The purpose of this study was to investigate whether there is an association between asthma and the intake of food with pro-oxidant or antioxidant activity (fat, alcohol, iron, zinc, and vitamins A and C), and to analyse whether any such association is specific to asthma or is found in airflow limitation in general. This study deals with 478 men, who were randomly selected from all the men born in Malmö in 1914. They were investigated using spirometry and their medical, occupational and dietary history was recorded in 1982-1983, at the age of 68 yrs, as part of the cohort study "Men born in 1914". Asthma was defined as a past or present physician's or nurse's diagnosis of asthma and airflow limitation was defined as a forced expiratory volume in one second/vital capacity ratio (FEV1/VC) of less than 70%. The relative risk of having asthma or airflow limitation as related to dietary intake at the age of 68 yrs was analysed after adjustments for smoking history and body mass index. Asthma was reported in 21 men and was not related to smoking history. Asthma was more common in men with a high fat intake (relative risk of asthma 1.74 for a 10% increase in fat intake, 95% confidence interval for the relative risk 1.13-2.68). The consumption of alcohol was higher for current smokers than ex-smokers and nonsmokers, and the intake of carbohydrates, vitamin C and iron was lower. Airflow limitation without asthma was present in 156 men and was related to smoking but not to dietary intake. Men with asthma had a significantly higher intake of fat than men without asthma. This difference appeared to be specific to asthma and was not found in airflow limitation in general.