Evening primrose fails to impress in research studies
The Irish Times
Health Supplement, p. 13
8 April 2008
DOES IT WORK? Although unlikely to cure any specific illness, evening primrose can help maintain good health
THE EVENING primrose is a North American wildflower that gets its name because each flower blossoms in the evening for one night only. The fruit pods contain small seeds from which evening primrose oil is extracted. This oil contains a relatively high proportion of essential fatty acids, including a number of omega-3 fatty acids, and vitamin E.
Much interest has been generated recently in the potential health benefits of this class of compounds. Some of them are known to be naturally important to the body’s immune system, and to have anti-inflammatory effects. In England, evening primrose oil has been called the King’s Cure-All because of its traditional use in treating a wide range of conditions.
More recently, it has been recommended for use orally for premenstrual syndrome (PMS), breast soreness and menopausal symptoms. It is also recommended as an anti-inflammatory agent for a variety of skin conditions such as dermatitis, eczema and psoriasis.
Evidence from studies
A large amount of research is currently under way on the potential benefits of essential fatty acids and omega-3 fatty acids. While a number of early studies produced promising results, many of them were small and poorly designed.
In Britain, the agency that regulates medicines had approved evening primrose oil as a prescription-only treatment for allergy-related eczema and breast soreness. However, after larger, better designed studies failed to find any benefit, the regulatory body withdrew the product licences in 2002. Similarly, more recent reviews of research on evening primrose for dermatitis have found little evidence of any benefit. As one reviewer stated, it’s “time to say goodnight” to evening primrose for inflammatory skin conditions.
Several high-quality controlled trials have also examined evening primrose in the treatment of PMS. While many of these were relatively small, the women taking evening primrose did not do any better than those taking a placebo. Similarly, relief from menopausal symptoms was not found in other studies. The one exception to this lack of benefit in women’s health was with mild breast soreness.
A small number of trials found that about half the participants had significant relief from breast soreness when they took evening primrose orally. However, women with more severe breast pain did not report improvements.
The one other area where evening primrose has demonstrated some effectiveness is as a treatment for osteoporosis. A product which combines evening primrose oil with fish oils and calcium has been found to bring improvements to bone density for older people with osteoporosis.
Evening primrose oil (as with other sources of essential fatty acids such as nuts, cold-water fish oil and blackcurrant oil) is generally safe and well tolerated. Evening primrose sometimes causes indigestion, nausea or abdominal pain, especially if taken in high doses.
The usual recommended dose is about 2g per day, but some people suggest that 4-8g should be used daily. Such large amounts could prove to be very expensive, and will also add a large number of calories to one’s diet. The British medical licence for evening primrose products was withdrawn because of a lack of evidence of effectiveness, not concerns about safety.
However, larger doses have been suspected of interfering with blood clotting and should therefore be used cautiously by anyone taking blood-thinning medication (such as aspirin or warfarin).
Large-scale studies of the diets of different populations have shown that people are generally more healthy when their diets contain sufficient amounts of essential fatty acids. These include the omega-3 fatty acids, fish oils and evening primrose oil. The typical Irish diet can be lacking in these compounds.
Thus, evening primrose oil used as a dietary supplement could play a role in maintaining good general health. However, the evidence from most studies shows that evening primrose is unlikely to cure any specific illness.