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Branched-Chain Amino Acids
The three essential amino acids leucine, isoleucine, and valine, which share a branched carbon side chain.
Also: BCAA, BCAAs
Metabolized primarily in skeletal muscle rather than liver. Leucine activates mTORC1 to stimulate muscle protein synthesis. Clinical uses include treatment of hepatic encephalopathy (where aromatic amino acids accumulate and BCAAs are depleted) and adjunctive nutrition support in cirrhosis. Sports supplementation is widely marketed but generally redundant when total protein intake is adequate.
How each textbook covers it
Krause and Mahan's Food and the Nutrition Care Process, 16th ed. — Chapter 29
Metabolized primarily in skeletal muscle rather than liver. Leucine activates mTORC1 to stimulate muscle protein synthesis. Clinical uses include treatment of hepatic encephalopathy (where aromatic amino acids accumulate and BCAAs are depleted) and adjunctive nutrition support in cirrhosis. Sports supplementation is widely marketed but generally redundant when total protein intake is adequate.
Modern Nutrition in Health and Disease, 12th ed. — Ch 1: Proteins and Amino Acids
BCAA supplementation is promoted in sports nutrition but, absent the other essential amino acids, does not maximize muscle protein synthesis. Elevated plasma BCAAs are a metabolic signature of insulin resistance and predict incident type 2 diabetes, though causality is debated. BCAA restriction extends healthspan in rodents and is the subject of active human research.
Related terms
Hepatic Encephalopathy, Insulin resistance, Leucine, Protein, mTOR, mTORC1