Vitamin E: Possible Preventative Strategy for COPD
Chronic obstructive pulmonary disease once carried a hopeless prognosis, and few physicians could imagine a simple, low-risk intervention. That perspective is a thing of the past, as evidenced by an intriguing study presented at a press conference held at the American Thoracic Society International Conference May 16.
Anne Hermetet Agler, doctoral candidate with Cornell University's Division of Nutritional Sciences, asked the research question: Does supplementation with vitamin E reduce chronic lung disease incidence? Her study's results suggest that vitamin E, known as a powerful antioxidant, may protect the lung against damage from free radicals.
Agler reviewed data compiled from the Women's Health Study, which originally focused on the effects of aspirin and vitamin E in the prevention of cardiovascular disease and cancer in nearly 40,000 women ages 45 and older. Study participants took 600 IU of vitamin E supplements or a placebo every other day for almost 10 years. Those with a diagnosis of chronic lung disease were excluded from study enrollment.
Results from Agler's secondary data analysis showed long-term use of vitamin E decreased the risk of new chronic lung disease by about 10 percent in both smokers and non-smokers.
"It was quite a robust effect of vitamin E," Agler said. "We're doing further research to look at the mechanisms of how that actually happens." She speculated that one of the major paths of delivery for vitamin E is HDL cholesterol, which is the form of cholesterol that is transported to the lung. Women tend to have higher HDL cholesterol levels than men.
Among 38,270 women without self-reported history of chronic lung disease at randomization, there were 760 new reports of chronic lung disease in the vitamin E group and 846 in the placebo group. Smoking was a strong predictor of the risk of chronic lung disease. The supplements appeared to have no effect on asthma incidence.
A limitation of the study is that participants self-reported a diagnosis of chronic lung disease, defined as emphysema, chronic bronchitis, or bronchiectasis. Additional studies based on spirometry measurements would help to confirm the protective role of vitamin E against chronic lung disease in women. Further studies also must be done to determine if vitamin E is equally effective in men and chronic lung disease.
Physicians currently do not recommend any vitamin supplement as a way to prevent or treat chronic lung disease.
Vitamin E, also known as alpha-tocopherol, is naturally found in nuts, seeds, vegetable oils, and green leafy vegetables. The recommended dietary allowance for vitamin E is 22.4 IU. Most vitamin-E-only supplements provide ≥100 IU of the nutrient, according to the National Institutes of Health Office of Dietary Supplements http://ods.od.nih.gov/factsheets/vitamine.asp. These amounts are substantially higher than the RDAs. The 1999-2000 National Health and Nutrition Examination Survey found that 11.3 percent of adults took vitamin E supplements containing at least 400 IU.
Doses of up to 1,500 IU a day of vitamin E appear to be safe; however, Agler pointed out that vitamin E may have detrimental effects in some people and has been shown to increase the risk of congestive heart failure in cardiovascular disease patients.
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