Q. How do I know if I need a dietary supplement?
A. 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.
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 (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.
Q. What does the Supplement Facts label on a dietary supplement tell me?
Sample Supplement Facts label
A. 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.
Q. What is the difference between the RDA and DV for a vitamin or mineral?
A. 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 of the National Academies of Sciences, Engineering, and Medicine. They vary by age, sex, 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 260 milligrams (mg) of calcium in one serving because the DV for calcium is 1,300 mg/day. If another food has 40% of the DV for calcium, it’s easy to see that it provides much more calcium.