Taurine does not fall with age after all, a second Science paper reports

In June 2023, Science published a paper arguing that taurine deficiency is a driver of ageing. It reported that circulating taurine declines with age in mice, monkeys and humans; that reversing the decline through supplementation increased health span and lifespan in mice and health span in monkeys; and that taurine reduced cellular senescence, protected against telomerase deficiency, suppressed mitochondrial dysfunction, decreased DNA damage and attenuated inflammaging [s2]. In humans, lower taurine concentrations correlated with several age-related diseases [s2]. The paper called for clinical trials to test whether taurine deficiency drives ageing in people [s2].

The supplement industry did not wait for the trials.

The follow-up

Two years later, in June 2025, Science published a second paper asking whether taurine is an ageing biomarker at all [s1]. The first requirement of the hypothesis is that taurine goes down with age. The authors checked, in three geographically distinct human cohorts, in non-human primates and in mice, measuring both longitudinally — repeatedly in the same population — and cross-sectionally [s1].

Circulating taurine concentrations increased or remained unchanged with age [s1].

That is a direct contradiction of the premise, not a quibble about effect size. The authors also examined whether taurine tracked age-related changes in health outcomes relating to gross motor function and energy homeostasis, and found considerable variability in those associations [s1]. Their conclusion is that changes in circulating taurine are not a universal feature of ageing, and that taurine's varied effects may depend on the temporal and physiological context of each individual [s1].

Why two careful studies can disagree

Neither paper is obviously wrong, and the disagreement is instructive about how ageing biomarkers behave.

Cross-sectional sampling compares different people of different ages at one moment. If younger and older participants differ in diet, muscle mass, kidney function or recent exercise — and taurine concentrations rise after acute endurance exercise [s2] — an apparent age trend can be produced by the composition of the sample rather than by ageing. Longitudinal sampling, following the same people over time, removes that confound, which is why the 2025 study reports both designs and gets the same answer from each [s1].

The other lesson is about the direction of inference. Even in the original paper, the human evidence was correlational: lower taurine concentrations were associated with several age-related diseases [s2]. The causal claims came from mice and monkeys [s2]. Illness lowers many circulating metabolites; that a marker is low in sick people does not establish that raising it makes them well.

What supplementation has actually done in people

The trials the 2023 paper called for have not answered the ageing question, because they were never designed to. What does exist is scattered across other outcomes.

A systematic review and meta-analysis of randomised controlled trials searched to January 2025 and found 7 trials, comprising 9 intervention arms and 402 participants, testing taurine on cognitive function [s3]. Taurine alone, or combined with exercise training, produced no significant effect on cognitive scores [s3]. Combining taurine with therapeutic drugs did not improve cognition beyond the drugs alone, although a subgroup analysis found a significant gain on the Mini-Mental State Examination, with a weighted mean difference of 3.09 (95% CI 2.29 to 3.90) [s3]. The reviewers' overall verdict was that the evidence is not sufficient to support taurine supplementation for enhancing cognitive function [s3].

Four hundred and two people across seven trials is a small evidence base for a compound sold at scale, and cognition is only one of the outcomes taurine is marketed for.

What this changes

Taurine remains a real and interesting molecule with genuine physiology behind it, and the 2023 mouse and monkey experiments have not been retracted or refuted. What has changed is the specific claim that made taurine a longevity product: that its decline with age is a fact about human ageing which supplementation corrects.

Measured properly, in three human cohorts, that decline did not appear [s1].

This is a useful case to hold on to, because the pattern recurs across the longevity field. A striking animal result, an inferred human deficiency, a supplement, and then — sometimes years later — the replication attempt that nobody markets. The replication is the part that tells you whether the intervention had a target.

This article describes research findings and is not medical or dietary advice.

Sources

1. [s1] Is taurine an aging biomarker? Science, published online June 5, 2025. https://doi.org/10.1126/science.adl2116
2. [s2] Taurine deficiency as a driver of aging. Science, published online June 2023. https://doi.org/10.1126/science.abn9257
3. [s3] Effects of taurine supplementation on cognitive function: a systematic review and meta-analysis of randomised controlled trials. International Journal of Food Sciences and Nutrition, published online May 4, 2025. https://doi.org/10.1080/09637486.2025.2499044