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A previous clinical study on pre-obesity subjects revealed that Bifidobacterium breve B-3 shows anti-obesity effects and possibly increases muscle mass. Here, we investigated the effects of B-3 on muscle function, such as muscle strength and metabolism, and some signaling pathways in skeletal muscle. Male rodents were orally administered live B-3 (B-3L) or heat-killed B-3 (B-3HK) for 4 weeks. We found that administration of B-3 to rats tended to increase muscle mass and affect muscle metabolism, with stronger effects in the B-3HK group than in the B-3L group. B-3HK significantly increased muscle mass and activated Akt in the rat soleus. With regard to muscle metabolism, B-3HK significantly increased phosphorylated AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α and cytochrome c oxidase (CCO) gene expression in the rat soleus, suggesting an effect on the AMPK-PGC1α-mitochondrial biogenesis pathway. Furthermore, B-3HK promoted oxidative muscle fiber composition in the gastrocnemius. We also observed a significantly higher level of murine grip strength in the B-3HK group than in the control group. These findings suggest the potential of heat-killed B-3 in promoting muscle hypertrophy and modifying metabolic functions, possibly through the Akt and AMPK pathways, respectively.

Keywords: Bifidobacterium breve B-3; mitochondria; muscle mass; probiotics; skeletal muscles.

Research Insights

SupplementHealth OutcomeEffect TypeEffect Size
Bifidobacterium breve MAK40B22BEnhanced Mitochondrial BiogenesisBeneficial
Bifidobacterium breve MAK40B22BImproved Muscle MetabolismBeneficial
Bifidobacterium breve MAK40B22BImproved Muscle StrengthBeneficial
Bifidobacterium breve MAK40B22BIncreased Muscle MassBeneficial
Bifidobacterium breve MAK40B22BPromoted Oxidative Muscle Fiber CompositionBeneficial
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