A nutrient often promoted for boosting focus and brain performance may carry an unexpected downside for men’s long‑term health, according to a new study.
Published in the journal Aging‑US on June 15, 2026, the research suggests that higher levels of the amino acid tyrosine in the blood could be linked to a shorter lifespan in men.
Understanding this link starts with the role amino acids play in the body, particularly compounds like tyrosine.
Why Tyrosine Matters
Tyrosine is one of the amino acids the body relies on to operate. Amino acids act as the building blocks of proteins and support essential processes such as tissue repair and enzyme production.
Alongside phenylalanine, tyrosine also plays a role in regulating metabolism and brain activity. It is naturally found in foods including meat, fish, eggs and dairy products, and is also sold in supplements aimed at improving concentration, energy and cognitive performance.
Its link to brain function comes from its role in producing neurotransmitters such as dopamine, norepinephrine and epinephrine. These chemicals shape mood, attention, motivation and the body’s response to stress.
What the Study Looked At
Researchers analyzed health and genetic data from more than 270,000 participants in the U.K. Biobank to examine whether these amino acids influence lifespan.
The team, led by Jie V. Zhao, Yitang Sun, Junmeng Zhang and Kaixiong Ye from the University of Hong Kong and the University of Georgia, used two approaches.
They assessed observed links between amino acid levels and mortality, and applied Mendelian randomization, a genetic method used to test whether those links may reflect a causal relationship.
What They Found
Both phenylalanine and tyrosine initially appeared to be associated with a higher risk of death, however, after further analysis, only tyrosine remained consistently linked to lifespan.
Men with higher levels of tyrosine in their blood were found to have a shorter life expectancy—genetic estimates suggested this could amount to nearly a year.
No significant association was found in women. Researchers also noted that men tend to have higher tyrosine levels than women, which may contribute to differences in average lifespan between the sexes.
Phenylalanine showed no association with lifespan once tyrosine was taken into account.
What Could Explain the Link
The study does not identify a single cause but points to several possible biological pathways.
One involves insulin resistance, a condition in which the body’s cells respond less effectively to insulin. This is linked to age‑related diseases including type 2 diabetes, cardiovascular disease and metabolic disorders.
Tyrosine’s role in neurotransmitter production may also influence how the body responds to stress over time—disruption in these systems could affect long‑term health.
Hormone‑related differences between men and women may offer another explanation for why the effect was only seen in male participants.
What It Means for Supplements
Tyrosine is widely used in products marketed to support focus and alertness, particularly during periods of stress.
The study did not test supplements directly or assess whether taking them affects lifespan, it focused only on naturally occurring levels of tyrosine in the blood.
As a result, the findings do not show that tyrosine supplements are harmful. However, they suggest that elevated levels of this amino acid may be worth closer attention when considering long‑term health.
Researchers also noted that reducing overall protein intake could lower tyrosine levels, though whether this would improve healthy aging remains unclear.
What Happens Next
The findings add to growing interest in how nutrients linked to brain function may also play a role in aging.
Further studies will be needed to confirm the results in other populations and to better understand the biological mechanisms involved. Researchers also aim to explore whether diet or lifestyle changes can safely influence tyrosine levels.
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