Sydney, Australia—“Everything in moderation” goes for good things, too. Branched chain amino acids (BCAAs), used for muscle building, can cause serotonin depletion, leading to overeating and depression—but not, importantly, because BCAAs are harmful, according to a study published in Nature Metabolism.
Rather, a press release on the study reports, it’s because of an amino acid imbalance. Researchers split mice into four groups and fed them 20% the standard amount of BCAAs, 50% the standard amount, 100% the standard amount, or double the normal amount. Mice fed double the standard amount increased their food intake, resulting in obesity and a shortened lifespan.
Excessively high levels of BCAAs in the blood, the press release explained, mean extra competition for transport into the brain, knocking out tryptophan, the amino acid responsible for serotonin. Serotonin plays a role in happiness, sleep, and appetite suppression.
Dr. Samantha Solon-Biet, from the University of Sydney’s Charles Perkins Centre and one of the study’s lead authors, said in the release: “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.”
Tryptophan can be found in seeds and nuts, soybeans, cheese, turkey, oats, and eggs, among other foods.