Epigenetic Clocks: Omega-3 Turned Them Back, Rapamycin Did Not

Exercise, a plant-rich diet, eating fewer calories, omega-3 fats and the weight-loss drug semaglutide all lowered the age estimated by so-called epigenetic clocks in human studies. Some popular hopes showed no detectable effect, including nicotinamide riboside, rapamycin and drugs that target aged cells. Plasma exchange, where blood plasma is removed and replaced, even pushed the clocks forward.

Epigenetic clocks read chemical tags on DNA that shift as we age. Computer models turn these tags into an estimate of biological age. Newer clocks track the risk of death more closely than the first ones did. The team searched the research systematically for human studies that measured these newer clocks before and after a treatment, and found 41. One example: in 958 healthy older adults, a daily multivitamin and mineral pill lowered one clock by 0.44 years over two years, compared with a dummy pill. Semaglutide was tested in people with HIV and abnormal fat distribution.

The authors stress that these numbers are estimates from a model. They do not directly mean the whole body ages more slowly or that people live longer. A shift in a clock can also be random measurement noise.