Dietary fat in respiratory diseases: A multi-case control study

Epidemiological studies provide some evidence that dietary fat intake is important in asthma and other respiratory diseases, even though the results are often conflicting. In the frame of the Genes Environment Interaction in Respiratory Diseases, an Italian population-based multi-case control study, we studied the associations between respiratory diseases and intake of total, animal, vegetal, saturated, monounsaturated and polyunsaturated dietary fat. The European Investigation into Cancer and Nutrition Food Frequency Questionnaire was used for dietary assessment in controls (n=345) and in subjects with asthma (past, n=76, or current, n=147), rhinitis (allergic, n=303, or non allergic, n=164) and chronic bronchitis (n=77).The associations between fat and respiratory diseases were estimated by means of multinomial (for asthma and rhinitis) or logistic (for chronic bronchitis) regression models. The estimates were adjusted for age, gender, centre, BMI, smoking habits, alcohol intake, physical activity, educational level and total energy intake. Current asthma risk was inversely related to the intake of vegetable fat (RRR=0.49, 95% CI 0.27–0.91 for the highest quartile as compared with the lowest one, p for trend=0.036). Monounsaturated fat showed a trend similar to vegetable fat but this trend was not statistically significant (p=0.139). A significant increased risk of allergic rhinitis was observed with increasing saturated fat (RRR = 1.92, 95% CI 1.17–3.16 for the highest quartile, p for trend=0.030). No other significant association was found between fat and respiratory diseases. Our results suggest that vegetable fat is protective for asthma, whereas saturated fat is a possible risk factor for allergic rhinitis.