The effect of supplementation with fish oil during pregnancy on breast milk immunoglobulin A, soluble CD14, cytokine levels and fatty acid composition J. A. Dunstan*, J. Roper*, L. Mitoulasw, P. E. Hartmannw, K. Simmer* and S. L. Prescott* School of *Paediatrics and Child Health and wBiomedical and Chemical Sciences, University of Western Australia, Perth, Western Australia Summary Background Breast milk contains many immunomodulatory factors (soluble CD14 (sCD14), IgA and cytokines) with the potential to influence infant immune development. Objective To determine if changes in breast milk o-3 polyunsaturated fatty acid (n-3 PUFA) composition as a result of maternal dietary fish oil supplementation during pregnancy can modify levels of these immunological parameters in breast milk. Method In a randomized controlled trial, 83 atopic women received either 4g fish oil capsules (containing 3.7 g n-3 PUFA) (n 5 40) or 4 g olive oil capsules (n 5 43) from 20 weeks gestation until delivery. Breast milk was collected 3 days post-partum and fatty acids were analysed by gas liquid chromatography and IgA, sCD14 and cytokines (IL-5, IL-6, IL-10, TNF-a and IFN-g) were quantitated by ELISA or time resolved fluorescence (TRF). Results o-3 docosahexaenoic acid (DHA; 22:6n-3) and eicosapentaenoic acid (EPA; 20:5n-3) levels were significantly higher (Po0.001) in breast milk from women supplemented with fish oil (n 5 33, DHA mean 1.15%, SD 0.47% and EPA mean 0.16%, SD 0.07%) than in samples from the control group (n 5 40, DHA mean 0.50%, SD 0.17% and EPA mean 0.05%, SD 0.02%). Breast milk arachidonic acid (AA; 20:4n-6) levels were significantly lower (P 5 0.045) in the fish oil group (mean 0.55%, SD 0.12%) compared with the control group (mean 0.61%, SD 0.14%). Breast milk IgA was positively correlated with DHA (P 5 0.046) and 22:5n-3 (P 5 0.003), but inversely correlated with linoleic acid (LA; 18:2n-6) (P 5 0.034). Levels of sCD14 were also positively correlated with 22:5n-3 (P 5 0.009). Cytokines involved in IgA synthesis (IL-10 and IL-6) were also significantly correlated with both IgA and n-3 PUFA levels, although there were no differences in the levels of breast milk IgA, sCD14 or cytokines between study groups. Conclusion Supplementation with fish oil during pregnancy significantly alters early post-partum breast milk fatty acid composition. o-3 PUFA levels were positively associated with IgA and sCD14 levels, suggesting a relationship between fatty acid status and mucosal immune function. Keywords allergy, breast milk, cytokines, docosahexaenoic acid, fish oil, infants, long chain polyunsaturated fatty acids, pregnancy Submitted 27 November 2003; revised 26 March 2004; accepted 27 April 2004 Introduction In addition to providing essential nutrients, breast milk also contains many factors (including antibodies, cells, cytokines and soluble CD14 (sCD14)) that provide some measure of immunological protection for infants during a period of relative immaturity. As well as protection from infection, immunological factors in breast milk may be important in other aspects of immune development. With increasing rates of allergic disease there has been growing interest in the protective effects of breastfeeding. Although not supported by all studies (discussed in [1, 2]), there remains a substantial body of evidence to suggest that breastfeeding may reduce the risk of developing allergic disease (discussed in [3]). It is not clear if this could be due to direct immunological properties of breast milk, or indirect effects on bacterial colonization or delayed introduction of potential dietary allergens. As such, there is growing interest in the immunological properties of breast milk and how these may be modulated by environ- mental changes (including maternal diet) and in turn influence infant immune development. Breast milk contains maternal antibodies to environmental proteins including allergens [4, 5], which may confer some protection from allergic diseases [6–8], possibly by reducing absorption of allergens. Other immune factors may modify intestinal colonization [9], which has also been implicated in the prevention of allergic disease. The soluble form of the bac- terial pattern recognition receptor CD14 (sCD14) is present in human milk at levels 20-fold higher than serum [10], sug- gesting that this may play a role in modulating local innate Correspondence: Susan L. Prescott, Department of Paediatrics, PO Box D184, Princess Margaret Hospital, Perth, WA 6001, Australia. E-mail: susanp@ichr.uwa.edu.au Clin Exp Allergy 2004; 34:1237–1242 doi:10.1111/j.1365-2222.2004.02028.x r 2004 Blackwell Publishing Ltd 1237