Have you taken echinacea to stay healthy through the winter, ginseng for more energy or valerian to ensure restful sleep? If so, you're not alone. According to the Office of Dietary Supplements, more than 38 million Americans take herbal supplements. With more Americans using herbs to improve their health, it's important to know how to choose and use them safely. "Herbs may play an important role in overall health and well-being, but many people are still learning what works and what should stay on the shelf," said registered dietitian Lynn Laboranti, M.S. "Consumers should do their homework and talk to their doctor about what herbs are right for them." What do you know about herbs? To test your herbal IQ, Laboranti poses the following questions: Q: Can echinacea boost immunity? A: Several scientific studies have shown echinacea to be an effective, natural way to boost immunity. When taken at the first sign of not feeling well, echinacea helps stimulate the body's natural defense system. Echinacea should not be taken for more than eight weeks at a time. Q: What does St. John's wort do? A: Clinical and laboratory research has earned St. John's wort a growing reputation as an herb that helps enhance mood. It has few side effects, but may cause light sensitivity and decrease the effectiveness of some prescription medications. It's important to talk to a health care professional before using St. John's wort or other herbal supplements if you take prescription drugs. Q: Does soy relieve menopause symptoms? A: Soy contains naturally occurring isoflavones, which have been shown to help relieve menopause-related hot flashes and night sweats. Soy foods and soy isoflavones also help support hormonal balance in women during the menopausal years. Experts recommend 30 to 65 mg of soy isoflavones (5-8 ounces of soy milk or 1 to 2 soy tablets) daily to receive a full benefit. If you choose to take herbs in tablet form, Laboranti recommends reading a product's label for additional safety and dosage information. Nature's Resource herbal supplements, found at drugstores like CVS and Walgreens, feature an extended, multipage safety label on the bottle. The booklet, called "Herbal ABCs," contains extensive information on the specific supplement, drug/herb interactions, contraindications, adverse effects, allergy warnings and special safety instructions.