People living with cancer may decide to explore dietary and herbal supplements as a way to improve health, assist with nutrition, or reduce treatment side effects. It is important to discuss the possible benefits and risks of individual supplements with your doctor before taking them.

• Dietary supplements are products that have one or more dietary ingredients, including vitamins, minerals, herbs, enzymes, amino acids, and hormones. They are typically taken by mouth as a pill, capsule, tablet, liquid, or powder. They can be bought without a prescription in pharmacies, and grocery and health food stores.
  
  
• Herbal supplements are a type of dietary supplement specifically containing plants or ingredients from plants. They are also called botanicals and may be used for therapeutic reasons, taste, and scent. Herbal supplements come in many forms (tablets, capsules, powders, and tea bags) and are also readily available in stores.

Supplements and CAM

Supplements are part of a diverse group of nonconventional/nonstandard approaches to medical treatment referred to as complementary and alternative medicine (CAM). Supplements are used in both complementary medicine and alternative medicine.

For instance, if someone takes an herbal supplement to help reduce nausea during chemotherapy, the supplement is being used as a complementary therapy. Many supplements can be safely used, under a doctor's guidance, to manage side effects of conventional treatment or improve a patient's physical or emotional well-being.

On the other hand, if a person is taking large doses of that same supplement in an effort to cure the cancer instead of having chemotherapy, it is considered an alternative therapy. Claims that supplements can cure cancer have not been proven, and some supplements can be harmful to a person's health.

Evaluating the safety of supplements

It can be difficult to determine the safety and effectiveness of dietary supplements. Information about dietary supplements is often based on anecdotal evidence (people's personal observations) instead of scientific studies. It is commonly believed that because herbs and other supplements are "natural" and have been used for centuries for medicinal purposes, that they are safe. The truth is, the safety of herbal supplements depends on many things, including the ingredients, dose, preparation, and how they work in the body.

The U.S. Food and Drug Administration (FDA) regulates dietary supplements differently than prescription medicine or over-the-counter drugs. The FDA does not approve dietary supplements for safety and effectiveness before they are sold. The FDA can only claim that a supplement is unsafe after consumers have reported problems with it. This means the degree of quality control depends on the manufacturer, the supplier, and others in the supplement's production process.

Claims made on the supplement label can also be confusing. The FDA allows the labels of dietary supplements to contain one of three types of claims: a health claim, nutritional claim, and structural or functional claim. However, keep in mind that product labels containing such claims must also include a disclaimer that reads, "This statement has not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease." In other words, the claim has probably not been tested and may not be true.

People undergoing cancer treatment need to be extremely cautious about the safety of dietary supplements, since they can interfere with surgery, chemotherapy, and radiation therapy. For instance, taking vitamin A may decrease the effectiveness of chemotherapy, the herb kava can interfere with anesthesia for surgery, and the herb echinacea may have immune-suppressing compounds.

Talking with your doctor about supplements

It is important for people to talk with their doctors about the use of supplements or other CAM therapies. These discussions may address the following points.

• Possible benefits and risks, depending on personal medical history
• 
  
  
• Possible interactions with current cancer treatments
• 
  
  
• Possible side effects
• 
  
  
• Dosage levels and length of treatment
• 
  
  
• New information on the supplement, preferably from clinical trials rather than personal stories

To help you weigh whether to take certain supplement, review Cancer.Net's Questions to Ask When Considering CAM section. Deciding whether, when, and how to use a dietary supplement to complement standard cancer treatments can be a complicated decision. Whatever the final decision may be, it's important to be an informed consumer and discuss the choice with a doctor.

Points to consider about supplements

• Even when taken at the recommended dose, some supplements can cause serious side effects, such as high blood pressure, nausea, diarrhea, constipation, fainting, headaches, seizures, heart attack, or stroke. Contact your doctor immediately if you experience any harmful side effects from the supplements.
• 
  
  
• When you are using a supplement for a health problem, then you are using it as a drug. This means the supplement's ingredients may interfere with prescription and over-the-counter medications you may already be taking. As stated above, it can also interact with cancer treatments.
• 
  
  
• It may not be safe to take certain herbal supplements if you have specific health problems, including high blood pressure, diabetes, mental health conditions, or heart disease.
• 
  
  
• Use only the supplement you and your doctor decide on. Buy only single-herb products that clearly show how much of the herb each dose contains. Use brands from companies you or your doctor know are reputable. For instance, some herbal supplements have been found to be contaminated with other unlabeled herbs, pesticides, prescription drugs, heavy metals, or other substances.
• 
  
  
• Look for a certification mark or seal from an independent, third-party organization. U.S. Pharmacopoeia, the Good Housekeeping Research Institute, and ConsumerLab.com are among those that monitor supplements. Although tests differ, such labels indicate the supplement has met certain manufacturing standards. The Good Housekeeping Research Institute also certifies some supplements as safe and effective.
• 
  
  
• Check the product label to see if the supplement has been scientifically tested. Contact the manufacturer for the test results, and ask your doctor to explain anything that isn't clear.
• 
  
  
• Be skeptical of supplements' label claims, particularly those that claim to cure cancer since no single device, remedy, or treatment can treat all cancers.

Additional resources

National Center for Complementary and Alternative Medicine (NCCAM):
What's in the Bottle? An Introduction to Dietary Supplements
Herbal Supplements: Consider Safety, Too

U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition: Overview of Dietary Supplements, Tips For The Savvy Supplement User: Making Informed Decisions and Evaluating Information

National Institutes of Health's Office of Dietary Supplements (ODS):
Dietary Supplements: Background Information
Botanical Dietary Supplements: Background Information

Memorial Sloan-Kettering Cancer Center: Information Resource: About Herbs, Botanicals & Other Products

Mayo Clinic:
Vitamin and mineral supplements: Use with care
Herbal supplements: What to know before you buy