Effect of Lactic Acid Bacteria-Fermented Soy Milk Extract (LEX) on Urinary 3-Indoxyl Sulfate in Japanese Healthy Adult Women: An Open-Label Pilot Study

Abstract

Objective:

For the general population, the intestinal microbiota and its environment, including its metabolites, are important not only for disease prevention but also for overall quality of life. A convenient method to monitor the intestinal environment is to measure levels of urinary 3-indoxyl sulfate (3-IS). This approach has been used for several years. This study aims to clarify the efficacy of a lactic acid bacteria (LAB) dietary supplement combined with multi-strain LAB-fermented soy milk (LEX) extract in healthy, adult women with high urinary 3-IS levels.

Materials and Methods:

Japanese women aged 30–50 years with high urinary 3-IS levels and a tendency toward constipation were enrolled in this study. Each of them received 10 mL of a LEX-containing dietary supplement daily for 4 weeks. The primary outcome was changes in urinary 3-IS levels, and the secondary ones included the amount of defecation and more subjective symptoms of their physical condition, such as the Constipation Assessment Scale (CAS).

Results:

Thirty participants were enrolled, and all completed the study. Every participant showed a statistically significant improvement in their level of urinary 3-IS after ingesting the test article for 4 weeks. Any changes in urinary 3-IS also showed a high correlation to initial 3-IS levels. Moreover, CAS scores and other subjective symptoms improved after ingestion of the LEX-containing dietary supplement. The level of urinary 3-IS showed a modest degree of correlation with the score of overall physical condition, including CAS (Pearson’s r = 0.21; p < 0.05).

Conclusion:

These findings suggest that orally ingested LEX improves urinary 3-IS levels as an index of the health of the intestinal environment and that monitoring urinary 3-IS levels is effective in assessing changes in the intestinal environment and overall physical condition.

Keywords:

• lactic acid bacteria
• soybean
• 3-indoxyl sulfate
• intestinal environment
• intestinal microbiota
• postbiotics

Acknowledgments

We would like to thank all participants and applicants who took part in the study. We appreciate Healthcare Systems Co., Ltd. for their technical assistance in conducting urine analysis. Furthermore, we give special thanks to Mizukoshi R. and Sato T. (B&S Corporation Co., Ltd.) for their assistance in setting up the test. Additionally, we would like to thank Enago for the English language review.

Funding

This study was funded by B&S Corporation Co., Ltd.

Disclosure

MF, RM, and YS receive compensation from B&S Corporation Co., Ltd. TY and MM receive compensation from Healthcare Systems Co., Ltd. KF has no conflicts of interest directly relevant to the content of this article. The authors report no other conflicts of interest in this work.