Evening primrose (Oenothera biennis) is a flowering plant native to North America that has naturalised widely across Europe and other temperate regions. It blooms in the evening — hence its common name. The oil extracted from its seeds is valued primarily for its unusual fatty acid composition, particularly its high content of gamma-linolenic acid (GLA), a polyunsaturated omega-6 fatty acid that is rare in common dietary oils.
What GLA is and why it matters
Most dietary omega-6 fatty acids consumed in modern diets are linoleic acid (LA) — found abundantly in vegetable oils like sunflower, corn, and soybean oil. The body can convert linoleic acid to GLA through an enzyme called delta-6-desaturase (D6D). However, this conversion is often inefficient due to several factors: high dietary intake of saturated fat, trans fats, or linoleic acid itself can down-regulate D6D activity; ageing also reduces D6D activity; and certain nutrient deficiencies (zinc, magnesium, B6) impair the enzyme.
GLA is one step further along the metabolic pathway from LA — it is converted to DGLA (dihomo-gamma-linolenic acid), which is then converted to either arachidonic acid (AA, a precursor of pro-inflammatory eicosanoids) or to anti-inflammatory eicosanoids including prostaglandin E1 (PGE1). PGE1 has vasodilatory, anti-inflammatory, and platelet aggregation-inhibiting properties. Supplementing directly with GLA bypasses the potentially rate-limiting D6D step, making GLA more readily available for DGLA and subsequent PGE1 production.
Evening primrose vs borage oil vs black currant oil
Evening primrose oil typically contains 8–10% GLA. Borage oil (Borago officinalis) is richer, containing 20–26% GLA, making it a more concentrated GLA source at equivalent volumes. Black currant seed oil contains 15–20% GLA plus a proportion of stearidonic acid (SDA), which enters the omega-3 pathway. Despite the higher GLA concentration in borage oil, evening primrose oil remains the most extensively studied form in clinical research.
Clinical research
Evening primrose oil has been studied across several conditions:
- Eczema and atopic dermatitis: Early trials showed significant improvements in skin symptoms. A 2013 Cochrane review, however, found the evidence for oral evening primrose oil in eczema was inconsistent and of poor methodological quality. More recent research has focused on topical GLA preparations rather than oral supplementation.
- Premenstrual syndrome (PMS): Several small trials have found improvements in breast tenderness (mastalgia) and PMS symptom scores with evening primrose oil supplementation.
- Rheumatoid arthritis: Trials using GLA (from borage and evening primrose oil) have shown reductions in joint tenderness and morning stiffness scores.
- Diabetic neuropathy: The MDDP trial and subsequent studies found that GLA supplementation for 12 months improved nerve conduction velocity and reduced neuropathic symptom scores in people with mild diabetic neuropathy.
Evening primrose oil in Lebanon
Supplements & More carries evening primrose oil softgels from US brands, available with cash on delivery across Lebanon.