WHAT IS EVENING PRIMROSE OIL? Evening primrose oil, sometimes known as vitamin F, is derived from the seed of the evening primrose plant. OUR EVENING PRIMROSE OIL SUPPLEMENT Our Evening Primrose Oil supplement blend combines linoleic acid (a source of omega 6), oleic acid (a source of omega 9). We guarantee a minimum 10% gamma linolenic acid (GLA) level. Our Evening primrose is cold pressed, unbleached, hexane free as well as herbicide and pesticide free. WHAT DOES EVENING PRIMROSE OIL DO? Linoleic acid contributes to the maintenance of normal blood cholesterol levels Essential fatty acids are needed for the growth and development of children.