Scientific interest in medicinal plants has burgeoned due to increased efficiency of new plant-derived drugs, growing interest in natural products and rising concerns about the side effects of conventional medicine. Based on current research and financial investments into medical plants, it seems that they will continue to play important roles in human health. This article reviews the current state of medical plant utilization, concerns over safety and perspective on the future development of medical plant markets.
The use of various herbal remedies and preparations are described throughout human history representing the origin of modern medicine. Many conventional drugs originate from plant sources: some of the most effective drugs are plant based, such as aspirin derived from bark of willow, digoxin derived from foxglove, quinine derived from the bark of cinchona, and morphine derived from the opium poppy. The development of drugs from plants by drug companies encourages large scale pharmacological screening of herbs. Chinese herbalism is the most dominant of the ancient herbal traditions. It is based on concepts of yin and yang and of Qi energy. Chinese herbs are considered “cooling” (yin), “stimulating” (yang) and are administered in combination according to the deficiencies or excesses of these qualities in the patient. Modern Western herbalism focuses on the effects of herbs on individual body systems rather than taking a holistic approach: herbs may be used for anti-inflammatory, haemostatic, expectorant, antispasmodic, or immunostimulatory properties. It is estimated that around 80% of the worldwide population uses herbal medicines, mainly as self-prescribed products. This type of herbal drug use is typically based on a simple matching of a particular herb to particular disease or symptom. For example, Valerian (Valeriana officinalis) for sleep disturbance and St John’s Wort for anxiety and stress. Health food shops for herbal remedies are now considered equivalent to conventional drugstores by some.
What is herbal medicine?
Herbal medicine is also called botanical medicine or phytomedicine, and is defined as the use whole plants or part of plants to prevent or treat illness. Plant parts used include seeds, berries, roots, leaves, bark, or flowers. Although a renaissance is occurring in herbal medicine all over the world, national control agencies such as the American Food and Drug Administration (FDA) still classify herbs as food supplements and forbid manufacturers from claiming that their products are able to treat or prevent specific diseases. As a result, these agencies do not exert any control over the manufacture of herbal medicine. This lax regulation system gives herbal medicine a bad image. For instance, there is no control over the amount of active compound in manufactured herbal products. However, some countries such as Germany are starting to regulate herbal remedies as if they were drugs. The German Commission E is conducting some research on safety and effectiveness of medical plant use.
Differences from conventional drug use
Herbal medicine and conventional medicine have three important differences:
- use of whole plants- Herbalists generally use unpurified whole plant extracts containing several different compounds. They claim that these can work together such that the effect of the whole herb is greater than the summed effects of its components. They also claim that toxicity is reduced when whole herbs are used instead of isolated active ingredients (“buffering”). Although two samples of a particular herbal drug may contain several active compounds in different proportions, practitioners claim that this is not generally problematic.
- herb combining- Several different herbs are used together. Practitioners say that combinations of plants improve efficacy and reduce adverse effects.
- different diagnostic approach- Herbal practitioners use different diagnostic principles than conventional practitioners. For example, they might observe the underfunctioning of a patient’s systems of elimination. A diuretic, choleretic, or laxative combination of herbs might be prescribed alongside herbs with anti-inflammatory properties.
Are herbs safe?
Herbal medicines appear relatively safe, but there is limited human research or prospective data concerning adverse effects and herbal-drug interactions. They are generally less potent than their pure drug relatives because they contain a mixture of many chemicals in small quantities. Even so, herbal products are not free of risk (see below).
How are herbal remedies prepared and taken?
Herbal remedies are taken internally or applied to the skin. Fresh herbs can also be incorporated into the diet. There are various methods of intensive herbal treatment:
- Tinctures are made by soaking the flowers, leaves, or roots of the chosen herbs in alcohol. these keep well and are easy to store.
- Infusions are less concentrated than tinctures. Infusions are made by soaking an herb in hot water for 10 to 15 minutes. The resulting infusion can be used as a tea, or it can be applied externally to the skin.
- Cold infusion involves soaking an herb in cold water for a long period, from 2 to 12 hours. It can then be either swallowed or applied to the skin.
- Decoctions are similar to infusions but are made from roots, barks, nuts, and seeds.
- Washes are external applications of cooled tea.
- Poultices are pastes made from bruised fresh herbs or dried herbs moistened with hot water. They are placed on a clean piece of cotton and then on the affected area.
Commonly used herbal medicines and treating illness
Herbal medicine aims to return the body to a state of natural balance, so that it can start healing itself. Different herbs act on different systems of the body. Some of the herbs that have been scientifically studied and found to be effective and safe include:
Echinacea – boosts the immune system and aids the body in fighting infection. It is used to treat ailments such as boils, fever and herpes. Echinacea is under investigation for its use in treating cancer and AIDS.
Dong quai (dang gui) – used for gynaecological complaints, such as premenstrual tension, menopause symptoms and period pain.
Garlic – can be used to reduce the risk of heart disease by lowering blood fats and cholesterol levels. The antibiotic and antiviral properties of garlic mean that it is also used to fight colds, sinusitis and other respiratory infections.
Ginger – many studies have shown ginger to be useful in treating nausea, including motion sickness and morning sickness.
Ginkgo biloba – commonly used to treat poor blood circulation and tinnitus (ringing in the ears). Some studies have found Ginkgo biloba to be effective in treating neurological disorders, such as memory loss and Alzheimer’s disease.
Ginseng – generally used for debility and weakness, for example during recovery from illness. It can be used to reduce blood pressure and cholesterol levels, however overuse of ginseng has been associated with raised blood pressure. Some studies show that ginseng can also boost immunity, improve mental functioning and speed the healing processes of the body.
Hypericum – commonly known as St John’s Wort. Numerous studies have demonstrated that hypericum is just as effective as some synthetic antidepressants in treating mild to moderate depression. It is also effective for anxiety and insomnia. Research is currently focusing on hypericum’s antiviral properties and its effect on AIDS. Recent information suggests that hypericum can interact with a number of prescription drugs, including the oral contraceptive pill.
Medical farming: hairy root culture, production of plant-derived biopharmaceuticals
In many industrialized countries, more and more individuals are turning to herbal medicines and plant-derived products to offset the high costs of personal healthcare. Many efforts have been made to commercialize production of the medical plant metabolites from plant-cell culture. Specific yields for several natural products are higher in plant cell and hairy root culture. Due to their fast growth rates and biochemical stability, �hairy root� cultures are considered a powerful choice for producing active compound from medical plants. Applications vary from the production of natural products and foreign proteins to a model for phytoremediation of organic and metal contaminants. Hairy roots will have a continuing role as an experimental model in plant metabolic engineering. Plants also have considerable potential for the production of biopharmaceutical proteins and peptides. As the demand for biopharmaceuticals is expected to increase, it would be wise to ensure that they will be available in significantly larger amounts on a cost-effective basis. Currently, the cost of biopharmaceuticals limits their availability. Plant-derived biopharmaceuticals are cheap to produce and store, easy to scale up for mass production, and safer than those derived from animals and microorganisms. Several biotechnology companies are now actively developing, field testing, and patenting plant expression systems. The first plant-derived recombinant pharmaceutical proteins are now waiting commercial approval by government, and many more are expected to follow.
Herbs are frequently used to treat or prevent a range of health problems. The use of herbal medicines has become a part of the mainstream all over the world. About 80% of the world’s population use herbal products as medications. Some use herbal products with conventional medications, others use them as a replacement. Although the high technology approaches of conventional medicine are especially useful for acute disease treatment and emergency care, herbal medicine is more suitable for dealing with chronic ailments. Because herbal medicine addresses an important health-care need, its continued integration into mainstream medicine should benefit everyone. This integration will require herbal medical education and training as well as an improved regulatory system for herbal medicine.
Prospective Data – Information about future trends obtained by data mining with powerful computers
Hairy Root Culture – Agrobacterium rhizogenes naturally transforms plant cells into factories for its own food production. This transformation results in cells which grow vigously and remain stable in culture, making them ideal for expression of foreign proteins in vitro.
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Canada’s Natural Health product regulations (from 2003) are available from Health Canada.
(Art by Jen Philpot)