Frequently Asked Questions (FAQ)

How do I know if I need a dietary supplement?

Many products are marketed as dietary supplements, and it is important to remember that supplements include not only vitamins and minerals, but also herbs and other botanicals, probiotics, fish oil, 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 by MyPlate and the Dietary Guidelines for Americans.

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. Also check with your health care provider before taking a supplement, especially if you take any medicines or other dietary supplements or if you have any health conditions.

Where can I find out how much of each vitamin and mineral I need?

To get a list of all vitamins and minerals and how much you need, check out the free online tool from the U.S. Department of Agriculture. Just input a few pieces of information about yourself including your age, height, and weight. You also can get a list of your daily calorie, protein, and other nutritional needs. Keep in mind that the amounts of vitamins and minerals you need include everything you get from food and beverages—you may or may not need a dietary supplement to achieve these amounts. Talk with your health care provider to help you determine which supplements, if any, might be valuable for you. For more detailed information about each vitamin and mineral, read our vitamin and mineral fact sheets.

In addition, you can get good sources of information on eating well from the Dietary Guidelines for Americans and MyPlate.

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

Scientific evidence supporting the benefits of some dietary supplements (for example, 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 healthy 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. Also, check with your health care provider before taking a supplement, especially if you take any medicines or other dietary supplements or if you have any health conditions.

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:

What does the Supplement Facts label on a dietary supplement tell me?

 All products labeled as dietary supplements carry a Supplement Facts label that is similar to the Nutrition Facts label found on food products. It lists the active ingredients and their amounts, plus other added ingredients like fillers, binders, and flavorings. It also gives a suggested serving size, but you and your health care provider might decide that a different amount is more appropriate for you.

In the Supplement Facts label, the amounts of vitamins, minerals, and other nutrients like dietary fiber are listed as a percentage of the Daily Value (%DV). Each nutrient has one DV that applies to all people aged 4 and older. For example, the DV for vitamin C is 90 milligrams (mg) and the DV for the B-vitamin biotin is 30 micrograms (mcg).

The %DV allows you to see how much a product contributes to your approximate daily needs for that nutrient. For example, if a supplement provides 50% of the DV for calcium, it contributes about half of your daily needs for calcium.

The U.S. Food and Drug Administration (FDA) has a webpage that describes the Nutrition Facts label and DV in more detail.

Where can I find free, accurate information about vitamins, minerals, herbs, and other dietary supplements?

Good places to start are theODS dietary supplement fact sheets, which provide helpful information about dietary supplement ingredients including recommended amounts, health effects, safety, and medication interactions. Many of the ODS fact sheets come in three versions—the easy-to-readConsumer versionin both English and Spanish, and the more detailedHealth Professional version. Read them online or print a copy. In addition,Herbs at a Glancefact sheets from the National Center for Complementary and Integrative Health (NCCIH) provide basic information on specific herbs and botanicals—common names, uses, potential side effects, and resources for more information.

Where can I find published scientific studies about dietary supplements?

You can search for medical and scientific studies on specific dietary supplement ingredients using PubMed. PubMed is a database of the National Library of Medicine that provides access to over 35 million journal citations for biomedical literature from MEDLINE, life science journals, and online books.

Where can I find out how much of each vitamin and mineral I need?

To get a list of all vitamins and minerals and how much you need, check out thefree online toolfrom the U.S. Department of Agriculture. Just input a few pieces of information about yourself including your age, height, and weight. You also can get a list of your daily calorie, protein, and other nutritional needs. Keep in mind that the amounts of vitamins and minerals you need include everything you get from food and beverages—you may or may not need a dietary supplement to achieve these amounts. Talk with your health care provider to help you determine which

I know that carrots are healthy and have lots of vitamin A. But I’ve also heard that too much vitamin A can be dangerous, so do I need to limit how many carrots I eat?

Vitamin A can be toxic at high doses, causing liver damage and birth defects if a woman is pregnant. However, this applies only to the form of vitamin A—called preformed vitamin A or retinol—that is found in foods from animals, such as beef liver, milk, milk products, and some dietary supplements.

Plant foods, such as carrots, spinach, and red peppers, contain a form of vitamin A called beta-carotene. Consuming high amounts of beta-carotene can turn your skin yellow-orange, but this condition is harmless. Beta-carotene does not cause birth defects or the other more serious effects caused by getting too much preformed vitamin A.

 I know that dairy products like milk, yogurt, and cheese contain vitamin B12, but why isn’t it listed on the Nutrition Facts labels?

Food labels are not required to list vitamin B12 unless it has been added to the food. Therefore, you can’t rely on product labels to learn if a food naturally contains vitamin B12 and if so, how much.

For example, one cup of milk contains 1.3 mcg of vitamin B12. That’s a little over 50% of the Daily Value (DV). Six ounces of plain yogurt has 1.0 mcg and 1 ½ ounces of cheddar cheese has 0.5 mcg.