Evening primrose oil is a rich source of gamma linoleic acid (GLA), which helps reduce chronic inflammation. Studies are mixed on a variety of conditions. It might not be helpful.
What Is Evening Primrose Oil?
Evening primrose is a flowering plant and a member of the willowherb family (Onagraceae). It is native to North America but also grows in Europe and parts of the Southern hemisphere.
Unlike evening primrose, many plants and vegetable oils contain linoleic acid, which has to be converted to GLA in the body to achieve the desirable effects. Evening Primrose Oil contains GLA so it bypasses this activation step .
Essential fatty acids are necessary for maintaining good health, but cannot be made by the body – they have to be taken in through food. Their actions are diverse: boosting skin health and hair growth, maintaining bone health, regulating metabolism, and maintaining fertility .
Gamma linolenic acid in evening primrose oil supports brain function and decreases inflammation. It’s become a popular supplement for immune system disorders, including autoimmune diseases and conditions characterized by chronic inflammation [5, 6, 1, 2].
It can be taken as a supplement or applied on the skin. The primary uses of the oil are for eczema, skin health, menstrual and menopausal symptoms, and lactation. It’s also used for diabetic neuropathy, premenstrual syndrome, rheumatoid arthritis, essential fatty acid deficiencies, dandruff, and some pregnancy-related complications .
The seed contains 15% protein, 24% oil, and 43% fiber.
The fatty acid components in the seed include about 70% linoleic and 10% gamma-linolenic (GLA) acids, while the rest make oleic, palmitic, and stearic acids.
Once the oil is pressed from the seeds, the fibers are removed and the fatty acids percentage rises.
The oil contains long-chain fatty alcohols, which also reduce inflammation .
It also contains two phytosterols: campesterol and b-sitosterol .
How Does Evening Primrose Oil Act?
Evening primrose oil fights oxidative stress in tissues and increases the master antioxidant glutathione, mainly in heart and blood. Boosting glutathione protects the tissues in the body from stressors.
GLA and alcohols in evening primrose oil also block inflammatory pathways in the body, reducing inflammatory substances, enzymes, and cascades.
Evening Primrose Oil Uses and Benefits
It’s not clear that evening primrose oil is powerful enough to treat any condition strongly. Instead, it seems like the most likely benefit may be some general anti-inflammatory and antioxidant action, and improvement in blood flow.
Current studies are too small to make any conclusion that it is definitively helpful in any condition.
1) Evening Primrose Probably Does Not Help Atopic Dermatitis/Eczema
Eczema is a very common chronic inflammatory skin condition that may require a combination of treatment approaches. Some researchers are considering a defect in the function of the enzyme delta-6-desaturase, which is responsible for the conversion of linoleic acid to gamma-linolenic acid, to be a factor in the development of this condition [8, 9, 10].
Several controlled trials revealed a noticeable improvement in inflammation, dryness, scaling, itch, redness, and overall severity of atopic eczema after 4 to 8 weeks of treatment when patients were treated with evening primrose oil [8, 11, 12, 13].
One review of 9 controlled trials found that GLA was more effective than the placebo at relieving atopic eczema .
The dose of Evening Primrose Oil does not appear to have a significant impact on outcomes. Groups treated with 320mg and 160mg had similar outcomes .
In 50 young adults with atopic eczema, there was an elevation of cis-linoleic acid which is connected to a deficit of gamma-linolenic acid, suggesting that those with eczema have a deficiency in the function of the delta-6-desaturase enzyme that converts linoleic acid to gamma-linolenic acid. In a double-blind placebo-controlled crossover trial, GLA partially fixed biochemical abnormalities and improved the clinical condition .
Levels of GLA are associated with the clinical efficacy of evening primrose oil in patients with atopic dermatitis, supporting the claims that atopic dermatitis is caused by a deficiency in the delta-6-desaturase enzyme that converts linoleic acid to GLA .
One review of 15 studies found that the largest and best-reported studies of EPO did not show convincing evidence of any benefit .
A review done by Cochrane concluded that consumption of evening primrose oil lacked an effect and was not an effective treatment for eczema. It also concluded that further studies would be hard to justify, which shows some confidence in their results that it doesn’t help .
Bottom line: It seems more likely than not that EPO is not a very effective remedy for eczema.
In an animal study, evening primrose oil in a model of a high saturated fat diet reduced oxidative stress in tissues .
Evening primrose oil reduced nitric oxide and blocked the release of TNF-alpha and other inflammatory substances in immune cells .
Long-Chain Fatty alcohols from Evening Primrose Oil have anti-inflammatory activity .
3) Evening Primrose Oil May Improve Skin Health
A 10-week study involving 45 participants with mild to moderate acne found that inflammatory and non-inflammatory acne lesions decreased significantly in the control group that was given 400mg gamma-linoleic acid .
Evening primrose oil improved the overall quality of the skin, in a 12-week trial. The oil increased moisture, elasticity, firmness, and decreased roughness significantly .
4) Cardiovascular Health
Another human study found that Evening Primrose Oil did not affect serum cholesterol, HDL cholesterol, or triglyceride values, and blood pressure remained unchanged .
Thromboxanes constrict blood vessels, increase blood pressure, and increases clotting (platelet aggregation). PGE1 helps relax blood vessels and increase blood flow. In a small human trial, GLA improved the cardiovascular profile by decreasing the ratio of thromboxanes to PGE1 .
Evening Primrose Oil in animals improved electrocardiographic pattern, lipid profile, cardiac biomarkers, and platelet formation .
GLA protects rats from atherosclerotic lesions and lowers inflammation .
5) Rheumatoid Arthritis
However, one review study from 2000 says most studies suggest some improvement in rheumatoid arthritis .
In a study in 2017, fish oil + evening primrose oil was able to improve symptoms and markers in rheumatoid arthritis. Fish oil + EPO were able to decrease CRP, ESR, and a disease activity score more than fish oil alone, but it’s not clear if improvement above fish oil alone was statistically significant .
6) Bone Health
The efficient absorption of calcium in humans is important for normal bone strength and inadequate gut calcium absorption can cause the bones to weaken .
In an animal study, a mixture of GLA and EPA was able to increase bone calcium content .
7) Neuropathy and Nerve Injury
A randomized trial of 12 patients taking 360mg of Evening Primrose Oil found a significant improvement of neuropathy symptoms .
Evening Primrose Oil helped axons and myelin in nerve fiber develop faster and better in an animal model of a crushed nerve injury .
Evening Primrose Oil caused a significant decrease in myelin breakdown in an animal study of diabetic retinopathy .
EPO treatment prevented the development of blood flow problems in diabetic rats .
Evening Primrose Oil had a significant protective effect against stomach ulcers in various animal models .
9) Kidney Stones
Evening Primrose oil decreased kidney stone risk factors in a human study of 16 people taking 1g .
Gamma-linolenic acid showed no significant effect when used in a double-blind human placebo-controlled trial to treat liver cancer .
One animal study showed that Evening Primrose Oil caused antitumor activity, suggesting it could be of value in future therapies .
In another animal study, Evening Primrose Oil was found to inhibit skin tag formation during its initial stage .
Primrose Oil Is Not Effective In These Conditions
- Breast pain/tenderness (Mialgia) [57, 58, 59, 60, 61]
- PMS [62, 63]
- Menopause 
- Fatigue [65, 66]
- ADHD [67, 68]
- Psoriasis 
- Asthma [70, 21]
- IBD 
- Obesity 
- Sjogren’s syndrome 
- Schizophrenia 
Evening primrose oil is generally safe when consumed in recommended dosages. Some reported side effects include nausea, stomach pain, and headaches .
The main side effects are gut related .
A case report warned that if EPO is taken for a prolonged period of time (more than one year), there is a potential risk of inflammation, thrombosis, and immunosuppression .
Lipoid pneumonia is an underdiagnosed disease that is caused by the aspiration of lipid particles into the lungs. There was a case report of someone getting this condition after EPO and the condition improving when they stopped it .
It should not be consumed prior to surgery, during pregnancy, by patients with a bleeding disorder, or by patients that are taking certain medications such as anticoagulants .
One study found that EPO may increase bleeding for people on Coumadin (warfarin) medication .
Evening Primrose Oil also has the potential to reduce serum lithium levels, so it is important to exercise caution with use .
It is important to consider that combining evening primrose oil with some herbs such as angelica, clove, danshen, garlic, ginger, ginkgo, red clover, and turmeric could increase bleeding time. The Natural Standard Research Collaboration states that allergy or hypersensitivity to evening primrose oil is uncommon, however, contact dermatitis is a possibility .
Natural Sources (or forms of supplementation)
The evening primrose wildflower was originally used by Native Americans and European settlers for food. The seeds were gathered and cold pressed for their oil. Today the oil is commonly encapsulated for supplemental use.
Primrose oil can be applied topically to the face to improve skin appearance and used on wounds after surgery, applied daily for six weeks to help with advanced healing. It can be used with or without a carrier to soothe inflammation, ease pain, and accelerate the natural healing process .
The recommended daily dose of evening primrose oil in the US is 500 mg in capsules, tablets, or drops before or after meals .
User experiences can be found online, some of which include a dramatic improvement in chronic pain and discomfort, better skin quality, and a decrease in hot flashes and premenstrual symptoms. Others noted adverse effects such as mood swings, nausea, and little to no positive improvement in symptoms.
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