant improvement, with scores decreasing from a baseline of 9.3 to 6.8 by the end of the study. This suggests that participants experienced reduced constipation symptoms.

However, the study also monitored plasma D-alanine and uremic toxin levels. While plasma D-alanine levels showed a significant increase—39% higher than baseline by week two—the primary endpoint regarding uremic toxins did not yield statistically significant results. The researchers noted that faecal indole levels, which are indicative of uremic toxins, increased during the initial weeks before showing a minor decline at the conclusion of the study.

Dr. Tanaka Oshima, a lead researcher at Kanazawa University, commented on the findings: "The increase in D-alanine suggests potential kidney protective properties, though further long-term studies are necessary to fully understand the implications of sake lees on gut health and kidney function."

Despite these limitations, the study highlights the potential for sake lees as a functional food that may contribute positively to digestive health. The researchers advocate for further investigations into the microbiome effects of sake lees and its long-term benefits on health outcomes.

The consumption of sake lees, a staple in Japanese cuisine, has been historically linked to health benefits, including the enhancement of gut microbiota. This aligns with prior research, such as a 2012 study published in the Journal of Nutritional Science, which indicated that daily intake of sake lees could relieve constipation in the general population.

As interest in functional foods grows, the implications of this research extend beyond mere dietary preferences, potentially influencing future dietary recommendations and health interventions aimed at managing constipation and improving gut health. The findings could also prompt food manufacturers to explore the development of new products leveraging the health benefits of sake lees, as the global market increasingly values functional foods.

In summary, while the pilot study presents promising insights into the health benefits of sake lees, further research is necessary to explore its long-term efficacy and potential as a dietary intervention for constipation and overall gut health.