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Frequently Asked Questions (FAQ)

Frequently Asked Questions (FAQ)

Table of Contents

Use and Safety of Dietary Supplements

Q. How do I know if I need a dietary supplement?

A. Because many products are marketed as dietary supplements, it is important to remember that supplements include vitamins and minerals, as well as herbs, botanicals and other substances.

Some supplements may help ensure that you get adequate amounts of essential nutrients or help promote optimal health and performance if you do not consume a variety of foods, as recommended in the MyPlateexternal link icon and Dietary Guidelines for Americansexternal link icon.

However, dietary supplements are not intended to treat, diagnose, mitigate, prevent, or cure disease. In some cases, dietary supplements may have unwanted effects, especially if taken before surgery or with other dietary supplements or medicines, or if you have certain health conditions.

Do not self diagnose any health condition. Work with your health care provider to determine how best to achieve optimal health and always check with your health care provider before taking a supplement, especially when combining or substituting them with other foods or medicine.

Q. How can I get more information about a particular dietary supplement such as whether it is safe and effective?

A. Scientific evidence supporting the benefits of some dietary supplements (e.g., vitamins and minerals) is well established for certain health conditions, but others need further study. This is partly due to the way dietary supplements are regulated by the U.S. Food and Drug Administration (FDA).

Research studies in people to prove that a dietary supplement is safe are not required before the supplement is marketed, unlike for drugs. It is the responsibility of dietary supplement manufacturers/distributors to ensure that their products are safe and that their label claims are accurate and truthful. If the FDA finds a supplement to be unsafe once it is on the market, only then can it take action against the manufacturer and/or distributor, such as by issuing a warning or requiring the product to be removed from the marketplace.

The manufacturer does not have to prove that the supplement is effective, unlike for drugs. The manufacturer can say that the product addresses a nutrient deficiency, supports health, or reduces the risk of developing a health problem, if that is true. If the manufacturer does make a claim, it must be followed by the statement "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."

Dietary supplements are not intended to treat, diagnose, mitigate, prevent, or cure disease. In some cases, dietary supplements may have unwanted effects, especially if taken before surgery or with other dietary supplements or medicines, or if you have certain health conditions. Whatever your choice, supplements should not replace prescribed medications or the variety of foods important to a healthful diet.

Do not self diagnose any health condition. Work with your health care provider to determine how best to achieve optimal health and always check with your health care provider before taking a supplement, especially when combining or substituting them with other foods or medicine.

In addition to talking with your health care provider about dietary supplements, you can search on-line for information about a particular dietary supplement. It is important to ensure that you obtain information from reliable sources such as:

For tips on evaluating sources of healthcare information on the Internet, please see the following document: How to Evaluate Health Information on the Internet: Questions and Answers.

Q. Where can I find information about the use of dietary supplements for a particular health condition or disease?

A. Scientific evidence supporting the benefits of some dietary supplements (e.g., vitamins and minerals) is well established for certain health conditions, but others need further study. Whatever your choice, supplements should not replace prescribed medications or the variety of foods important to a healthful diet.

Dietary supplements are not intended to treat, diagnose, mitigate, prevent, or cure disease. In some cases, dietary supplements may have unwanted effects, especially if taken before surgery or with other dietary supplements or medicines, or if you have certain health conditions.

Do not self diagnose any health condition. Work with your health care provider to determine how best to achieve optimal health and always check with your health care provider before taking a supplement, especially when combining or substituting them with other foods or medicine.

In addition to talking with your health care provider about dietary supplements for a particular health condition or disease, you can search on-line for information. It is important to ensure that you obtain information from reliable sources such as:

For tips on evaluating sources of healthcare information on the Internet, please see the following document: How to Evaluate Health Information on the Internet: Questions and Answers.

Q. What is the difference between the RDA and DV for a vitamin or mineral?

Many terms are used when referring to either the amount of a particular nutrient (such as calcium or vitamin D) you should get or the amount in a food or dietary supplement. The two most common are the Recommended Dietary Allowance (RDA) and the Daily Value (DV). These terms can be confusing.

RDAs are recommended daily intakes of a nutrient for healthy people. They tell you how much of that nutrient you should get on average each day. RDAs are developed by the Food and Nutrition Board at the Institute of Medicine of the National Academies. They vary by age, gender and whether a woman is pregnant or breastfeeding; so there are many different RDAs for each nutrient.

DVs, established by the U.S. Food and Drug Administration (FDA), are used on food and dietary supplement labels. For each nutrient, there is one DV for all people ages 4 years and older. Therefore, DVs aren't recommended intakes, but suggest how much of a nutrient a serving of the food or supplement provides in the context of a total daily diet. DVs often match or exceed the RDAs for most people, but not in all cases.

DVs are presented on food and supplement labels as a percentage. They help you compare one product with another. As an example, the %DV for calcium on a food label might say 20%. This means it has 200 mg (milligrams) of calcium in one serving because the DV for calcium is 1,000 mg/day. If another food has 40% of the DV for calcium, it's easy to see that it provides much more calcium than the first food.

The FDA has a Web page that lists the DVs for all nutrientsexternal link icon and provides additional details.

Q. Where can I report a complaint about a particular dietary supplement or find contact information for a supplement company?

A. To report an illness or injury associated with a dietary supplement, please talk with your health care provider and contact the U.S. Food and Drug Administration (FDA)external link icon.

To report a complaint involving misleading advertising, fraud, or other consumer protection matters associated with a dietary supplement, please contact the Federal Trade Commission (FTC)external link icon. The FTC also has a helpful web page with tips for resolving common consumer problemsexternal link icon that provides links to state, local and national organizations that might be able to help.

If you are having trouble finding contact information for a dietary supplement manufacturer or distributor, check our Dietary Supplement Label Databaseexternal link icon. It provides contact information for many dietary supplement companies.

Purchasing Dietary Supplements

Q. Where can I purchase dietary supplements?

A. Dietary supplements are available without a prescription through a number of retail outlets including grocery stores, drug stores, general merchandise retailers, natural food stores and specialty health and nutrition stores. Many dietary supplements can also be purchased online through the Internet.

Q. Which brand(s) of dietary supplements should I purchase?

A. There are a number of factors including price, quality and availability that may influence your buying decision. The Office of Dietary Supplements (ODS) does not test, analyze or rate dietary supplements, nor can we recommend certain brands. You may wish to ask your health care provider to make a recommendation.

If you have questions about a specific brand of dietary supplements, you can contact the manufacturer for more information. Ask to speak to someone who can address your questions, some of which may include:

  1. What information does the firm have to substantiate the claims made for the product? Be aware that sometimes firms supply so-called "proof" of their claims by citing undocumented reports from satisfied consumers, or graphs and charts that could be mistaken for well conducted scientific research.
  2. Does the firm have information to share about tests it has conducted on the safety or efficacy of the ingredients in the product?
  3. Does the firm follow good manufacturing practices and have a quality control system in place to determine if the product actually contains what is stated on the label and is free of contaminants?
  4. Has the firm received any adverse events reports from consumers using their products?

In addition, there are a few independent organizations that offer "seals of approval" that may be displayed on certain dietary supplement products. These indicate that the product has passed the organization's quality tests for things such as potency and contaminants. These "seals of approval" do not mean that the product is safe or effective; they provide assurance that the product was properly manufactured, that it contains the ingredients listed on the label and that it does not contain harmful levels of contaminants.

The following is a list of several organizations offering these programs:

Q. How do I know if the supplement that I purchased contains the ingredients that it claims on the label or if it is contaminated?

A. You should be aware that the U.S. Food and Drug Administration (FDA) does not analyze the content of dietary supplements. However, in 2007, FDA issued Good Manufacturing Practices (GMPs) for dietary supplements, a set of requirements and expectations by which dietary supplements must be manufactured, prepared, and stored to ensure quality. Manufacturers are expected to guarantee the identity, purity, strength, and composition of their dietary supplements. For example, the GMPs aim to prevent the inclusion of the wrong ingredients, the addition of too much or too little of a dietary ingredient, the possibility of contamination (by pesticides, heavy metals such as lead, bacteria, etc.), and the improper packaging and labeling of a product. Large companies are required to comply with FDA's dietary supplement GMPs now, and the smallest companies by June 2010. Some manufacturers voluntarily follow the FDA's GMPs for drugs, which are stricter.

Some manufacturers use the term "standardized" to describe efforts to make their products consistent. However, U.S. law does not define standardization. Therefore, the use of this term (or similar terms such as "verified" or "certified") does not guarantee product quality or consistency.

If you have questions about a specific brand of dietary supplements, you can contact the manufacturer for more information. Ask to speak to someone who can address your questions, some of which may include:

  1. What information does the firm have to substantiate the claims made for the product? Be aware that sometimes firms supply so-called "proof" of their claims by citing undocumented reports from satisfied consumers, or graphs and charts that could be mistaken for well conducted scientific research.
  2. Does the firm have information to share about tests it has conducted on the safety or efficacy of the ingredients in the product?
  3. Does the firm follow good manufacturing practices and have a quality control system in place to determine if the product actually contains what is stated on the label and is free of contaminants?
  4. Has the firm received any adverse events reports from consumers using their products?

In addition, there are a few independent organizations that offer "seals of approval" that may be displayed on certain dietary supplement products. These indicate that the product has passed the organization's quality tests for things such as potency and contaminants. These "seals of approval" do not mean that the product is safe or effective; they provide assurance that the product was properly manufactured, that it contains the ingredients listed on the label and that it does not contain harmful levels of contaminants.

The following is a list of several organizations offering these programs:

Q. With so many dietary supplements to choose from, how can I compare the ingredients and doses in one product with those in another?

A. The Dietary Supplement Label Database (DSLD) contains label information from thousands of dietary supplement products available in the U.S. marketplace. It can be used to search, for example, for a specific ingredient in a product, a particular supplement manufacturer, text on a label, and a specific health-related claim.

Regulatory Information

Q. Who is responsible for overseeing the regulation of dietary supplements in the United States?

A. In the United States, the U.S. Food and Drug Administration (FDA) has regulatory responsibility for dietary supplements. FDA regulates dietary supplements under a different set of regulations than those covering "conventional" foods and drug products (prescription and over-the-counter). Under the Dietary Supplement Health and Education Act of 1994, the dietary supplement manufacturer is responsible for ensuring that a dietary supplement is safe before it is marketed. FDA is responsible for taking action against any unsafe dietary supplement product after it reaches the market.

Manufacturers must make sure that product label information is truthful and not misleading. FDA's post-marketing responsibilities include monitoring safety, e.g. voluntary dietary supplement adverse event reporting, and product information, such as labeling, claims, package inserts, and accompanying literature.

For more information, please contact the FDA Center for Food Safety and Applied Nutritionexternal link icon via their Web site or at 1-888-723-3366.

The Federal Trade Commission (FTC) regulates advertising of dietary supplements in national or regional newspapers and magazines; in radio and TV commercials, including infomercials; through direct mail to consumers; or on the Internet. The FTC requires that all information about supplements be truthful and not misleading.

For more information, please contact the FTCexternal link icon via their website.

Q. How do I produce, market, import, distribute or sell a dietary supplement in the United States?

A. The Center for Food Safety and Applied Nutrition of the U.S. Food and Drug Administration handles all regulatory matters for dietary supplements. Please contact CFSANexternal link icon via their website for more information or call 1-888-723-3366.

Dietary Supplement Sales and Market Data

Q. Where can I locate information or data on dietary supplement sales and usage?

A. The Office of Dietary Supplements (ODS) does not track dietary supplement sales or usage. You can search for publications on these topics through databases of medical and scientific literature:

In addition to searching for scientific publications, you may wish to contact market research companies that provide sales and marketing data for the nutrition industry. For example, the Nutrition Business Journalexternal link icon provides market data and analysis of the global nutrition industry, including dietary supplements.

ODS Web site Materials and Link Requests

Q. Can I reproduce fact sheets and other materials found on the Office of Dietary Supplements Web site?

A. Most of the information available from the Office of Dietary Supplements (ODS) Web site is within the public domain and unless stated otherwise, may be freely downloaded and reproduced, provided the content has not been changed or modified. You may also link to individual pages within the ODS Web site, provided that attribution is made to the ODS and any descriptive notes accurately reflect the content of the page being linked to.

At times the ODS Web site may contain documents or links to documents, such as full-text journal articles that may be copyright protected. Permission to reproduce copyrighted documents may be required.

Q. Can I add a link to the Office of Dietary Supplements Web site from my Web site?

A. The ODS encourages linking to its public Web resources. If you wish to link to the ODS Web site, please direct your link to http://ods.od.nih.gov. If you intend to provide a description with your link, the ODS would prefer the wording:

"The Office of Dietary Supplements, a part of the National Institutes of Health, works to strengthen knowledge and understanding of dietary supplements by evaluating scientific information, stimulating and supporting research, disseminating research results, and educating the public about the efficacy and safety of dietary supplements in order to foster an enhanced quality of life and health for the U.S. population."

The abbreviated description "http://ods.od.nih.gov: The Web site of the Office of Dietary Supplements" is also acceptable.

You may also link to individual pages within this site, provided that attribution is made to the ODS and any descriptive notes accurately reflect the content of the page being linked to.

Q. How can I nominate my Web site for a link from the Office of Dietary Supplements Web site?

A. ODS provides links to government-sponsored or government-supported Web sites that meet the following criteria:

  • Relates to the mission of the ODS;
  • Complements and enhances the information on the ODS Web site;
  • Provides credible, accurate, current, science-based information;
  • Is subject to adequate procedures for the review and updating of material;
  • Primarily focuses on information or educational content, rather than the promotion of a product or service;
  • Adheres to adequate policies regarding external links and privacy of user data.

These criteria may change to reflect new Web policies at the ODS.

If your Web site meets the above criteria, you may nominate your Web site for a link from the ODS Web site by contacting us.

All submissions will be reviewed by ODS staff or external reviewers with expertise in the topic. Currently linked sites undergo periodic re-review. You will receive a decision via email in approximately 1 month.

To provide information from non-government-sponsored or -supported Web sites to our Web site visitors, ODS links to the National Library of Medicine Web site MedlinePlusexternal link icon. MedlinePlus provides good health information for health professionals and consumers from the National Institutes of Health and other trusted sources on over 700 diseases and conditions. If your Web site provides reliable, science-based information on dietary supplements, we suggest that you contact MedlinePlusexternal link icon to inquire about establishing a link from their Web site.

Media Inquiries

Q. I am with the media and would like to talk with someone from the Office of Dietary Supplements about my dietary supplement questions. How should I proceed?

A. Our Media Resources Web page has information about our office and staff and provides links to dietary supplement fact sheets, databases, and other resources. If you need information you haven't found on our Web site, or if you wish to request an interview, please send an e-mail to ODSMedia@mail.nih.gov (for media inquiries only). In the body of the e-mail, include your questions, affiliation and deadline. This allows us to research your questions and have the appropriate staff member contact you. We will make every effort to meet your deadline.

The Office of Dietary Supplements (ODS) has provided this material as a service to our users. All health-related material and links contained in this document are provided for information purposes only and do not represent endorsement by or an official position of the ODS or any other Federal agency. The ODS is not responsible for the information at the linked sites and does not endorse any products or services found there.

The information in this document does not replace medical advice. Advice on treatment or care of an individual patient should be obtained through consultation with a physician or trained health care practitioner who has examined that patient or is familiar with that patient's medical history.

Reviewed: July 01, 2013