Food and nutrient intakes and asthma risk in young adults.

BACKGROUND: Some aspects of diet are relatively newly recognized potential risk factors for asthma, but the evidence to date is conflicting. OBJECTIVE: The goal was to determine whether the food and nutrient intakes of adults with asthma differ from those of adults without asthma. DESIGN: This was a community-based, cross-sectional study of 1601 young adults ( +/- SD age: 34.6 +/- 7.1 y) who were initially recruited by random selection from the federal electoral rolls in Melbourne in 1999. Subjects completed a detailed respiratory questionnaire, a validated semiquantitative food-frequency questionnaire, skin-prick testing, and lung function tests, including a methacholine challenge test for bronchial hyperreactivity (BHR). A total of 25 nutrients and 47 food groups were analyzed by using multiple logistic regression with alternate definitions of asthma and atopy as the outcomes. RESULTS: Whole milk appeared to protect against current asthma (odds ratio: 0.66; 95% CI: 0.46, 0.97), doctor-diagnosed asthma (0.73; 0.54, 0.99), BHR (0.68; 0.48, 0.92), and atopy (0.71; 0.54, 0.94). Conversely, soy beverage was associated with an increased risk of current asthma (2.05; 1.19, 3.53), doctor-diagnosed asthma (1.69; 1.04, 2.77), and BHR (1.65; 1.00, 2.71). Apples and pears appeared to protect against current asthma (0.83; 0.71, 0.98), asthma (0.88; 0.78, 1.00), and BHR (0.88; 0.77, 1.00). CONCLUSIONS: The consumption of dairy products, soy beverages, and apples and pears, but not of nutrients per se, was associated with a range of asthma definitions. Dietary modification after diagnosis is one possible explanation for this finding. Intervention studies using whole foods are required to ascertain whether such modifications of food intake could be beneficial in the prevention or amelioration of asthma.

A valid food frequency questionnaire for measuring dietary fish intake.

There is considerable interest in the potentially protective effects of high fish consumption on many chronic diseases. Many epidemiological studies use food frequency questionnaires (FFQ) to quantify usual dietary fish intake, so it is important to validate this assessment against objective markers. The objective of this study was to determine the relationship between plasma percentage fatty acids and dietary fish intake as assessed by a FFQ. A semiquantitative FFQ was completed by 174 adults from the community (aged 26-49 years) who also had venous blood analysed for plasma percentage fatty acids. Following linear regression modelling, total non-fried fish intake was a significant predictor of n-3 (regression coefficient, B = 0.94; 95% CI = 0.60-1.28), docosahexaenoic acid (DHA; B = 0.73; 95% CI = 0.47-0.99) and the ratio of n-6: n-3 fatty acids (B = -1.0; 95% CI = - 1.35- -0.65). Steamed, grilled or baked fish was a small but significant predictor of eicosapentaenoic acid (EPA) levels (B = 0.13; 95% CI = 0.05-0.21) while total fish intake was a predictor of n-6 fatty acids (B = -0.88; 95% CI = -1.41- -0.36). This semiquantitative FFQ could be useful for ranking subjects according to their likely plasma n-3, DHA, and n-6 fatty acid intake and the ratio of n-6: n-3 fatty acids, when the available resources may simply not permit biological markers to be used.