According to a medical review released Monday, people on heart disease medication, especially the elderly may find taking herbal remedies, such as, ginkgo biloba, St. John’s wort and other widely used herbal supplements, increases the potency of the prescription drugs or make them less effective.

The team of experts concluding their review published in the Journal of the American College of Cardiology believe mixing herbs and drugs may also cause serious heart rhythm problems, including bleeding.

According to the report, it is especially concerning to find elderly patients using herbal supplements, as typically they suffer from more than one disease and are already at a greater risk of bleeding, due to taking multiple medications.

While, there have been other studies warning about using unregulated herbal supplements, the current review studied the interaction of supplements and cardiovascular drugs when taken together.

In a telephone interview, Dr. Arshad Jahangir, a cardiologist with the Mayo Clinic in Arizona said the effect of some of these herb-drug interactions on blood clotting, liver enzymes, with some medications, and on electrocardiogram can be life-threatening.

‘They don’t even consider that herbs could have a negative effect,’ he said. ‘Their impression is that natural is safe.’

With over 15 million Americans using herbal remedies, Jahangir said doctors and patients need to be informed about the potential harmful side-effects of herbal products.

However, an industry trade association, the Council for Responsible Nutrition said the article was an attack on herbal supplements, many of which offer healthy benefits, eliminating the potential risk of a drug interaction by discussing the matter you’re your doctor.

Many take Ginkgo biloba to sharpen cognitive skills, while St. John’s wort fights depression and sleep disorders.

According to him, while Ginkgo biloba, is supposed to sharpen the mind, it increases a risk of bleeding when taken with the blood-thinner warfarin or aspirin, as does garlic believed to boost the immune system, researchers noted.

Further, Jahangir said even grapefruit juice, used to assist weight-loss, has potential dangers, as it interferes with enzymes that break down drugs in the digestive system, including the statins used for lowering cholesterol levels, including amiodarone (Cordarone) for treating and preventing abnormal heart rhythms.

He recommends healthcare providers adopt a more probing attitude when looking at patients, actively asking whether they are using alternative or complementary medicine, as many of them do not disclose their use of herbal remedies.

According to The Nutritional Business Journal, an industry publication, in 2008 herbal supplement sales are estimated to have increased over 6% reaching $25.2 billion.