Essential components of dietary restriction revealed
The study, a collaboration between researchers at the University’s Charles Perkins Centre and the Monash Biomedicine Discovery Institute published in Nature Communications, looked at the impact of reducing essential amino acids in the diet of mice.
Researchers found by reducing the amount of two amino acids - threonine and tryptophan - in young healthy mice, they were able to burn more calories than they consumed, without calorie reduction, keeping them lean and healthy and without the side-effect of lower muscle mass.
A low-threonine diet even protected mice that were morbidly obese and prone to developing Type 2 diabetes.
Professor Stephen Simpson, Academic Director of the Charles Perkins Centre and an author on the paper said the pre-clinical study adds another piece of the puzzle to our understanding of the role of diet in metabolic health and longevity.
We are beginning to understand how critical the balance of dietary amino acids is to the control of appetite, health and ageing.
While a moderate reduction in dietary protein and therefore essential amino acids can have health and ageing benefits, diets devoid of essential amino acids will make people sick very quickly and are not recommended.
However, this study led by Dr Adam Rose of Monash University suggests a reconsideration of the functions of these two amino acids in nutrition which warrants further exploration.
"Once we understand which particular dietary components are needed for the health-promoting effects of these diets we can design strategies to mimic them, simulating the effects without having the negative side effects,” Dr Rose said.
A highlight of the study was an experiment in which the team genetically manipulated the mice to be able to synthesise the essential amino acid threonine, which blocked the health-promoting effects of the low threonine diet and saw the mice gain weight, proving that these two amino acids can hold the key to a new diet approach.
The study builds on earlier work by Professor Simpson, Dr Samantha Solon-Biet and the team published in Nature Metabolism that examined the impacts that dietary branched-chain amino acids (BCAAs) and other essential amino acids such as tryptophan and threonine have on appetite and the health and body composition of mice.
The earlier study suggested excessive long-term consumption of BCAAs may reduce lifespan, negatively impact mood and lead to weight gain, particularly when coupled with an imbalance of tryptophan and threonine.
"These studies both support increasing findings that the quality of protein, not just the quantity, is a powerful mediator of metabolic health," said Dr Solon-Biet.
Declaration: Author Dieter Schmoll is an employee of Sanofi-Aventis Deutschland GmbH, a pharmaceutical company. All other authors declare no competing interests.