Dr. Yadav, together with colleagues at the National Institute of Immunology in New Delhi, first measured taurine levels in people’s blood and found a steady decline with age. In 60-year-olds, taurine levels were about one-third of those in small children.

His team then gave high-dose taurine supplements to middle-aged mice and rhesus monkeys and compared their health outcomes to animals that did not get the amino acid boost. Six months of treatment were enough to see improvements in bone density, sugar metabolism and immune function in the monkeys, while the mice showed these benefits and more.

The mice gained less weight, had stronger muscles, were less anxious and showcased multiple improvements on a cellular level, including a reduction in the number of so-called zombie cells, old cells that stop dividing but continue to wreak havoc on neighboring tissues‌. Taurine also increased the average life span of the mice by 12 percent for females and 10 percent for males. The supplement had a similar impact on worm longevity.

The researchers also found supporting evidence for the anti-aging potential of taurine in people by analyzing two data sets. One, involving nearly 12,000 middle-aged individuals living in eastern England, showed a connection between low taurine levels and diseases such as obesity, diabetes and hypertension. The other, involving athletes from Germany, found that high-intensity exercise could naturally enhance taurine levels — which could account for some of the anti-aging benefits of physical activity.

What taurine does inside the body isn’t yet clear. Experiments in mice and worms point to a role for taurine in maintaining the health of mitochondria, energy-producing factories inside each cell. But more work is needed, noted Christy Carter, a health scientist administrator at the National Institute on Aging. “We are not sure how it’s working,” she said.