What is evening primrose oil?
Evening primrose oil (EPO) is extracted from the seeds of the evening primrose plant (Oenothera biennis). This plant is native to North America, where indigenous peoples used it in traditional medicine for centuries.
What makes evening primrose oil special is its high content of gamma-linolenic acid (GLA) — a rare omega-6 fatty acid that typically comprises 8–10% of the oil (Timoszuk et al., 2020). GLA is an intermediate in the metabolic pathway between linoleic acid and arachidonic acid and participates in the synthesis of prostaglandins — substances that regulate inflammatory processes (Fan & Chapkin, 1998).
How does evening primrose oil work?
GLA is a long-chain polyunsaturated fatty acid that the body normally produces from linoleic acid (the most common omega-6) using the enzyme delta-6-desaturase. In some individuals, this enzymatic conversion may be slow (Horrobin, 1993), which is why direct GLA consumption may be beneficial.
In the body, GLA is converted to dihomo-gamma-linolenic acid (DGLA), which is a precursor to certain prostaglandins — hormone-like substances involved in regulating inflammation, pain and body temperature (Sergeant et al., 2016).
Evening primrose oil also contains linoleic acid (approximately 70–75%), which is an essential fatty acid.
Evidence and research
Important note: The European Food Safety Authority (EFSA) has not approved specific health claims for evening primrose oil supplements. Claims submitted regarding skin health, hormonal balance and PMS have not received approval.
What the scientific literature shows:
- GLA is an omega-6 fatty acid that participates in prostaglandin synthesis
- Evening primrose oil has been a popular research subject in women's health, particularly in the context of the menstrual cycle and menopause
- Some studies have examined the role of GLA in the fatty acid composition of skin
- Results have been inconsistent and EFSA has not approved any health claims
Since there are no approved EFSA claims, we cannot state that evening primrose oil treats, prevents or alleviates any disease or condition.
How to take evening primrose oil
Evening primrose oil is available as soft capsules and liquid oil. Typical dosages in the scientific literature have ranged from 500–3000 mg per day.
Usage recommendations:
- Take with food — fatty acids are better absorbed with meals
- Divide the dose — larger doses can be split into 2–3 times per day
- Store cool — polyunsaturated fatty acids oxidise easily; keep in a sealed container in a cool place
- Be patient — GLA effects take time; results may not appear until several weeks of use
Evening primrose oil is generally well tolerated. Possible side effects include digestive discomfort and headache.
Who might benefit from evening primrose oil?
- Women seeking hormonal support — GLA participates in prostaglandin synthesis linked to the reproductive system
- People with dry skin — GLA is part of the fatty acid composition of skin
- People with slow GLA production — older adults, diabetics and those with certain genetic variations
- Vegans and vegetarians — GLA is naturally found in very few plant sources
Warning: Evening primrose oil may affect blood clotting. Do not use before surgery or alongside blood-thinning medications without consulting your doctor.
Frequently asked questions
Does evening primrose oil help with PMS? While evening primrose oil has been popular for PMS relief, EFSA has not approved this claim. Study results have been inconsistent.
Does evening primrose oil improve skin? GLA is part of the skin's fatty acid composition, but EFSA has not approved skin health claims for evening primrose oil. Linoleic acid (also present in the oil) does contribute to the maintenance of normal skin.
Is evening primrose oil the same as fish oil? No. Evening primrose oil is a source of omega-6 (GLA), while fish oil is a source of omega-3 (EPA/DHA). These are different fatty acids with different properties.
Can men take evening primrose oil? Yes, evening primrose oil is not exclusively for women. GLA is a fatty acid needed by the bodies of both sexes.
How long does it take for evening primrose oil to work? Since GLA is slowly integrated into cell membranes, effects may not become apparent until 8–12 weeks of regular use (Horrobin, 1993).
References
- Fan, Y. Y., & Chapkin, R. S. (1998). Importance of dietary gamma-linolenic acid in human health and nutrition. Journal of Nutrition, 128(9), 1411–1414.
- Horrobin, D. F. (1993). Fatty acid metabolism in health and disease: the role of delta-6-desaturase. American Journal of Clinical Nutrition, 57(5 Suppl), 732S–737S.
- Sergeant, S., Rahbar, E., & Chilton, F. H. (2016). Gamma-linolenic acid, dihomo-gamma linolenic, eicosanoids and inflammatory processes. European Journal of Pharmacology, 785, 77–86.
- Timoszuk, M., Bielawska, K., & Skrzydlewska, E. (2020). Evening primrose (Oenothera biennis) biological activity dependent on chemical composition. Antioxidants, 9(8), 708.
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Disclaimer
A food supplement is not a substitute for a varied and balanced diet and a healthy lifestyle.
