Effects of three-month oral supplementation of beta-carotene and vitamin Con serum concentrations of carotenoids and vitamins in middle-aged subjects: A pilot study for a randomized controlled trial to prevent gastric cancer in high-risk Japanese population

Prior to a randomized controlled trial to prevent gastric cancer by oral su pplementation of beta-carotene and vitamin C in a high-risk Japanese popula tion, we examined the serum response to three-month oral supplementation of beta-carotene (0, 3, 30 mg/day) and vitamin C (0, 50, 1000 mg/day) by a th ree-by-three factorial design using 54 subjects (age range=40-69 years). Se rum concentrations of carotenoids, alpha-tocopherol, and ascorbic acid were examined at baseline, and one, two, and three-month points. Both serum bet a-carotene and ascorbic acid were significantly higher in high-dose groups than in each placebo group during the supplementation. The serum beta-carot ene increased gradually (597-830% increase) during the study, whereas the s erum ascorbic acid reached nearly a steady-state at the one-month point and remained stable thereafter (88-95% increase). No statistically significant interaction between beta-carotene and vitamin C supplementations was obser ved either for serum beta-carotene or for serum ascorbic acid. Among carote noids and alpha-tocopherol examined, serum lycopene in the high-dose beta-c arotene group was significantly higher than in the placebo group at all poi nts. No unfavorable change in carotenoids and alpha-tocopherol was observed in any group.