Led by Jie V. Zhao, Yitang Sun, Junmeng Zhang, and Kaixiong Ye from the University of Hong Kong and the University of Georgia, the research team focused on phenylalanine and tyrosine. Their findings suggest that higher tyrosine levels are associated with shorter life expectancy in men, raising the possibility that longevity strategies may need to differ by sex.

Amino Acids, Brain Function, and Aging

Phenylalanine and tyrosine are amino acids that play important roles in metabolism and brain activity. They are naturally present in protein rich foods and are also sold as dietary supplements. Despite their widespread use, scientists still do not fully understand how these compounds may affect the aging process over time.

Tyrosine is especially notable because it helps produce neurotransmitters such as dopamine, which influence mood, motivation, and cognitive performance. Because of its role in brain chemistry, tyrosine has drawn increasing interest in aging research.

Large UK Biobank Study Examines Lifespan

To investigate potential links to longevity, the researchers analyzed health and genetic data from more than 270,000 participants in the UK Biobank. They used both observational data and genetic techniques to assess whether blood levels of phenylalanine and tyrosine were related to overall mortality and predicted lifespan.

At first, both amino acids appeared to be associated with a higher risk of death. However, after deeper analysis, only tyrosine showed a consistent and potentially causal relationship with reduced life expectancy in men. Genetic modeling suggested that men with elevated tyrosine levels could live nearly one year less on average. No meaningful association was found in women.

The connection remained even after accounting for other related factors, including phenylalanine. This strengthens the possibility that tyrosine itself may independently influence aging. Researchers also noted that men generally have higher tyrosine levels than women, which may help explain part of the longstanding lifespan gap between the sexes.

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

Possible Biological Explanations

Scientists are still working to understand why tyrosine might affect lifespan in men. One possibility involves insulin resistance, a condition linked to many age related diseases. Tyrosine is also involved in producing stress related neurotransmitters, which may influence metabolic and hormonal pathways differently in men and women. Variations in hormone signaling could help explain why the effect appeared only in men.

Supplement Use and Longevity Questions

Tyrosine is often marketed as a supplement to improve focus and mental performance. Although this study did not directly test tyrosine supplements, the findings raise questions about its long term impact on health and lifespan.

The researchers suggest that individuals with high tyrosine levels might benefit from dietary adjustments. Approaches such as moderating overall protein intake could potentially lower tyrosine levels and support healthier aging.

More research will be needed to confirm these results and to determine whether changes in diet or lifestyle can safely reduce tyrosine levels and promote longer life.