Herbal Drugs: Therapeutic use

Last modified: Sunday, 31. May 2009 - 3:59 pm

The potential therapeutic effects of herbal drugs have not been extensively tested or conclusively proven. However, scientific study of herbals is under way in the United States and abroad, and many herbs may well prove to be useful. The results of initial studies on many herbals, such as saw palmetto and St. John’s wort, are promising.
Because herbal medicines are not classified as drugs by the FDA, the manufacturers of herbals cannot make claims that their product is effective at treating any disease or disorder. They can, however, make more general health claims. For example, companies that sell St. John’s wort cannot say their product is useful for treating depression or anxiety, but they can say St. John’s wort “helps support a healthy emotional balance” or “helps maintain a positive attitude.”
Despite the lack of conclusive evidence on their effectiveness, herbal drugs are widely believed to be useful in treating a variety of conditions, both common and unusual, and mild and serious. Common conditions for which people take herbal drugs include colds and flu, muscular aches and pains, acne, indigestion, constipation, coughs, corns, menstrual cramps, dandruff, diarrhea, fatigue, flatulence, frostbite, warts, hair loss, headaches, heartburn, insect bites, lice, motion sickness, nausea, insomnia, dizziness, and warts. (The PDR-HM lists 25 herbal medicines used to relieve flatulence.)
More serious conditions for which people take herbal drugs include depression, irregular heartbeat and other heart problems, arthritis, arteriosclerosis (hardening of the arteries), asthma, high blood pressure, various cancers, diabetes, epilepsy, gallstones, sexually transmitted diseases, hepatitis, jaundice, malaria, measles, obesity, tetanus, tuberculosis, and ulcers.
As popular interest in herbal medicines grows, scientists have been conducting more clinical trials (studies in people) to evaluate herbals’ effectiveness at treating particular disorders. One source of reliable, scientific knowledge on herbal drugs is the reports from the German government’s herbal watchdog agency, the so-called “Commission E.” After reviewing the scientific literature on more than 300 herbals, this commission approved more than 200 and disapproved about 100 for use in Germany. Building upon the work of Commission E, the PDR-HM, published in the United States, lists about 600 herbal medicines, and gives an evaluation of the usefulness of each. Another good source is the Clinical Evaluation of Medicinal Herbs and Other Therapeutic Natural Products, also published in the United States. This book evaluates and reports on the clinical trials performed on a wide variety of herbs.
Following is a list of popular herbal drugs in the United States, the Therapeutic use or uses for which people take them, and what scientists have learned so far about their effectiveness:
• Echinacea. The several varieties of this plant, also called the purple coneflower, are used to strengthen the body’s immune system and for both prevention and treatment of colds and flu. Sixteen clinical trials involving over 3,000 patients have produced mixed results. In some of the studies, echinacea reduced the severity and duration of colds and flu. However, the evidence that this herb can actually prevent colds and flu is weak at best.
• Garlic. Fresh and dried garlic are used to lower cholesterol and to treat the common cold, coughs, bronchitis, fever, and inflammation of the mouth. Garlic appears to be effective for these uses. Twenty-five clinical trials involving more than 1,000 patients have tested garlic’s cholesterol-lowering properties. Although these studies produced mixed results, they indicate overall that garlic can reduce cholesterol by about 10%. Other uses for which garlic has not been proven effective include treatment of menstrual pain and diabetes.
• Ginkgo. The leaves and seeds of this plant, native to China, Japan, and Korea, are used to improve age-related loss of memory, including the dementia associated with Alzheimer’s disease, and to relieve ringing of the ears and a type of pain and weakness in the limbs called intermittent claudication. More than 40 studies involving more than 1,000 patients show that ginkgo has a modest effect on dementia and intermittent claudication, but does not seem to help with memory loss or ringing of the ears.
• Ginseng. The dried roots of this plant, which is native to China, are believed to increase stamina and concentration. Few well-designed, rigorous studies of ginseng have been conducted, and those that have been done found no evidence for ginseng’s effectiveness.
• Saw palmetto. The fruit of this plant, indigenous to the southern coastal regions of the United States, is used to relieve urination problems caused by an enlarged prostate gland. Sixteen short-term clinical trials involving approximately 3,000 men indicate that saw palmetto is effective for this use, although long-term trials need to be done to confirm the herb’s effectiveness. The herb improves urine flow, although it does not seem to reduce the size of the prostate. In some European countries, saw palmetto is commonly prescribed for men with an enlarged prostate.
• St. John’s wort. The dried buds and flowers of this plant are used to treat mild to moderate depression and anxiety. More than 30 well-designed studies involving thousands of patients show the herb works about as well as conventional antidepressants for treating mild to moderate depression.

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