People take these supplements for a variety of reasons, such as the desire to actively participate in treatment and to improve nutrition. In many cases, friends or family members encourage people with cancer to try the supplements. But while many dietary supplements may be touted as cancer cures, to date there is no evidence that these products are effective treatments for the disease.

Vitamins, Minerals, and Other Dietary Supplements

Some people with cancer take large amounts of vitamins, minerals, and other dietary supplements in an effort to enhance their immune systems or even destroy cancer cells. Some of these substances can be harmful. In fact, large doses of some vitamins and minerals may reduce the effectiveness of chemotherapy and radiation therapy.

Your doctor, nurse, or dietitian may advise you to supplement your diet with certain vitamins and minerals during treatment. This is especially true if you are unable to eat an adequate diet. In most cases, however, a supplement that contains 100 percent of the US Recommended Daily Allowances (US RDA) is usually sufficient.

Many people believe that if a pill or supplement can be found on store shelves, then it is safe and effective. At this time, there are no regulations controlling the safety, content, and quality or dose recommendations for these products. The US Food and Drug Administration (FDA) does not require manufacturers of these products to print possible side effects on their labels. The FDA cannot pull a dietary supplement or herbal product from the market unless it can prove that the product is unsafe.

If you are considering taking dietary supplements, talk with your doctor or nurse first. If you are already taking supplements, bring the bottle(s) with you to your doctor for approval on the dose and to ensure that the ingredients do not interfere with your health or cancer treatment.

Antioxidants

Antioxidants are substances that protect the body's cells from damage caused by free radicals (by-products of the body's normal processes). Examples of antioxidants include vitamin C, vitamin E, beta carotene, and selenium. If you want to take in more antioxidants, health experts recommend eating a variety of fruits and vegetables, which are good sources of antioxidants. Taking large doses of antioxidant supplements is usually not recommended while undergoing chemotherapy and radiation therapy. Talk with your doctor to determine the best time to take antioxidant supplements.

Herbs

Herbs have been used to treat disease for hundreds of years. Today, herbs are found in a variety of products such as pills, liquid extracts, teas, and ointments. While many of these products are harmless and safe to use, others can cause severe and harmful side effects and interfere with proven cancer therapies including chemotherapy, radiation therapy, and recovery from surgery. If you are interested in using products containing herbs, talk about it with your doctor or nurse first.

Safety Considerations

• Tell your health care team about any herbal products and supplements that you are using or are considering for use. Bring the bottle(s) of the supplement to your doctor for approval of the dose and to ensure that the ingredients do not interfere with your health or cancer treatments.
• Ask your doctor or nurses for reliable information on dietary supplements.
• Check the product labels for both the quantity and concentration of active ingredients contained in each product.
• Stop taking the product immediately and call your doctor if you experience side effects such as wheezing, itching, numbness, or tingling in your limbs.