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Does This Oil Help Eczema?
In 2013, a Cochrane review found evening primrose oil to be largely ineffective for the treatment of eczema. Prior to this review, past studies have only produced mixed results and there was a significant doubt that this medicinal oil may help eczema patients. However, evening primrose oil contains the right ingredients to provide relief for eczema. What are these ingredients and how can they help? Is the Cochrane review the final word on the effectiveness of evening primrose oil in the treatment of eczema? What may account for the negative results for this oil? This article provides all the answers you need.
Evening primrose oil is extracted from the seeds of Oenothera biennis, a flowering plant native to North and South America.
The major medicinal phytochemicals in evening primrose oil are the omega-6 fatty acids, linolenic acid and gamma linolenic acid. Evening primrose seed oil contains 70% linolenic acid and about 10% gamma linolenic acid.
In fact, gamma linolenic acid was first isolated from evening primrose seed oil before it was extracted from borage oil, safflower oil, blackcurrant and hemp seed oil.
Evening primrose oil is used in both traditional and conventional medicine to treat a number of conditions. Some of these are listed in the table below.
There are no conclusive evidences for most of the indications listed above. In some cases, new studies have disproved the efficacy of evening primrose oil in the treatment of certain diseases.
Evening primrose oil supplements are available either in oil form or as capsules. These products are standardized to contain 8% gamma linolenic acid.
The usual recommended doses of evening primrose oil vary between 2 g and 8 g per day.
Linolenic acid is an unsaturated omega-6 fatty acid. It is naturally synthesized in the body and can also be obtained from diet.
This polyunsaturated fatty acid is used to synthesize arachidonic acid, the precursor of prostaglandins.
Therefore, linolenic acid is a pro-inflammatory fatty acid. However, it is still an essential fatty acid that is needed to make the protective membranes of cells. In fact, regular consumption of diets poor in linolenic acid can result in dry, scaly skin, one of the signs of eczema.
Linolenic acid is converted to gamma linolenic acid in the body. In addition, linolenic acid also has antioxidant properties.
Gamma linolenic acid is one of the two forms of linolenic acid (the other form is alpha linolenic acid). Therefore, it is also an omega-6 fatty acid.
The conversion of linolenic acid to gamma linolenic acid is driven by the enzyme, delta-6-desaturase.
When this enzyme is impaired, a deficiency in gamma linolenic acid may result. The activity of this enzyme falls as we grow older and during certain disease states.
Although gamma linolenic acid is an omega-6 fatty acid, it is actually not pro-inflammatory. Even though the body makes certain prostaglandins and thromboxanes from this compound, gamma linolenic acid blocks the formation of pro-inflammatory leukotrienes.
Because of this unique property, gamma linolenic acid supplements are believed to have anti-inflammatory effects. Therefore, they are regularly recommended for people with arthritis, autoimmune disorders, premenstrual syndrome and eczema.
Studies investigating the benefits of evening primrose oil in the treatment of eczema have only produced mixed results. However, a recent Cochrane review concluded that evening primrose oil does nothing for people with eczema.
On the other hand, it is important to note that there are a good number of studies that have found evening primrose oil effective for eczema.
A 2011 review identified more than 30 human studies that reported positive results for eczema patients treated with this medicinal oil.
One study involving over 1,000 eczema patients showed that evening primrose oil relieved itching, swelling, redness, crusting and dry, flaky skin.
Against these positive studies are equally large and well-designed studies and reviews that found no such benefits for eczema patients. This pool of negative studies was used by the British MCA (Medicines Control Agency, the equivalent of FDA) to mandate that evening primrose oil products should no longer be marketed as eczema “cures”.
How May Evening Primrose Oil Help Eczema
The possible benefits of evening primrose oil in the treatment of eczema rest with the anti-inflammatory properties of gamma linolenic acid and the antioxidant property of linolenic acid.
Although these medicinal properties of the omega-6 fatty acids of evening primrose oil are still being studied, it seems likely that they can help relieve the symptoms of eczema.
Gamma linolenic acid may reduce inflammation in the skin and, therefore, help reduce skin swelling and redness.
Linolenic acid, on the other hand, may help reduce oxidative stress in the skin by mopping up harmful free radicals before they damage the cells and secretory glands of the skin. Therefore, the antioxidant effect of linolenic acid can relieve itching and prevent the flaking of the skin.
Although the recent Cochrane review turned the tide against the use of evening primrose oil in the treatment of eczema, there are past studies that actually found this oil effective for relieving the symptoms of eczema.
One of such positive studies was published in the journal, The Clinical Investigator, in 1992. In this review, the authors focused on placebo-controlled trials that were also well-designed.
In their review, they found that patients who received evening primrose oil supplements reported less dryness, scaliness and inflammation than controls. However, they noted that the studies that found benefits for eczema patients were the ones in which both the placebo groups and the evening primrose oil groups were receiving treatment at the same time.
In contrast, they found that trials that had crossover designs (participants switching between evening primrose oil supplements and placebo) produced conflicting results.
In their opinion, the authors considered evening primrose oil safe and effective for the treatment of eczema.
The lack of consensus from drug trials investigating the benefits of evening primrose oil has long dogged the use of the medicinal oil in the treatment of eczema. Consider these 2 studies from the ‘80s.
A 1988 study published in the journal, Drugs Under Experimental and Clinical Research, investigated the benefits of long-term oral supplementation of evening primrose oil in a group of children with atopic eczema.
The researchers found that the children who received evening primrose oil had significantly fewer and less severe symptoms than those who did not after only 4 weeks.
The results of the study also showed that this improvement was maintained through to the end (20 weeks) of the study.
The researchers of this study not only recorded positive results but also linked them to the improvement in the fatty acid compositions of plasma (blood), lymphocyte (lymph cell) and neutrophil (immune cell).
In sharp contrast, a 1985 study published in the Journal of the American Academy of Dermatology found no such benefits.
Here, the researchers recruited 123 patients (children and adults) with atopic eczema for a double-blind, crossover study. At the end of the study, they found that evening primrose oil (Efamol) did not improve the scaly skin, itching, redness or severity of the participants’ eczema.
Of course, this is an example of a crossover study that did not find any benefits of using evening primrose oil in the treatment of eczema.
In a paper published in the British Medical Journal in 2003, Hywel C. Willams, a professor of dermatoepidemiology at the University of Nottingham and a coordinating editor of the Cochrane Skin Group at that time, presented a brief overview of the state of research on evening primrose oil and eczema.
Besides repeatedly asserting that evening primrose oil was ineffective for eczema, the expert noted that the withholding of drug trial data by researchers commissioned by manufacturers of the herbal supplement.
In addition, he addressed the notion that high doses of evening primrose oil are required to improve atopic eczema by quoting the results of a double-blind, placebo-controlled, parallel study published in the same journal earlier that year.
The quoted study concluded that the high-dose gamma linolenic acid supplement did not produce better results than placebo in 151 eczema patients involved in the trial.
Lastly, the expert noted that most of the positive studies often quoted in this field of research have never been published in peer-review journals. Therefore, their designs and results were likely flawed.
The 2013 Cochrane Review was the most damning evidence against the use of evening primrose oil supplements in the treatment of eczema.
After reviewing 19 studies that met the Cochrane criteria for inclusion, the reviewers concluded that evening primrose oil did not perform better than placebo at improving the symptoms of eczema.
Evening primrose oil was not the only oil discredited by this review. The editors also found that borage oil (another excellent source of gamma linolenic acid) did not fare better than placebo in the treatment of eczema.
In conclusion, the researchers believed that this Cochrane review provided conclusive evidence to finally show that the use of evening primrose oil supplements by eczema patients was not justified. They, however, mentioned that evening primrose oil may increase the risk of bleeding when combined with anticoagulants such as warfarin.
Even the Cochrane reviewers noted that the studies included in their review were short and small (the largest involved only 160 participants).
Therefore, critics would argue that longer and larger studies are needed to reach a worthy conclusion about the efficacy of evening primrose oil in the treatment of eczema.
Besides finding fault with the length and size of these studies, the design can also determine its outcome.
As mentioned above, positive results tend to come out of parallel studies in which one group of participants received only placebo while the other group received only evening primrose oil.
However, a more subtle but important factor may be responsible for the mixed results obtained from these studies.
In a paper published in the journal, Clinical Pharmaceutical Biotechnology in 2006, the authors discussed two meta-analyses investigating the effectiveness of evening primrose oil (Efamol, specifically) for eczema patients.
The authors noted that the 1989 meta-analysis produced a stronger positive result than the second analysis done 10 years later. However, the second meta-analysis (which involved 26 studies and 1,207 eczema patients) still showed that evening primrose oil relieved itching, swelling, crusting and redness.
From the second analysis, the reviewers noted that it took 4 – 8 weeks after starting on evening primrose oil supplement for patients to begin to experience improvements in their symptoms.
This observation strengthens the argument for longer studies and the cumulative effect of the oil.
Secondly, the reviewers noted that patients who did not respond well to evening primrose oil were likely to be taking steroids too.
Therefore, the reviewers believed that the diminishing responsiveness to evening primrose oil was linked to increasing use of potent steroids among eczema patients.
Oral and topical steroids are commonly prescribed for eczema patients to temporarily provide relief.
In conclusion, the reviewers noted that increased steroid use as well as new findings about the abnormal fatty acid metabolism and immune responses of some eczema patients may help determine who can benefit the most from evening primrose oil supplements.
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