Lack of long-term effect of vitamin C supplementation on blood pressure.
In a double-blinded randomized controlled trial, we investigated the long-term effect of vitamin C supplementation on blood pressure. A total of 439 Japanese subjects with atrophic gastritis initially participated in the trial using vitamin C and beta-carotene to prevent gastric cancer. Before and on early termination of beta-carotene supplementation, 134 subjects dropped out of this trial, whereas 120 and 124 subjects took the vitamin C supplement daily at either 50 mg or 500 mg, respectively, for 5 years. Before supplementation, neither systolic nor diastolic blood pressure was significantly related with the serum vitamin C concentration. This relationship was unchanged after adjustment for age, body mass index, and alcohol intake or after stratification by gender. After 5 years, systolic blood pressure significantly increased in groups, regardless of vitamin C dose, compared with baseline. Systolic blood pressure in the high-dose group (500 mg daily) increased from 125.4 to 131.7 mm Hg (5.88 mm Hg increase; 95% confidence interval [CI], 3.11 to 8.65). This value was similar with that of the low-dose group (5.73 mm Hg increase; 95% CI, 2.62 to 8.83) and of the dropout group (4.52 mm Hg increase; 95% CI, 1.26 to 7.77). There was no difference in change of diastolic blood pressure among the 3 groups. In conclusion, we observed no reduction in blood pressure with long-term moderate doses (500 mg/day) of vitamin C supplementation in a high-risk population for stomach cancer and stroke.
Kim
Mi Kyung
MK
Epidemiology and Biostatistics Division, National Cancer Center Research Institute East, Kashiwa, Japan.
Sasaki
Satoshi
S
Sasazuki
Shizuka
S
Okubo
Shunji
S
Hayashi
Masato
M
Tsugane
Shoichiro
S
D000328:Adult; D000368:Aged; D000975:Antioxidants / Q000008:administration & dosage / Q000032:analysis / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects*; D003971:Diastole; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D005757:Gastritis, Atrophic / Q000188:drug therapy; D006801:Humans; D006973:Hypertension / Q000517:prevention & control; D007564:Japan; D008297:Male; D008875:Middle Aged; D013274:Stomach Neoplasms / Q000517:prevention & control; D013599:Systole; D013995:Time; D016896:Treatment Outcome; D019207:beta Carotene / Q000008:administration & dosage
D000975:Antioxidants; D019207:beta Carotene; D001205:Ascorbic Acid