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Herbal Supplements


Article updated and reviewed by Larry A. Weinrauch, MD, Assistant Professor of Medicine, Harvard Medical School on July 7, 2005.

Herbal supplements are made from natural plants and are used by some individuals to supplement traditional medical treatments. They are not considered drugs and are therefore not regulated by the Food and Drug Agency (FDA). This absence of regulation means that the effectiveness, quality, and quantity of the ingredients have not been independently verified.

It is likely that some herbs improve certain conditions. Many of today's pharmaceuticals originate from plants. Digitalis, used to treat congestive heart failure, initially came from the leaves of the foxglove plant. Taxol, from the yew tree is used for chemotherapy, belladonna is used for respiratory and gastrointestinal complaints, and many other medications are extracted from nature. Ethical pharmaceutical houses undergo stringent regulation to produce these as medications.


Herbal supplements are available in capsules, liquids, and powders. Americans spend over a billion dollars a year on herbal remedies. Manufacturers of these supplements are making millions of dollars from consumers. Yet the proof of efficacy is often scant, and the consistency of the product is often unreliable.

The popularity of herbs often stems from testimonials or exaggerated bits of scientific evidence. There have been few rigorous clinical trials testing these compounds for effectiveness or safety.

Results of some studies show that it is critical that you discuss which herbal supplements you are taking with your physician in order to prevent interactions with your other medications, or even side effects from combinations of herbal preparations.

Herbs and spices, of course, can make bland foods more appealing. Eastern countries such as China and India have appreciated this dual function of herbs and spices for thousands of years.

Now, Western medicine is attempting to identify and isolate the beneficial compounds in these familiar substances. Basil, cumin and turmeric are spicing up American tables. Some studies from researchers in India hint that these strongly flavored spices possess cancer prevention properties. Some examples of herbs and spices being researched include:

Capsaicin, the chemical that gives red pepper its fire, has been found to be helpful in treating joint pain in some patients, and may be beneficial for gastrointestinal problems.

Echinacea, a member of the daisy family, is touted as a remedy for colds or flu. Studies show that Echinacea does contain substances capable of strengthening the immune system to fight infection, and may, in some cases, shorten the duration of colds and flu (although not prevent them). It may also be helpful in the treatment of urinary tract infections. Evidence of effectiveness is however quite weak.

Garlic is a favorite of health advocates. Some studies indicate that garlic may lower cholesterol. This effect is not sustained after three months and appears to be limited to raw garlic. The gastrointestinal and odiferous effects are considered by some to be quite limiting. Some studies show that Ginkgo biloba extract can stimulate blood flow in the brains, arms, and legs of older adults. This benefit is quite limited. As Ginkgo biloba can increase the risk of bleeding, its use with anticoagulants, aspirin, or anti-inflammatory drugs should be curtailed.

Turmeric has a mild, slightly bitter, peppery flavor and adds a rich golden color to dishes. It may also boost the immune system.

St. John’s wort has been proven to be effective in the treatment of mild to moderate depression. However, in 2000, the U.S. Food and Drug Administration warned that it can interfere with protease inhibitors, drugs that are widely used to treat AIDS. Studies since then show that St. John's wort interferes with an enzyme called P450 that the body uses to break down about half of all drugs. Because of this, St. John's wort is believed to inhibit many of the most widely prescribed medicines, as well as digoxin and beta-blockers used for heart disease, seizure medicines and drugs used to prevent organ rejection after transplants.

Oleander was once used for treating heart failure, but is now considered too toxic and can cause poisoning that resembles digitalis toxicity.

Ephedra (Ma huang) has been used as a dietary supplement, a stimulant, and a remedy for asthma, allergies, and nasal congestion. Its use has been associated with sudden death and it was banned in the US by the FDA in 2003.

Many other preparations have been used for everything from menopausal symptoms (Black cohosh, evening primrose, soy) to cholesterol lowering (plant stanols, garlic, guggulipid, sugar cane extract) with little demonstration of effectiveness.

Whether the herbs are effective as claimed or not, they do interact with medications and each other. Uninformed multiple herb use can lead to unexpected side effects, toxicity, and even death. The greater the number of medications taken, the greater the number of possible interactions.


Is there scientific evidence that this herb is safe?

Is their any proof of effectiveness?

Is it approved by the FDA for treating any medical problem or condition?

Will it interact with any other drugs that I'm currently taking or might take in over-the-counter medication?

Will there be side effects?

Can it aggravate an existing condition such as diabetes or arthritis?

Editorial review provided by VeriMed Healthcare Network.