Effects of Branch Chain Amino Acids on Glucose Tolerance in Obese Pre-Diabetic Subjects

Branched-Chain Amino Acids (BCAAs, including leucine, isoleucine, and valine) regulate multiple cellular functions as nutrient signaling. For example, BCAAs regulate insulin and glucagon secretion and thus glucose metabolism1. BCAAs, especially leucine, is one key regulator of mTOR signaling, which is the central component of a complex signaling network of insulin signaling, cell growth, and proliferation. BCAAs also regulate protein synthesis and degradation in various tissues. Increasing dietary uptake of BCAAs improved the parameters associated with obesity and T2DM, such as body composition and glycemia levels. However, these beneficial effects are not conclusive. Moreover, other studies have shown that circulating branched-chain amino acid concentrations are associated with obesity and future insulin resistance in children and adolescents. This is a 12-week, randomized, crossover study with 10 obese subjects with prediabetes. Subjects will be randomly assigned to take 20g BCAA or low-BCAA protein a day for 4 weeks, then switch to BCAA or low-BCAA protein for 4 weeks after a 2-week washout. At baseline and weeks 4, 6 and 10 weeks glucose, insulin and triglyceride levels will be tested at time 0, 30 min, 60 min, and 120 min after 75 grams of glucose load. In addition to laboratory tests vital signs, weight and body composition will be done.