Living healthier longer is everyone's dream. And it is no coincidence that research on aging and strategies to slow it down is one of the most active branches of modern medicine. Concrete results continue to be lacking for now. But the promising discoveries are only piling up. An example comes from the University of Wisconsin, where a group of researchers has just published a study demonstrating how it is possible to extend the life of mice by about a third by simply reducing the dietary intake of a single amino acid: isoleucine.
Is too much a bad thing?
Isoleucine is an essential amino acid for our body, which we must obtain from the diet because it cannot be synthesized by our body. This does not mean, however, that one cannot take too much. Indeed: some research in recent years has revealed that diets excessively rich in proteins could be harmful precisely due to the extra intake of some amino acids, such as isoleukin. And indeed, a 2021 study identified a link between the metabolic health of the population, and intake of isoleukin in the diet.
There are no certainties yet, but these clues have pushed researchers at the University of Wisconsin to delve deeper into the issue. “Different components of our diet can have an impact on health that goes beyond their calorie function,” explains Dudley Lamming, one of the authors of the new study. “We tried to investigate this further by studying a component that many people may take in excessive quantities.”
The experiment
The researchers used laboratory mice in their experiments, which were divided into different groups and fed three different diets: one in which all the amino acids normally consumed with food were present, one in which all the amino acids were reduced by two thirds, and one in which only isoleutin was reduced by the same proportion. The animals were followed from six months of life (the equivalent of 30 years for a human), and monitored until the moment of death.
The results revealed that mice in the group fed a lower amount of isoleucine lived on average 33% longer than animals in the other two groups. Furthermore, compared to mice with a normal diet, those in the group with reduced isoleucine intake proved to age healthier, with better values in several markers of metabolic health.
No more isoleucine?
Should we therefore consume less isoleucine to live healthier and longer? It is too early to say, because the study was carried out on mice, and the results cannot therefore be extended to humans without further research. Even if it turns out to be true, the authors of the research themselves underline that eliminating isoleucine from the human diet is easier said than done, given that the adoption of a low-protein diet can have deleterious effects on health, and cut a reduction of isoleucine alone on the metabolic needs (and eating habits and preferences) of each of us would not be simple at all.
“We can't just prescribe a low-isoleucine diet to everyone,” admits Lamming. “But being able to limit the beneficial effects down to the elimination of a single amioacid would bring us closer to understanding the biological processes involved, and perhaps even finding potential therapeutic interventions for humans, such as an isoleucine inhibitor might be.”