The following are key points to remember about herbal medications in cardiovascular medicine:

1. The aim of this review is to describe norms regulating the use of herbal medications, and to summarize the evidence available on the efficacy and safety of the herbal medications most commonly used in cardiovascular medicine.
2. In the United States, herbal medications are regulated by the Food and Drug Administration (FDA) under a category of dietary supplement, which does not need to be approved as safe or effective for a given disease/condition prior to entering the market. The FDA's role is mainly to monitor their safety by reviewing serious adverse events reported by the manufacturer, consumers, or health care professionals through the Safety Reporting Portal. They can only be found unsafe after the discovery of harm.
3. Among the potential therapeutic properties found in many of the herbal medications claimed to reduce heart and vascular disease, hypertension, low-density lipoprotein cholesterol (LDL-C), and platelet reactivity include the flavonoids and chemicals showing antioxidant, anti-inflammatory, and platelet inhibition activity as well as by modulating endothelial nitric oxide-enhancing endothelial function. The major side effects are gastrointestinal and headaches and the drug interactions with many cardiovascular drugs using cytochromes CYP2D6 and CYP3A4, leading to an increase in the levels of atorvastatin, simvastatin, warfarin, diltiazem, verapamil, and propranolol. The 4 G’s (garlic, gingko, grape seeds, and green tea) should be avoided in persons treated with antiplatelet or anticoagulant medications.
4. There is no clinical value for Asian ginseng. Flaxseed oil is rich in alpha-linolenic acid and is effective as a bile resin, which at high doses can reduce LDL-C by 15%, but may result in gastrointestinal distress and interfere with intestinal absorption of oral medications.
5. Garlic has a mild effect on blood pressure and LDL-C (10% reduction), but has not been shown to affect clinical outcome in peripheral vascular occlusive disease or hypertension. Ginkgo leaf extract (gingko biloba) has been used in the treatment of lung disease. Well controlled clinical trials have shown no benefit on memory, cognition, or coronary heart disease.
6. Grape seeds have been claimed to have benefit for the treatment of many cardiovascular conditions, including atherosclerosis, hypertension, hypercholesterolemia, chronic venous insufficiency, and diabetic retinopathy and neuropathy. Antioxidant compounds such as resveratrol are mainly found in grape skin, whereas proanthocyanidin complexes, vitamin E, flavonoids, and linoleic acid are highly concentrated in seeds. There are no good clinical trials and the seeds can cause many side effects.
7. Green tea is rich in flavonoids and vitamins and has been used as a possible treatment for improving mental alertness and aiding in weight loss. Large observational studies have found that green tea may reduce cardiovascular morbidity and mortality when consumed in high doses (at least 3 cups a day) and for a long-term. It has caused reversible liver toxicity.
8. Hawthorn may have some benefit on hypertension, hyperlipidemia, arrhythmias, and congestive heart failure. Clinical studies have shown it to improve various parameters in chronic heart failure, and while safe, it did not affect outcome.
9. Soybeans or soy have a high content of proteins, and isoflavones, which are compounds with both estrogen-like properties and anti-estrogen activity. American Heart Association and European guidelines have suggested there may be a clinical value of high intake of soy protein (40-50 g) for decreasing cardiovascular morbidity and mortality when used as a substitute for animal sources of protein high in saturated fat. However, they may increase risk of breast, uterine, and ovarian cancer.
10. Use of herbal medications for the treatment of cardiovascular diseases is not supported by scientific evidence. Although most of the herbs demonstrate an effect on biological mechanisms associated with cardiovascular disease, available clinical studies are limited in sample size and appropriate controls. Physicians should be certain patients inform them regarding all supplements, particularly herbal, which can result in serious bleeding and drug interactions. And physicians should try to assess whether patients are not taking their medication as prescribed because of the preference for herbal supplements, which they perceive as safe and not “drugs.”

Keywords: alpha-Linolenic Acid, Anticoagulants, Atherosclerosis, Blood Pressure, Cholesterol, LDL, Cytochrome P-450 CYP2D6, Cytochrome P-450 CYP3A, Dietary Supplements, Drug Interactions, Herb-Drug Interactions, Estrogens, Flavonoids, Garlic, Ginkgo biloba, Heart Failure, Hypercholesterolemia, Hypertension, Isoflavones, Linoleic Acid, Linseed Oil, Lung Diseases, Ovarian Neoplasms, Pharmaceutical Preparations, Propranolol, Primary Prevention, Simvastatin, Soybean Proteins, Verapamil, Vitamin E, Warfarin, Weight Loss

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