Antiasthmatic effects of gamma linolenic acid -high dose Evening Primrose Oil and Borage Oil stimulate allergen tachyphylaxis of sensitized guinea pigs and prevent allergen sensitization.

Evening primose oil (EPO) and borage oil (BO), which contain high amounts of gamma linolenic acid (10% or 20%) and are described to stimulate prostaglandin E biosynthesis, were investigated in guinea pigs for their ability to stimulate an important active self protecting mechanism against allergens ("allergen tachyphylaxis"). Groups of 12 guinea pigs sensitized to ovalbumin were fed over five days with either EPO or BO (100mg/kg/day or 1 g/kg/day) prior to sequential allergen inhalation challenges (time 0', 10', 20', 60', 70' and 80'). Bronchial obstruction was measured by whole body plethysmography. 100 mg/kg EPO did not alter the bronchial reactions of the animals; 100 mg and 1 g/kg BO stimulated AT whereas EPO stimulated AT in a concentration of 1 g/kg only. 100 mg/kg of both oils reduced allergen sensitization.