Serum fatty acids in infants, reflecting family fish consumption, were inversely associated with allergy development but not related to farm residence.

Aim: In this study, differences in serum fatty acid patterns between farm and nonfarm infants were investigated and related to subsequent allergy development. We also related allergy-related serum fatty acids to maternal diet and breast milk fatty acids.

Methods: The FARMFLORA birth cohort included 28 farm and 37 nonfarm infants. Serum was obtained from 21 farm infants and 29 controls at four months post-partum and analysed for phospholipid fatty acids. Allergy was diagnosed by paediatricians at three years of age.

Results: Serum fatty acid patterns were similar in farm and control infants, although farm infants had lower 18:1 omega-7 proportions. Serum proportions of eicosapentaenoic acid (EPA) were unrelated to farming status, but lower in children who subsequently developed allergy, with an odds ratio of 0.47 and 95% confidence interval of 0.27-0.83 (p = 0.01) for every 0.1% EPA increase. The infants' serum EPA proportions correlated with breast milk EPA proportions, which, in turn, correlated with maternal oily fish intake during lactation.

Conclusion: The allergy-protective effect of farming was not linked to infant serum fatty acid composition. However, healthy infants had higher proportions of EPA in their sera, probably reflecting a family diet rich in fish, compared to subsequently allergic children.