Effect of omega-3 fatty acid concentrations in plasma on symptoms of asthma at 18 months of age.
The objective of this study was to assess the relation between observed levels of omega-3 fatty acids in plasma and symptoms of asthma and atopy in children at 18 months of age. A total of 616 women at risk of having a child who would develop asthma because of a family history were recruited from the antenatal clinics of six hospitals in Sydney, Australia. Families were randomized to either active omega-3 supplemented or control group. The active group received a daily tuna fish oil supplement and omega-3-rich margarines and cooking oils and the control group received a placebo supplement with polyunsaturated margarines and cooking oils. When the children were 18 months of age an assessment of symptoms was carried out by a research nurse blinded to treatment group allocation. Atopy was measured by skin prick tests, blood was collected to determine serum immunoglobulin E (IgE), and plasma fatty acid concentrations. A total of 376 children (61.0% of total recruited) completed an assessment at 18 months and had blood taken to determine plasma fatty acid concentrations. Omega-3 fatty acid levels were expressed in quintiles of exposure 'as treated' without reference to treatment group allocation. Wheeze ever, doctor visits for wheeze, bronchodilator use and nocturnal coughing were significantly reduced in children in the higher exposure quintiles. Serum IgE was reduced in the highest quintile but not significantly so. There was no difference in diagnosed asthma or atopy between the exposure quintiles. Although wheeze at this age may not be a good indicator of asthma in later childhood, it is encouraging that some symptoms have been reduced in children with high omega-3 fatty acid concentrations in plasma.