Studies Depict Herbs that Can Help or Hurt

The growing popularity of herbal supplements is spurring increased research into their benefits. While many studies of individual supplements have shown promise, they often have not used the stringent US research standards, which require double-blind comparisons to placebos (compounds composed of inert ingredients). In such a study, neither the patient nor the researcher knows who was treated by the supplement or the placebo before the results are in. This eliminates subconscious favoritism on the part of the researchers and unbridled enthusiasm by study subjects that can skew results.

After careful review of studies, however, certain findings can be applied to those patients or physicians interested in herbal supplements.

Echinacea: Compared to a placebo, echinacea appears to reduce flu symptoms and respiratory infections. However, no well-defined studies have determined appropriate dosages. Maximum adult dosage is 1.5 to 7.5 ml of tincture per day. Do not use for more than eight successive weeks or for progressive systemic diseases, such as AIDS.

Feverfew/featherfew: A double-blind, placebo-controlled (DBPC) study showed a 70% reduction in migraine headaches compared to a placebo. Up to 15% of users develop oral ulcers or gastrointestinal irritation. It should not be used during pregnancy or by people with coagulation problems. Recommended dosage should be gradually increased up to 125 mg per day (2-3 leaves) containing 0.2% parthenolide.

Garlic: No studies have adequately proven garlic (allicin) to have anti-cancer effects or to decrease risk factors of atherosclerosis.

Ginkgo Biloba: Several studies of good quality have concluded that ginkgo biloba extract may stabilize or slightly improve social functioning or cognitive performance in patients with dementia. Medical College researchers are studying its effects on Alzheimer's disease. Ginkgo biloba has also been shown to be more effective on premenstrual syndrome and vertigo than placebos. Doses range from 120 mg to 240 mg daily of extract with 24% flavone glycosides and six percent terpene lactones. Exercise caution if taking aspirin regularly.

Ginger: Results are conflicting. Some find that 250 mg to one gram of powdered ginger root taken up to several times a day can help with nausea with minimal side effects.

Ginseng: Contradicting results. Not recommended for pregnant or lactating women or small children. Note that "Siberian ginseng" (E senticosis) is not true ginseng.

Milk Thistle: Results are preliminary, but may help liver disorders, such as alcohol-related cirrhosis, with few side effects. A common dosage is a 140-mg capsule of 70% silymarin, two to three times a day.

St. John's Wort: Optimal dosing and long-term side effects have not been determined. But a dosage of 300 mg three times a day of an extract standardized to 0.3% hypericin appears to be effective in treating mild to moderate depression and may have anti-inflammatory and anti-infective benefits, as well. Do not take during pregnancy or with other psychotropic drugs.

Saw Palmetto Plant Extract: Evidence suggests that this extract (S. repens) is helpful for men with benign prostatic hyperplasia (enlarged prostate) by improving urologic symptoms and urine flow measures. The extract was comparable to finasteride (Proscar), the standard treatment, but had fewer side effects and costs less. Compared to those taking a placebo, men taking the extract were nearly twice as likely to report improvement in symptoms. The most frequently reported dosage of the extract was 160 mg twice a day. More research is needed, particularly for long-term effects.

The effects of supplements in research vary from laboratory animals to humans. Be careful when taking herbal supplements and always tell your physician or pharmacist what supplements you are taking to avoid drug interactions. Herbs are drugs and contain hundreds of components that may be toxic. Another thing to watch for is that the quantity and quality of ingredients in many herbal supplements leave much to be desired. Often the best products are from Europe, where quality control regulations exist.

MCW Health News presents up-to-date information on patient care and medical research by the physicians of the Medical College of Wisconsin.