Polyunsaturated n-3 fatty acids and the development of atopic disease

The relationship between polyunsaturated long-chain fatty acids and atopy h as been discussed for decades. Higher levels of the essential fatty acids l inoleic acid and alpha -linolenic acid and lower levels of their longer met abolites in plasma phospholipids of atopic as compared to nonatopic individ uals have been reported by several, but not all, studies. Largely similar f indings have been reported in studies of cell membranes from immunological cells from atopics. and nonatopics despite differences in methodology, stud y groups, and definitions of atopy. An imbalance in the metabolism of the n -6 fatty acids, particularly arachidonic acid and dihomo-gamma -linolenic a cid, leading to an inappropriate synthesis of prostaglandin (PG) E-2 and PG E(1) was hypothesized early on but has not been corroborated. The fatty aci d composition of human milk is dependent on the time of lactation not only during a breast meal but also the time of the day and the period of lactati on. This explains the discrepancies in reported findings regarding the rela tionship between milk fatty acids and atopic disease in the mother. Prospec tive studies show disturbances in both the n-6 and n-3 fatty acid compositi on between milk from atopic and nonatopic mothers. Only the composition of long-chain polyunsaturated n-3 fatty acids was related to atopic developmen t in the children, however. A relationship between lower levels of n-3 fatt y acids, particularly eicosapentaenoic acid (20:5 n-3), and early developme nt of atopic disease is hypothesized.