The components in milk fat could be responsible for lower rates of asthma among young children, concludes a study in Thorax, which challenges previous findings linking fish fatty acids to lower incidence of the disease.
Researchers from the Netherlands found that pre-school children who ate full fat milk and butter daily were less likely to develop asthma later on. Fruit juice, vegetables and fish were also associated with slightly lower rates of the respiratory disease, but these differences were not statistically significant, reported the team.
Omega-3 fatty acids in fish have previously been linked to lower risk of developing asthma, however there was no association between eating fish once a week and asthma or wheeze in this study.
Evidence supporting the benefits of dairy products has generally come from studies assessing the protection offered from living on a farm. It is thought that modern lifestyle, including pollution and hygiene, contributes to the risk of developing asthma, and growing up on a farm appears to have protective effects. But in the current study, only 2 per cent of the children assessed lived on a farm, leading researchers to associate the benefits purely with diet.
Dietary information for around 3000 two-year-olds was collected and the researchers followed-up for asthma symptoms when the children reached three years old. Asthma at age three was lower in children who consumed full cream milk daily (only 3.4 per cent, compared to 5.6 per cent who did not drink milk regularly) and butter daily than in those who did not (only 1.5 per cent compared to 5.1 per cent). Similarly, wheeze was lower in children who consumed milk products, including yoghurt and chocolate milk, and butter daily than in those who did not.
Daily consumption of brown bread was also associated with lower rates of asthma and wheeze. The researchers noted the strong associations between the frequent consumption of certain foods, such as brown bread and full cream milk, or margarine and cheese.
The results provide evidence for a beneficial association between daily consumption of products containing milk fat and the development of asthma and wheeze in young children, concluded the authors. Various components of the products involved could play a role, such as different fatty acids, but also antioxidants or other micronutrients, they suggest.
They also highlight the theory linking the modern diet, which sees a reduction in consumption of saturated fat and increase in omega-6 polyunsaturated fatty acids, with increase in cases of asthma and eczema in the western world. Margarine consumption was not directly linked to incidence of asthma and wheeze in these results, but further research should assess the "quantitative importance of different foods", they write.