Oentothea biennis seeds contain up to 15% fatty oil and are obtained by using cold pressing or hexane extraction method. Fatty oil contains omega-6 fatty acids, cis-linoleic acid and cis-gamma-linolenic acid (also known as gamolenic acid). Linoleic acid is an essential fatty acid, which the human body cannot synthesize, and it can be obtained from food. The body synthesizes gamma-linolenic acid from linoleic acid through an enzyme. gamma-linolenic acid affects the production of prostaglandins (a group of physiologically active hormone-like lipids), which are important to reduce inflammatory processes. As a result, evening primrose oil, helps to balance hormones and helps to relieve problems, which are related to menstrual cycle. In addition, it helps to maintain the health of the skin and connective tissue.