Polyunsaturated fatty acids in school children in relation to allergy and serum IgE levels.

Altered composition of polyunsaturated fatty acids (PUFA) has been observed in allergic individuals and it has been proposed that this is due to an impairment of delta-6-desaturase activity. We have studied the composition of PUFA in serum phospholipids in twenty-two 12-15 year old children with asthma and/or allergic dermatitis and 23 non-atopic controls of similar age. The relative levels of docosahexaenoic acid (DHA, C22:6n-3) and total n-3 long-chain polyunsaturated fatty acids (LCP) were lower (1.46% +/- 0.54 vs. 1.90% +/- 0.58, P = 0.01 for DHA and 2.34% +/- 0.67 vs. 2.80% +/- 0.77, P < 0.05 for total n-3 LCP) and the ratio of total n-6 to n-3 LCP was higher (P < 0.01) in the allergic children than in the controls. In addition to these differences, the relative levels of docosapentaenoic acid (DPA, C22:5n-3) and the ratio of arachidonic acid (AA, C20:4n-6) to dihomo-gamma-linolenic acid (DHGLA, C20:3n-6) were also lower in the 12 allergic children with positive skin prick test, as compared with the SPT negative children (both P < 0.05). In non-allergic children, the levels of total n-3 correlated with n-6 LCP (r = 0.76, p < 0.001). Furthermore, the n-3 LCP, i.e. EPA, DPA and DHA, correlated significantly with each other (r = 0.52-0.78, all p < 0.01) and correlated with n-6 LCP, i.e. C20:2, DHGLA and AA respectively (r = 0.56-0.83, all P < 0.01). Most of these correlations were absent in allergic children. Higher levels of C20:2n-6 and lower levels of eicosapentaenoic acid (EPA, C20:5n-3) were recorded in 11 allergic children with serum IgE above the median level (56 kU/l), as compared to 11 with lower IgE levels (both P < 0.05). Furthermore, the levels of C20:2n-6 correlated with the IgE levels in the children (r = 0.65, P = 0.001). The findings could not confirm an impaired delta-6-desaturase activity in allergic school children and suggest that a disturbance of LCP metabolism is associated with allergic diseases.