Herbals and the Heart: New Review Seeks to Sum Up Dearth of Data on Effects and Hazards

One in five American adults has used a herbal supplement at some point, yet a full 70% of patients say they do not tell their doctors about supplement use, according to a new review of herbal medications in cardiovascular medicine.

Rosa Liperoti, MD (Università Cattolica del Sacro Cuore, Rome, Italy), and colleagues say cardiologists should “improve their knowledge” of herbal products in order to do a better job of asking their patients what they are taking, and of communicating what the risks could be.

A good first step might be to read their review, published in the Journal of the American College of Cardiology this week. It zeros in on the herbal remedies most commonly used in cardiovascular medicine, as well as those known to have effects on the heart.

“Use of alternative medicine and herbal remedies is extremely common in Western countries, and physicians should know the risk and benefits of these treatments and be able to discuss them with their patients,” senior author Graziano Onder, MD (Università Cattolica del Sacro Cuore), told TCTMD.

In fact, Onder believes education could be more formal, suggesting that a course on herbal medications be mandatory in medical schools, not because physicians will be prescribing these agents but rather so that they understand how these might interact with other medications, what benefits they might have, and what safety issues could arise.

No Premarket Approval Needed

Liperoti et al point out that in the United States, herbal medications are regulated in the “dietary supplements” category and thus do not require premarket approval and do not need to demonstrate safety or efficacy prior to their market release. While the US Food and Drug Administration can remove unsafe products from the market, safety data are collected voluntarily through a Safety Reporting Portal, where the manufacturer, consumer, or healthcare professional can file a report.

Likewise, in the European Union, herbal products do not require proof of safety and efficacy prior to their approval and are only removed from the market when they are found to have caused harm. There are also no regulations guaranteeing a given supplement actually contains the ingredients listed on the label, or the purity of that product.

“There are studies that show that sometimes herbal medications are contaminated with other herbs or with conventional medications to get the effect that they are supposed to give,” Onder said.

In their review, Liperoti et al focus on 10 herbal medications specifically used for the treatment of cardiovascular conditions, known by their common names as Asian ginseng, astragalus, flaxseed oil, garlic, ginkgo, grape seed, green tea, hawthorn, milk thistle, and soy. The authors then provide possible indications, biological and clinical data, and safety concerns.

To TCTMD, Onder stressed that any formal studies testing these agents are “very fragmented,” small in size, and in many cases have results published in Japanese or Chinese, not English. “That makes it difficult to put together everything that is known about herbal medications,” he said.

How Herbals Affect the Heart

Asked what remedies should be on the radar of cardiologists, Onder had no shortage of examples.

“For example, ginkgo and garlic might reduce platelet function, possibly leading to an increased risk of bleeding if taken together with aspirin or anticoagulants,” he suggested. “Cranberry (which is used to prevent urinary tract infections in women), goldenseal (a product used as an antimicrobial to prevent common colds and upper respiratory tract infections), and Asian ginseng [all] might inhibit the enzymes involved in the metabolism of warfarin, causing INR elevation and increased risk of bleeding. Green tea contains small amounts of vitamin K and therefore can antagonize the effect of warfarin. Hawthorn might increase digoxin blood concentration. These are only some examples of possible risks related to the use of herbal medications.”

That said, he continued, “Due to the lack of preclinical data and clinical studies focusing on the effects of herbal medications, data on the safety profiles of these medications are limited.”

Consumers often harbor the misconception that because herbal medications are “natural,” they are safe—that’s despite the fact that roughly 25% of currently commercialized medications are derived from plants used in traditional medicine, the review notes. And while historically there has been some animosity between naturopathic practitioners and conventional medicine physicians that may have led to unwillingness among patients to discuss natural products, prescribed by alternative healthcare practitioners, with their doctors, Onder says believes the communication gap is a two-way street. “Often physicians do not ask. They say, ‘Well, these are not real medications, so it’s not something I want to know about.’ But they should see that these are part of the therapy that their patient is getting.”

As for what to do with information patients provide, Onder points to web portals by government and regulatory agencies that can offer reliable and updated sources of information on herbal products. His recommendation: the National Center for Complementary and Integrated Health, which outlines specific herbs or botanicals and their potential interactions.