Study Links Elevated Tyrosine Levels to Reduced Lifespan in Men

A large study of over 270,000 individuals indicates that a common amino acid may influence how long men live.

Researchers led by Jie V. Zhao, Yitang Sun, Junmeng Zhang, and Kaixiong Ye from the University of Hong Kong and the University of Georgia explored whether phenylalanine and tyrosine—two amino acids involved in metabolism and brain function—are associated with lifespan. Their analysis revealed a clear sex‑specific pattern: higher tyrosine concentrations correlated with shorter life expectancy in men, whereas no significant effect was observed in women.

The results could eventually shed light on why aging and longevity differ between the sexes, although further research is required before any health recommendations can be made.

The research was published in Aging-US under the title “The role of phenylalanine and tyrosine in longevity: a cohort and Mendelian randomization study.”

Why Tyrosine Matters

Amino acids serve as the building blocks for proteins. Phenylalanine and tyrosine are present in protein‑rich foods and are also sold as dietary supplements. Beyond protein synthesis, these molecules participate in key biological processes. Tyrosine, in particular, is a precursor for neurotransmitters such as dopamine, which regulates mood, motivation, and cognition.

Despite their importance, the long‑term impact of variations in phenylalanine and tyrosine levels on aging remains poorly understood.

More Than 270,000 People Studied

To examine this question, the team analyzed data from more than 270,000 participants in the UK Biobank, a extensive repository of health and genetic information from UK residents.

The investigators employed two complementary strategies. First, they assessed the relationship between circulating levels of phenylalanine and tyrosine and mortality‑related outcomes, including predicted lifespan. Second, they applied genetic techniques to test whether the observed associations might reflect a causal link.

One of these genetic approaches was Mendelian randomization, which uses naturally occurring genetic variants as instrumental variables to infer causality. Because these variants are assigned at conception, preceding most lifestyle exposures and disease onset, the method can provide stronger evidence for cause‑and‑effect than observational analyses alone.

Initially, higher concentrations of both amino acids appeared to be linked to an increased risk of death. Upon closer inspection, however, tyrosine emerged as the consistent driver of this association.

Tyrosine Linked to a Shorter Lifespan in Men

The genetic analyses suggested that elevated tyrosine levels may have a potentially causal relationship with reduced life expectancy in men. According to the researchers’ estimates, higher tyrosine could shorten male lifespan by nearly one year.

No comparable pattern was detected in women; tyrosine showed no significant effect on female lifespan.

The association persisted after adjusting for phenylalanine and other related factors, supporting the idea that tyrosine may have an independent influence on aging.

The researchers also noted that men generally exhibit higher tyrosine levels than women. This difference might contribute to the well‑documented gap in average lifespan between the sexes, although the current findings do not establish tyrosine as the cause of that disparity.

“Phenylalanine showed no association with lifespan in either men or women after controlling for tyrosine.”

Why Might Tyrosine Affect Longevity?

The exact mechanisms linking higher tyrosine levels to shorter lives in men remain unknown.

One hypothesis involves insulin resistance, a condition in which cells become less responsive to insulin, the hormone that regulates blood glucose. Insulin resistance is associated with several age‑related diseases and could therefore provide a plausible connection between tyrosine and longevity.

Tyrosine also serves as a precursor for neurotransmitters involved in the stress response. Since hormonal and signaling pathways can differ between men and women, this divergence might help explain why the observed lifespan effect appears only in males.

These ideas remain speculative and will require further investigation.

What the Findings Mean for Tyrosine Supplements

Tyrosine is widely marketed as a dietary supplement and is often promoted for enhancing focus, alertness, and mental performance. The new results raise questions about whether chronically elevated tyrosine levels could have unintended long‑term consequences.

Importantly, the study did not directly test tyrosine supplements. Consequently, the results do not demonstrate that taking a tyrosine supplement shortens lifespan.

Instead, the investigation examined endogenous tyrosine concentrations and their relationship with longevity. The authors suggest that individuals with unusually high tyrosine levels might benefit from dietary adjustments aimed at lowering those concentrations.

One possible approach is to reduce overall protein intake, which could decrease tyrosine exposure. However, it remains uncertain whether deliberately lowering tyrosine through diet would actually extend lifespan or improve health.

Further research will be needed to confirm the findings, elucidate the underlying biological mechanisms, and determine whether diet or lifestyle interventions can safely modify tyrosine levels in ways that promote healthier aging.

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