Pollution and respiratory disease: can diet or supplements help? A review.

Pollution is known to cause and exacerbate a number of chronic respiratory diseases. The World Health Organisation has placed air pollution as the world's largest environmental health risk factor. There has been recent publicity about the role for diet and anti-oxidants in mitigating the effects of pollution, and this review assesses the evidence for alterations in diet, including vitamin supplementation in abrogating the effects of pollution on asthma and other chronic respiratory diseases. We found evidence to suggest that carotenoids, vitamin D and vitamin E help protect against pollution damage which can trigger asthma, COPD and lung cancer initiation. Vitamin C, curcumin, choline and omega-3 fatty acids may also play a role. The Mediterranean diet appears to be of benefit in patients with airways disease and there appears to be a beneficial effect in smokers however there is no direct evidence regarding protecting against air pollution. More studies investigating the effects of nutrition on rapidly rising air pollution are urgently required. However it is very difficult to design such studies due to the confounding factors of diet, obesity, co-morbid illness, medication and environmental exposure.