Tyrosine, an amino acid, is increased in the blood of people who are obese or diabetic. Among people who are obese, those at the highest risk of developing diabetes tend to have higher tyrosine levels. (Agencies)
"It was unknown whether this was simply a marker of diabetes risk or could be playing a direct role in the disease. Our work suggests that tyrosine has a direct effect," said study senior author Alfred Fisher, of the Barshop Institute for Longevity and Aging Studies at the University of Texas Health Science Center at San Antonio.
"This will be tested in small human clinical trials. Our team will augment tyrosine levels in study participants for a short period and observe whether this changes the ability of the body to respond to insulin, which is a key hormone involved in controlling blood sugar levels," Fisher said.
"This will not be detrimental to participants, as the increase will be transient and well below the level of what is clinically relevant," he said.
As a postdoctoral fellow at the University of California, San Francisco, Fisher found that increasing the levels of tyrosine in roundworms promoted their longevity.
Worms with mutations of certain genes lived 10 per cent to 20 per cent longer. One combination of genetic mutations produced an almost 60 per cent increase in life span.
"In both humans and worms, the effect is due to an inhibition of insulin signalling. Interfering with this pathway produces longevity in worms, whereas in people it leads to insulin resistance and an elevated risk of developing diabetes," Fisher said.
The study is published in the journal PLOS Genetics.
Tyrosine, an amino acid, is increased in the blood of people who are obese or diabetic. Among people who are obese, those at the highest risk of developing diabetes tend to have higher tyrosine levels.