A large study involving more than 270,000 people has linked higher blood levels of the amino acid tyrosine to a shorter lifespan by nearly a year in men.
Tyrosine is found naturally in protein-rich foods and is also sold as a supplement for boosting focus and mental performance. Food sources include dairy products, fish, poultry, eggs, soy products, nuts, seeds and legumes.
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 connected to lifespan.
Their results show tyrosine levels were associated with shorter life expectancy in men, while no significant effect was detected in women.
Amino acids are the molecular building blocks that the body uses to make proteins. Phenylalanine and tyrosine are both found in foods that contain protein, and they are also available in dietary supplements. Beyond their role in protein production, these amino acids also participate in other biological process.
The researchers found that elevated tyrosine levels may have a potentially causal relationship with reduced life expectancy in men. According to the researchers’ estimates, higher tyrosine could shorten male lifespan by nearly one year. The researchers found no significant effect of tyrosine on female lifespan.
Scientists do not yet know exactly why higher tyrosine levels might be associated with shorter lives in men. One possible explanation involves insulin resistance. This occurs when cells become less responsive to insulin, the hormone that helps control blood sugar. Insulin resistance is associated with several diseases that become more common with age. This could therefore provide one possible link between tyrosine and longevity.
Tyrosine is also used by the body to make neurotransmitters involved in the stress response. Hormones and related signaling pathways can function differently in men and women, which could help explain why the apparent lifespan effect emerged only in men.
