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Understanding Dietary Supplements1

Daniel Staub and Anne Mathews2

More than half of adults in the United States take at least one dietary supplement (Bailey et al. 2013). Whether you belong to this majority or not, it is important to know in what situations supplements may be effective for improving health and wellness. Important considerations include your age, lifestyle habits, and current health conditions. If you decide that you may benefit from taking a dietary supplement or are already a supplement user, this fact sheet will help you know how to choose a supplement that is safe, effective, and appropriate for you.

What Are Dietary Supplements?

A dietary supplement is “a product intended for ingestion that contains a ‘dietary ingredient’ intended to add further nutritional value to (supplement) the diet” (USDA 2015). This “dietary ingredient” may be a vitamin, mineral, herb, amino acid, or a variety of other substances (USDA 2016). Such products are most commonly found in tablet, powder, or capsule form (NIH 2011). All products labeled as dietary supplements must meet quality standards established by the Food and Drug Administration (FDA). Meeting these standards does NOT ensure that the supplement is safe or effective (NIH 2011). Listed below are some of the most common dietary supplements (USDA 2016).

  • Calcium

  • Echinacea

  • Fish Oil

  • Ginseng

  • Glucosamine

  • Chondroitin Sulfate

  • Garlic

  • Vitamin D

  • St. John’s Wort

  • Saw Palmetto

  • Ginkgo

  • Green Tea

To clearly understand what dietary supplements are, it helps to understand what dietary supplements are not. Dietary supplements are not regulated as drugs and are not permitted to contain ingredients that are approved as drugs or are under investigation as a new drug. Dietary supplements are not intended to treat, diagnose, prevent, or cure diseases, and supplement companies are not permitted to make any drug claims on the supplement label (USDA 2016). Supplements are not meant to replace a healthy diet. Instead, they are intended to supplement one’s diet by providing nutrients or other substances that might be lacking or that might help lessen disease risk (NIH 2011).

Should I Be Using Dietary Supplements?

In most circumstances, dietary supplements are not necessary for optimal health (USDA 2016). The nutritional needs of healthy adults can be met through a well-planned diet that includes a variety of nutrient-dense foods as outlined in the Dietary Guidelines for Americans and MyPlate (see below). However, following a healthful diet on a regular basis can be challenging for some people, and there are instances in which dietary supplements can improve nutritional status or help manage certain health conditions (USDA 2016). Whether or not these benefits apply to you is dependent on your unique situation. Benefits of supplements vary with age, gender, diet, lifestyle, family history, and health status. Below are some instances in which supplementation may be beneficial (NIH 2011):

  • supplemental vitamin D for darker-skinned individuals and those with limited sun exposure

  • supplemental vitamin B12 for a person following a strict vegan diet

  • supplementation with fish oil for a person with a family history of heart disease Talk with your doctor first if you take an anticoagulant medication (blood thinner) like Coumadin.

  • folic acid for women of childbearing age

For more information on a healthy diet see the Dietary Guidelines for Americans 2015–2020:; and MyPlate:

Supplement use is typically warranted when dietary intake is inadequate, needs for a particular nutrient are increased, or disease risk is a concern. Evaluating your nutritional needs, the nutritional adequacy of your diet, and your disease risk profile are complex tasks. It is recommended that you work together with your health care provider to determine if supplements are right for you.

For more information on vitamins, minerals, and other nutrients see: These fact sheets can provide a good basis for a discussion with your health care provider about whether or not you should take a vitamin/mineral supplement (NIH n.d.) .

Regulation of Dietary Supplements

The FDA is the agency responsible for regulating dietary supplements. The regulation of supplements is different from the regulation of food and drugs. Unlike drugs, supplements are not reviewed or approved prior to being sold to consumers. The Dietary Supplement Health and Education Act (DSHEA), passed in 1994, established that prior approval of nutritional supplements is not required. Instead of a requirement to demonstrate safety and effectiveness of their products, companies are required by the FDA to prove that their products are free of impurities or contaminants and are labeled in a way that is accurate and not misleading. Companies are responsible for reporting any serious and harmful side effects caused by their products only after they are on the market. If serious side effects occur, the FDA may remove a supplement from the market (USDA 2015, USDA 2016).

Evaluating the Safety and Efficacy of Supplements

Although supplement companies do not need to prove the safety and effectiveness of their products before they are sold to consumers, there are still several steps you can take as a supplement buyer to ensure that a supplement (not a particular product) is generally safe and effective.

For starters, do your research. Take time to read up on the supplement of interest using non-commercial sources of information such as the National Institute of Health (NIH), FDA, and US Department of Agriculture (USDA). These government agencies have developed supplement fact sheets that list a variety of supplements and provide current scientific information about the supplements in a concise and easy-to-understand way. After presenting the proposed benefits of a given supplement, they provide a summary of what the current science says regarding its safety and effectiveness based on actual human studies and case reports. They point out any side effects and cautions that may be associated with that supplement, but not with a particular product that is on the market. If you would like to research a supplement using these tools, check out the links below.

Another measure you can take to help determine if a supplement is safe, effective, and right for you is to discuss it with your healthcare provider. This is especially important if you are pregnant, nursing, or considering giving the supplement to a child. Most dietary supplements have not been thoroughly tested for safety in these populations (USDA 2016). When talking with your healthcare provider, be sure to ask about any potential drug interactions associated with the supplement. It is important to detail any medications you are taking or any conditions you may have to ensure that there are no risks to you when using the supplement. In addition, your healthcare provider may offer important insights regarding the dosage, length of use, and other important considerations specific to you.

Once you have verified a supplement is safe, effective, and appropriate for you, you need to find a reputable manufacturer. Research may show that a supplement is safe and effective, but that does not mean that all products labeled as that supplement are safe and effective, or even that the product actually contains the supplement that is listed on the label in the amount that is shown. There are often various forms and strengths of a supplement, as well as other ingredients added to the supplement. There also may be variability in quality of the product. Even though the FDA has established quality standards for dietary supplements, it does not perform quality checks on a consistent basis. However, there are several independent organizations that offer quality testing of supplements (USDA 2016). They award their seal of approval only to those brands that are properly manufactured, contain the ingredients that are listed on the label in the amounts stated, and do not have harmful levels of contaminants (USDA 2016). These organizations include

Additionally, you should ask your healthcare provider for brand recommendations to ensure that the brand is not only reputable, but meets your specific needs.


Dietary supplements cannot replace the benefits of a healthy, well-balanced diet, but may offer some additional benefits. To find out if you could potentially benefit from the use of a particular supplement, visit some of the sources listed above and talk to your healthcare provider. Remember, supplements do not need to be proven safe and effective before being sold, so be careful and only consider information from non-biased sources like the government websites provided in this article, not the manufacturer. If you find that a supplement is safe, effective, and appropriate for you, be sure to choose a reputable brand with special consideration to the form, dosage, and quality. If you take the time to follow these recommendations, you can effectively maximize the potential benefits to your health while avoiding potential risks.

For more information, visit the NIH’s Office of Dietary Supplements FAQ page at or talk to your healthcare provider.


Bailey, R.L., J.J. Gahche, P.E. Miller, P.R. Thomas, and J.T. Dwyer. 2013. “Why US Adults Use Dietary Supplements.” JAMA Intern Med 173(5):355–361. doi:10.1001/jamainternmed.2013.2299.

National Institutes of Health (NIH), Office of Dietary Supplements. 2011. Dietary Supplements: What You Need to Know.

National Institutes of Health (NIH), Office of Dietary Supplements. n.d. Vitamin and Mineral Supplement Fact Sheets. 2016. Questions to Ask Before Taking Vitamin and Mineral Supplements.

US Food and Drug Administration (USDA). 2016. Dietary Supplements: What You Need to Know.

US Food and Drug Administration (USDA). 2015. What is a Dietary Supplement.



This document is FSHN16-2, one of a series of the Food Science and Human Nutrition Department, UF/IFAS Extension. Original publication date May 2016. Visit the EDIS website at


Daniel Staub, student; and Anne Mathews, assistant professor, Food Science and Human Nutrition Department; UF/IFAS Extension, Gainesville, FL 32611.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.