Study Links High Levels of Amino Acid Tyrosine to Shorter Lifespan in Men
A study of 272,475 UK Biobank participants links high blood levels of the amino acid tyrosine to a shorter lifespan in men by about 0.91 years, with no significant effect seen in women. Experts advise against long-term tyrosine supplementation without medical consultation.
Tyrosine Levels and Life Expectancy
Tyrosine, an amino acid found in protein-rich foods and widely sold as a dietary supplement to improve alertness and focus, is at the center of a new study raising questions about its long-term effects. Researchers have found that high levels of tyrosine in the blood are associated with a shorter lifespan in men, while no similar significant effect was identified in women.
The study analyzed data from 272,475 participants in the UK Biobank. Among the subjects, 23,964 deaths were recorded, including 14,230 men and 9,734 women. The researchers examined plasma levels of tyrosine and phenylalanine and compared them with mortality data, adjusting for confounding factors such as age, weight, smoking, alcohol consumption, physical activity, education, and socioeconomic status.
The Role of Tyrosine in the Body
Tyrosine is an amino acid used by the body to synthesize proteins and plays a critical role in producing neurotransmitters, including dopamine, norepinephrine, and epinephrine. These chemicals are involved in regulating mood, cognition, motivation, and stress responses. It occurs naturally in dairy products, meat, fish, eggs, legumes, and other protein-rich foods, and is also marketed as a supplement designed to enhance mental focus and alertness.
Initially, the researchers found that high levels of both phenylalanine and tyrosine were linked to an increased risk of mortality. However, after applying statistical and genetic methods designed to isolate the effects of the two substances, tyrosine emerged as the prominent factor. According to one analysis, a genetically predicted higher level of tyrosine was associated with an estimated reduction of 0.91 years in male life expectancy, with a statistical uncertainty range spanning from 0.21 to 1.6 years.
Practical Implications and Recommendations
Although the study did not directly monitor individuals taking tyrosine supplements, it focused on circulating tyrosine levels in the bloodstream and a genetic predisposition to high levels over time. The study authors explicitly noted:
"Lifetime internal exposure is not identical to taking a supplement for a limited period."
The practical implication is that there is currently no basis for individuals to stop consuming protein-rich foods or to self-impose protein restrictions. Furthermore, it has not been proven that lowering tyrosine levels through diet extends human lifespan. Nevertheless, the findings warrant further research, particularly among those who take tyrosine supplements regularly. Until clearer answers are available, experts advise against starting long-term use of the supplement without professional medical consultation.
