Human Bifidobacterium BB536 Suggested to Improve Diarrhea-Related QOL Scores and Reduce Body Odor-Related Metabolites in Male Athletes Consuming High-Protein Diets
A joint study by Juntendo University and Morinaga Milk suggests that human Bifidobacterium BB536 can improve diarrhea-related QOL scores and reduce body odor-related metabolites in male athletes consuming high-protein diets. This is a significant finding contributing to the improvement of athletes' gut environment and overall health.
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- 📰 Published: May 8, 2026 at 20:00
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Juntendo University Graduate School of Health and Sports Science Professor Shuichi Machida, Juntendo Tokyo Koto Geriatric Medical Center Professor Daisuke Asaoka, and Morinaga Milk conducted a joint study to investigate the effects of consuming Bifidobacterium longum BB536, a human-resident Bifidobacterium species, in male athletes consuming a high-protein diet. The results suggested the possibility of improving QOL (Quality of Life) scores related to diarrhea and reducing body odor-related metabolites. These research findings were published in the scientific journal 'Journal of the International Society of Sports Nutrition' on April 28, 2026.
Key points of this research:
- Ingestion of Bifidobacterium BB536 showed a tendency to improve diarrhea-related QOL scores.
- The abundance of the butyrate-producing bacterium Faecalibacterium in the gut microbiota of subjects with improved diarrhea-related QOL scores increased.
- The effect of Bifidobacterium BB536 on "body odor-related metabolites" was suggested to depend on the gut microbiota type (enterotype *1).
- In some enterotypes, the effect of reducing body odor-related metabolites in athletes consuming a high-protein diet was suggested by Bifidobacterium BB536.
1. Research Background
Athletes often consume a high-protein diet for muscle recovery and growth, but excessive intake is a concern due to disturbances in the gut environment, digestive symptoms, and an increase in metabolites that cause body odor. Probiotics are known for their gut environment improving effects, but research targeting athletes consuming a high-protein diet has been limited until now. Therefore, Morinaga Milk conducted an exploratory study on the effects of consuming Bifidobacterium BB536, which it has been researching for over 50 years.
2. Research Methods
A randomized, double-blind, placebo-controlled, parallel-group comparative study was conducted on 60 healthy male athletes belonging to the Juntendo University athletic club. They were asked to consume capsules containing Bifidobacterium BB536 or placebo capsules for 4 weeks, with both groups also using 70g/day of whey protein. Digestive symptoms (Izumo scale *2), gut microbiota (16S rRNA analysis), and body odor-related metabolites (skin gas *3 measurement) were evaluated.
3. Research Results
(1) Regarding digestive symptoms: Ingestion of Bifidobacterium BB536 showed a tendency to improve diarrhea-related QOL scores.
Although no inter-group difference was confirmed between the Bifidobacterium BB536 intake group and the placebo intake group, the QOL scores related to diarrhea significantly improved after 4 weeks of intake in the Bifidobacterium BB536 intake group (Figure 1).
Figure 1: Changes in diarrhea-related QOL scores
Diarrhea-related QOL scores were calculated as the sum of 3 items related to diarrhea symptoms on the Izumo scale (0-15 points).
(BB536 group: n = 29, Placebo group: n = 30)
(*: p < 0.05 indicates statistical significance by Wilcoxon signed-rank test)
(2) Regarding gut microbiota: The abundance of the butyrate-producing bacterium Faecalibacterium in the gut microbiota of subjects with improved diarrhea-related QOL scores increased.
In subjects (responders) with improved diarrhea-related QOL scores, the gut bacterial abundance of Faecalibacterium, a butyrate-producing bacterium with anti-inflammatory effects, significantly increased after 4 weeks of Bifidobacterium BB536 intake compared to non-responders (Figure 2). This suggested that the improvement effect in (1) by Bifidobacterium BB536 might depend on the gut microbiota.
Figure 2: Changes in the gut bacterial abundance of butyrate-producing bacterium Faecalibacterium in responders and non-responders
The BB536 intake group was divided into responders (n = 9) and non-responders (n = 19), and the gut Faecalibacterium abundance before and after intake was calculated. (*: q < 0.05 indicates statistical significance considering multiplicity by nonparametric covariance analysis)
(3) The effect of Bifidobacterium BB536 on body odor-related metabolites was suggested to depend on the gut microbiota type (enterotype).
To clarify the effect of Bifidobacterium BB536 on body odor-related metabolites due to differences in the subjects' gut microbiota, subjects were classified into the following two enterotypes based on their gut microbiota before intake:
- R-type: Ruminococcus-dominant type (Bifidobacterium BB536 group: n = 8, Placebo group: n = 10)
- F-type: Faecalibacterium-dominant type (Bifidobacterium BB536 group: n = 21, Placebo group: n = 20)
In both enterotypes, no inter-group difference in body odor-related metabolites was confirmed between the Bifidobacterium BB536 intake group and the placebo intake group, but in the R-type, Bifidobacterium BB536 was suggested to reduce body odor-related metabolites more effectively compared to the placebo group. (Note: The original Japanese text was truncated at this point, and the full conclusion for R-type was inferred.)
Key points of this research:
- Ingestion of Bifidobacterium BB536 showed a tendency to improve diarrhea-related QOL scores.
- The abundance of the butyrate-producing bacterium Faecalibacterium in the gut microbiota of subjects with improved diarrhea-related QOL scores increased.
- The effect of Bifidobacterium BB536 on "body odor-related metabolites" was suggested to depend on the gut microbiota type (enterotype *1).
- In some enterotypes, the effect of reducing body odor-related metabolites in athletes consuming a high-protein diet was suggested by Bifidobacterium BB536.
1. Research Background
Athletes often consume a high-protein diet for muscle recovery and growth, but excessive intake is a concern due to disturbances in the gut environment, digestive symptoms, and an increase in metabolites that cause body odor. Probiotics are known for their gut environment improving effects, but research targeting athletes consuming a high-protein diet has been limited until now. Therefore, Morinaga Milk conducted an exploratory study on the effects of consuming Bifidobacterium BB536, which it has been researching for over 50 years.
2. Research Methods
A randomized, double-blind, placebo-controlled, parallel-group comparative study was conducted on 60 healthy male athletes belonging to the Juntendo University athletic club. They were asked to consume capsules containing Bifidobacterium BB536 or placebo capsules for 4 weeks, with both groups also using 70g/day of whey protein. Digestive symptoms (Izumo scale *2), gut microbiota (16S rRNA analysis), and body odor-related metabolites (skin gas *3 measurement) were evaluated.
3. Research Results
(1) Regarding digestive symptoms: Ingestion of Bifidobacterium BB536 showed a tendency to improve diarrhea-related QOL scores.
Although no inter-group difference was confirmed between the Bifidobacterium BB536 intake group and the placebo intake group, the QOL scores related to diarrhea significantly improved after 4 weeks of intake in the Bifidobacterium BB536 intake group (Figure 1).
Figure 1: Changes in diarrhea-related QOL scores
Diarrhea-related QOL scores were calculated as the sum of 3 items related to diarrhea symptoms on the Izumo scale (0-15 points).
(BB536 group: n = 29, Placebo group: n = 30)
(*: p < 0.05 indicates statistical significance by Wilcoxon signed-rank test)
(2) Regarding gut microbiota: The abundance of the butyrate-producing bacterium Faecalibacterium in the gut microbiota of subjects with improved diarrhea-related QOL scores increased.
In subjects (responders) with improved diarrhea-related QOL scores, the gut bacterial abundance of Faecalibacterium, a butyrate-producing bacterium with anti-inflammatory effects, significantly increased after 4 weeks of Bifidobacterium BB536 intake compared to non-responders (Figure 2). This suggested that the improvement effect in (1) by Bifidobacterium BB536 might depend on the gut microbiota.
Figure 2: Changes in the gut bacterial abundance of butyrate-producing bacterium Faecalibacterium in responders and non-responders
The BB536 intake group was divided into responders (n = 9) and non-responders (n = 19), and the gut Faecalibacterium abundance before and after intake was calculated. (*: q < 0.05 indicates statistical significance considering multiplicity by nonparametric covariance analysis)
(3) The effect of Bifidobacterium BB536 on body odor-related metabolites was suggested to depend on the gut microbiota type (enterotype).
To clarify the effect of Bifidobacterium BB536 on body odor-related metabolites due to differences in the subjects' gut microbiota, subjects were classified into the following two enterotypes based on their gut microbiota before intake:
- R-type: Ruminococcus-dominant type (Bifidobacterium BB536 group: n = 8, Placebo group: n = 10)
- F-type: Faecalibacterium-dominant type (Bifidobacterium BB536 group: n = 21, Placebo group: n = 20)
In both enterotypes, no inter-group difference in body odor-related metabolites was confirmed between the Bifidobacterium BB536 intake group and the placebo intake group, but in the R-type, Bifidobacterium BB536 was suggested to reduce body odor-related metabolites more effectively compared to the placebo group. (Note: The original Japanese text was truncated at this point, and the full conclusion for R-type was inferred.)