Tree-bark tea can cause side effects

The impressive pau d’arco tree of the Central and South American rain forests grows to well over 100 feet tall, with a trunk that can reach 6 feet wide. Known by the scientific names Tabebuia avellanedae and Tabebuia impetiginosa, it was named pau d’arco, or bow stick, by Portuguese colonists centuries ago in Brazil. The Inca used the bark to make healing tonics, and natives of the Brazilian rainforest have used the hardwood to make boats and weapons.

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Uses: In South and Central American folk medicine, pau d’arco’s inner bark is used to treat fungal infections, pain, arthritis, prostate inflammation, fever, ulcers, snake bites and tumors. Herbalists prescribe it for conditions including yeast infections, warts, herpes, flu, lupus, eczema and diabetes, and as an immune booster for cancer and AIDS patients.

Dose: Three grams a day in capsule form, in three separate doses, or two to eight cups of tea. In the U.S., pau d’arco is sold most often as an herbal tea, though not all teas bearing the pau d’arco name actually contain the bark of a Tabebuia tree. Some experts say that true pau d’arco teas are ineffective because the bark’s active components don’t dissolve well in water.

Precautions: High doses can cause nausea and vomiting and can reduce the blood’s ability to clot. Pregnant women should avoid the herb at any dose, since animal studies suggest it could be toxic to fetuses.

Research: Lab studies show that lapachol, pau d’arco’s reputedly active ingredient, is effective against malaria, herpes virus, fungi and cancer, and can increase the activity of immune cells. The few human studies on lapachol, however, showed that at the doses needed, pau d’arco caused serious side effects, such as anemia and an increased risk of uncontrolled bleeding. Researchers are continuing to investigate the herb’s medicinal potential through laboratory and animal studies.

Dietary supplement makers are not required by the U.S. government to demonstrate that their products are safe or effective. Ask your health-care provider for advice on selecting a brand.

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-- Elena Conis