Human Bifidobacterium BB536 Suggested to Improve Diarrhea-Related QOL Scores and Reduce Body Odor-Related Metabolites in Male Athletes Consuming High-Protein Diets
Joint research by Morinaga Milk Industry and Juntendo University has suggested that male athletes consuming high-protein diets, when supplementing with human-resident Bifidobacterium longum BB536, experienced improvements in diarrhea-related Quality of Life (QOL) scores and a reduction in body odor-related metabolites. These research findings were published on April 28, 2026, in the scientific journal 'Journal of the International Society of Sports Nutrition'.
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- 📰 Published: May 8, 2026 at 20:00
- 🔍 Collected: May 8, 2026 at 11:31
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Morinaga Milk Industry, in collaboration with Professor Shuichi Machida of Juntendo University Graduate School of Health and Sports Science and Professor Daisuke Asaoka of Juntendo Tokyo Koto Geriatric Medical Center, conducted joint research to investigate the effects of ingesting Bifidobacterium longum BB536, a human-resident Bifidobacterium species, in male athletes consuming high-protein diets. The results suggested improvements in diarrhea-related Quality of Life (QOL) scores and a reduction in body odor-related metabolites. These research findings were published on April 28, 2026, in the scientific journal 'Journal of the International Society of Sports Nutrition'.
Key points of this research achievement:
● Ingestion of Bifidobacterium BB536 showed a trend towards improvement in diarrhea-related QOL scores.
● An increase in the abundance of the butyrate-producing bacterium Faecalibacterium in the gut microbiota was observed in subjects whose diarrhea-related QOL scores improved.
● The effect of Bifidobacterium BB536 on “body odor-related metabolites” may depend on the gut microbiota type (enterotype*1).
● In some enterotypes, an effect of reducing body odor-related metabolites was suggested in athletes consuming high-protein diets.
1. Research Background
Athletes often consume high-protein diets for muscle recovery and growth, but excessive intake is a concern due to potential disruption of the gut environment, digestive symptoms, and an increase in metabolites that cause body odor. While probiotics are known to improve the gut environment, research targeting athletes consuming high-protein diets has been limited. Therefore, Morinaga Milk Industry exploratively investigated the effects of ingesting Bifidobacterium BB536, which it has been researching for over 50 years.
2. Research Methods
A randomized, double-blind, placebo-controlled, parallel-group comparison study was conducted involving 60 healthy male athletes belonging to Juntendo University's sports club. Participants ingested capsules containing Bifidobacterium BB536 or placebo capsules for 4 weeks, with both groups concurrently consuming 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 trend towards improvement in diarrhea-related QOL scores.
Although no inter-group difference was observed between the Bifidobacterium BB536 intake group and the placebo intake group, the diarrhea-related QOL score 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 total score 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 statistically significant difference by Wilcoxon signed-rank test)
② Regarding gut microbiota: An increase in the abundance of the butyrate-producing bacterium Faecalibacterium in the gut microbiota of subjects whose diarrhea-related QOL scores improved.
In subjects whose diarrhea-related QOL scores improved (responders), the gut microbiota abundance of Faecalibacterium, a butyrate-producing bacterium with anti-inflammatory properties, significantly increased after 4 weeks of Bifidobacterium BB536 intake compared to non-responders (Figure 2). This suggests that the improvement effect in ① by Bifidobacterium BB536 may depend on the gut microbiota.
Figure 2: Changes in gut microbiota 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 abundance of intestinal Faecalibacterium was calculated before and after intake. (*: q < 0.05 indicates statistically significant difference adjusted for multiplicity by nonparametric covariance analysis)
③ The effect of Bifidobacterium BB536 on body odor-related metabolites may depend on the gut microbiota type (enterotype).
To clarify the effect of Bifidobacterium BB536 on body odor-related metabolites due to differences in 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 observed between the Bifidobacterium BB536 intake group and the placebo intake group, but in the R-type, an effect of reducing body odor-related metabolites was suggested.
Key points of this research achievement:
● Ingestion of Bifidobacterium BB536 showed a trend towards improvement in diarrhea-related QOL scores.
● An increase in the abundance of the butyrate-producing bacterium Faecalibacterium in the gut microbiota was observed in subjects whose diarrhea-related QOL scores improved.
● The effect of Bifidobacterium BB536 on “body odor-related metabolites” may depend on the gut microbiota type (enterotype*1).
● In some enterotypes, an effect of reducing body odor-related metabolites was suggested in athletes consuming high-protein diets.
1. Research Background
Athletes often consume high-protein diets for muscle recovery and growth, but excessive intake is a concern due to potential disruption of the gut environment, digestive symptoms, and an increase in metabolites that cause body odor. While probiotics are known to improve the gut environment, research targeting athletes consuming high-protein diets has been limited. Therefore, Morinaga Milk Industry exploratively investigated the effects of ingesting Bifidobacterium BB536, which it has been researching for over 50 years.
2. Research Methods
A randomized, double-blind, placebo-controlled, parallel-group comparison study was conducted involving 60 healthy male athletes belonging to Juntendo University's sports club. Participants ingested capsules containing Bifidobacterium BB536 or placebo capsules for 4 weeks, with both groups concurrently consuming 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 trend towards improvement in diarrhea-related QOL scores.
Although no inter-group difference was observed between the Bifidobacterium BB536 intake group and the placebo intake group, the diarrhea-related QOL score 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 total score 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 statistically significant difference by Wilcoxon signed-rank test)
② Regarding gut microbiota: An increase in the abundance of the butyrate-producing bacterium Faecalibacterium in the gut microbiota of subjects whose diarrhea-related QOL scores improved.
In subjects whose diarrhea-related QOL scores improved (responders), the gut microbiota abundance of Faecalibacterium, a butyrate-producing bacterium with anti-inflammatory properties, significantly increased after 4 weeks of Bifidobacterium BB536 intake compared to non-responders (Figure 2). This suggests that the improvement effect in ① by Bifidobacterium BB536 may depend on the gut microbiota.
Figure 2: Changes in gut microbiota 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 abundance of intestinal Faecalibacterium was calculated before and after intake. (*: q < 0.05 indicates statistically significant difference adjusted for multiplicity by nonparametric covariance analysis)
③ The effect of Bifidobacterium BB536 on body odor-related metabolites may depend on the gut microbiota type (enterotype).
To clarify the effect of Bifidobacterium BB536 on body odor-related metabolites due to differences in 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 observed between the Bifidobacterium BB536 intake group and the placebo intake group, but in the R-type, an effect of reducing body odor-related metabolites was suggested.