Effect of a Bifidobacterium-Containing Acid-Resistant Microcapsule Formulation on Gut Microbiota: A Pilot Study

Approximately 10 Bifidobacterium species are known to inhabit the human intestinal tract. Bifidobacteria have been reported to possess a variety of probiotic benefits. However, when bifidobacteria are consumed internally as probiotics, the bacteria are killed by gastric acid. Therefore, we developed acid-resistant microcapsules containing Bifidobacterium breve M-16V and B. longum BB536, which are unaffected by gastric acid, and evaluated whether the microcapsule formulation increased the amount of bifidobacteria in the stool after administration compared with the powder formulation. The results revealed no significant difference in the percentage or number of B. longum between before and after administration of the powder or microcapsule formulation in children. By contrast, the bacterial count of B. breve was significantly increased after microcapsule formulation administration (1.5 × 10⁵ copies/g after administration versus 2.8 × 10⁴ copies/g before administration, p = 0.013). In addition, the increase in the bacterial count of B. breve in stools after administration of microcapsule formulation was approximately 1000-fold higher than that after powder formulation administration (p = 0.018). In conclusion, the results indicate that the microcapsule formulation is efficiently transferred to the large intestine without the adverse effects of gastric acidity in children.