Evening primrose is a plant native to North America, but grows in Europe and parts of the Southern Hemisphere as well. It has yellow flowers that bloom in the evening. Evening Primrose Oil contains substantial amounts of polysaturated omega-6 fatty acids, essential fatty acids (EFAs) which are needed by the body to regulate a number of activities including insulin utilization, heart function and mood. Since the body does not produce EFAs, they must be ingested through proper diet or supplementation. In addition to omega-6 fatty acids, Evening Primrose Oil contains linoleic acid and gamma-linolenic acid (GLA).