If you have questions about your tyrosine or protein intake, it is worth talking them through with a doctor rather than guessing. Published in the journal Aging, the research linked higher blood tyrosine to a shorter lifespan in men, with no significant effect found in women, across more than 270,000 people in the UK Biobank. The researchers measured tyrosine already circulating in the blood. They never recorded, assigned or tested a supplement, so the work does not show that taking a tyrosine supplement shortens life.
What the study measured
Researchers Jie V. Zhao, Yitang Sun, Junmeng Zhang and Kaixiong Ye, from the University of Hong Kong and the University of Georgia, examined whether phenylalanine and tyrosine, two amino acids found in protein-rich foods and sold as supplements, are connected to how long people live. The paper, published in Aging in October 2025, started from a known pattern: the authors note that "Protein restriction increases lifespan, however, the specific amino acids affecting lifespan are unclear." They tested whether tyrosine might be one of those amino acids.
Tyrosine has roles beyond building protein. The body uses it to make neurotransmitters such as dopamine, the chemical messenger that helps regulate mood, motivation and thinking. The authors cite animal experiments in which tyrosine is involved in the response to a low-protein diet, and in which restricting tyrosine intake lowered internal tyrosine levels and prolonged lifespan. Those results came from animals, not people.
The team used two methods on UK Biobank data. First, Cox regression tested the association between blood concentrations of each amino acid and death. Second, two-sample Mendelian randomization used naturally occurring genetic differences as a way to probe whether the relationship might go beyond simple association. Because genes are assigned before many lifestyle choices and diseases develop, the technique can sometimes provide stronger clues about cause and effect than an observational study alone.
What the blood and genetic analyses found
At first, higher levels of both amino acids appeared tied to a higher risk of death. When the researchers looked more closely, tyrosine was the one that stood out. After the multivariable analysis controlled for phenylalanine, the study reported that higher tyrosine remained related to a shorter lifespan in men, at about 0.91 fewer years of life, with a 95% confidence interval running from roughly 0.21 to 1.60 fewer years. For women, the estimate was 0.36 fewer years, with a confidence interval from about 0.23 more years to 0.96 fewer years. Because that range crosses zero, the analysis did not find a statistically significant association in women. Phenylalanine showed no association with lifespan in either sex once tyrosine was accounted for.
Men generally had higher tyrosine levels than women. The authors say that difference could contribute to the documented gap in average lifespan between the sexes, but the findings do not establish that tyrosine is responsible for that gap.
Why this does not mean a supplement shortens life
The study measured a blood concentration, not a supplement dose. The researchers analyzed circulating tyrosine and genetic variants. They did not assign tyrosine, record who took it, or compare users with non-users.
The authors concluded that reducing tyrosine in people with high concentrations may contribute to prolonging lifespan. That wording describes a possibility to study further. The paper did not test a protein-restricted diet as a treatment, did not show that lowering tyrosine extends human life, and did not set a safe target level. It remains unclear whether lowering tyrosine through diet would actually improve health.
How tyrosine might affect lifespan
Scientists do not yet know why higher tyrosine might track with shorter lives in men. One proposed explanation is insulin resistance, when cells respond less to the hormone that controls blood sugar, a state linked to several age-related diseases. Tyrosine is also used to make neurotransmitters involved in the stress response, and related signaling can work differently in men and women, which could help explain why the pattern appeared in men. The paper presents these as hypotheses that need more investigation, not as proven mechanisms.
What this says about brain supplements in general
Tyrosine is marketed for focus and mental performance, which puts it among the brain supplements that medical reviewers already question. A Harvard Health article, reviewed by Dr. Pieter Cohen and published in February 2026, reports that about one in four adults over age 50 take at least one supplement to improve brain health. Dr. Cohen, an internist with Harvard-affiliated Cambridge Health Alliance, said, "There’s no evidence to suggest there’s an ingredient in supplements that can improve brain health." The article notes the FDA does not oversee supplement product testing or ingredient accuracy.
Label accuracy is a separate concern. A 2020 scoping review in the Journal of Alternative and Complementary Medicine, which analyzed products marketed for brain health and cognitive performance, selected 12 products from the 650 it identified. Eight of the 12, or 67%, had at least one ingredient listed on the label that was not detected in analysis, and compounds not reported on the label were detected in 10 of the 12, or 83%. That review did not test tyrosine for lifespan and does not confirm the Aging finding; it describes how often brain supplement contents differ from their labels.
What to do now
- Do not stop tyrosine or start a low-protein diet on your own because of this study. Talk to a qualified clinician first.
- If you take a tyrosine supplement, write down the reason, the dose and how long you have taken it, and review that with a health professional.
- If a clinician has found that your tyrosine is high, ask what caused it and whether monitoring makes sense.
- If you have questions about this research, talk them over with a qualified health professional.
FAQ
Does taking a tyrosine supplement shorten lifespan?
The study did not test tyrosine supplements. It analyzed tyrosine already circulating in the blood and genetic variants linked to it, so it does not show that taking a tyrosine supplement shortens lifespan.
How much shorter was the estimated lifespan for men with higher tyrosine?
After controlling for phenylalanine, the Aging paper estimated about 0.91 fewer years of life in men, with a 95% confidence interval from roughly 0.21 to 1.60 fewer years. The authors describe this as an association, not a proven effect of a supplement.
Was higher tyrosine linked to a shorter lifespan in women?
The estimate for women was 0.36 fewer years, with a confidence interval from about 0.23 more years to 0.96 fewer years. Because that range crosses zero, the analysis did not find a statistically significant association in women.
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