ALCAR+LA supplementation significantly lowers the steady-state age-related accumulation of lipid peroxidation. MDA, a marker of lipid peroxidation, was measured by gas chromatography/MS as described (29, 30). Results show no statistical increase (P ≥ 0.05) in MDA levels with ALCAR, LA, or both supplements in liver tissue from young animals. MDA levels were significantly increased in liver from old rats relative to young controls, and ALCAR supplementation alone further increased hepatic MDA content over that of nonsupplemented old rats. LA alone and ALCAR+LA supplementation significantly decreased hepatic MDA content in livers from old rats. Columns denoted by the same letter are statistically different (P ≤ 0.05) from each other.