Effects of beta-carotene repletion on beta-carotene absorption, lipid peroxidation, and neutrophil superoxide formation in young men.

The chemopreventive effects of beta-carotene are usually attributed to its antioxidant properties. To determine the effects of beta-carotene supplementation on different parameters of oxidative metabolism, 15 normal young male subjects (18-30 yrs) were placed on a carotenoid-free liquid diet for two weeks prior to entry into the study. Blood was then measured for five carotenoids, retinol, retinyl palmitate, retinol-binding protein, alpha-tocopherol, vitamin C, zinc, lipid peroxides, and neutrophil superoxide production. Absorption tests were performed with 15 mg of beta-carotene to determine absorption curves for each subject. Subjects were then divided into two groups and given either 15 (n = 7) or 120 (n = 8) mg of beta-carotene daily for four weeks along with the same carotenoid-free liquid diet. The absorption test and the blood measurements were repeated. After repletion with beta-carotene, serum lipid peroxide levels decreased in both groups (p less than 0.05), but no other changes were noted in either the neutrophil superoxide production or in the levels of any of the vitamins measured. In contrast to vitamin E, the superoxide scavenging ability of beta-carotene apparently does not contribute to its effects in lowering serum lipid peroxide levels.

RCT Entities:   Population Interventions Outcomes