Effects of Three‐month Oral Supplementation of β‐Carotene and Vitamin C on 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 supplementation of β‐carotene and vitamin C in a high‐risk Japanese population, we examined the serum response to threemonth oral supplementation of β‐carotene (0, 3, 30 mg/day) and vitamin C (0, 50, 1000 mg/day) by a three‐by‐three factorial design using 54 subjects (age range=40–69 years). Serum concentrations of carotenoids, α‐tocopherol, and ascorbic acid were examined at baseline, and one, two, and threemonth points. Both serum β‐carotene and ascorbic acid were significantly higher in high‐dose groups than in each placebo group during the supplementation. The serum β‐carotene increased gradually (597–830% increase) during the study, whereas the serum ascorbic acid reached nearly a steady‐state at the one‐month point and remained stable thereafter (88–95% increase). No statistically significant interaction between β‐carotene and vitamin C supplementations was observed either for serum β‐carotene or for serum ascorbic acid. Among carotenoids and α‐tocopherol examined, serum lycopene in the high‐dose β‐carotene group was significantly higher than in the placebo group at all points. No unfavorable change in carotenoids and α‐tocopherol was observed in any group.