Women's Health Support Herbal Supplement Gluten Free Guaranteed Quality Laboratory Tested 21st Century’s® Evening Primrose Oil is an excellent source of gamma-linoleic acid (GLA), an essential fatty acid. Fatty Acids play a major role in the maintenance of healthy skin, cell membrane structure, cardiovascular and nervous system support.* Evening Primrose Oil is used in Europe and Asia to aid the symptoms of PMS. 21st Century’s® Evening Primrose Oil contains the highest levels of GLA (10%). And thoroughly tested to assure specific levels of the important active ingredients are present for maximum benefit.