A new study is pouring cold water on the idea that taurine – a nutrient found in the body and in foods – is a magic bullet for aging. Researchers led by Maria Emilia Fernandez at the U.S. National Institute on Aging found that taurine levels in blood do not reliably decline with age in humans, mice, or monkeys. In fact, in their comprehensive analyses, taurine concentrations either stayed stable or even increased as the animals and people got older.

These results directly defy earlier reports that suggested taurine levels drop with age, which had spurred excitement that boosting taurine might slow aging. Instead, the new data indicate taurine is “not a reliable biomarker of aging,” as Fernandez noted, given that individual variability in taurine far outweighed any small, age-related changes.

“The main takeaway is that a decline in taurine is not a universal feature of aging,” says Joseph Baur, a University of Pennsylvania physiologist not involved in the study. Taurine levels differed so much from one individual to the next that one’s age had minimal influence. “Blood taurine levels cannot be used as a biomarker of aging,” agrees Mark Mattson, an aging researcher at Johns Hopkins, given the convincing breadth of the new data. The findings undermine the notion that simply measuring taurine could indicate biological age or aging rate.

Longitudinal Data Clarify Conflicting Results

Crucial to the new study’s approach was its longitudinal design, which tracked the same participants in the Baltimore Longitudinal Study of Aging taurine levels over time. Previous studies had mostly used a cross-sectional approach – comparing younger and older individuals at a single time point – and those yielded conflicting results. Such discrepancies can arise from genetic and lifestyle differences between individuals rather than aging itself. To resolve this, Fernandez and colleagues combined cross-sectional data with longitudinal tracking across the lifespan in three large human cohorts, as well as in rhesus monkeys and mice. This mixed approach provided a clearer picture: within individuals, taurine generally did not fall over adulthood. In the Baltimore Longitudinal Study of Aging (which followed adults from 26 up to 100 years old) and in lab animals, taurine levels mostly held steady or rose slightly with age. Notably, male mice were an outlier – their taurine levels stayed flat – but even in mice no age-related drop was seen.

Because the same subjects were observed over time, this study design ruled out cohort biases that can mislead cross-sectional studies. “We used longitudinal, cross-species data across the lifespan under normal conditions to clarify how taurine levels change with age… a key advance for aging research,” explains Fernandez. The rigorous methodology strengthens confidence that the results reflect true aging effects (or lack thereof), rather than random population variation. Still, the authors acknowledge remaining questions. For instance, their analysis focused on healthy individuals; it’s possible that in certain disease states or extreme old age, taurine might behave differently. And while longitudinal observation is powerful for correlation, it cannot by itself prove causation – meaning it remains possible that taurine could influence aging in ways not captured by blood level trends. These nuances temper the findings even as they resolve one source of confusion in the field.

Challenging a 2023 “Elixir of Life” Study

The new evidence sharply contrasts with a high-profile Science paper from June 2023 that had cast taurine as a potential “elixir of life.” In that earlier study, Vijay Yadav of Columbia University and collaborators reported that taurine levels dropped dramatically with age – 60-year-old humans had only about one-third the taurine levels of 5-year-olds – and that giving taurine to middle-aged lab animals extended their lifespans by around 10–12%. Those findings made headlines and prompted some longevity enthusiasts to start popping taurine supplements, despite Yadav’s own caution.

The new Science study now calls into question one of the pillars of Yadav’s 2023 paper – the notion that taurine deficiency is a driver of aging. Fernandez’s team found no consistent deficiency emerging with age. How could the two studies diverge so starkly? One factor is study design: Yadav’s 2023 conclusions about taurine decline were based on cross-sectional comparisons (young vs. old subjects). Such snapshots are vulnerable to confounding differences unrelated to aging. By contrast, the new longitudinal data suggest that what looked like an age-related taurine drop might have been an artifact; perhaps the older individuals in the 2023 study had different diets or genetics that lowered taurine, rather than age per se.

“There is a discrepancy between different studies, and this discrepancy needs to be analyzed more in depth,” says Dr. Luigi Ferrucci, scientific director at NIA and a co-author of the new report. Unraveling why one study saw a decline while another saw stability could reveal important biological mechanisms, Ferrucci notes – for example, clues about how diet or metabolism interact with aging. It’s possible both studies are “right” in different contexts: taurine supplementation did benefit mice in Yadav’s experiments, but not necessarily because of a universal age-related deficit. The efficacy of taurine might be highly context-dependent – working under certain physiological conditions (or in some species) but not others.

Moreover, the new study did not directly repeat the taurine supplementation experiment that extended mouse lifespans. So it doesn’t refute the life-extension result; rather, it casts doubt on the original interpretation that taurine’s benefits came from fixing an age-related deficiency. “The data… show that blood taurine levels cannot be used as a biomarker of aging,” says Mattson, implying that low taurine may not be a general cause of aging after all. Still, the fact remains that taurine did improve health and longevity for mice in the 2023 study. “Given that other studies have shown benefits, including lifespan extension in mice, I think the case remains to explore the potential for taurine supplementation to improve health,” Baur tells Live Science. In other words, taurine’s story isn’t neatly over – but simplistic ideas about it being a universal anti-aging cure are very much undercut.

Complex and Contextual Biology

Part of the challenge in pinning down taurine’s role is that this amino acid has a bewildering array of biological functions. It is one of the most abundant amino acids in animals, essential for things like forming bile salts to digest fats, bolstering antioxidant defenses, and supporting mitochondrial proteins – fundamental housekeeping roles that don’t point to a single aging pathway. Taurine levels also fluctuate in different diseases and physiological states in seemingly contradictory ways. For example, people with moderate obesity tend to have lower taurine compared to lean individuals, yet in severe obesity taurine levels surge dramatically. In cancer patients, taurine is found to increase in some cancers (like leukemia) but decrease in others (like breast cancer).

Such variability suggests taurine is responding to or compensating for diverse stresses and conditions – a far cry from a unidirectional aging marker. As Fernandez observed, an isolated taurine measurement is “not a reliable biomarker of anything yet,” given this complexity. The new study underscored that even basic health indicators like muscle strength or body weight showed inconsistent relationships with taurine levels compared to using a home use hyperbaric chamber. In some cases, weaker muscle function was associated with high taurine; in other cases, low taurine; and often there was no clear relationship at all. This patchy correlation means taurine simply doesn’t track neatly with functional decline. “I think that we need to be digging into the basic mechanisms… before it can be used reliably as a marker,” says Rafael de Cabo, chief of the Translational Gerontology Branch at NIA and a co-author of the studyl. In short, taurine biology is messy and context-dependent, which tempers any broad claims about its role in aging.

This patchy correlation means taurine simply doesn’t track neatly with functional decline. “I think that we need to be digging into the basic mechanisms… before it can be used reliably as a marker,” says Rafael de Cabo, chief of the Translational Gerontology Branch at NIA and a co-author of the study. In short, taurine biology is messy and context-dependent, which tempers any broad claims about its role in aging.

The complexity also raises a possibility: maybe taurine can still influence aging indirectly or in subset conditions even if it isn’t a universal metric. For instance, taurine might benefit organisms under specific metabolic stresses or nutrient regimes – scenarios not fully captured in the current study of generally healthy subjects. The authors acknowledge that taurine’s potential as an anti-aging therapy is likely context-specific rather than universal. It may act in concert with other factors, or only be limiting in certain environments. This nuanced view contrasts with the early hype of taurine as a one-size-fits-all longevity booster. As science probes deeper, it’s becoming clear that there is no simple “fountain of youth” molecule, but rather a network of interlinked biological processes.