Effect of dietary n-3/n-6 fatty acid ratio on the total count, fatty acid composition, and histamine and leukotriene concentrations of mast cells in tunica mucosa bronchiorum of type I allergic guinea pig

To search for the most effective dietary n-3/n-6 ratio to suppress the type I allergic response, we performed basic experiments that applied parameters associated with the type I allergy, Guinea pigs fed on diets containing lipids with the n-3/n-6 ratio at different levels and the polyunsaturated fatty acid/saturated fatty acid ratio of a fixed level were sensitized with ovalbumin and reared for two weeks, The lowest or critical level of the n-3/n-6 ratio which produced a significant difference in the parameters was as follows: about 2.0 for the response of mast cells and eosinophils; 0.5 and 1.0, respectively, for the uptake of n-3 and n-6 polyunsaturated fatty acids and decreased histamine production; and 0.2 for decreased leukotriene B-4 and total leukotrienes 4, and increased leukotrienes 5/leukotrienes 4, The critical level of the n-3/n-6 ratio thus differed widely according to the parameter, Overall, the upper limit for the dietary n-3/n-6 ratio to suppress antigen-induced type I allergic responses is suggested to be around 1.0.