Finnish researchers have put the blame for an increased incidence of allergies among children on dietary habits. The move contradicts many previous theories, which included seeing environmental pollution as the cause, and is detailed in a study published in the journal Allergy (2001;p 56:pp. 425-428).

The study reviewed data collected over nine years on 462 children between the ages of three and 18 in 1980, and 308 children of the same ages in 1986.

According to Dr Teija Dunder and colleagues at the University of Oulu, it is still too soon to make dietary recommendations on the back of his study. However further evidence of a link between dietary fats and allergies has been found. Certain fatty acids, such as polyunsaturated fats, are believed to promote the formulation of prostaglandin E2, which prompts the immune system to release a protein that creates an allergic reaction. 

The increasing emphasis amongst health officials on balancing the dietary intake of unsaturated fats (such as those in margarine) and saturated fats (such as those in butter) is important, but may be to blame for the increasing rate of childhood allergies, according to the study. The researchers found that children who ate more margarine than butter eventually developed allergies. Meanwhile those children who ate more butter did not develop allergies.

According to the study: "Our results support the hypothesis that the quality of the fat consumed in the diet is important for the development of [allergic] diseases in children. The possibility of preventing [allergic] diseases by supplementation or by changing the fatty acid composition of the diet of young children remains to be tested by clinical trials."

While it appeared to be a less significant factor, the children with allergies also tended to eat less fish. Indeed, the researchers have linked higher fish intake to lower rates of asthma.