By Erin Dummert RD, CD

Herbs have been used in traditional Chinese, Japanese, and Indian medicine for centuries to treat everything from insomnia and indigestion to depression and anxiety. In recent years, herbal supplements have bombarded the marketplace, claiming to offer natural treatments for life threatening diseases, including cancer.

If you have been diagnosed with cancer, it is natural to want to try everything to cure this life threatening disease. As a result, even though you may have never used them, herbal supplements may begin to look appealing. However, the use of supplements brings up many issues, including safety, effectiveness, and drug interactions. Here are some important things you should know if you are a cancer patient who is using, or thinking of using herbal supplements in conjunction with conventional cancer treatment.

Powerful herbal supplements

Herbal supplements can act like drugs. In fact, many cancer drugs are made from herbs. Due to their ability to fight cancer, herbal supplements have been made a part of conventional cancer treatment. However, if not used in the proper amounts, or when taken with other supplements or medicines, they can cause serious harm.

The word natural is often associated with safety. However, there are many natural substances that can cause serious harm. For instance, cyanide and marijuana are natural, yet their harmful effects are well known. The herbal supplements kava, used for anxiety, and comfrey, used for treatment of cancer, have been shown to cause serious damage to the liver.

Herbal supplements are less regulated

In the United States, herbal supplements are regulated as foods rather than drugs. This means that they do not have to meet the same standards as medications for proof of safety or effectiveness, making it easy for manufacturers to make false claims about their products. In fact, studies of many herbal supplements have found differences between what is listed on the label and what is actually in the bottle. Some herbal supplements have even been found to contain dangerous metals, prescription drugs, microorganisms, and other substances. (See also the following article from TheDietChannel: How to Protect Yourself When Purchasing Supplements.)

Supplements can interact with your treatment

Many herbal supplements interact with common chemotherapy drugs. The herb St. John's Wort, used to treat depression, has been shown to significantly decrease the effectiveness of the chemotherapy drug Camptosar. This effect can last up to 3 weeks after stopping the herbal supplement. Other herbs can interfere with medicines that affect blood clotting. People who take Coumadin (Warfarin) should avoid herbal supplements due to their potential to significantly alter blood clotting time.

Due to their ability to modify the liver's metabolism of drugs, the following herbal supplements are not recommended for people receiving chemotherapy or oral drug treatment:

• Garlic
• Ginkgo
• Ginseng (Siberian)
• Goldenseal
• Milk Thistle
• St. John's Wort
• Turmeric (supplement form).

In addition, the following herbal supplements increase sensitivity to light, and should be avoided during radiation therapy:

• Chrysanthemum
• Dong quai
• Shitake mushroom
• St. John's Wort.

Get professional advice

Despite the many concerns of health professionals, many cancer patients still use herbal supplements in combination with conventional cancer treatments. For these patients, it is strongly recommended that they seek the advice of a trained herbal professional and discuss all supplements with their oncologist before starting any herbal regimen.

Do your research

Here are some reputable resources on herbal supplements:

• The Herb-Drug Interaction Handbook by Sharon Herr R.D.
• Tyler's Honest Herbal: a Sensible Guide to the Use of Herbs and Related Remedies by Varro Tyler Ph.D., Sc.D. and Steven Foster
• Office of Dietary Supplements
• American Botanical Council