A large study involving more than 270,000 people suggests that a common amino acid may be linked to 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 examined whether phenylalanine and tyrosine, two amino acids involved in metabolism and brain function, are related to lifespan (lifespan). Their results point to a notable difference between men and women. Higher tyrosine levels were associated with shorter life expectancy in men, while no significant effect was detected in women.
The findings could eventually help scientists better understand why aging and longevity differ between the sexes, although much more research is needed before the results can be translated into health recommendations.
The research was published in Aging-USA titled “The role of phenylalanine and tyrosine in longevity: a cohort and Mendelian randomization study.”
Why is tyrosine important?
Amino acids are the molecular building blocks that the body uses to make proteins. Phenylalanine and tyrosine are found in protein-containing foods and are also available in dietary supplements.
Beyond their role in protein production, these amino acids participate in important biological processes. Tyrosine is especially interesting because the body uses it to produce neurotransmitters such as dopamine. Neurotransmitters are chemical messengers that allow nerve cells to communicate, and dopamine helps regulate functions including mood, motivation, and thinking.
Despite these important functions, scientists still do not fully understand how long-term differences in phenylalanine and tyrosine levels might influence aging.
More than 270,000 people studied
To investigate, the researchers analyzed information from more than 270,000 participants in the UK Biobank, a large research database containing genetic and health data on people in the UK.
The team used two complementary approaches. First, they looked for associations between blood concentrations of phenylalanine and tyrosine and outcomes related to death and expected life expectancy. They also used genetic methods to investigate whether the relationships could go beyond a simple association.
One such approach was Mendelian randomization. This method uses naturally occurring genetic differences between people as a way to test whether a particular biological factor can contribute to an outcome. Because genes are assigned before many lifestyle choices and diseases develop, the technique can sometimes provide stronger clues to cause and effect than an observational study alone.
Initially, higher levels of both amino acids appeared to be associated with a higher risk of death. But when the researchers examined the relationships more closely, tyrosine was the one that consistently stood out.
Tyrosine linked to shorter lifespan in men
Genetic analyzes suggested that elevated tyrosine levels may have a potentially causal relationship with reduced life expectancy in men. According to researchers’ estimates, a higher level of tyrosine could shorten male life expectancy by almost a year.
The same pattern was not observed in women. The researchers found no significant effect of tyrosine on female life expectancy.
The relationship also held after the researchers accounted for phenylalanine and other related factors, strengthening the possibility that tyrosine itself may have an independent connection to aging.
The team also found that men generally have higher levels of tyrosine than women. That difference could potentially contribute to the well-documented gap in average lifespan between the sexes, although the findings do not establish that tyrosine is responsible for that gap.
“Phenylalanine showed no association with life expectancy in either men or women after controlling for tyrosine.”
Why might tyrosine affect longevity?
Scientists still don’t know exactly why higher levels of tyrosine might be associated with shorter lifespans in men.
One possible explanation involves insulin resistance. This occurs when cells become less receptive to insulin, the hormone that helps control blood sugar. Insulin resistance is associated with several diseases that become more common with age and could therefore provide a possible link between tyrosine and longevity.
The body also uses tyrosine to produce neurotransmitters involved in the stress response. Hormones and related signaling pathways may function differently in men and women, which could help explain why the apparent lifespan effect arose only in men.
However, these mechanisms remain hypotheses and will require further investigation.
What the findings mean for tyrosine supplements
Tyrosine is widely sold as a dietary supplement and is often touted to improve concentration, alertness, and mental performance. Therefore, the new findings raise questions about whether chronically high levels of tyrosine could have unwanted long-term consequences.
Importantly, the researchers did not directly test tyrosine supplements. Therefore, the results do not show that taking a tyrosine supplement shortens life expectancy.
Instead, the study examined tyrosine levels in the body and its relationship to longevity. The researchers suggest that people with unusually high tyrosine concentrations could potentially benefit from dietary changes designed to reduce those levels.
One possible strategy is to restrict protein intake, which could reduce tyrosine exposure. However, it is still unclear whether deliberately reducing tyrosine through diet would actually extend lifespan or improve health.
More research will be needed to confirm the results, uncover the biological mechanisms involved, and determine whether dietary or lifestyle changes can safely alter tyrosine levels in ways that promote healthier aging.