Kundu, P. et al. Sci. Transl. Med. 11, eaau4760 (2019)

A variety of studies have reported changes in gut microbiota (GM) composition during the aging process, but the effects of these changes on host physiology remain poorly understood. Studies in mice have shown that aging-associated GM promote age-related inflammation, but a study in humans revealed that GM of extremely long-living people is enriched in health-associated microbes.

A new study suggests that the GM of old mice has beneficial properties by showing that young germ-free mice receiving a GM transplant from old donor mice exhibited increased neurogenesis in the hippocampus and increased intestinal growth. The study also reports that old donor GM induced the expression of FGF21, a prolongevity hormone that can influence neuronal viability.