Gordon Research Institute

School of Advanced Nutritional and Medical Research

European Journal of Clinical Nutrition advance online publication 24 August 2005; doi: 10.1038/sj.ejcn.1602261

Guarantor: S Sasazuki.

Contributors: The study was designed and supervised by YT, SS and ST. SO, and MH coordinated the fieldwork and advised on the study design. SS analyzed the data, interpreted the current findings, and wrote the paper.

S Sasazuki(1), S Sasaki(2), Y Tsubono(3,4), S Okubo(5), M Hayashi(5) and S Tsugane(1)

1. Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, Chuo-ku, Tokyo, Japan

2. Division of Dietary Reference Intakes, National Institute of Health and Nutrition, Toyama, Shinjuku-ku, Tokyo, Japan

3. Division of Health Policy, School of Public Policy, Tohoku University, Sendai, Japan

4. Division of Clinical Epidemiology, School of Medicine, Tohoku University, Sendai, Japan

5. Hiraka General Hospital, Ekimae-cho, Yokote, Japan

Correspondence: Dr S Sasazuki, Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan. E-mail: ssasazuk@gan2.res.ncc.go.jp

Received 21 September 2004; Revised 15 June 2005; Accepted 29 June 2005; Published online 24 August 2005.

Abstract

Objective:

To investigate the relationship between the common cold and vitamin C supplementation.

Design:

A double-blind, 5-year randomized controlled trial.

Setting:

A village in Akita prefecture, one of the regions in Japan with the highest mortality from gastric cancer.

Subjects:

Participants in annual screening programs for circulatory diseases conducted under the National Health and Welfare Services Law for the Aged, and diagnosed as having atrophic gastritis. Of the 439 eligible subjects, 144 and 161 were assigned to receive 50 or 500 mg of vitamin C, respectively, after protocol amendment. During the supplementation phase, 61 dropped out, and 244 completed the trial.

Intervention:

Daily vitamin C supplementation of 50 mg (low-dose group) or 500 mg (high-dose group).

Results:

Total number of common colds (per 1000 person-months) was 21.3 and 17.1 for the low- and high-dose groups, respectively. After adjustment for several factors, the relative risks (95% confidence interval (CI)) of suffering from a common cold three or more times during the survey period was 0.34 (0.12?0.97) for the high-dose group. No apparent reduction was seen for the severity and duration of the common cold.

Conclusion:

A randomized, controlled 5-year trial suggests that vitamin C supplementation significantly reduces the frequency of the common cold but had no apparent effect on the duration or severity of the common cold. However, considering several limitations due to protocol amendment, the findings should be interpreted with caution.

Sponsorship:

This study was supported in part by Grants-in-Aid for Cancer Research and for the Second Term Comprehensive 10-Year Strategy for Cancer Control from the Ministry of Health, Labor and Welfare of Japan.