Evening Primrose Oil provides the fatty acids Linoleic Acid (LA) and Gamma Linolenic Acid (GLA). Not all fatty acids can be made in the body so must be supplied through diet or supplementation. Within the body Linoleic Acid is metabolised to GLA, which is essential for the production of certain hormones called prostaglandins. Human breast milk is one of the richest natural sources of GLA, whilst LA can be found in safflower, hemp and sunflower oils.