Oil pressed from the seeds of the evening primrose plant (Oenothera biennis), which has been used medicinally for centuries. The oil is rich in the polyunsaturated fatty acid linoleic acid (see essential fatty acid) and also contains gamma-linolenic acid. The latter component is claimed by some to be the active ingredient of the oil but this is not proven. Symptom relief has been reported for rheumatoid arthritis, breast pain, premenstrual syndrome, eczema, diabetic neuropathy, cancer, hypercholesterolaemia, and heart disease, although study results have been negative or mixed.
Subjects: Medicine and Health.