Like many traditional herbal remedies, evening primrose oil has recently enjoyed a revival in interest and is now one of the most popular of all nutritional supplements with sales in the last year reaching 33 million pounds. It has a long and distinguished history as a medicine. Ancient herbalists listed numerous ailments that could be […]
By Lamberts Española, Technical Department.
Like many traditional herbal remedies, evening primrose oil has recently enjoyed a revival in interest and is now one of the most popular of all nutritional supplements with sales in the last year reaching 33 million pounds. It has a long and distinguished history as a medicine. Ancient herbalists listed numerous ailments that could be healed by the plant and, in this country it became known as the ‘King’s Cure All’. North American Indians used the plant’s leaves as a poultice to heal wounds and brewed cough mixtures from its roots.
Research into the plant’s pharmacological properties began in this country in the 1960s and quickly revealed its potential for a wide range of applications. In recent years, cross-pollination and widespread planting of evening primrose has ensured that oils of a consistently high quality are now available.
The seeds of the evening primrose contain an essential fatty acid (EFA) called linoleic acid and substantial amounts of a substance called gamma linolenic acid (GLA). EFAs are vitamin-like fats that are vital for good health, but which cannot be manufactured by the body – they need to be present in the diet. EFAs have two main functions: they are vital constituents of cell membranes and they are precursors of (i.e. can be converted into) prostaglandins. These are hormone-like substances which regulate numerous biochemical processes, including:
preventing thrombosis and lowering blood pressure
enabling insulin to work more efficiently
preventing inflammation and controlling arthritis
slowing down the rate of production of cholesterol
improving peripheral circulation
maintaining normal, healthy skin
controlling the menstrual cycle
Our diet usually provides EFAs in the form of linoleic acid and the body has to convert this into GLA before it becomes biologically active. GLA is in turn converted into prostaglandins. Although the body can produce GLA from an EFA called linoleic acid, sometimes a number of factors can interfere with this conversion process. Efficiency depends upon the linoleic acid being in the biologically active ‘cis’ form, as opposed to the less active ‘trans’ form, which actually interferes with the conversion process. Almost all processed foods, including vegetable oils, contain large quantities of the ‘trans’ form. Other factors which hamper efficient conversion include a diet high in saturated fats and cholesterol, a moderate or high alcohol intake, the ageing process, stress, smoking and certain medical conditions such as diabetes mellitus and viral infections.
Supplementation with GLA in the form of evening primrose oil is effective as it is supplying this important nutrient in a readily usable form – the body does not need to convert it in any way.
Traditional Uses Of Evening Primrose Oil
More than 200 clinical trials in 21 countries have examined the effect of GLA in a wide range of disorders. It is now well established as a treatment for Pre-menstrual syndrome having undergone numerous double blind, placebo-controlled trials throughout the world”’. Evening primrose oil capsules have been found to improve symptoms such as depression, irritability and anxiety and have proved particularly beneficial to women who suffer from pre-menstrual breast pain(²). These improvements were noted even in women who found no relief from other treatments. Dosage varied between two and four 500 mg capsules per day.
A number of studies have demonstrated evening primrose oil’s efficacy in the treatment of benign breast disease (tender, lumpy breasts associated with the menstrual cycle) and in recent years, it has been licensed as a treatment for this condition. Many women going through the menopause find that evening primrose oil can help to reduce the severity of some of their symptoms.
Evening primrose oil is also being used and researched in conjunction with other medical conditions, with varying results.
A series of studies have examined the effect of evening primrose oil on atopic eczema (the type of eczema that runs in families and is associated with asthma and hayfever). Biological studies have shown that people affected with eczema have difficulty in converting cis-linoleic acid to GLA and it is interesting to note that breast-fed babies, who derive GLA from their mothers’ milk are less likely to develop atopic eczema.(3)
Results have been variable but they do suggest that in some people, evening primrose oil can reduce the itching associated with eczema. However, it takes from six to twelve weeks before any improvement is seen.
A double blind, placebo-controlled study on the effect of evening primrose oil was carried out at Glasgow University Medical School.(4) Its aim was to compare the effects of evening primrose oil and of an 80:20 combination of evening primrose oil and fish oil, on rheumatoid arthritis. The 52 patients taking part all suffered from rheumatoid arthritis which had been stabilised with non-specific anti-inflammatory drugs (NSAIDs). Eighteen patients received placebo (dummy pill) for 18 months and the remaining 34 patients received either 6 g of evening primrose oil or 6 g of evening primrose oil plus fish oil, followed by placebo. Of the patients receiving evening primrose oil, 60% were able to withdraw completely from the NSAID therapy and 25% were able to halve their NSAID dose. Of the patients taking the combined evening primrose/fish oil supplement, 60% were able to stop their NSAID treatment and 35% were able to reduce the dose. When patients were switched to placebo, those who had improved while taking the supplements deteriorated. While these results have yet to be duplicated in other treatment centres, they certainly suggest that this area merits further investigations.
This is a common complication of diabetes mellitus in elderly patients. Symptoms include numbness, tingling and burning in the lower limbs and feet, and sometimes the arms and hands. This can lead to serious and disabling problems such as ulcers, infection and swelling. Although the cause of this condition is not fully understood, it is thought those affected may have abnormal levels of EFAs and prostaglandins. A number of small studies have shown that patients given evening primrose oil showed a significant improvement in symptoms.(6)
Interesting initial results have been gained from using evening primrose oil in a range of other conditions. Alcoholics undergoing withdrawal therapy were found to return to normal liver function more rapidly when given evening primrose oil.(5) Hyperactive children who are atopic (allergic to certain substances) respond to treatment with evening primrose oil capsules. Some studies have shown that evening primrose oil improves general well being in patients with multiple sclerosis. Other areas currently under review include obesity, high blood pressure, raised cholesterol concentrations and defence against viral infections.
The seeds from the evening primrose oil are normally pressed to extract the oil. Superior forms of the nutrient contain ‘cold’ pressed oil which has been extracted without using heat processing. Recommended daily dosage varies between 250 and 1,000 mg. Increased dosages up to 4000 mg can be recommended. The oil contained within the capsules can also be applied directly to the skin or alternatively, a range of skin care products containing evening primrose oil are now available.
Certain groups of people should consult their GP before taking evening primrose oil: epileptics, people with a history of psychiatric disorders, those taking medications called phenothiazines or women who are planning to become pregnant. Side effects are rare although headache and mild nausea are occasionally reported. These are best avoided by taking evening primrose oil with food.
Brush MG, Evening primrose oil in the treatment of the pre-menstrual syndrome. In: Horrobin DF, ed Clinical Uses of Essential Fatty Acids, Montreal: Eden Press, 1982; pp. 155-162
Preece PE. Hanslip JI, Pashby NL, et al. Evening primrose oil for mastalgia. In: Horrobin Up, ed Clinical Uses of Essential Fatty Acids, Montreal: Eden Press, 1982; pp. 147-154
Manku MS, Horrobin DS, Norse N et al. Reduced levels of prostaglandin precursors in the blood of atopic patients: Defective delta-6-desaturase functions as a biochemical basis for atopy. Prostaglandins Leukeotrienes Med 1982; 9: 615-628
Belch JJ, Ansell D, Madhok R, Sturrock RD. The effect of evening primrose oil and EPO/fish oil combination on rheumatoid arthritis: A double blind study. Br J Rheumatol 1986; 25: Abst.75
Scott, PJ, Current Therapeutics (Australia), 1986,26, 13