The supplemental vitamin industry is worth $39 billion USD and continues to grow. Nearly half of adults in the U.S. and 70% of older adults ages 71+ take a vitamin; about one-third of them use a comprehensive multivitamin pill.  But is this truly a necessity?
There are certainly diseases caused by a lack of specific nutrients in the diet. Classic examples include scurvy (from a lack of vitamin C), beri-beri (vitamin B1), pellagra (vitamin B3), and rickets (vitamin D). But these conditions are rare in the U.S. and other developed countries where there is generally more access to a wide range of foods, some of which are fortified with vitamins. Individual vitamin supplementation may also be essential in certain cases, such as a deficiency caused by long-term poor nutrition or malabsorption caused by the body’s digestive system not functioning properly.
This page specifically discusses the use of multivitamins, which typically contain about 26 different vitamins and minerals, and often provide 100% of the Recommended Daily Allowance of these micronutrients. We will explore situations that a multivitamin may be health-promoting, as well as if there is a benefit or harm in taking extra nutrients from a pill if the diet is already adequate.
Who May be at Risk for a Nutrient Deficiency?
For those who eat a healthful diet, a multivitamin may have little or no benefit. A diet that includes plenty of fruits, vegetables, whole grains, good protein sources, and healthful fats should provide most of the nutrients needed for good health. But not everyone manages to eat a healthful diet. When it comes to specific vitamins and minerals, some Americans get less than adequate amounts, according to criteria set by the National Academy of Medicine. For example, more than 90% of Americans get less than the Estimated Average Requirement for vitamin D and vitamin E from food sources alone. 
Certain groups are at higher risk for a nutrient deficiency:
- Older age. The elderly are at risk for poor food intake for various reasons: difficulty chewing and swallowing food, experiencing unpleasant taste changes caused by multiple medications, or isolation and loneliness that can depress appetite. They also have trouble absorbing vitamin B12 from food. The National Academy of Medicine, in fact, recommends that people over the age of 50 eat foods fortified with vitamin B12 or take vitamin B12 pills that are better absorbed than from food sources. 
- Pregnancy. Getting enough folate, a B vitamin, is especially important for women who may become pregnant, since adequate folate can help lower the risk of having a baby with spina bifida or anencephaly. For the folate to be effective, it must be taken in the first few weeks of conception, often before a woman knows she is pregnant. Yet in the U.S., half of all pregnancies are unplanned. That’s why the Centers for Disease Control and Prevention recommend that all women of childbearing age (ages 15 to 45) consume 600 micrograms a day of folic acid.  This amount and other important nutrients for pregnancy—iron, calcium, vitamin D, and DHA—are available in a prenatal multivitamin.
- Malabsorption conditions. Any condition that interferes with normal digestion can increase the risk of poor absorption of one or several nutrients. Examples:
- Diseases like celiac, ulcerative colitis, or cystic fibrosis.
- Surgeries that remove parts of digestive organs such as having a gastric bypass for weight loss or a Whipple procedure that involves many digestive organs.
- Illnesses that cause excess vomiting or diarrhea can prevent nutrients from being absorbed.
- Alcoholism can prevent nutrients, including several B vitamins and vitamin C, from being absorbed.
- Certain medications. Some diuretics commonly prescribed to lower blood pressure can deplete the body’s stores of magnesium, potassium, and calcium. Proton pump inhibitors prescribed for acid reflux and heartburn can prevent the absorption of vitamin B12 and possibly calcium and magnesium. Levodopa and carbidopa prescribed for Parkinson’s disease can reduce the absorption of B vitamins including folate, B6, and B12.
A note on vitamin D
Which Multivitamin Should I Choose?
Multivitamins come in various forms (tablets, capsules, liquids, powders) and are packaged as a specific combination of nutrients (B-complex, calcium with vitamin D) or as a comprehensive multivitamin.
Supplements are a multibillion-dollar industry, with endless designer labels of brands from which to choose. However, an expensive brand name is not necessary as even standard generic brands will deliver results. Look for one that contains the Recommended Daily Allowance amounts and that bears the United States Pharmacopeia (USP) seal of approval on the label. This seal ensures that the ingredients and amounts of that ingredient listed on the label are contained in the pill. The USP also runs several tests that confirm the pill to be free of contaminants like heavy metals and pesticides and has been manufactured under sanitary and regulated conditions.
That said, you may wish to consider the following factors before starting a multivitamin or any supplemental vitamin.
Reasons to use a multivitamin:
- I am eating a limited diet or my appetite is poor so that I am eating less than usual.
- I am following a restricted diet for longer than one week. This could be prescribed such as a liquid diet after a surgical procedure, or a self-imposed diet such as on with the goal of weight loss.
- I have a condition that reduces my body’s ability to absorb nutrients (celiac disease, ulcerative colitis) or have undergone surgery that interferes with the normal absorption of nutrients (gastric bypass surgery, Whipple procedure).
- I temporarily have increased nutrient needs, such as being pregnant.
- I’m very busy and just can’t eat a balanced diet every day.
Reasons that may not need a multivitamin:
- I eat well but am feeling tired all the time (discuss first with your doctor so they can investigate other possible causes).
- I eat a pretty good diet but want to improve my health as much as possible, so it couldn’t hurt to get some extra nutrition from a vitamin.
- I have osteoporosis and need more calcium, or I have iron-deficiency anemia and need more iron (in both scenarios, you may only need to take those individual nutrients rather than a comprehensive multivitamin).
If you are unsure about taking a multivitamin, you may wish to consult with a registered dietitian who can evaluate your current diet to determine any missing nutrients. At that time, suggestions to improve your food intake of those nutrients will be provided, or one or more supplemental vitamins may be prescribed if that is not possible. Always inform your doctor of all supplements you are taking in case of potential interactions with medications.
Mega-doses (many times the Recommended Daily Allowance) of vitamins are not recommended. This can potentially interfere with the absorption of other nutrients or medications, or can even become toxic if too much is taken for a long period.
Finally, be wary of supplemental vitamin labels that bait you with promises of “supporting brain health or energy production or healthy skin and hair.” These are general statements about a vitamin that are included for marketing purposes only, but are not specific to the supplement itself. Also be wary of vitamins that contain extras, like herbs and botanicals, which are typically lacking in research about long-term effects and potential adverse effects.
Multivitamins and Health
Knowledge about the optimal intakes of vitamins and minerals to prevent chronic diseases is not set in stone. More long-term studies looking at this relationship are needed.
There is no arguing that multivitamins are important when nutritional requirements are not met through diet alone.  The debate is whether vitamins are needed when the diet is adequate to prevent deficiency in nutrients, as some research has shown no benefit or even harmful effects when taking supplemental vitamins and minerals.
- After a review of 26 clinical and cohort studies, the U.S. Preventive Services Task Force concluded there was insufficient evidence to support any benefits of multivitamins or individual vitamins for the primary prevention of cardiovascular disease or cancer among healthy, nutrient-sufficient adults. 
For many diseases, but especially for cancer, only long-term trials are informative. The following studies looked at the effect of multivitamins on specific diseases and included healthy people as well as those with chronic diseases at the start of the study:
A randomized double-blind placebo-controlled trial provided a multivitamin or placebo to more than 14,000 male physicians, some with a history of cancer. After 11 years, the men taking a MVI had a significant 8% reduction in total cancers, compared with men taking a placebo. The results did not differ among men who had a history of cancer at the start of the study and men who were healthy at baseline. 
The Physicians’ Health Study II, a randomized double-blind placebo-controlled trial, provided a multivitamin or placebo to more than 14,000 male physicians, some with a history of cardiovascular disease. After 11 years, compared with the placebo, there was no significant effect of a daily MVI on cardiovascular events. 
Some research has suggested that the rates of death appear higher in people using multivitamins. However, one major flaw in these studies was that many of the participants had already developed some type of serious illness. They may have started using vitamins after their health deteriorated, hoping for a benefit. But in those cases, taking a multivitamin might have been too late.
- The Iowa Women’s Health Study looked at the use of 15 vitamins and minerals, including multivitamins, at three different intervals and identified the numbers of women who died over a 19-year period. It showed that women over the age of 55 who took multivitamins were at higher risk for dying than those who did not.  A similar risk was found for other vitamins and minerals, including folate, vitamin B6, iron, magnesium, and zinc.
- The Iowa study, however, didn’t exclude women who were sick or take into account how long they were using the vitamins. As a result, it is unknown whether the women were already taking vitamins when they became ill, or if they became ill and then started taking vitamins. In women who were already sick, taking vitamins was unlikely to lower their risk of dying.
The Bottom Line
It is important to remember that a multivitamin cannot in any way replace a healthful well-balanced diet. The main purpose of a multivitamin is to fill in nutritional gaps, and provides only a hint of the vast array of healthful nutrients and chemicals naturally found in food. It cannot offer fiber or the flavor and enjoyment of foods so key to an optimal diet. However, multivitamins can play an important role when nutritional requirements are not met through diet alone. When this is the case, an expensive brand name is not necessary, as even standard store brands will deliver results. Look for one that contains the Recommended Daily Allowance amounts and that bears the United States Pharmacopeia (USP) seal of approval on the label.
- Bailey RL, Gahche JJ, Lentino CV, Dwyer JT, Engel JS, Thomas PR, Betz JM, Sempos CT, Picciano MF. Dietary supplement use in the United States, 2003–2006. The Journal of nutrition. 2011 Feb 1;141(2):261-6.
- Fulgoni III VL, Keast DR, Bailey RL, Dwyer J. Foods, fortificants, and supplements: where do Americans get their nutrients?. The Journal of nutrition. 2011 Oct 1;141(10):1847-54.
- Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes: Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, DC: National Academy Press, 1998.
- Rautiainen S, Manson JE, Lichtenstein AH, Sesso HD. Dietary supplements and disease prevention—a global overview. Nature Reviews Endocrinology. 2016 Jul;12(7):407-20.
- Fortmann SP, Burda BU, Senger CA, Lin JS, Whitlock EP. Vitamin and mineral supplements in the primary prevention of cardiovascular disease and cancer: an updated systematic evidence review for the US Preventive Services Task Force. Annals of internal medicine. 2013 Dec 17;159(12):824-34.
- Gaziano JM, Sesso HD, Christen WG, Bubes V, Smith JP, MacFadyen J, Schvartz M, Manson JE, Glynn RJ, Buring JE. Multivitamins in the prevention of cancer in men: the Physicians’ Health Study II randomized controlled trial. JAMA. 2012 Nov 14;308(18):1871-80.
- Sesso HD, Christen WG, Bubes V, Smith JP, MacFadyen J, Schvartz M, Manson JE, Glynn RJ, Buring JE, Gaziano JM. Multivitamins in the prevention of cardiovascular disease in men: the Physicians’ Health Study II randomized controlled trial. JAMA. 2012 Nov 7;308(17):1751-60.
- Mursu J, Robien K, Harnack LJ, Park K, Jacobs DR. Dietary supplements and mortality rate in older women: the Iowa Women’s Health Study. Archives of internal medicine. 2011 Oct 10;171(18):1625-33.
The contents of this website are for educational purposes and are not intended to offer personal medical advice. You should seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website. The Nutrition Source does not recommend or endorse any products.