High pressure liquid chromatography was used to evaluate the effects of several naturally occurring food components (selenium, vitamins A, E, B6 and C) on the in vitro metabolism of aflatoxin B, (AFB,). AFB, was incubated with a liver microsomal enzyme metabolizing system with varying concentrations of each nutrient. The following nutrients and levels either inhibited or reduced the metabolism of AFB,: sodium selenite (25 pg/mL), d-cY-tocopherol(25, 250 and 2500 FglmL), pyridoxine hydrochloride (2.5 PglmL), L-ascorbic acid (25 and 2500 pg/mL) and mixture containing 500 p,g/mL of each chemical. Retinol acetate at levels of 2.5 and 25 pg/mL increased the level of AFB 1 metabolized.