The herbal supplement Ginkgo biloba does not prevent heart attacks or stroke, a new study finds. But it might reduce the risk of peripheral artery disease, study results suggest. This condition causes clogged leg arteries. The study included 3,069 people, age 75 or older. They were randomly assigned to two groups. One group received ginkgo twice a day. The other received placebo (fake) pills. Researchers kept track of both groups for six years. In that time, there was no difference between groups in the rates of death, stroke or heart attack. But there was a difference in peripheral artery disease rates. People taking ginkgo were only half as likely to develop this disease as people taking placebos. The study was released online by the journal Circulation. HealthDay News wrote about it November 24.

By Robert H. Shmerling, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

Imagine there was a safe and natural remedy that's been used for thousands of years to preserve memory, prevent dementia and maintain heart health. Would you be tempted to take it? I might, but I'd also want to know if there's evidence that it actually works.

That's exactly the question addressed by a new study of Ginkgo biloba. This herbal supplement is an extract from leaves of the ginkgo tree. The new research is part of a large, well-designed study of whether ginkgo can prevent dementia or Alzheimer's disease. In the latest study, researchers also assessed ginkgo's impact on heart and artery disease.

More than 3,000 elderly people were randomly assigned to take ginkgo or a placebo for about 6 years. The study found no difference in the rates of heart attack or stroke based on what pills people took. In an earlier study, researchers also found no evidence that ginkgo can prevent dementia or Alzheimer disease.

However, the new study did find a 50% lower rate of peripheral artery disease among those taking ginkgo. This disease causes narrowed arteries in the legs. But only 35 people in the study developed it. Therefore, more research is needed to see if ginkgo can prevent this condition.

It's disappointing that ginkgo did not prevent heart attack or stroke. And I'm skeptical that it will prove effective for peripheral artery disease. If ginkgo biloba does not work for heart attack and stroke, it seems unlikely it will help peripheral artery disease. This artery problem tends to respond to the same treatments as heart attack and stroke. However, we'll need more research to know for sure.

What Changes Can I Make Now?

If you take ginkgo to prevent heart disease or stroke, you'd be better off choosing other, proven methods.

• Exercise regularly.
• Maintain a healthy body weight.
• Choose a well-balanced diet that is high in fruits and vegetables while low in saturated and trans fats.
• Get your blood sugar, blood pressure and cholesterol levels checked. If one or more of these are not in an ideal range, a change of diet and increased exercise may get them there. However, many people need medicines.
• Don't smoke.

If you already have heart or artery disease (such as prior heart attack or stroke), talk to your doctor about treatments. Those with proven value include:

• Aspirin or other blood thinners
• Beta blockers, such as atenolol (Tenormin). These drugs lower blood pressure, slow the heart and help it relax.
• ACE inhibitors, such as lisinopril (Zestril). These medicines lower blood pressure, improve heart failure and help protect the kidneys.
• Statins, such as atorvastatin (Lipitor). Statins reduce cholesterol and may reduce inflammation in narrowed arteries around the heart.

Other drugs may also be recommended. They may include nitrates and calcium-channel blockers.

Let your doctor know about all of the medicines and supplements you are taking. This is important regardless of whether they require a prescription. Even all-natural, over-the-counter supplements can interact with other medicines you take. This can make a medicine less effective, increase the risk of side effects, or both.

What Can I Expect Looking to the Future?

You can expect more studies of popular supplements such as ginkgo. Perhaps it will prove effective for heart attack and stroke if taken by those at risk at an earlier age. And we need much larger studies to determine whether it can truly prevent peripheral artery disease. If it can, that would be big news indeed. Millions of people have this bothersome and potentially serious condition.

If research studies find that a particular supplement is not effective, I would expect less use. However, that's not always the case. It can be hard for people to stop taking a treatment they believe helps them. This is especially true for conditions that have no highly effective treatment (such as dementia). As future well-designed studies are completed, I hope their results will be well-publicized. Then consumers will be fully armed with the most current scientific knowledge.