Over the past few days, there has been some UK coverage of a recent study carried out in Australia reporting that elevated branched-chain amino acids (BCAAs) are associated with obesity and insulin resistance.

In a joint statement, the European Specialist Sports Nutrition Alliance (ESSNA) and the International Council on Amino Acid Science (ICAAS) responded:

“This novel and interesting basic research in mice is a very weak indicator of the effects of BCAAs in exercising humans. First, the study does not make any correlation to humans. Humans metabolise protein and amino acids very differently to mice, for example mice gain weight on different macronutrient ratios than humans do. Therefore, the reported observations in mice cannot be translated to humans directly – and, in fact, the opposite has previously been reported in human beings, with a 2018 study revealing that a high protein diet can in fact benefit patients with type 2 diabetes.

“Second, it’s important to understand the science behind this: protein is made up of 20 amino acids, including the BCAAs, and the BCAAs are made up of three essential amino acids: leucine, isoleucine and valine. Insulin and BCAA act as two interlinked signals to modulate muscle protein synthesis and degradation, so there is partial overlap between the two signalling paths. Indeed, it has been reported since the early 1990s that subjects with insulin resistance and obesity have elevated blood levels of BCAA. However, this is not caused by dietary intake of BCAA from foods or supplements. Their blood BCAA levels are elevated because obese subjects have a defect in protein metabolism and are unable to inhibit the breakdown of BCAA. Therefore, the elevated BCAA levels in obese diabetics are due to metabolic problems caused by diabetes and obesity, and are entirely irrelevant to oral intake of protein or BCAA.

“We are disappointed in the ill-informed and misleading media reporting on this study. It’s crucial to note that the authors of this study themselves concluded that the observed metabolic findings were non-specific outcomes of overeating, not results of toxicity of BCAA as such. One has to consider that the mice were ingesting huge amounts of BCAA daily over the course of their life span. In fact, we agree with the authors that too much of one thing is never good.

“It is regrettable that the reporting has been so widespread and inaccurate, doubly so when considering the industry continues to deal with many contentious misconceptions. Protein and its building blocks, amino acids, has a multitude of health benefits and there is a plethora of existing research that shows that protein supplements can help exercising consumers, from supporting muscle mass growth, to maintenance of bones, to many aspects of recovery.”