On The Shelf
Mickie Cathers
Evening primrose oil (Oenothera biennis) is commonly used for its potential health benefits treating acne, rheumatoid arthritis, premenstrual syndrome, perimenopause symptoms, and other inflammatory conditions. What are the real benefits and limitations?
Background
Evening primrose is a plant native to North America, Europe, and parts of Asia. The oil is extracted from the plant’s seeds and is rich in polyunsaturated omega-6 essential fatty acids such as linoleic acid and g-linolenic acid. g-linolenic acid is metabolized into prostaglandin E1, a potent anti-inflammatory mediator. Additionally, evening primrose oil contains other bioactive compounds, such as flavonoids and phenolics, which add to the seed’s antioxidant and anti-inflammatory properties.
Is there a benefit?
Several studies have evaluated evening primrose oil for the treatment of systemic disorders accompanied by chronic inflammation. It has also been proposed as a remedy for breast pain and induction of labor.
Acne
A randomized controlled trial published on July 21, 2022, in Nutrients evaluated the effect of evening primrose oil supplementation in patients with acne vulgaris. At the conclusion of the 9-month intervention, the authors reported that during isotretinoin treatment, supplementation with evening primrose oil significantly increased skin hydration. However, sebum is responsible for the formation of acne lesions, and evening primrose oil didn’t reduce sebum levels.
Induction of labor
Research published in the Journal of Obstetrics and Gynaecology dispels the belief that evening primrose oil aids in labor induction. The authors of this triple-blind, placebo, randomized controlled, clinical trial examined evening primrose oil’s effect on the duration of pregnancy and labor.
The authors followed 80 first-time low-risk patients at 40 weeks of pregnancy who received either 1,000 mg capsules of evening primrose oil or placebo twice daily for 7 days. Kalati and colleagues found no significant differences in gestational age at delivery, labor duration, or neonatal outcomes between the evening primrose oil and placebo groups.
Relief of premenstrual symptoms
Evening primrose oil is considered a treatment for breast swelling, irritability, and bloating due to gamma-linolenic acid converting to prostaglandin E1, preventing prolactin from triggering symptoms. The g-linolenic acid in evening primrose oil is also thought to inhibit prostaglandins that cause breast pain. However, systematic reviews have shown no significant difference in efficacy between evening primrose oil and placebos or other treatments, though the supplement did result in fewer adverse effects than other products.
Mixed results
Authors of a systematic review of clinical trials published in BMC Complementary Medicine and Therapies on February 15, 2024, evaluated the effectiveness of evening primrose oil on various inflammatory conditions. Sharifi and colleagues noted positive effects for skin hydration and barrier function, but results were mixed for rheumatoid arthritis.
Modest results were reported for diabetes, atopic eczema, menopausal hot flashes, and mastalgia, and no effectiveness in dermatitis, arthritis, premenstrual syndrome, or acne. The authors highlighted the need for cautious interpretation due to heterogenous scientific literature, underscoring the importance of conducting more rigorous trials.
Dosage and availability
Evening primrose oil is available as a supplement or topical product online and in stores as a liquid or capsule. The oil can be diluted in a carrier oil or added directly to moisturizers, lotions, soaps, and facial serums. Recommended dosages in clinical trials ranged from 1 g/day to 6 g/day.
What to tell your patients
Evening primrose oil may be beneficial for improved skin hydration in healthy adults and is generally considered safe. Adverse effects are usually mild and may include stomach pain, nausea, or diarrhea. Evening primrose oil may not be suitable for patients on blood thinners as it can increase bleeding. Caution patients taking lopinavir, as the HIV medication may be affected by evening primrose oil. ■