Anti-ageing effects of popular supplement taurine challenged

Massive study finds limited connection between ageing and taurine levels in people, monkeys and mice

Levels of the amino acid taurine did not correlate reliably with strength measures in older humans.Credit: Karen Haibara/AFP/Getty

Research suggests that blood levels of the amino acid taurine might not be as closely linked to ageing as previous research had suggested. Led by scientists at the US National Institute on Aging (NIA) in Baltimore, Maryland, the study casts doubt on the use of taurine as an ageing biomarker — something that could be measured to help determine a person’s health status — and on its use as a dietary supplement to stave off the effects of ageing¹.

“We clearly show that there’s no need for taurine supplementation as long as you have a healthy diet,” says Rafael de Cabo, a gerontologist at the NIA. The results were published today in Science.

Scientists not involved in the research highlight the rigour of the analysis, which looked at taurine levels in hundreds of humans over time, as well as in rhesus monkeys (Macaca mulatta) and mice. “Taurine levels were not decreasing [with age] and are not related to any abnormality that they could see in this very good longitudinal study,” says geneticist Nir Barzilai, director of the Institute for Aging Research at Albert Einstein College of Medicine in New York City. Nevertheless, the study looked only at natural taurine levels in the body, and not at whether supplements have any benefits. “That’s something that has yet to be tested,” he says.

Bullish on taurine

Taurine is sold over-the-counter as a dietary supplement, and it is an ingredient in popular caffeinated energy drinks such as Red Bull and Monster Energy. Various health effects have been attributed to taurine, including improving focus and energy levels. But these claims have not been thoroughly evaluated.

Taurine, first isolated from ox bile in 1827, is not considered an essential amino acid.

In a 2023 study, also published in Science², researchers found that levels of taurine seemed to decline in mice, monkeys and humans as they aged. Daily supplements of the amino acid seemed to extend the lifespan and improve the health of taurine-deficient mice.

But something about the research “didn’t click”, de Cabo says. His team had been collecting results that showed taurine levels increasing or remaining stable with age.

Whereas the previous study on taurine was cross-sectional in design, meaning that it collected data from animals of different ages at a single point in time, de Cabo’s team also collected longitudinal data, taking samples from the same individuals over time.

In humans, they studied three different populations, one of which (the Baltimore Longitudinal Study of Aging) included more than 740 participants aged 26–100. In animals, they followed monkeys until they were up to 32 years old and mice up until 27 months — almost their entire lifespan.

In nearly all cohorts, except the male mice group, taurine levels increased with age.

The authors also examined taurine’s relationship with things such as muscle strength and body weight. Although there were some associations — such as higher taurine being linked to stronger knee strength in one human cohort — the results were inconsistent across age groups, sexes and species. In some cases, higher taurine levels correlated with strength deficiencies. On the basis of these findings, levels of taurine in the blood “are unlikely to serve as a good biomarker of ageing”, says co-author Maria Emilia Fernandez, a gerontologist at the NIA. Finding simple, reliable biomarkers for ageing has long been a goal for the field, because they might provide a shortcut in evaluating drugs and treatments for the maladies of ageing.

De Cabo’s study is “more convincing” than the previous one, says geneticist David Sinclair at Harvard University in Boston, Massachusetts. In recent years, there has been an over-reliance on cross-sectional data sets, such as those used in the earlier study, he says — and those are highly variable. That variability, he says, can lead to misinterpretations and false-positive conclusions.