Q. Does hawthorn extract relieve heart failure symptoms?

A. A review of existing studies on extracts of the leaves, berries and flowers of the hawthorn plant shows it could be useful in improving symptoms of mild to moderate heart failure. It may not extend your life span, but could make you feel better.

Heart failure is a serious condition that is both debilitating and deadly. It is often due to clogged arteries that stress the heart by forcing it to work harder. As a result, the heart becomes enlarged and is unable to pump enough blood throughout the body. This causes blood and fluid to back up into the lungs. Fluid also builds up in the feet, ankles and legs, causing swelling. Fatigue and shortness of breath are also common symptoms.

Hawthorn works by relaxing the muscles in arteries around the heart, making it easier for blood to flow to the heart. It also may work directly on the heart by increasing the force of heartbeats.

Researchers from the Cochrane Collaboration combined the results of 10 studies on hawthorn. Seven of these studies looked at using hawthorn as an addition to conventional medications. Results show that hawthorn improves heart function, shortness of breath, fatigue and exercise tolerance in people with heart failure. There is good evidence that when used alongside of conventional therapy, hawthorn could bring additional benefits.

In contrast, a large, unpublished study last year found only limited benefit from hawthorn. This study was looking at longevity. Results showed that hawthorn has little effect on extending longevity.

It must be emphasized that hawthorn should only be taken under a physician's supervision. It can interact with heart and blood pressure medications, requiring doses of these medications to need adjustment. Also, hawthorn may have side effects, although usually they are infrequent and transient. They include dizziness, nausea, sweating and upset stomach.

The patients in these studies had mild to moderate heart failure. Hawthorn might cause greater side effects in patients with more severe cases who must take more powerful drugs to control their disease.

Those with heart failure should follow a low-sodium diet to reduce swelling. They are often asked to restrict their fluid intake, too.

Hawthorn should not replace conventional therapy but may be useful as an addition. Further study is needed to compare hawthorn to conventional medications used to treat heart failure.

Amy Tousman is a registered dietitian and certified diabetes educator with Nutrition Unlimited in Kailua. Hawai'i experts in traditional medicine, naturopathic medicine and diet take turns writing the Prescriptions column. Send questions to: Prescriptions, Island Life, The Advertiser, P.O. Box 3110, Honolulu, HI 96802; islandlife@honoluluadvertiser.com; or fax 535-8170. This column is not intended to provide medical advice.