Can a pill replace exercise? Swigging this molecule gives mice benefits of working out

The compound betaine, which becomes more abundant in men who take up jogging, could confer some of the anti-ageing advtanages of physical activity

Young men who took up regular running experienced changes in their gut microbiome and more, including their levels of the molecule betaine.Credit: John Macdougall/AFP/Getty

A molecule made by the kidneys and found in some foods can reproduce some of the myriad benefits of exercise — and slow some signs of ageing — when fed to mice¹.

Betaine is a modified amino acid that plays an important role in metabolism. Results published on 25 June in Cell show that consistent exercise raises levels of the compound, at least in young men. The study also found that feeding betaine to aged mice boosts their immune health and grip strength.

Whether it will have similar beneficial effects in people remains to be seen. But there is a need for treatments that can mimic the effects of exercise, says Christiane Wrann, a neuroscientist at Massachusetts General Hospital in Boston, who was not involved in the study. “There are people in the aging population who don’t have the capacity anymore to exercise to the extent they need,” she says.

No pill measures up

For now, there is no drug like exercise. It can sharpen the mind, soothe inflammation, and rally cells to repair damaged tissue. It helps keep some diseases at bay, or eases their symptoms. “Physical activity is a recognized efficient and low-cost way to promote health and fight aging,” says Guanghui Liu, who studies regenerative medicine at the Chinese Academy of Sciences in Beijing. “But its deep-level molecular mechanisms are still not fully clear.”

To learn more, Liu and his colleagues enlisted the aid of 13 healthy young men willing to put their fitness goals on hold and lounge about for 45 days of limited physical activity. After that, the volunteers ran 5 kilometres every one or two days. The researchers took blood and stool samples from the men and made a variety of physiological measurements on them after their 45-day rest, and again after 25 days of their new running routine.

A detailed analysis of those samples revealed the extent to which exercise reshapes the body at a molecular level. After 25 days of regular running, there were changes in immune cells, lipid metabolism, the gut microbiome, and more.

One of the biggest changes was in the abundance of betaine. Following up on these results in mice, the team found that exercise induced betaine production primarily in the kidneys. They also found that the molecule binds to and inhibits a protein called TBK1 that is known to promote aging in cells and organs.

Furthermore, old mice that drank water spiked with extra betaine had stronger muscles, less inflammation and more youthful skin than their counterparts who did not get the supplement.