Scientific Research Validates Use of Many Herbs
Use of herbs to treat illness is arguably one of the oldest forms of medicine, and continues to be practiced worldwide. Despite criticism by some scientists that herbal therapies have no rational basis, or are ineffective, a new review in the January issue of Annals of Internal Medicine discusses the benefits of several common herbal treatments, including ginkgo, St. John’s wort, ginseng, echinacea, saw palmetto, and kava, as documented by published medical research.1 The author also evaluates the safety of these herbs and lists potential or known interactions with conventional medications.
Ginkgo (Ginkgo biloba) has traditionally been used for a variety of illnesses, but controlled trials have been limited to only a handful of conditions. The review article’s author feels that the benefits of ginkgo are well documented for those suffering from age-related cognitive decline (dementia) and a disease of decreased blood flow to the legs (intermittent claudication). Taking ginkgo for memory impairment and ringing in the ears (tinnitus) may be helpful, although the evidence is not as strong as for the other ailments. Ginkgo has been associated with serious adverse effects, including bleeding episodes and seizures and should not be taken with blood-thinning medications. The recommended level of intake is 120 to 320 mg per day of a standardized extract containing 22% to 27% flavone glycosides and 5% to 7% terpene lactones.
The author believes St. John’s wort (Hypericum perforatum) to be an effective treatment for mild to moderate depression, based on multiple well-designed, controlled trials. He notes that St. John’s wort is as effective as several prescription medications, including tricyclic antidepressants. However, evidence supporting the use of St. John’s wort for severe depression is not convincing and the most recent study examining this issue found no benefit of St. John’s wort in severely depressed individuals.2 St. John’s wort has few reported side effects, but may cause increased sensitivity to light and decrease the effectiveness of some drugs, such as blood thinners or birth control pills. There is also some evidence that St. John’s wort may interact with selective serotonin-reuptake inhibitors (SSRIs), such as Prozac® or Zoloft,® leading to an overload of serotonin. Therefore this combination should be avoided. Studies indicate 900 mg per day of a standardized extract containing 0.3% hypericin is an appropriate amount to use.
People have often used ginseng to treat insomnia, increase energy, control blood sugar, improve concentration, and increase physical performance. The author points out that "ginseng" is a broad term describing several species of plants, which include Siberian ginseng (Eleutherococcus senticosus), Asian ginseng (Panax ginseng), American ginseng (Panax quinquefolius), and Japanese ginseng (Panax japonicus). The focus in this article is on Siberian ginseng. Despite the popularity of ginseng, studies have failed to demonstrate that this herb is an effective treatment for the previously mentioned conditions. There is very weak evidence that Asian ginseng may reduce the risk of cancer and American ginseng may help blood sugar control in type 2 diabetics, but more research is needed to verify these preliminary reports. Although reported side effects of Asian ginseng are few, insomnia, diarrhea, headaches, and schizophrenia have been associated with long-term use; in addition, the herb may interfere with medications that thin the blood or control blood sugar. The author recommends 200 to 600 mg per day of Asian ginseng extract for short-term use only.
Echinacea (Echinacea angustifolia and purpurea) is a common, controversial herb primarily used for upper respiratory infections and to reduce the effects of the common cold. Evidence from controlled studies suggests that echinacea helps decrease the symptoms of a cold, but does not prevent the cold from developing. The author points out that different species and preparations of echinacea were used in many of the trials, so it is unclear if any one type of echinacea or any particular preparation is superior to another. Echinacea is tolerated very well and has only been linked with a few sporadic reports of side effects, which were mostly allergic in nature. The recommended intake level varies, depending on the form used, but 3,000 mg per day of dried root or 9 ml daily of pressed juice are often recommended.
Older men often use saw palmetto (Serenoa repens) to treat urinary problems associated with benign prostatic hyperplasia (BPH). Several trials have found saw palmetto to improve the symptoms of BPH and one study even showed it to be as effective as finasteride (Proscar®). Side effects are rare, but may include upset stomach. There are no known interactions with prescription drugs. The amount most often used in studies is 320 mg per day of a standardized extract containing 85% to 95% fatty acids and sterols.
Cultures from the South Pacific have traditionally used kava kava (Piper methysticum) as a recreational drink, but it is primarily used in Western cultures to treat anxiety. Seven controlled studies found kava to be an effective short-term treatment for generalized anxiety and one study found that it worked as well as oxazepam (Serax®). Kava has come under recent scrutiny, with several reports of liver toxicity in the last several months, even when taken at the recommended level. (Healthnotes Newswire, Dec. 13, 2001) Long-term use of kava may also lead to dry, flaky skin, hair loss, weight loss, or loss of appetite. However, these are reversible once use of kava is discontinued. The recommended level of intake is 70 to 240 mg per day of dried root extract. Given the current concern with kava toxicity, it should only be taken under the supervision of a physician.
The author comments that a problem with many herbs is the lack of long-term, well-controlled studies. He expresses additional concern over the lack of quality control and standardization of herbal products, given that some products tested have been found to be contaminated or do not contain the amount of ingredient listed on the label. He recommends people try to use the actual product used in studies whenever possible.
There may also be interactions between herbs and prescription medications that need to be addressed. While some information is starting to surface to identify these interactions, there is likely not known about mixing prescription medications with herbs. More research is necessary to clarify these complicated issues.
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1. Ernst E. The risk-benefit profile of commonly used herbal therapies: ginkgo, St. John’s wort, ginseng, echinacea, saw palmetto and kava. Ann Intern Med 2002;136:42–53.
2. Shelton RC, Keller MB, Gelenberg A, et al. Effectiveness of St. John’s wort in major depression: a randomized controlled study. JAMA 2001;285:1978–86.
Darin Ingels, ND, MT (ASCP), received his bachelor’s degree from Purdue University and his Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. Dr. Ingels is the author of Garlic and Cholesterol: Everything You Need to Know (Prima, 1999) and Natural Treatments for High Cholesterol (Prima, 2000). He currently is in private practice in Westport, CT, where he specializes in environmental medicine and allergies. Dr. Ingels is a regular contributor to Healthnotes and Healthnotes Newswire.
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