Findings published in Nature Metabolism from the University of Sydney’s Charles Perkins Centre suggest that while great for building muscle, being over reliant on branched-chain amino acids (BCAAs) [which protein shakes are high in] can reduce lifespan, negatively impact mood and lead to weight gain.
“While diets high in protein and low in carbohydrates were shown to be beneficial for reproductive function, they had detrimental effects for health in mid-late life, and also led to a shortened lifespan,” explains Dr Samantha Solon-Biet. Her research investigated how nutrition affected metabolic health, reproduction, appetite and ageing.
“What this new research has shown is that amino acid balance is important – it’s best to vary sources of protein to ensure you’re getting the best amino acid balance."
"BCAAs are a group of three essential amino acids: leucine, isoleucine and valine, and are most commonly found in red meat and dairy. Whey protein - the most popular form of fitness protein - is made from dairy by-products and contains high levels of BCAA," writes the media announcement.
In the study, scientists tested the impact of dietary BCAAs and other amino acids on the health and body composition of mice.
The rodents were split into four groups, all with different BCAAs intake.
Mice who were fed twice the recommended intake of BCAAs also increased their food intake, resulting in obesity and a shortened lifespan.
“Supplementation of BCAAs resulted in high levels of BCAAs in the blood which competed with tryptophan for transport into the brain,” explains Academic Director of the Charles Perkins Centre's and researcher from the School of Life and Environmental Sciences Professor Stephen Simpson.
“Tryptophan is the sole precursor for the hormone serotonin, which is often called the ‘happiness chemical’ for its mood-enhancing effects and its role in promoting sleep. But serotonin does more than this, and therein lay the problem.
“This then lowered serotonin levels in the brain, which in turn was a potent signal to increase appetite. The serotonin decrease caused by excess BCAA intake led to massive overeating in our mice, which became hugely obese and lived shorter lives,” he adds.