Many of today’s popular herbal supplements, including St. John’s wort, ginkgo biloba, garlic and even grapefruit juice can pose serious risks to people who are taking medications for heart disease, says a new review.

More than 15 million Americans reportedly use herbal remedies or high-dose vitamins.

The use of these products is especially concerning among elderly patients who take multiple medications and are already at greater risk of bleeding, according to the study authors.

“Many people have a false sense of security about these herbal products because they are seen as ‘natural’,” Arshad Jahangir, Professor of medicine and Consultant Cardiologist at Mayo Clinic in Arizona, said.

“But ‘natural’ doesn’t always mean they are safe. Every compound we consume has some effect on the body, which is, in essence, why people are taking these products to begin with.” Arshad added.

In addition to their direct effects on body function, these herbs can interact with medications used to treat heart disease, either reducing their effectiveness or increasing their potency, which may lead to bleeding or a greater risk for serious cardiac arrhythmias (erratic heartbeats).

“We can see the effect of some of these herb-drug interactions - some of which can be life-threatening - on tests for blood clotting, liver enzymes and, with some medications, on electrocardiogram,” Jahangir said.

According to the report, a major concern is that patients do not readily disclose their use of herbal remedies, and healthcare providers may not routinely ask about such use.

“If patients aren’t satisfied with their care today, many will turn to herbs because they believe these compounds can help them manage chronic conditions or improve health and prevent future disease,” said Jahangir.

Two nationwide surveys conducted in 1990 and 1997 found that the number of visits to complementary and alternative providers increased from 427 million to 629 million, whereas the number of visits to primary care physicians remained basically unchanged, said a Mayo Clinic release.

These findings are slated for publication in the forthcoming issue of the Journal of the American College of Cardiology.

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