Fat intake and breast milk fatty acid composition in farming and nonfarming women and allergy development in the offspring.

Background: Children growing up on small family farms are at much lower risk of developing allergy than other children. We hypothesized that low intake of margarine and polyunsaturated fats among farming families could contribute to this protection.

Methods: Twenty-eight mother-infant pairs living on small dairy farms and 37 nonfarm rural resident pairs were recruited in the FARMFLORA birth cohort. Food items expected to affect dietary fat composition were recorded by food frequency questionnaires during pregnancy and by 24-h recalls followed by 24-h food diaries during lactation. Allergy was diagnosed by doctors, using strict predefined criteria. Maternal diet and breast milk fat composition were compared between farming and nonfarming mothers and related to children's allergy at age 3 y.

Results: Farming mothers consumed more butter, whole milk, saturated fat, and total fat than nonfarming mothers, who consumed more margarine, oils, and low-fat milk. Farming mothers' breast milk contained higher proportions of saturated and lower proportions of polyunsaturated fat. Allergy was eight times more common in nonfarm children. Mothers of allergic children consumed more margarine and oils than mothers of nonallergic children.

Conclusion: Low maternal consumption of margarine and vegetable oils might contribute to the allergy-preventive effect of growing up on small dairy farms.