Vitamins C, E Reduce Effects of Air Pollution
Children with asthma who supplement with antioxidant vitamins C and E are less likely to experience breathing problems triggered by air pollution than are children who do not take supplements, according to a clinical trial published in the American Journal of Respiratory and Critical Care Medicine (2002;166:703–9).
For this clinical trial, the authors recruited 160 children with asthma who were living in the Mexico City metropolitan area. Each child was randomly assigned to take either 50 IU of vitamin E and 250 mg of vitamin C per day or a placebo for twelve weeks. Twice weekly, the researchers checked the asthma symptoms of each child by standard lung tests called pulmonary function tests. The asthma symptoms on each day were then correlated with the severity of air pollution in the Mexico City area the previous day.
When ozone levels in the air went up, asthma symptoms increased significantly in the children who were taking placebo. In children taking the vitamins, however, no increase in lung symptoms occurred with increasing ozone levels. That finding suggests that taking vitamins C and E protects against the adverse effects of air pollution. The protective effect of the vitamins appeared to be the greatest in children who tended to have the most severe asthma symptoms.
The researchers believed that the antioxidants helped by improving the function of the smallest airways in the lungs, either by reversing constriction or by reducing secretion. Previous studies in animals and healthy (non-asthmatic) adults have supported this conclusion.
Air Pollution—A Major Public Health Issue
Ozone is not emitted directly into the air, but is instead a by-product of other pollutants. It is formed by the reaction between heat, sunlight, and the volatile carbon compounds given off by automobiles, factories, and other industrial products. Because heat and sunlight are necessary for the formation of ozone, the highest ozone concentrations are found in hot, sunny climates such as those in Mexico City or Los Angeles.
While clean air standards and regulations on automobile emissions have helped reduce air pollution, air quality remains a serious problem in the United States. The Environmental Protection Agency (EPA) estimates that at least 20,000 premature deaths occur every year in the United States due to air pollution. Globally, this number may exceed 500,000 per year.
In addition to triggering symptoms of asthma, ozone can worsen symptoms of other lung diseases, such as emphysema and chronic bronchitis. Ozone exposure in childhood can impair lung development, leading to increased risk of lung disease later in life. Levels of ozone greater than 85 parts per billion (ppb) are thought to be associated with increased disease risk. Parents wishing to find local ozone exposure levels can consult the EPA Web site (www.epa.gov), where daily updates are available.
What Do These Results Mean to Children with Asthma?
This study supports the notion that supplementation with vitamins C and E protects against asthma reactions that can result from ozone exposure.
Previous studies have suggested that supplementing with antioxidants, including vitamin C, beta-carotene, lycopene, and selenium, may reduce the symptoms of asthma, irrespective of the level of pollution in the air; however, not all studies agree.
The results of the new study suggest that it may be wise to take extra vitamins C and E if one is exposed to high concentrations of ozone (as in many large metropolitan areas). It is not as clear whether children living in areas with better air quality would benefit from a similar strategy.
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Matt Brignall, ND is a graduate of the University of Michigan and Bastyr University. He works at the Seattle Cancer Treatment and Wellness Center, where he specializes in complementary medicine approaches to cancer. He has been published in several journals, including Alternative Medicine Review, Coping With Cancer, and the Journal of the National Cancer Institute. Dr. Brignall also teaches clinical nutrition at Bastyr University in Kenmore, WA. He is a regular contributor to Healthnotes, Healthnotes Newswire, and the Healthnotes Quick!Reference series.
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