Purified borage oil, also known as starflower oil, contains a minimum of 23 per cent gamma linolenic acid (GLA), an essential fatty acid that is needed for normal skin function. Evening primrose oil, often taken to treat eczema too, also contains GLA, but in lower concentrations.
GLA supplementation has been widely investigated for treatment of atopic eczema but although it has consistently proved safe and well tolerated, efficacy has been inconsistent.
Noting that doses used in previous studies may have been too low, researchers from the George Eliot Hospital near Coventry in the UK and the University of Leicester identified 151 patients with atopic eczema. Every day for 12 weeks they received either borage oil containing 920mg of GLA (the highest dose used in a trial to date) or placebo in matching capsules.
Symptoms, scored using recognised scales, were assessed at baseline and at two, four, eight and 12 weeks. These include itching, sleep disturbance and irritability.
The symptoms and signs improved to a similar degree in both groups, with a marginally greater improvement in the placebo group. The authors suggest that GLA is unlikely to offer any useful benefit in treatment of atopic eczema.
"These data are compatible with results from the largest studies in which evening primrose oil was used as a supplement of gamma-linolenic acid," write the authors.
The results are also compatible with previous trials on borage oil, they said, adding that the high dose used in their study appears to refute "any contention that the response is dose-related".
In an accompanying editorial, Professor Hywel Williams writes: "This…study, along with the recent decision of the UK Medicines Control Agency to withdraw the product licence [for evening primrose oil], suggests that GLA supplementation for atopic dermatitis has had its day."
Full findings are reported in BMJ, volume 327, pp 1385-7.