Essential fatty acids (EFAs) are healthy fats that play a crucial role in overall well-being, including mood and brain function, cardiovascular health and joint health. One of the two groups of therapeutic fatty acids is called omega 6. The active substance in omega 6 is gamma-linolenic acid (GLA), and although many of the vegetable oils used in food are a source of omega 6, they do not provide large amounts of GLA. Evening primrose oil is high in GLA and is not normally included in the diet, so therapeutic doses are combined with supplements. The fatty acids in evening primrose oil help balance hormone-like substances, prostaglandins, which helps relieve symptoms of premenstrual syndrome (PMS), rheumatoid arthritis, and skin disorders without causing unwanted side effects.