In which part of the body are essential amino acids oxidized?

• A. Muscle
• B. Kidney
• C. Small intestine
• D. Liver

Answer: (D)

The liver is the main site where essential amino acids are oxidized. After absorption, these amino acids are delivered to the liver, where they undergo transamination and oxidative deamination to remove the amino group and convert their carbon skeletons into usable intermediates for the TCA cycle, glucose, or lipid synthesis. The liver also handles the detoxification of nitrogen via the urea cycle. While muscle will catabolize some amino acids (notably branched-chain amino acids) for energy during fasting, the overall oxidation of essential amino acids occurs primarily in the liver.