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3 April 2008

'Omega-3 can help control eczema'

A diet rich in omega-3 fatty acids can reduce the severity of eczema symptoms reported one newspaper (28 March 2008). The newspaper report generally accurately summarised the findings of a well-conducted randomised controlled trial. The small size of the trial means that further research is needed to confirm the findings.

A diet rich in omega-3 polyunsaturated fatty acids can help eczema sufferers reduce the severity of their symptoms, reported the Daily Telegraph (1) on 28 March 2008.

The report was based on a study published in the British Journal of Dermatology (2) involving 53 volunteer patients aged 18-40 years of age who were suffering from atopic eczema. The study was a randomised controlled trial undertaken in Germany: 44 participants completed the study course, 21 in the study group and 23 in the control group. The study group received a daily dose of 5.35 g of omega-3 docosahexaenoic acid (DHA) and 0.37 g of eicosapentaenoic acid (EPA) for 8 weeks. The control group received a daily dose of saturated fatty acids over the same period. After 8 weeks eczema symptoms had improved significantly in the DHA group but not in the control group. However, the difference between the groups was not statistically significant.

The Daily Telegraph (1) accurately reported the results. The research appears well conducted but the small sample size and lack of a significant difference between groups mean that further research is needed to confirm the findings.

Evaluation of the evidence base for omega-3 fatty acids in eczema
Where does the evidence come from?

The evidence comes from a randomised controlled trial led by Margitta Worm and conducted in the Charité Department of Dermatology and Allergology in Berlin, Germany.
What were the authors' objectives?

To determine the impact of dietary n-3 polyunsaturated fatty acids docosahexaenoic acid (DHA) on clinical and immunological variables in patients with atopic eczema.
What was the nature of the evidence?

This was a randomised controlled trial (RCT) involving fifty-three patients suffering from atopic eczema aged 18-40 years.
What interventions were examined in the research?

Patients received a daily dose of 5.35 g of omega-3 docosahexaenoic acid (DHA) and 0.37 g of eicosapentaenoic acid (EPA) compared with a control group receiving a daily dose of 4.17 g of caprylic acid and 2.84 g capric acid over 8 weeks.
What were the findings?

After 8 weeks patients in the DHA group showed a significant clinical improvement of atopic eczema in terms of a decreased Severity Scoring of Atopic Dermatitis (SCORAD) score equivalent to an 18% reduction in symptoms. The control group also showed an improvement in SCORAD score over the same period, equivalent to an 11% reduction in symptoms, but this reduction was not significant. However, there was no statistically significant difference between the DHA and control groups.

A significant reduction of anti-CD40/interleukin 4-mediated IgE synthesis of peripheral blood mononuclear cells (PBMC) was detected in the DHA group only. Supplementation led to a modulated activation status of PBMC in both groups. The DHA group showed an increase of plasma n-3 PUFA and a decrease in the n-6/n-3 PUFA ratio.
What were the authors' conclusions?

The clinical results imply that dietary DHA may be beneficial in supporting the standard treatment of eczema. Different doses of DHA and long-term treatment may be more effective in patients with atopic eczema but the results need to be confirmed in a larger study.
How reliable are the conclusions?

The research was a generally well-conducted RCT. Appropriate methods were used for randomisation and the trial was double-blinded. A major limitation was the small sample size, which limited the statistical power of the comparisons and meant that the authors could not exclude the possibility of a placebo effect influencing the results. A larger follow-up study would be required to address these shortcomings.
Systematic reviews

Information staff at CRD searched for systematic reviews relevant to this topic. Systematic reviews are valuable sources of evidence as they locate, appraise and synthesize all available evidence on a particular topic.

There were no related systematic review identified on the Cochrane Database of Systematic Reviews (CDSR) however there was one on the Database of Abstracts of Reviews of Effects (DARE)(3).
References and resources

1. Omega-3 can help control eczema. The Daily Telegraph, 28 March 2008, p2.

2. Koch C, Dölle S, Metzger M, Rasche C, Jungclas H, Rühl R, Renz H, Worm M. Docosahexaenoic acid (DHA) supplementation in atopic eczema: a randomized, double-blind, controlled trial. British Journal of Dermatology 2008;158(4):786-792.

3. Van Gool C J, Zeegers M P, Thijs C. Oral essential fatty acid supplementation in atopic dermatitis: a meta-analysis of placebo-controlled trials. British Journal of Dermatology 2004;1506(4):728-740. [DARE Abstract]

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