Just as herbs can interact synergistically or antagonistically when combined, so can herbs and pharmaceutical drugs. For example, one in four people in the United States over 45 years of age takes statins, a class of pharmaceutical drug used to lower blood cholesterol levels. Statins work by inhibiting an enzyme that produces cholesterol in your body, so they are considered important in reducing heart disease. The statins are broken down by another enzyme system in your body, leading to their elimination.
But bergamottin, a compound in grapefruit, can block the process that breaks down statins, allowing them to build up to levels that can quickly become toxic, resulting in severe liver, kidney, and muscle damage. That’s why physicians advise their patients not to consume this fruit or its juice while taking statins. Now researchers are considering the possibility of using grapefruit compounds to increase the amount and effects of certain drugs in the body so that smaller amounts of these drugs can be used.
Ginkgo (Ginkgo biloba) dilates blood vessels, which helps with cardiovascular conditions, such as high blood pressure. Adverse effects could occur when combining ginkgo with other antihypertensive or certain antidepressant drugs.
In a recent preliminary study, a patient who drank a single 8-ounce glass of grapefruit juice daily increased the absorption of a specific chemotherapeutic drug by up to 350 percent. While much further research is necessary, the study suggests that drugs modulated by plant compounds, such as those found in grapefruit, could be prescribed in smaller amounts.
Many herb-drug interaction charts can be found online. While there are many potentially problematic herb-drug interactions, scientific data has shown that most (but not all) commercially produced herbal products, as well as the herbs themselves (except, of course, for the toxic species) are generally safe when used under the supervision of a knowledgeable health-care practitioner.
The extraordinary chemical diversity of herbs has remarkable potential to improve human health and well-being. To achieve this potential, rigorous clinical trials under standardized, reproducible conditions are needed. Pilot experiments — small-scale clinical trials with herbs and patients — can provide guidance for the design of larger studies. The gold standard for evaluating any new therapy — drug or herb — is the randomized, blind, placebo-controlled clinical trial, where participants are randomly placed into groups receiving the treatment or placebo and they do not know which of the treatments they are receiving. These types of studies will allow medical researchers to determine which herbs are effective for treating specific health conditions and which ones could help us stay healthy as we age, and — of equal importance — which herbs lack sufficient evidence of safety or efficacy, and which might interfere with the proper action of the pharmaceutical drugs we take.
In many ways, medicine is returning to its original roots: using plants to improve the quality of our lives.