Chaparral, also known as stinkweed, stinks - literally! And it tastes downright unpleasant. So the herb's major healing benefit comes as something of a surprise - it's a mouthwash. We're not talking minty fresh here. You wouldn't want to reach for it before puckering up for your morning kiss.

But don't let that stop you - the unassuming chaparral shrub, native to the American Southwest, contains a chemical that may spell death to some of the germs that cause tooth decay. It owes its use in healing to a chemical called NDGA (nordihydroguaiaretic acid), which kills the bacteria and other microorganisms that turn fats and oils rancid.

If, as some people believe, effective medicine smells foul and tastes terrible, chaparral should be a terrific healer. Its leaves exude a waxy resin that smells like creosote and is the source of its popular names: Stinkweed, grease-wood, and creosote bush (though the plant contains no creosote).

The Southwest Indians rubbed chaparral resin on burns. They used chaparral tea to treat colds, bronchitis, chicken pox, snake bite, and arthritis. And they heated the tips of its twigs and applied the hot resin to painful teeth.

White settlers adopted the plant and used it externally for bruises, rashes, dandruff, and wounds, and internally for diarrhea, stomach upset, menstrual problems, venereal diseases, and cancers of the liver, kidney, and stomach.

Chaparral was listed as an expectorant (to clear mucus from the respiratory system) and bronchial antiseptic in the U.S. Pharmacopoeia from 1842 to 1942. But today, few herbalists mention it. Those who do suggest using it externally to prevent wound infections, and internally for intestinal parasites and bacterial and viral illnesses.

Chaparral is an intriguing and controversial herb. The chemical it contains, NGDA, is approved by the U.S. Department of Agriculture as a preservative in lard and animal shortenings. NGDA's antiseptic action, combined with its traditional use for toothache, prompted scientists to test it against the bacteria that cause tooth decay.

A study in the Journal of Dental Research shows chaparral mouthwash reduces cavities by 75 percent. Oral microorganisms also cause gum disease, the leading cause of tooth loss in adults. Chaparral mouthwash is no substitute for regular brushing and flossing, but it may provide added protection. And you don't have to worry about the smell lingering either.

NGDA is also a powerful antioxidant, meaning it helps prevent the cell damage scientists believe eventually causes cancer. For more than 100 years, chaparral has been a popular folk treatment for cancer. The National Cancer Institute has received many testimonials from people claiming the herb cured their cancers. Some laboratory studies agree chaparral has anti-tumor effects.

The medical literature from the National Cancer Institute contains several case reports of tumor shrinkage in people who used chaparral. One published in Cancer Chemotherapy Reports tells of a man diagnosed by University of Utah physicians with malignant melanoma, the most serious skin cancer. The doctors urged surgery, but the man refused, saying he intended to treat himself with chaparral tea. The Utah medical team was aghast, but eight months later, the man returned with "marked regression" of his cancer.

When it comes to Arthritis, some animal studies agree chaparral has anti-inflammatory action, lending credence to its traditional use in treating arthritis. Try it and see if it helps your stiffness. And life-extension advocates say antioxidants like NGDA help slow the aging process and might even extend the human life span. One French study shows NGDA significantly extends the average life span of laboratory animals. Other scientists claim the chemical almost doubles the average life span of laboratory insects. Scientists have not been able to extend the human life span, but these antioxidant results are certainly intriguing.

For a mouthwash or infusion, use 1 tablespoon of dried leaves and stems per quart of boiling water. Steep 1 hour. Gargle or drink up to 3 cups a day. Because of its unpleasant taste, you might want to add honey and lemon to the infusion, or else mix it with a beverage tea.

Chaparral should not be given to children under age 2. Older children and people over 65 may use a full-strength gargle, but for internal use, they should start with a low-strength preparation and increase strength if necessary.

Although NGDA is a food preservative approved by the U.S. Department of Agriculture, the Food and Drug Administration removed it from the list of substances generally regarded as safe in 1968 because experimental animals fed large amounts for long periods developed kidney and lymph-system problems. No human kidney or lymphatic disease has ever been documented in chaparral users, but to be prudent, those with kidney and lymph conditions should not use this herb.

For healthy individuals, chaparral is considered safe in amounts typically recommended. Chaparral should be used in medicinal amounts only in consultation with your doctor. If urinary difficulties or swollen glands develop, stop using it, and consult a doctor for possible kidney or lymphatic problems. If chaparral causes minor discomforts, such as stomach upset or diarrhea, use less or stop using it. Let your doctor know if you experience any unpleasant effects or if the symptoms for which the herb is being used do not improve significantly in two weeks.