5 Things You Should Know About Herbs and Supplements

5 things to know about herbs, supplements, and cancer Cancer.Net/Blog
April 16, 2015
Amber Bauer, ASCO staff

2008 study published in the Journal of Clinical Oncology reported that between 14% and 32% of people with cancer start using supplements after their diagnosis. People with cancer often use dietary and herbal products to boost their health, improve their nutrition, or reduce side effects associated with treatment. Unfortunately, fewer than half of oncologists discuss the risks and benefits of supplement use with their patients, according to survey results published in 2014.

Although many people see herbs and supplements as "natural" and these products are available in any grocery store, there are important things to know before you consider taking them. share on twitter 

1. No dietary or herbal product can cure cancer.

Many drugs used as part of chemotherapy are derived from plants and have been thoroughly tested in clinical trials. On the other hand, very few oral herbal supplements have undergone rigorous scientific testing. When supplements are used instead of standard treatments for cancer they are called alternative treatments. However, there really are no alternatives to standard cancer treatment. Approaches marketed as alternative therapies do nothing to treat cancer. They are unproven and unsafe.

2. The U.S. Food and Drug Administration (FDA) does not approve dietary products.

New drugs have to be scientifically tested and then approved by the FDA before companies can make them available to patients and doctors, but the FDA evaluates dietary supplements under a different set of regulations. The efficacy of dietary supplements does not have to be demonstrated in clinical trials before they are sold. The FDA usually investigates the safety of a suspicious product only after people who have used it report problems. This means the quality and safety of these products is left to the manufacturer, the supplier, and others involved in the production process.

3. Herbs may interact with chemotherapy and other drug treatments.

Most herbs and dietary supplements have not been studied together with chemotherapy, so doctors don’t usually know how they will interact with each other. share on twitter In general, taking herbs at the same time as chemotherapy can cause unexpected side effects or reduce the effectiveness of cancer medications. For example, St. John's wort can cause potentially dangerous interactions with chemotherapy. In addition, herbs like ginger and garlic can interfere with anticoagulant drugs, such as warfarin, increasing the risk of bleeding.

4. Antioxidant supplements may make cancer treatments less effective.

There is conflicting information about taking antioxidants during cancer treatment. Some think antioxidants help destroy cancer cells or protect healthy cells from being damaged by cancer treatment. However, there is evidence that antioxidant supplements may make chemotherapy and radiation therapy less effective. Talk with your doctor about the potential risks and benefits of taking antioxidant supplements before using them.

5. Some supplements may help reduce specific side effects of treatment.

Some herbs and nutritional supplements have been tested in clinical trials and shown to help manage specific side effects of cancer treatment. For example, American ginseng and Astragalus root used in traditional Chinese medicine may help reduce some side effects of chemotherapy, such as fatigue. Nutritional supplements like glutamine, vitamin B6, vitamin E, and omega-3 have been tested as treatments for peripheral neuropathy. However, these supplements are not appropriate for everyone, and more research is needed to confirm their safety and effectiveness.

Approved by the Cancer.Net Editorial Board, 04/2015


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