Evening Primrose Oil

Figure 1. A flowering Evening Primrose plant.

Evening Primrose Oil (EPO) is the generic name for the dietary supplement derived from the common Evening Primrose, or Oenothera biennis. The Evening Primrose is a species of flowering plant in the family Onagraceae, native to eastern and central North America, from Newfoundland west to Alberta, southeast to Florida, and southwest to Texas, and widely naturalized elsewhere in temperate and subtropical regions.

The Evening Primrose is traditionally used by indigenous people in North America as food and medicine. Most parts of the plant are edible. The roots can be eaten raw or cooked like potatoes. The leaves can be eaten raw in salads or cooked like spinach or in soups. Native American tribes made tea from the evening primrose leaves and used it as a dietary aid.

EPO is obtained from the seeds of the plant. The seeds have a protein content of about 15%, an oil content of 24%, and contain about 43% cellulose. The proteins are especially rich in the sulphur-containing amino acids, methionine and cysteine, and tryptophan. The seeds also contain the polyunsaturated fatty acid linolenic acid, more specifically gamma-linolenic acid, an Omega-6 fatty acid found in plant oils.

Taken as a dietary supplement, the GLA in EPO may help to manage acne by reducing skin inflammation and the number of skin cells that cause lesions. It may also help the skin retain moisture. EPO may also help with inflammatory skin conditions such as eczema and overall skin health. Studies have suggested that EPO may help with symptoms of premenstrual syndrome (PMS) such as depression, irritability, and bloating (as GLA converts to prostaglandin E1 which helps prevent prolactin from triggering PMS).

EPO may also help with menopause symptoms, arthritis, and high cholesterol although there is insufficient scientific evidence to conclusively support the efficacy of these applications.

EPO is generally considered safe for most people to use short term. Side effects are usually mild and may include an upset stomach, stomach pain, headache, and soft stools.