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

Abstract

Prior to a randomized controlled trial to prevent gastric cancer by oral supplementation of β β β β-carotene and vitamin C in a high-risk Japanese population, we examined the serum response to threemonth oral supplementation of β β β 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 α α α-tocopherol, and ascorbic acid were examined at baseline, and one, two, and threemonth points. Both serum β β β β-carotene and ascorbic acid were significantly higher in high-dose groups than in each placebo group during the supplementation. The serum β β β 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 β β β-carotene and vitamin C supplementations was observed either for serum β β β β-carotene or for serum ascorbic acid. Among carotenoids and α α α α-tocopherol examined, serum lycopene in the high-dose β β β β-carotene group was significantly higher than in the placebo group at all points. No unfavorable change in carotenoids and α α α α-tocopherol was observed in any group.Key words: β-Carotene -Ascorbic acid -Supplements -Nutrient -Randomized controlled trial Gastric cancer has long been the most common cancer in Japan.1) Several epidemiologic studies have reported protective effects of high intake of β-carotene and vitamin C (ascorbic acid) and their high serum or plasma concentration levels against gastric cancer.2, 3) Vitamin C in fruits and vegetables is considered to be a preventative substance inhibiting nitrosamine formation and also acting as a free radical scavenger.2, 4) Atrophic gastritis is considered to be a precursor of intestinal-type gastric cancer. 5) A protective effect of β-carotene against the progression of atrophic gastritis has been reported. 6)Based on these findings, we planned a randomized controlled trial to test the preventative effect of oral β-carotene and vitamin C supplementation for a high-risk population, i.e., subjects with atrophic gastritis. 7) However, the effects of oral supplementation of β-carotene and vitamin C on the serum concentrations have not yet been established in Japanese populations. Prior to the study, we conducted a pilot study using subjects of a health check-up program to evaluate the effect of supplementation of β-carotene and vitamin C on the serum levels. 8) MATERIALS AND METHODS Study designThe study design has been reported elsewhere.8) Briefly, the subjects were recipients of a health check-up program in a local general hospital with chronic atrophic gastritis diagnosed on the basis of pepsinogen I less than 70 mg/ml and pepsinogen I/pepsinogen II ratio less then 3.0. The age ranged from 40 to 69 years. Among 90 subjects screened, 55 subjects, 35 men and 20 women, participated in the trial. The participants were randomly ass...

Effect of vitamin C on common cold: randomized controlled trial

“…Thus, the period for which subjects took the initial capsule ranges from 2 to 5 months. On the basis of the results of our pilot study (Sasaki et al, 2000), no statistically significant interaction between 3-month supplementation of b-carotene and vitamin C was seen either for serum bcarotene or for ascorbic acid. In fact, further adjustment for initial b-carotene treatment did not have any influence on the effect of vitamin C on common cold; adjusted RR and 95% CI for suffering from common cold three or more times during the survey period was 0.35 (0.12-0.97) in high-dose group.…”

“…High dose of b-carotene and vitamin C (Sasaki et al, 2000), the serum level of ascorbic acid acted simultaneously for the placebo and 50-mg supplemented groups; the percent changes in serum ascorbic acid from baseline for the placebo and 50-mg groups were 31 and 23% at 1 month, 37 and 23% at 2 months, and 31 and 29% at 3 months, respectively. In comparison with previous studies, the supplementation amount of 500 mg per day for the high-dose group in our study does not seem large.…”

“…The long duration of supplementation may have resulted in the apparent reduction in incidence of the common cold. In fact, in a pilot supplementation study, the serum ascorbic acid level nearly reached a steady state and remained stable from 1 month onwards (Sasaki et al, 2000). In addition, the season during which a study is conducted could affect the apparent role of vitamin C in susceptibility to the common cold.…”

Long-term vitamin C supplementation has no markedly favourable effect on serum lipids in middle-aged Japanese subjects

“…Thus, we set 500 mg as the dosage for the high-dose group. This amount of vitamin C is half of that which we tested in a pilot study (Sasaki et al 2000), in which no adverse effect was observed from taking 1000 mg vitamin C. In most randomized clinical trials of vitamin C, there was no apparent adverse effect of a higher dose of vitamin C (, 1000 mg/d). Results from other large intervention trials with higher doses of vitamin C suggest no evidence of any potential hazard with , 1000 mg/d (Brown et al 2001).…”

“…The vitamin C doses were set based on the pilot study (Sasaki et al 2000) in which we examined the serum response to 3-month oral supplementation of vitamin C (0, 50 or 1000 mg/d). In that study, the high-dose group (1000 mg/d) showed a significant increase in serum concentrations at each point during supplementation (1, 2 and 3 months), with no adverse effect.…”