Urolithin A is a natural compound formed by the bacteria in the colons of about half of elderly people after consuming certain foods. Urolithin A seems to improve the function of mitochondria (the "powerhouses" inside our cells). However, clinical research with urolithin A suggested only limited benefit in improving muscle health in middle-aged and older adults. Urolithin A has also been touted for treating osteoarthritis (painful, worn joints), but has it been shown to be helpful in people? Find out in our full answer by signing in as a CL member.
Also see our separate article about other supplements for building and maintaining muscle.