RoseMarie Pierce, B.Sc. Pharm., “The Holistic Pharmacist”
One of the most popular supplements on the North American market, evening primrose oil (EPO) has been promoted as a treatment for everything from alcoholism to obesity. Research suggests that evening primrose oil may be especially valuable in managing diabetes neuropathy (nerve damage), eczema and PMS. Evening primrose oil may lessen many symptoms of PMS, notably mastalgia (breast pain and tenderness), dysmenorrhea (painful menstruation), fluid retention and depression.
The evening primrose plant, a native of North America, was one of the first plants brought back to Europe by the early settlers. Called evening primrose because its yellow flowers open at dusk, this wildflower can now also be found growing like a weed throughout Europe and parts of Asia. North American Natives have long used the plant and its root for treating skin disease, breathing problems, neuralgia, and gastro-intestinal disorders. Even though many parts of the plant have been traditionally used, it is the oil from its small, reddish seeds that is responsible for evening primrose’s most beneficial medicinal effects. While there is little or no proof that EPO lives up to all of the historical claims, scientific studies do support its use in treating eczema, inflammation and symptoms of PMS.
What Makes EPO Different from Other Vegetable Oils?
Evening primrose oil is a rich source of omega-6 essential fatty acids (EFAs) that are also widely found in unsaturated vegetable oils, nuts, and seeds. Evening primrose oil (EPO) offers an added benefit: an easily absorbable source of gamma-linolenic acid (GLA), another omega-6 essential fatty acid. Although the body can very slowly make GLA from other omega-6 essential fatty acids, there is no one food that has appreciable amounts of GLA. As an added complication, the formation of GLA in the body may be blocked by a typical Western diet, which is high in saturated fats and processed vegetable oil, such as margarine, collectively known as the “bad fats”. Stress, excess alcohol, smoking, poor eating and a number of commonly occurring diseases such as diabetes and hypothyroidism can also interrupt GLA formation. Evening primrose oil provides a concentrated source of 9 to 10 percent GLA and is highly valuable to those who cannot otherwise convert enough “good fat” consumed from food into GLA.
Although borage oil, black currant oil, and hemp seed oil contain higher amounts of GLA, these oils may not be as efficiently absorbed or as biologically active. Most of the studies investigating the effects of GLA have used evening primrose oil, and for this reason it is the preferred source of GLA.
What Is the Significance of Gamma-Linolenic Acid (GLA)?
The body converts this special essential fatty acid, GLA, into short-lived, highly reactive hormone-like compounds called prostaglandins (PGs). Prostaglandins are found in every cell in the body and play a role in regulating a vast number of bodily functions. As part of the immune system, PGs can either inhibit or create inflammation. When the human diet is high in the “bad fats” the body will make prostaglandins (called PG2s) that tend to increase inflammation. When the body is supplemented with GLA in the form of evening primrose oil this helps to make the kind of prostaglandins (PG1s) that decrease inflammation, promote T-cell function, reduce cholesterol production and have both anticoagulant (blood thinning) and blood pressure lowering actions. In addition, GLA is an important component of every cell membrane particularly those around the brain, the nervous system and the skin.
How Evening Primrose Oil Works to Help PMS
Numerous scientific studies have demonstrated that supplementing with GLA in the form of evening primrose oil has a significant effect on the symptoms of PMS. GLA relieves premenstrual breast pain and tenderness and other PMS symptoms including painful periods, headaches, depression, irritability and bloating.
PMS has been linked to excessive and detrimental prostaglandin (notably PG2s) production. In women who demonstrate the above PMS symptoms, PG2 series prostaglandins (the ones that cause inflammation) are commonly found in high concentrations, and PG1 series prostaglandins are usually deficient. GLA supplements can alter the essential fatty acid content of the cell membranes as well as the hormone receptors in breast tissue and raise the body’s production of PG1.
The tenderness, swelling and pain associated with cyclic mastalgia and fibrocystic breasts have been alleviated with evening primrose oil in more that one scientific study. The Cardiff Mastalgia Clinic at the University of Wales has provided much of what we know about the benefits of evening primrose oil. In open studies performed at the Cardiff Mastalgia Clinic, EPO has been found to produce positive effects in 44% of women with cyclical mastalgia [Pye et al., Clinical experience in treatments for mastalgia. Lancet 2: 373-377, 1985].
How Do Women Best Get the Benefits of Evening Primrose Oil?
Benefits are clearly demonstrated at a dosage range of 2 to 6 grams of EPO per day, providing 200 to 600 mg. of GLA. However, EPO must be taken over a prolonged period of time, for at least 4 to 6 months, in order to obtain best results. Taking EPO capsules with food ensures proper absorption and helps to reduce digestive complaints. For best results, decrease the intake of saturated “bad” fats, such as shortening and margarine because they compete with EPO and other essential fatty acids for absorption in the body. Other nutrients are needed as co-factors to enhance the effectiveness of EPO; these include vitamin B6, zinc, magnesium, niacin and Vitamin C and are beneficial to take with EPO.
Adverse effects in humans are very rare and limited to headache, nausea (if taken on an empty stomach) and diarrhea. Evening primrose oil should be used with caution in people suffering from epilepsy, schizophrenia or those taking prescription anticoagulant medications such as coumadin. The benefits of EPO may be reduced in those taking beta-blockers (a blood pressure and heart medication) due to the fact that beta-blockers decrease the production of PG1s.
Many experts recommend taking EPO capsules that contain a small amount of vitamin E. The fatty acids in EPO break down quickly; vitamin E slows this process. Whether in capsule or liquid form, a supplement of evening primrose oil can clearly play a role in alleviating many of the most prominent PMS concerns and, as research is now showing, may provide benefits for women during menopause.
RoseMarie Pierce, B.Sc.Pharm, earned her degree in Pharmacy from Dalhousie University in 1972. After extensive studies in herbal and nutritional medicine, RoseMarie integrated these disciplinary practices with her pharmacy education to become Canada’s first Holistic Pharmacist.