Consumption of unpasteurized milk and its effects on atopy and asthma in children and adult inhabitants in rural Poland

Background Consumption of unpasteurized cow's milk has been identified as a possible protective factor for atopy and asthma. Most studies have been conducted among children and in farming populations. We investigated the effects of consumption of unpasteurized milk in early life on atopy, asthma, and rhinitis in village and town inhabitants in a region of Poland and assessed whether any protective effects of milk consumption differed according to place of residence and farming status. Methods We surveyed the inhabitants (aged >5years) of a small town and seven nearby villages in southwest Poland (n=1700, response rate 88%). Participants (or their parents for those <16years of age) completed a questionnaire on farm exposures and symptoms of asthma and rhinitis. In particular, information was collected on unpasteurized milk consumption in early life. Atopy was assessed using skin prick tests. Results Consumption of unpasteurized milk in the first year of life was inversely associated with atopy and asthma both among town and village inhabitants town: adjusted odds ratio (aOR) for atopy 0.46 [95% confidence interval (CI) 0.370.52] asthma 0.51 (0.320.74); villages: atopy 0.59 (0.440.70) and asthma 0.59 (0.420.74). For atopy, the protective effect was more clearly seen among nonfarmers (0.42; 0.340.46) than in farmers (0.82; 0.541.11). For doctor-diagnosed hay fever and current rhinitis symptoms, the protective effect was only observed among town inhabitants and/or nonfarmers. Conclusions Early-life exposure to unpasteurized milk may protect against atopy, asthma, and related conditions, independently of place of residence and farming status, and in both children and adults.