Vitamin C for preventing and treating pneumonia

Hemilä H, Louhiala P

Summary

Vitamin C supplementation may have preventive effects in populations with a high incidence of pneumonia and may have therapeutic effects in populations with low plasma vitamin C levels

Pneumonia is infection of the lungs caused by bacteria, viruses or other infectious agents. Its clinical diagnosis is sometimes difficult. Pneumonia is more common in young children and in the aged. In developing countries it causes two million deaths annually among young children. In the USA it is the most common cause of death from infection. Vitamin C was identified in the early 1900s. Suggestions that one of its biological roles may be in resisting infections are supported by numerous animal studies. We looked for studies in humans. We found three trials that looked at whether vitamin C prevents pneumonia. Two of the preventive trials studied soldiers while the third studied boys in a UK boarding school in the 1940s. Two further trials looked at whether vitamin C might help in curing pneumonia. One studied patients aged 66 to 94 years in the UK with pneumonia. Benefit was restricted to those who were most ill and had low vitamin C levels. For the other trial, in the former Soviet Union, the social and nutritional backgrounds of the patients were not described. Overall, the results of the five identified trials suggested vitamin C is beneficial in both preventing and treating pneumonia. However, these trials were carried out in such extraordinary conditions that the results may not apply to the general population. More research is needed; but in the meantime, supplementing pneumonia patients who have low plasma vitamin C levels may be reasonable because of its safety and low cost.