Heart patients get herbal supplement warning

February 1, 2010 The study published in the Journal of American College of Cardiology showed Saint John's Wort could make blood pressure and cholesterol pills less effective.

Ginkgo biloba, typically used to sharpen the mind, could interact with coumadin or aspirin to increase the risk of internal bleeding.

Researchers say many patients don't tell their doctors they are taking over-the-counter supplements.

More than 15 million Americans use herbal remedies or megavitamins in hopes of improving health.