How to take I usually recommend the borage oil source of GLA, since it is the most cost effective and concentrated, meaning that fewer pills are necessary. It comes in 1000-mg capsules, which contain 240 mg of GLA. One per day is usually adequate. Evening primrose oil contains 40 mg of GLA per 500-mg capsule (usual dose--six per day); and black currant oil contains about 80 mg per capsule, and three per day is an adequate dose. After therapeutic results, the dose may be lowered for maintenance.