Provided are beneficial bacteria that can be beneficially applied across a wide range of age groups and a composition containing the same. Bifidobacterium longum subspecies longum NITE BP-02564 and/or Bifidobacterium longum subspecies longum NITE BP-02565； bacteria classified as Bifidobacterium longum subspecies longum, having utilization ability for sialic acid； and a composition containing the bacteria are also provided. More preferably, a composition containing sialic acid is also provided. More preferably, a composition containing at least one carbohydrate selected from the group consisting of arabinoxylan, arabinan, pectic galactan, and oligosaccharides derived therefrom or containing at least a carbohydrate derived from a gramineous plant or a carbohydrate derived from a solanaceous plant are also provided.
