Evening Primrose

Evening primrose is a tall biennial, usually 0.5 to 1.5 meters, that forms a leafy rosette in its first year and a flowering stalk in the second. The pale yellow, four-petaled flowers open in the evening and wither by the next day. After flowering, the plant produces upright, four-chambered capsules packed with very small, angular, reddish-brown to blackish seeds, each barely larger than a pinhead. The seeds are mostly processed rather than eaten directly. They are cold-pressed into a pale golden oil with a light, slightly nutty smell, sold in liquid form or in softgel capsules. The roots and young shoots were once also eaten as a vegetable.

Oenothera biennis is native to eastern and central North America, from Newfoundland to Florida and west to the Rocky Mountains. Indigenous peoples across the region used the plant for food and medicine, including poultices and teas. It reached Europe in the early seventeenth century, probably as a garden curiosity or as a seed contaminant in ship ballast, and it became widely naturalized across Europe and temperate Asia. The genus name Oenothera is of uncertain Greek origin, sometimes linked to a wine-related plant name, while the common name refers to the flowers opening at dusk.

Native North Americans used evening primrose roots, leaves and seeds for food and as remedies for wounds, bruises and digestive complaints. European settlers adopted these uses, and the plant gained the folk name king's cure-all in the seventeenth and eighteenth centuries, reflecting a reputation that far outran its documented effects. Roots were boiled and eaten, and the plant was cultivated in European gardens, where its roots were known as German rampion.

The modern story begins in the twentieth century, when chemists identified gamma-linolenic acid (GLA) in the seed oil, an omega-6 fatty acid also found in borage and blackcurrant seed oils. This led to a boom in evening primrose oil supplements, especially in the 1980s and 1990s, marketed for eczema, premenstrual symptoms, breast pain and menopausal complaints. Large reviews have generally found weak or inconsistent evidence for most of these claims, and in some countries the oil has been licensed for specific uses and later withdrawn. Today the plant is grown commercially in several countries for seed oil, and wild populations are common along roadsides and fields.

Evening primrose seed oil is taken as a supplement and is also used in skin-care products, lotions and massage oils. It is not suited to high-heat cooking and is generally used as a finishing or supplement oil. Traditional uses of other parts include eating boiled roots, young leaves and flower buds as a vegetable, and making teas or poultices from the leaves and stems. Seeds can be pressed at home with small oil presses, but most commercial oil is extracted from seed grown for the purpose and sold as capsules, usually standardized to a given GLA content.

The oil typically contains roughly 70 percent linoleic acid and about 8 to 10 percent GLA. Research on its use for eczema, breast pain, menopausal hot flashes and premenstrual symptoms has produced mixed or negative results in larger reviews, and effects, when seen, tend to be small. Some studies suggest minor benefits for skin dryness, but evidence is not strong enough to recommend it as a treatment for any condition. Talk with a healthcare professional before using it for a health concern.