Evening Primrose Oil Helps Premenstrual Syndrome

More than forty percent of menstruating women are affected by premenstrual syndrome (PMS) and for many of these women, the symptoms are severely debilitating. PMS presents with a vast array of symptoms - most commonly, abdominal bloating, breast pain, headaches, fatigue, fluid retention, pelvic pain, mood swings, aggression, memory impairment, insomnia and anxiety. These symptoms are usually absent during the week following the period, but can appear at any time during the two weeks (most commonly during the last four days) preceding menstruation, and then decline at the beginning or in the first days of the period.

Although the exact cause of PMS is not known, there are many theories. One of these theories involves a hormone named prolactin which is normally elevated in breast-feeding women. Women with PMS are believed to develop an excessive sensitivity to normal or mildly elevated prolactin levels.

How Evening Primrose Oil Works against PMS

Researchers, puzzled to explain why even normal levels of a hormone present in every woman's body could cause so many symptoms in so many women may have found an answer. The body produces a number of short-acting hormones derived from fatty acids. These short-acting hormones are named prostaglandins. One of these prostaglandins (prostaglandin E1) appears to counteract and oppose the negative effects of prolactin. Women with PMS may not produce enough prostaglandin E1 to suppress prolactin's effects. In the absence of optimal levels of prostaglandin E1, prolactin is able to "run riot".

This is where evening primrose oil comes into the picture. Evening primrose oil contains high amounts (10%) of an omega-6 fatty acid named gamma-linolenic acid (GLA). GLA is usually produced within women's bodies from another, more common dietary omega-6 essential fatty acid named linoleic acid. Many women have a metabolic blockage that prevents the conversion of linoleic acid to GLA, necessitating the intake of the pre-formed GLA (as supplied by evening primrose oil). GLA is absolutely necessary for the production of prostaglandin E1, the final compound that may prevent the symptoms of PMS by opposing prolactin.

Scientific Proof

Three double-blind, placebo-controlled studies, one large open study on women who had failed other kinds of therapy for PMS and one large open study on new patients all demonstrated that evening primrose oil is a highly effective treatment for the depression and irritability, the breast pain and tenderness, and the fluid retention associated with PMS.

In one of these studies, women with PMS received either evening primrose oil or a placebo for two menstrual cycles and then switched treatments for a further two cycles. Overall improvement using evening primrose oil was deemed to be 60% compared with 40% with placebo. Maximum symptom improvement was observed for irritability and depression.

In another study, thirty women with severe PMS were treated with 3,000 mg of evening primrose oil per day or a placebo. After four menstrual cycles, women receiving evening primrose oil experienced decreased PMS symptoms (especially less depression).

In yet another study, 68 women with severe PMS who had not improved on other medications received 2,000 - 4,000 mg of evening primrose oil per day commencing three days prior to the onset of symptoms until the commencement of menstruation. Sixty one percent of women experienced total relief of their PMS symptoms and a further 23% reported partial relief. Thirty six of the women originally reported painful breasts. Seventy two percent of these women experienced total relief and 14% experienced partial relief of their painful breasts after evening primrose oil treatment.

Other Oils Help Too! Although all of the clinical trials testing the theory that gamma-linolenic acid (GLA), as a precursor for prostaglandin E1, may improve PMS symptoms, have used evening primrose oil, it is likely that other similar oils may be similarly or more effective than evening primrose oil. Evening primrose oil contains 10% GLA but other oils contain even higher percentages. Borage seed oil (also known as starflower oil) contains 24% GLA and blackcurrant seed oil contains 18% GLA. One could safely assume that both of these oils would exert similar or better effects against PMS symptoms on the basis of their higher GLA content.

Helper Nutrients Don't forget that evening primrose oil's (or borage seed oil's or blackcurrant seed oil's) GLA content must first be converted to prostaglandin E1 for it to relieve PMS symptoms. Nutrients known to increase the conversion of GLA from these oils to prostaglandin E1 include magnesium, vitamin B6, zinc, vitamin B3 and vitamin C. Supplementing with these helper nutrients could increase the benefits of this regime against PMS.

The Take-Home Message

• Scientific studies have demonstrated that 2,000 - 4,000 mg (average 3,000 mg) per day of evening primrose can significantly reduce the symptoms of PMS.
• Alternative dietary supplemental oils are likely to work just as well (and possibly better) than evening primrose oil. These are borage seed oil (starflower oil) - 1,250 mg per day; or blackcurrant seed oil - 1,666 mg per day. These alternatives are usually more economical because their higher GLA content permits lower (and less cumbersome) doses.
• Nutrients that improve the conversion of the GLA from evening primrose oil, starflower oil or blackcurrant seed oil to prostaglandin E1 are likely to maximise the effectiveness of these oils against PMS symptoms. These helper nutrients are magnesium, vitamin B6, zinc, vitamin B3 and vitamin C.
• It may be necessary to use evening primrose oil (or the alternative oils mentioned) for up to four menstrual cycles before their effects against PMS become evident.
• These supplemental oils are most effective when taken with meals.