Hawthorn has been used for centuries as a treatment for heart problems. In the last few decades, carefully prepared extracts from the dried leaves, flowers and fruits of this bush have been tested in randomised, placebo controlled trials for chronic heart failure. A new Cochrane review brings this knowledge together and shows that a few months of treatment with the Hawthorn extract, in addition to the person's regular medicines, is beneficial, and that the side effects are generally tolerable. People allocated to take the extract, usually in the form of a capsule a day, found that they were less breathless and were more able to take exercise, than people allocated a placebo.

The reputation of the Hawthorn bush as a treatment for heart problems has been built up over hundreds of years. However, a single active ingredient has not yet been found. Instead, the effects of this plant on the heart seem to be due to its complex mixture of chemicals. Research into whether it is helpful to people with chronic heart failure has focused, therefore, on the use of specially prepared and standardised extracts.

The authors of the new Cochrane review looked for randomised trials in which these extracts had been compared with a placebo. They found a total of 14 such studies, stretching back through the last few decades of the medical literature. These trials included about a thousand patients.

There were various differences between the studies and, so, they could not all be combined into a single statistical analysis, but a number of meta-analyses were possible. For example, bringing together the results of five of the trials, with nearly 400 patients, found a significant increase in maximum workload when measured in the laboratory. Likewise, symptoms such as shortness of breath and tiredness were less common among people allocated the Hawthorn extract rather than the placebo. The extract did have some side effects. But these tended to be uncommon and mild.

In summary, the authors of the Cochrane review conclude that the best evidence currently available shows that hawthorn extract has significant benefits for patients with chronic heart failure, when used along with their usual medication.

This Cochrane review is available in full at www.mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD005312/frame.html

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February 18 2008