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Quest Vitamins LTD,
8 Venture Way,
Aston Science Park,
B7 4AP.

Tel: 0121 359 0056
Fax: 0121 359 0313
Registered in England No. 2530437

Evening Primrose Oil (Oenotherae)


Evening primrose oil (EPO) is high in the omega 6 fatty acid gammalinolenic acid (GLA), which is readily converted in the body to prostaglandin E1.

Evening primrose is a member of the rosebay willow herb family. Its country name is derived from the fact that its primrose yellow flowers open mainly in the evening. The seeds from the flowers of the plant are harvested and pressed to release the oil.


GLA is an important intermediary in the metabolic conversion of linoleic acid to prostaglandin E1. Essentially that pathway goes as follows: Linoleic acid (LA) is converted into gammalinolenic acid (GLA). GLA is then converted into dihomo-gammalinolenic acid, which in turn is converted into the final product, prostaglandin E1.

The normal diet is quite sufficient in the essential fatty acid linoleic acid, but the first step (LA to GLA) in its conversion to prostaglandin E1 can be easily blocked. Among the known blocking agents are: viruses, carcinogens, cholesterol, saturated fatty acids, trans fatty acids, alcohol, insufficient insulin, excess dietary alpha-linolenic acid (found in linseed and blackcurrant oils), radiation, and the ageing process.

Dietary GLA can therefore be extremely valuable since it skips these potential blockages.

Various nutrients are also required for the production of prostaglandin. Zinc, Magnesium, Biotin, and vitamin B6 are needed for the first step of the process, the conversion of LA to GLA. Selenium, Vitamin C, Niacin, and zinc are needed for the subsequent conversion of GLA into prostaglandin E1.


For cyclic mastalgia (breast pain related to menstrual cycles) or Eczema, 200-400 mg GLA daily (2-4 g of evening primrose oil).
For diabetic neuropathy, 400-600 mg GLA daily (4 to 6 g of evening primrose oil).
For rheumatoid Arthritis, 2000 to 3000 mg purified GLA. (Should only be taken under the guidance of a medical professional).

Take with food. Signs of improvement may take 6 months to develop.


Pre-menstrual syndrome (PMS):
Evening primrose oil has been used with successful results in women with PMS. It has been suggested that PMS may be linked with a minor abnormality of essential fatty acid metabolism, resulting in an inefficient conversion of fatty acids to prostaglandin E1 (PGE1). Evidence shows that prostaglandin E1 (derived from Essential Fatty Acids) is able to reduce the biological actions of prolactin, an agent responsible for some PMS symptoms (1). However, some other studies do not support these results (2).

In another study, evening primrose oil was used with remarkable success. The symptoms of swollen abdomen and breast discomfort were eradicated in 95% of the women, irritability in 80%, Depression in 74%, swollen fingers and ankles in 79% and Anxiety in 53%. The only two symptoms that persisted in more than half of the women were tiredness and Headaches (3).

Evening primrose oil has also been reported to substantially reduce the symptoms of Benign Breast Disease (4).

Evening primrose oil may be effective treatment for diabetic neuropathy, which involves pain and/or numbness due to nerve damage (5,6).

Heart and Cholesterol:
Evening primrose oil has been shown to lower high serum cholesterol levels. Dietary supplementation with evening primrose oil has also been shown to reduce platelet aggregation (blood clotting) in those fed a normal or high fat diet (7,8).

Blood Pressure:
Studies have shown that GLA from evening primrose oil significantly reduces blood pressure and may also inhibit the development of Hypertension (9).

Skin Conditions:
Evening primrose oil has been used successfully in patients with atopic Eczema. A double blind cross-over study was used with adults taking either 4, 8 or 12 x 500mg capsules daily and children taking 4 or 8 x 500mg capsules daily. Results indicated that evening primrose oil brought significant clinical improvement to Dermatitis, especially at the higher intakes (10).

Multiple sclerosis:
Evening primrose oil is routinely used by Multiple sclerosis sufferers (11). The unusual pattern of fatty acids found in the brain of MS sufferers may return to normal within a few months of taking EPO.

Rheumatoid Arthritis:
49 patients, all long-standing sufferers of Arthritis and taking non-steroidal anti-inflammatory (NSAID) drugs, were given either evening primrose oil or evening primrose oil plus Fish Oils. 60% of the patients were able to withdraw completely from NSAID treatment, and another 25% were able to cut their NSAID dosage in half. Evening primrose oil with Fish Oils was slightly more effective than EPO alone (12).


Evening primrose oil can be used without harm at levels of up to 5-6g daily.


Alpha linolenic acid (found in linseed and blackcurrant oil) has a blocking effect on the conversion of GLA/linoleic acid into prostaglandins.

Evening primrose oil should be avoided by epileptics as it may exacerbate a certain type of temporal lobe epilepsy.

Also, evening primrose oil is best not taken with drugs for Schizophrenia.

Occasionally, evening primrose oil may cause nausea, Headaches or Skin eruptions when first taken. Symptoms can be lessened by taking with a meal.


1. "Primrose oil in the treatment of Pre-menstrual syndrome", B Larsson & S Fianu, Dept. Obstetrics and Gynaecology, Hudding University Hospital, Sweden, 1986.
2. J Obstetrics and Gynaecology, 1993,81;1:93-98.
3. Current Therapeutic Research, 1989, 46;1:58-63.
4. "Handbook of Dietary Supplements", Pamela Mason, Blackwell Science, 1995.
5. Keen H, Payan J, Allawi J, et al. Treatment of diabetic neuropathy with gamma-linolenic acid. The Gamma-Linolenic Acid Multicenter Trial Group. Diabet Care 16: 8-15, 1993.
6. Jamal GA and Carmichael H. The effect of gamma-linolenic acid on human diabetic peripheral neuropathy: a double-blind placebo-controlled trial. Diabet Med 7: 319-323, 1990.
7. Lipids, 1997,32;10:1069-1074.
8. Annales de la Nutrition et de l?Alimentation, 1980,34;2:277-290.
9. Prostaglandins Leukot Essent Fatty Acids, 1993,49;4:809-814.
10. The J Int Medical Res, 1994;22:24-32.
11. The Lancet, 1997,350;9092:1685.
12. Annals of the Rheumatic Diseases, 1988,47:96-104.

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