Browsing by Subject "Ascorbic Acid"

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  • Hemilä, Harri (2017)
    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.
  • Hemilä, Harri (2017)
    I read with great interest Dr Shader’s editorial that discussed vitamin C. I share many of his concerns about methodologic and statistical problems in the vitamin C trials. Nevertheless, some of my conclusions of the field are more positive. On the basis of the currently published findings of randomized controlled trials (RCTs), there is no justification to encourage general populations of Western countries to take vitamin C regularly to prevent colds, cancers, or cardiovascular diseases. Vitamin C, however, is a water-soluble antioxidant, and it is possible that its administration may have effects on people who have elevated levels of oxidative stress in their body. Oxidative stress is increased, for example, by heavy exertion, infections, and cardiac operations. Furthermore, the level of vitamin C synthesis is increased by various forms of stress in those animals that synthesize their own vitamin C. By analogy, larger vitamin C intakes might be beneficial for humans when they are under some forms of stress because humans are unable to synthesize their own vitamin C.