Vitamin C and Infections

Nutrients. 2017 Mar 29;9(4):339. doi: 10.3390/nu9040339.

Abstract

In the early literature, vitamin C deficiency was associated with pneumonia. After its identification, a number of studies investigated the effects of vitamin C on diverse infections. A total of 148 animal studies indicated that vitamin C may alleviate or prevent infections caused by bacteria, viruses, and protozoa. The most extensively studied human infection is the common cold. Vitamin C administration does not decrease the average incidence of colds in the general population, yet it halved the number of colds in physically active people. Regularly administered vitamin C has shortened the duration of colds, indicating a biological effect. However, the role of vitamin C in common cold treatment is unclear. Two controlled trials found a statistically significant dose-response, for the duration of common cold symptoms, with up to 6-8 g/day of vitamin C. Thus, the negative findings of some therapeutic common cold studies might be explained by the low doses of 3-4 g/day of vitamin C. Three controlled trials found that vitamin C prevented pneumonia. Two controlled trials found a treatment benefit of vitamin C for pneumonia patients. One controlled trial reported treatment benefits for tetanus patients. The effects of vitamin C against infections should be investigated further.

Keywords: ascorbic acid; bacteria; bacterial toxins; common cold; herpes zoster; pneumonia; protozoa; respiratory tract infections; tetanus; viruses.

Publication types

  • Review

MeSH terms

  • Animals
  • Ascorbic Acid / therapeutic use*
  • Ascorbic Acid Deficiency / complications
  • Common Cold / drug therapy*
  • Humans
  • Pneumonia / drug therapy*
  • Pneumonia / etiology
  • Pneumonia / prevention & control
  • Tetanus / drug therapy
  • Vitamins / therapeutic use*

Substances

  • Vitamins
  • Ascorbic Acid