A large study of more than 270,000 people suggests that higher levels of the amino acid tyrosine may be associated with a shorter lifespan in men—but not women.
Researchers Jie V. Zhao, Yitang Sun, Junmeng Zhang, Kaixiong Ye, and colleagues from the University of Hong Kong and the University of Georgia examined whether phenylalanine and tyrosine—two amino acids involved in metabolism, protein production, and brain function—may influence longevity.
The findings revealed notable differences between men and women. Higher tyrosine levels were linked to shorter life expectancy in men, while researchers found no significant association between tyrosine and longevity in women.
The results may help scientists better understand why aging and lifespan differ between the sexes. However, further research is needed before the findings can be translated into dietary or medical recommendations.
This research, published under the title “The Role of Phenylalanine and Tyrosine in Longevity: A Cohort and Mendelian Randomization Study,” examined the relationship between these amino acids and lifespan.
Why Is Tyrosine Important?
Amino acids are the building blocks the body uses to produce proteins. Phenylalanine and tyrosine are both found naturally in protein-rich foods and are also available in dietary supplements.
In addition to supporting protein production, these amino acids play important roles in the body. Tyrosine is especially significant because it is used to produce neurotransmitters such as dopamine. These chemical messengers help nerve cells communicate and are involved in mood, motivation, attention, and thinking.
Despite their essential biological functions, scientists do not yet fully understand how long-term differences in phenylalanine and tyrosine levels may affect aging and life expectancy.
Study Analyzed Data From More Than 270,000 People
For the study, researchers analyzed health and genetic information from more than 270,000 participants in the UK Biobank, a large database containing medical and genetic data from people across the United Kingdom.
The researchers used two complementary methods. First, they examined the relationship between blood levels of phenylalanine and tyrosine, mortality outcomes, and predicted lifespan. They then used genetic techniques to investigate whether these associations might reflect more than a simple correlation.
One of the methods was Mendelian randomization. This approach uses naturally occurring genetic differences to study whether a biological factor may contribute to a particular health outcome. Because genetic characteristics are established before many lifestyle factors and diseases develop, this method can provide additional evidence about potential cause-and-effect relationships.
At first, higher levels of both amino acids appeared to be associated with a greater risk of death. However, a more detailed analysis consistently highlighted tyrosine as the amino acid most strongly associated with longevity—particularly in men.
Higher Tyrosine Levels Were Associated With Shorter Lifespans in Men
Genetic analyses suggested that elevated tyrosine levels may have a potentially causal relationship with shorter life expectancy in men. The researchers estimated that higher tyrosine levels could be associated with a reduction in lifespan of nearly one year in men.
The same association was not observed in women. In the study, tyrosine did not have a statistically significant effect on female longevity.
The relationship remained after researchers accounted for phenylalanine and other related factors. This finding strengthens the possibility that tyrosine may have an independent association with aging and lifespan.
The researchers also observed that men generally had higher tyrosine levels than women. This difference could potentially contribute to the well-established gap in life expectancy between men and women, although the study does not prove that tyrosine causes this difference.
“After controlling for tyrosine, phenylalanine showed no association with longevity in either men or women.”
Why Might Tyrosine Affect Longevity?
Scientists do not yet know why higher tyrosine levels may be associated with a shorter lifespan in men.
One possible explanation involves insulin resistance, a condition in which the body’s cells respond less effectively to insulin. Because insulin resistance is linked to several age-related diseases, it may provide one potential connection between tyrosine levels and longevity.
Tyrosine also contributes to the production of neurotransmitters and hormones involved in the body’s stress response. These hormonal and signaling pathways may function differently in men and women, which could help explain why the observed association with longevity appeared only in men.
However, these explanations remain theoretical. More research is needed to determine whether they accurately describe the biological mechanisms involved.
What Do the Findings Mean for Tyrosine Supplements?
Tyrosine is widely available as a dietary supplement and is often marketed to support focus, attention, and mental performance. The study raises questions about whether chronically elevated tyrosine levels could have unintended long-term effects.
Importantly, the researchers did not directly study tyrosine supplements. Therefore, the findings do not show that taking tyrosine supplements shortens lifespan.
Instead, the study examined naturally occurring tyrosine levels in the body and their association with longevity. The results also do not establish that lowering tyrosine levels through diet will extend lifespan or improve health.
Because tyrosine is found in many protein-rich foods, reducing overall protein intake could lower exposure to the amino acid. However, intentionally restricting protein or tyrosine may carry health risks and should not be undertaken without guidance from a qualified healthcare professional.
Additional studies are needed to confirm these findings, explain the possible biological mechanisms, and determine whether tyrosine levels can be safely modified through diet or lifestyle changes to support healthy aging.
Source: www.sciencedaily.com