The Efficacy of Herbs

Unlike modern pharmaceutical drugs, which are developed after years of rigorous clinical trials, herbs do not undergo this type of testing. This means that the efficacy of many herbal medicines has not been established. In addition, the pharmacokinetics of most herbal medicines is not well understood and pharmacodynamics (how the different components work together to produce an effect) is often unknown. The result is that herbal medicine may cause adverse effects in some people.

Nevertheless, herbal medicine remains widely used around the world. It is estimated that consumers spend $5.1 billion per year on herbs. Herbal medicines are used by people for a variety of reasons, from general health maintenance to the treatment of specific ailments. Many patients seek alternative therapies because of concerns about side effects from traditional pharmaceuticals, which are sometimes very strong and potentially toxic.

Herbal medicines are complex and are typically made up of several different plant ingredients. The quality of the raw materials used in making herbal preparations is important to guarantee their safety and efficacy. The quality of the raw material is affected by the temperature, humidity and light exposure at the time the plants are harvested. The method of harvesting, drying and packing, and the age of the plants are also important factors. The composition of herbal preparations varies from batch to batch. This is partly because the chemical analysis techniques available only rarely succeed in isolating and characterizing all secondary metabolites present in a plant extract.

The use of herbal medicines has been documented since ancient times. The first herbalists believed that illness was caused by a loss of balance, and that herbs could restore this balance. Hippocrates, who lived from 460-380 BC, described various medicinal uses for herbs, including the treatment of diseases such as malaria and leprosy. Later, Ayurvedic texts from India described the use of herbal medicines, and how to combine them in medicinal recipes.

Herbal medicinal products are also used by cancer patients for supportive care, as a supplement to chemotherapy or radiation therapy, and to assist in recovery from surgery. However, few herbal medicines have been tested in conjunction with chemotherapy drugs to determine the optimal dosages and their interaction with chemotherapy agents. As a result, many oncologists advise their patients to avoid herbal medications and dietary supplements during chemotherapy.

A number of regulatory models for herbal medicinal products exist, ranging from the strict scientific approach adopted by Germany’s Commission E (phytotherapy and herbal substances) to the regulatory system employed in Canada which includes a combination of scientific data and traditional knowledge. In the future, the emerging “omic” technologies (eg genomics and proteomics) will enable a holistic understanding of how the individual constituents in herbal medicinal products act and interact in biological systems. This may lead to a more robust clinical evidence base for herbal medicine. Until then, herbal medicines should be used only under a doctor’s supervision. Ayurvedic and Chinese herbal medicines have additional safety and quality issues to consider.