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Do You Know What’s Really in Your Dietary Supplements?

By Margaret Martin, RD, MS, LDN, CDCES September 24, 2014Pearls of Wisdom Blog

When faced with a serious condition like a cancer diagnosis, human nature is to do everything you can to win the fight against cancer. Many times people will turn to dietary supplements as part of their fighting arsenal. But do you know what’s really in your dietary supplements?

What are supplements?

The term “dietary supplements” refers to any vitamins, minerals, herbs, or a combination of these in a powder, pill or liquid form. Dietary supplements of this type are generally marketed as “healthy,” and many of us think nothing of taking one or more dietary supplement each day. But, there are risks associated with taking a dietary supplement, just as there are with any treatment or medication.

Who is keeping watch on dietary supplements?

Dietary supplements are defined and regulated by Congress, and the U.S. Food and Drug Administration (FDA) can stop the production of a dietary supplement whenever they have undeniable evidence that the supplement poses a significant risk to health. The supplements most commonly stopped by the FDA have been those targeting weight loss. The U.S. Department of Health and Human Services has developed a set of standards to which manufacturers of dietary supplements should adhere. These standards are called the Good Manufacturing Practices (GMPs).

Still, since dietary supplements are not defined as drugs, they are not evaluated under the same rules for effectiveness and safety as medications. The labeling requirements for dietary supplements are very different manufacturers of supplements are not required to list all ingredients or to publish potential dangers of their products on their labels. Dietary supplements may contain contaminants or harmful ingredients. Thus there can be issues of purity, quality, and strength in dietary supplements’ labeling.

What should you look for when shopping for dietary supplements?

There are two major independent organizations that evaluate and test dietary supplements for purity, quality, labeling, and strength. Manufacturers can voluntarily submit their products to these agencies for evaluation and verification. To spend your dietary supplement dollar wisely, look for the logo of the U. S. Pharmacopeia (USP) and the National Sanitation Foundation (NSF) on supplements before you buy. Products that are verified by the USP can be found at For products approved by the NSF, go to

How should you use dietary supplements?

Dietary supplements can act like a medication in your body or negatively affect your treatments for cancer. Always discuss any dietary supplement with your oncology healthcare team before taking them. Most cancer centers have a list of herbs or dietary supplements that need to be avoided or used only with the physician’s permission during treatment. Ask your doctor or healthcare team member today.

Summary: Despite the variety of governmental agencies with responsibilities around dietary supplements, purity, accurate labeling, and the absence of harmful additions are not a given in the United States. If you are thinking about using dietary supplements, remember that they are intended to “supplement” the diet that you consume, not to replace foods and beverages. The best and safest form of nutrition is traditional food and beverages. The human body has a sophisticated balance that is dependent on foods and beverages for nutrition, in both nutrient absorption and nutrient use. Do your homework and talk with your oncology team before using supplements.



American Cancer Society’s Complete Guide to Nutrition for Cancer Survivors

Margaret Martin, RD, MS, LDN, CDCES

Author Margaret Martin, RD, MS, LDN, CDCES

Nutrition Educator Margaret Martin is a Licensed Dietitian and Nutritionist in the State of Tennessee as well as a Certified Diabetes Educator. Margaret graduated from the University of Alabama with a Bachelor of Science in Dietetics and received her Master’s Degree in Nutrition Science & Public Health from the University of Tennessee. With more than 10 years of experience in Clinical Nutrition, Margaret has also worked in the insurance industry with WellPoint Inc. and Blue Cross Blue Shield providing telephonic nutrition consultations, service assistance, and web-based nutrition education. In her free time Margaret volunteers with the American Lung Association’s annual “Lung Force Walk" in Middle Tennessee. She belongs to the Oncology Nutrition & Diabetes Care and Education Dietetic Practice Groups of the Academy of Nutrition and Dietetics.

More posts by Margaret Martin, RD, MS, LDN, CDCES

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