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A study published in Acta Paediatrica by Swedish scientists indicates that omega-3 supplementation of expectant mothers during pregnancy and the first few months of breast feeding may lead to a reduced risk of allergies in their offspring.
Over recent years, allergic diseases have increased and factors which may have contributed to this include environment and choice of foods. The authors of this recent study suggest that decreased omega 6 / omega 3 fatty acid ratios may help decrease the risk of sensitisation. Their aim therefore was to evaluate the effect of omega-3 long chain polyunsaturated fatty acid (LCPUFA) supplementation during pregnancy and lactation on the risk of allergic sensitisation and disease during the first year of life.
Furuhjelm et al recruited 145 Swedish women for the study. Family allergy history was assessed and all the families had at least one parent or older child with either current allergic symptoms or a previous history of them. Food diaries were taken at the 25th gestational week and six months after birth. Maternal blood samples were taken at the start of the study and within one week of delivery. Exposure to tobacco smoke, plus data on breast feeding and food introduction was also collected at 3, 6 and 12 months after delivery. After drop outs and exclusions, 117 children were followed up in accordance with the plan. Women were randomly divided into two groups. One group received supplementation with omega 3 fatty acids, at an amount corresponding to around 100g salmon daily. The other group received a placebo. Supplementation started at the 25th week of gestation and the women were encouraged to continue it throughout pregnancy and lactation. Maternal blood was analysed for immunoglobulin E (IgE) – this being the predominant antibody associated with allergic response- to a series of airborne antigens. Infants were assessed for IgE antibodies toward egg, milk and wheat at 3 and 12 months and skin prick tests were performed on the children for cows’ milk, egg white, and wheat flour at 6 and 12 months.
The researchers indicated that as expected women in the omega 3 group showed significantly higher levels of omega 3 fatty acids EPA and DHA a week after delivery compared to those measured at the start of the study and in women in the placebo group. They found that food allergy during the first year of life of the offspring was significantly less frequent in the omega 3 group compared to the control. The scientists found that the risk of developing a positive skin prick test of any kind, a positive skin prick to egg or IgE associated eczema within the first year was 3 to 4 times less in the omega 3 group and that the risk of developing a food allergy was reduced 10 times in this group compared to the control.
Furuhjelm et al propose several mechanisms for this effect including one in which both EPA and DHA change the fluidity of immune cell membranes and reduce levels of the omega 6 fatty acid arachidonic acid. Inhibition of the metabolism of arachidonic acid may be linked to lower allergic sensitisation and the production of less inflammatory eicosanoids. Other anti-inflammatory effects of both EPA and DHA in early immune development may also involve the actions of bioactive lipids, lipoxins, neuroprotectins and resolvins, but all these require much further research to see if they do, indeed, play a part.
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