TAURINE AND AGING: A 2023 HEADLINE AND A 2025 REVERSAL

In June 2023, Science published a paper titled "Taurine deficiency as a driver of aging." In June 2025, the same journal published a paper titled "Is taurine an aging biomarker?" that reported the opposite finding in three human cohorts. Both are worth reading at what they actually measured.

What the 2023 Paper Reported

Singh and colleagues, publishing in Science (2023;380(6649):eabn9257), reported that circulating taurine concentrations declined with age in mice, monkeys and humans. Reversing that decline through supplementation increased health span and life span in mice, and health span in monkeys. Mechanistically, the authors reported that taurine reduced cellular senescence, protected against telomerase deficiency, suppressed mitochondrial dysfunction, decreased DNA damage and attenuated inflammaging.

In the human portion, lower taurine concentrations correlated with several age-related diseases, and taurine concentrations increased after acute endurance exercise. The authors' own conclusion was appropriately conditional — that taurine deficiency may be a driver of aging, and that clinical trials in humans "seem warranted" to test whether it actually is. The paper's competing-interest statement discloses that Columbia University filed provisional patent applications on which the senior author is an inventor.

The conditional framing did not survive the news cycle. What circulated was the supplement-shaped version.

What the 2025 Paper Reported

Fernandez and colleagues at the National Institute on Aging published "Is taurine an aging biomarker?" in Science (2025;388(6751):eadl2116). They measured circulating taurine in three geographically distinct human cohorts, plus nonhuman primates and mice — both longitudinally (the same individuals repeatedly over time) and cross-sectionally.

Their finding: circulating taurine concentrations increased or remained unchanged with age across those cohorts. They also reported considerable variability in how taurine associated with age-related changes in gross motor function and energy homeostasis, and noted that within-individual differences in taurine often exceeded the age-related differences.

Our results suggest that changes in circulating taurine are not a universal feature of aging, and that its pleiotropic effects may be dependent on the temporal and physiological context of each individual.

Worth being precise about scope: this paper is about whether low taurine tracks aging, not about whether supplementing does anything. The authors do not rule out benefit from supplementation in older adults, particularly in people who start with genuinely low circulating levels or who have chronic disease.

A Third Dataset, Measured in Men Aged 20 to 93

Marcangeli and colleagues published a direct test in Aging Cell in October 2025 (24(10):e70191), and this is the one most relevant to anyone training seriously past 50, because it measured performance rather than just blood levels.

They assessed 137 men aged 20 to 93 — both physically inactive and physically active — looking for associations between circulating taurine and age, muscle mass, strength, physical performance, and mitochondrial function. They found no association with any of them. The paper's title is its conclusion: "Experimental Evidence Against Taurine Deficiency as a Driver of Aging in Humans."

That is an observational cross-section, not a supplementation trial, and it cannot tell you what happens if you take taurine. What it can say is that among 137 men spanning seven decades, how much taurine was in their blood did not track how strong they were, how much muscle they carried, or how well their mitochondria functioned.

What the Supplementation Trials Have Measured

Separately from the biomarker argument, there is a small human supplementation literature. It is mostly short, mostly in clinical or untrained populations, and mostly at 3 g/day.

On cognition, Cao and colleagues published a meta-analysis in International Journal of Food Sciences and Nutrition (2025;76(4):370-380) pooling 7 RCTs across 9 intervention trials and 402 participants. Taurine, given alone or combined with exercise training, did not produce significant effects on cognitive scores. A subgroup combining taurine with therapeutic drugs did show a Mini-Mental State Examination improvement (WMD 3.09, 95% CI 2.29 to 3.90), but the authors' overall stated conclusion is that the evidence is not sufficient to support taurine for enhancing cognitive function.

On performance, a 2025 Bayesian network meta-analysis in the Journal of the International Society of Sports Nutrition (22(1):2566371) pooled 12 studies on caffeine, taurine, and the two combined. The credible effects belonged to the combination: caffeine plus taurine on anaerobic capacity (g = 0.46, 95% CrI 0.19 to 0.71) and reaction time (g = 0.75, 95% CrI 0.29 to 1.18) versus either alone. Taurine on its own showed only a possible tendency toward reduced blood lactate (g = −0.30, 95% CrI −1.01 to 0.42) — a credible interval spanning zero. Effects on aerobic performance were described by the authors as variable and context-dependent.

On body composition and metabolic markers, the trials are small and combine taurine with training. Samadpour Masouleh and colleagues (Nutrients 2021;13(11):3958) randomized 40 women with type 2 diabetes, mean age 53, across four arms of 10 for 8 weeks; their stated conclusion was that taurine supplementation alone failed to show hypoglycemic or hypolipidemic properties, with the effects appearing only when combined with training. A 2026 trial in Nutrients (18(14):2325) randomized 44 men with obesity into four arms of 11 for 12 weeks and found the exercise-plus-taurine group came out ahead on body mass, BMI and body fat percentage — with the authors stating directly that given 11 people per group, "these findings should be considered preliminary and exploratory" and require replication in larger, adequately powered trials before any clinical translation.

What Nobody Has Measured Yet

Searching PubMed for taurine supplementation trials in masters athletes returns nothing. Searching for randomized taurine trials measuring muscle strength or sarcopenia outcomes in older adults returns nothing. I could not find a randomized trial of taurine supplementation in trained athletes over 50 measuring performance, strength or muscle outcomes.

The population the supplement is marketed to on longevity grounds — trained, older, already doing the work — is the population with no trial in it. What exists instead is mouse and monkey lifespan data, three human cohort studies that disagree with the premise, and a handful of small short trials in people with obesity or type 2 diabetes.

The Protocol

What the evidence as it stands can and cannot carry:

• The mouse and monkey health span data from 2023 is real animal data. It has not been reproduced as a human outcome by any trial to date.
• Three separate human datasets — the NIA's three cohorts and the 137-man Aging Cell study — reported that circulating taurine does not reliably fall with age. The premise the supplement case was built on is the part that did not replicate.
• The human supplementation trials that exist are short (8 to 12 weeks), small (10 to 11 per arm), and run in clinical or untrained populations. Their own authors describe them as preliminary.
• Where taurine did move something, it was usually alongside training, and the training arms moved things too.
• Taurine at 3 g/day is the dose used across these trials, and the trials did not report safety concerns at that dose over those durations. That is a statement about what those studies observed, not a safety clearance.

The thing worth carrying out of this is less about taurine specifically and more about how the sequence went: a striking animal paper with a conditional human conclusion, an unconditional headline, and then two years later a set of human measurements that did not support the premise. That sequence is common enough in the longevity supplement space to be worth recognizing on sight — and the two-year gap is why the boring interventions with decades of human outcome data keep earning their place first.

Battle Hard. — Will Power