A PROSPECTIVE-STUDY OF DIET AND ADULT-ONSET ASTHMA

A role for diet in the pathophysiology of asthma may be mediated by al tered immune or antioxidant activity with consequent effects on airway inflammation. We evaluated associations between several dietary facto rs assessed by a semiquantitative food frequency questionnaire, and in cidence of asthma over a 10-yr period in 77,866 women 34 to 68 yr of a ge. Women in the highest quintile of vitamin E intake from diet, but n ot from supplements, had a risk of 0.53 (95% confidence interval [CI] = 0.33 to 0.86) compared with women in the lowest quintile. This relat ionship, however, was attenuated when the contribution from nuts, a ma jor source of vitamin E in these data and a possible allergen, was rem oved (relative risk = 0.74 [0.50 to 1.10], p for trend = 0.007). Posit ive associations were found for vitamins C and E from supplements, but appeared to be explained by women at high risk of asthma initiating u se of vitamin supplements prior to diagnosis. A nonsignificant inverse association with carotene intake was noted, but no clear relations wi th asthma were demonstrated for intake of linoleic acid or omega-3 fat ty acids. These data suggest that antioxidant supplementation and inta ke of various fats during adulthood are not important determinants of asthma, although vitamin E from diet may have a modest protective effe ct.