Evening primrose oil epo comes from the seeds of the evening primrose plant like blackcurrant seed oil and borage oil epo contains gamma linolenic acid gla a fatty acid that the body converts to a hormone like substance called prostaglandin e1 peg1where is it found epo is found primarily in supplements its presumed active ingredient gla can also be found in blackcurrant seed oil and borage oil supplements epo may help to maintain normal bodily functions and may maintain the health