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Before you buy a dietary supplement, read the label carefully. Look at the claims, packaging, ingredients, and directions for use. It can be easy to misread the claims that are being made about products.
The makers of dietary supplements are allowed to make 3 kinds of claims on the labels of their products (or in their advertising):
These are the most confusing claims. The following are structure or function claims that are considered OK for dietary supplements:
Structure or function claims are not reviewed by the FDA. In fact, labels with these types of claims must include the disclaimer “This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.”
It’s easy to misunderstand structure or function claims. For example, many people believe that a statement like? “helps maintain a healthy prostate gland” means the product has been proven to prevent or treat diseases like prostate cancer. This is not the case.
Don’t assume that because a product claims to support or promote healthy body function that it prevents or reduces the risk of any disease, including cancer.
Unlike the case with medicines, supplement makers cannot claim that their product can treat, diagnose, prevent, or cure diseases. For example, they can't say the supplement “reduces arthritic pain” or “treats heart disease.” Claims like these can only be made for medicines (drugs) that have been proven to do what they claim. Making such a claim automatically makes the product a drug, which would then be required to have the same proof of safety and effectiveness that the FDA requires for all drugs.
There are several organizations that provide quality testing and allow products to show a seal of quality assurance if they pass specific tests. This seal usually means that quality standards were used when making the product. They also test to be sure the ingredients listed on the label are actually in the product and that it doesn’t contain any contaminants or harmful chemicals.
Examples of organizations that offer quality testing are*:
*Inclusion on this list does not imply endorsement by the American Cancer Society.
There’s a lot of misleading information out there. Even for those who are usually well informed, it can be hard to find reliable information about the safe use and potential risks of dietary supplements.
Along with the American Cancer Society, other sources of reliable information include:
National Cancer Institute’s Office of Cancer Complementary and Alternative Medicine
Website:
Offers in-depth information about complementary and alternative therapies with a focus on cancer. Includes sections on talking to your healthcare provider about CAM, information about specific therapies, and frequently asked questions.
National Institutes of Health’s Office of Dietary Supplements
Website:
Provides information about wise supplement use and detailed fact sheets about individual vitamins and supplements. Also has an app you can use to keep up with supplements on your smart phone; choose My Dietary Supplements Mobile App on the left menu bar.
National Center for Complementary and Integrative Health (NCCIH)
Website:
Has information on complementary and alternative therapy-related topics and clinical trials including a section with fact sheets about many herbs.
Memorial Sloan Kettering Cancer Center - About Herbs and Botanicals
Website:
Provides information about herbs, botanicals, supplements, and more, for consumers and health care professionals. Also offers the About Herbs mobile app for free.
US Food and Drug Administration – Dietary Supplements
Website:
Includes information about labels, rules, regulations, and more about dietary supplements. Includes information about reporting problems with dietary supplements.
*Inclusion on this list does not imply endorsement by the American Cancer Society.
The American Cancer Society medical and editorial content team
Our team is made up of doctors and oncology certified nurses with deep knowledge of cancer care as well as editors and translators with extensive experience in medical writing.
Supplement Your Knowledge: Dietary Supplement Education Initiative
Website: www.fda.gov/food/information-consumers-using-dietary-supplements/supplement-your-knowledge
This site includes fact sheets and videos about dietary supplements for the public, educators and healthcare professionals. Materials for the public are available in English and Spanish.
Food and Drug Administration. Dietary Supplements. Last updated 8/16/2019. Accessed at https://www.fda.gov/food/dietary-supplements on May 12, 2021.
Harvie M. Nutritional supplements and cancer: Potential benefits and proven harms. Am Soc Clin Oncol Educ Book. 2014:e478-86.
National Center for Complementary and Integrative Health. Dietary and Herbal Supplements. Last updated February 2020. Accessed at https://www.nccih.nih.gov/health/dietary-and-herbal-supplements on May 27, 2021.
Office of Dietary Supplements, National Institutes of Health. What You Need to Know: Dietary Supplements. Accessed at http://ods.od.nih.gov/HealthInformation/ on May 11, 2021.
Last Revised: August 30, 2021
American Cancer Society medical information is copyrighted material. For reprint requests, please see our Content Usage Policy.
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