DOES IT WORK?Limited studies using hawthorn extracts to treat mild heart failure have had positive results, writes Dónal Ó Mathúna.
THE HAWTHORN tree is native to Ireland and has a long tradition in Irish folklore.
The tree is a member of the genus Crataegus, of which there are hundreds of species.
The name hawthorn comes from old English words which mean "thorny hedge". In ancient times, it was the symbol of fertility and marriage. The healing powers of the hawthorn were invoked by leaving a token on the tree. It was believed that this would result in the disease remaining on the tree also.
More specifically, herbalists claim the flowers, leaves and fruit can help with a number of heart problems. In Germany and some other countries, an extract of hawthorn leaves and flowers is available on prescription for mild heart failure.
Evidence from studies
Laboratory and animal studies have shown that hawthorn extracts contain several compounds that affect the blood and the heart. The extracts contain antioxidants, which are well known to be important in promoting healthy blood flow.
Other isolated compounds can dilate blood vessels, reduce blood pressure, lower cholesterol levels and directly impact the heart in ways that allow it to function better.
A systematic review, published earlier this year, found 14 double-blind, randomised controlled trials of hawthorn for heart failure. Almost all of these involved patients with relatively mild symptoms of heart failure as measured by their ability to tolerate exercise safely.
In most studies, the patients were also receiving conventional medical treatment. The review found that patients taking hawthorn with conventional therapy could exercise significantly longer on a stationary bicycle than those using conventional therapy alone.
Overall, a roughly 10 per cent improvement in exercise tolerance occurred with hawthorn, compared to one group of drugs (ACE inhibitors) which, on average, give about a 20 per cent improvement.
Other measurements provided evidence that the beneficial effects of hawthorn are significantly better than placebo. However, none of the studies lasted long enough to measure whether people taking hawthorn were less likely to develop more serious heart conditions or die from heart disease. The maximum benefit from hawthorn was usually seen after six to 12 weeks taking 240-600mg of a standardised extract. The two most commonly used extracts are standardised against two different components: either 2.2 per cent flavonoids or 18.8 per cent procyanidins.
Problematic aspects
In general, hawthorn rarely caused side effects, and those which occurred tended to be mild and short-lived. However, hawthorn has a traditional reputation as a sedative.
This usage has not been confirmed by research, but side effects of fatigue and drowsiness have been reported in those using higher doses of hawthorn for their heart.
Problems have also been reported, with people developing heart palpitations and their blood pressure dropping too low, leading to dizziness. Hawthorn could potentiate or interfere with other heart medications, but research has not been conducted in this area.
Recommendations
The evidence from research studies shows that hawthorn provides additional benefits for chronic heart failure patients who are also receiving conventional therapy.
Studies are not available to show whether these benefits occur if hawthorn is used alone. Many effective medicines and lifestyle changes (diet, smoking cessation, exercise, etc) are helpful for chronic heart failure. These should all be considered when deciding whether to use hawthorn in addition. Since hawthorn does contain compounds that affect the heart, it is important to consult a doctor if you are considering using it.
Anyone already on any sort of heart medicine should not start hawthorn before talking to a doctor or pharmacist.
Since almost all the research was conducted with patients with mild symptoms of heart failure, there is no evidence that hawthorn benefits those with more serious heart problems.
• Dónal O'Mathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University. He authored Alternative Medicine: The Christian Handbook(Zondervan, 2007)
• If you would like a particular product reviewed, e-mail healthsupplement@irish-times.ie