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Questions to Ask Before Taking Vitamin and Mineral Supplements


Information from the U.S. Department of Agriculture

Are you considering taking vitamin or mineral supplements? Do you think
you need them? Or, that they “can’t hurt” so you may as well take them?
Here are some questions to ask before you decide to take them.

Do I really need them?
First and foremost, nutritional needs should be met by eating a variety
of foods as outlined in the Dietary Guidelines for Americans. In some
cases, vitamin/mineral supplements or fortified foods may be useful for
providing nutrients that may otherwise be eaten in less than recommended
amounts. If you are already eating the recommended amount of a
nutrient, you may not get any further health benefit from taking a
supplement. In some cases, supplements and fortified foods may actually
cause you to exceed safe levels of intake of nutrients.

(Note that fortified foods are those to which one or more essential
nutrients have been added, to increase their nutritional value.)

The Dietary Guidelines for Americans makes these recommendations for certain groups of people:

  • People over age 50 should consume Vitamin B12 in its crystalline
    form, that is, from fortified foods (like some fortified breakfast
    cereals) or as a supplement.
  • (Note that older adults often have a reduced ability to absorb
    Vitamin B12 from foods. However, crystalline Vitamin B12, the type of
    Vitamin B12 used in supplements and in fortified foods, is much more
    easily absorbed.)
  • Women of childbearing age who may become pregnant and adolescent
    females should eat foods that are a source of heme-iron (such as meats)
    and/or they should eat iron-rich plant foods (like cooked dry beans or
    spinach) or iron-fortified foods (like fortified cereals) along with a
    source of Vitamin C.
  • Women of childbearing age who may become pregnant and those who
    are pregnant should consume adequate synthetic folic acid daily (from
    fortified foods or supplements) in addition to food forms of folate from
    a varied diet.
  • Older adults, people with dark skin, and people who get insufficient exposure to sunlight should consume extra Vitamin D from
  • Vitamin D-fortified foods and/or supplements.

It is important to note that vitamin/mineral supplements are not a
replacement for a healthful diet. Remember that in addition to vitamins
and minerals, foods also contain hundreds of naturally occurring
substances that can help protect your health.

Here are some questions that the Food and Drug Administration recommends
asking yourself and discussing with your doctor when considering
whether you should take a vitamin/mineral supplement:

  • Do you eat fewer than two meals per day?
  • Is your diet restricted? That is, do you not eat meat, milk, or
    milk products, or do you eat fewer than five servings of fruits and
    vegetables per day?
  • Do you eat alone most of the time?
  • Without wanting to, have you lost or gained more than 10 pounds in the last 6 months?
  • Do you take three or more prescription or over-the-counter medicines a day?
  • Do you have three or more drinks of alcohol a day?

Should I talk to my doctor about taking vitamin/mineral supplements?

Yes, you and your doctor should work together to determine if a vitamin/mineral supplement is right for you.

If you are already taking dietary supplements, you should inform your
doctor. Research shows that many people do not let their doctors know
that they are taking a dietary supplement or are considering taking one.
You may think side effects happen only with prescription medicines, but
some dietary supplements can cause side effects if taken with other
medications or if certain health conditions exist. Even if you don’t
take medication or have a chronic health problem, the wrong dietary
supplement, or the wrong amount, can cause problems. So, check with your
doctor before taking a dietary supplement.

Where can I find scientifically sound information about vitamin/mineral supplements?

Your doctor is a good place to start. In addition, pharmacists and registered dietitians are helpful.

The NIH Office of Dietary Supplements has a series of vitamin and
mineral fact sheets that provide scientifically-based overviews of a
number of vitamins and minerals. They can provide a good basis for a
discussion with your doctor about whether or not you should take a
vitamin/mineral supplement. MedlinePlus is another good source of

The Food and Drug Administration (FDA) has a variety of articles and
consumer advisories to help consumers inform themselves about dietary
supplements, including warnings and safety information, labeling,
evaluation information, and FDA’s role in regulating dietary

For those interested in looking directly at scientific studies, the
PubMed Dietary Supplement Subset is a good database to search.

What should I do if I suspect I may be having a side-effect from a dietary supplement?

First, stop taking the supplement. Next, tell your doctor or health care
professional. The MedWatch Reporting Program also gives you information
about how to report a problem to the Food and Drug Administration.

In summary, check with your doctor or a registered dietitian about
which, if any, vitamin or mineral supplements might be right for you.
And remember that while there are circumstances when it may be
appropriate to take vitamin/mineral supplements, they are not a
replacement for a healthful diet.

For more information about supplements, vitamins, and other nutritionally related questions, visit

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