Urolithin

Urolithin B is a gut microbial metabolite of dietary ellagitannins, studied for muscle growth and protection against muscle wasting. It increased muscle size and reduced denervation-induced atrophy in mice. A 2026 study found distinct effects on gene expression in cultured human muscle cells, but did not test a supplement in people. Its muscle evidence remains preclinical; it is not interchangeable with urolithin-a.