Do Multivitamins Do More Harm Than Good?

Do Multivitamins Do More Harm Than Good?

Is popping a multivitamin each morning a quick and easy way to protect against deficiency or are you doing your body more harm than good when you take vitamins in supplement form? Multivitamins are among the most popular supplements because people see them as a way to make up for dietary shortfalls. However, research doesn’t necessarily support the benefits of taking a multivitamin supplement.

What Does Research Show About Multivitamins?

A meta-analysis of 26 studies looking at multivitamin and mineral supplements for the prevention of health problems, including heart disease and cancer, showed taking vitamins and minerals in supplement form offered no protective benefits. All the news wasn’t bad – one study involving almost 15,000 men found a small reduction in cancer, but not heart disease risk among men who took a multivitamin daily.

Less reassuring is a study published in JAMA in 2011 showing older women who took a multivitamin with minerals had a HIGHER risk for mortality compared to those who didn’t. Based on this study, supplemental iron and copper was linked with the greatest mortality increase while calcium seemed to slightly lower the risk of dying prematurely. This isn’t surprising since iron can act as an antioxidant or pro-oxidant, meaning it can cause oxidative damage in higher quantities. Too much copper can also be a problem. A study showed taking copper in supplement form may reduce immune function and throw antioxidant status off balance. Plus, your body has a hard time excreting it. In addition, high doses of copper interfere with absorption of other minerals, including zinc.

The reality: Most men and women past menopause do not need an iron or copper supplement and may be harmed by it. Prior to menopause, some women can benefit from an iron supplement but don’t take one unless you know your iron stores are low. Ask your doctor to check an iron panel at your next visit.

A number of studies looking at multivitamin use have weaknesses because most of the data on vitamin use is self-reported. Plus, people who are already unhealthy may be more likely to take a vitamin and mineral supplement. Still, the results raise concerns about taking a multivitamin, especially when there’s a better way to get vitamins and minerals – by eating a healthy diet. There’s enough evidence against taking multivitamins that the U.S. Preventive Services Task Forces states:

“The current evidence is insufficient to assess the balance of benefits and harms of the use of multivitamins for the prevention of cardiovascular disease or cancer”

In addition, the U.S. Preventive Services Task Forces recommends against taking vitamin E or beta-carotene in supplement form. Good advice since a study showed these supplements don’t lower the risk of heart disease and are linked with a slight increase in heart disease and overall mortality. Keep in mind, some multivitamins contain up to three times the recommended daily allowance of vitamin E. Another study published in the New England Journal of Medicine showed men who smoked and took vitamin E, beta carotene or both for five years were at higher risk for dying of lung cancer or heart disease.

Avoid Supplementing with Isolated Vitamins Unless You’re Deficient

B vitamins in supplement form may also be problematic. Multivitamins contain the B vitamin folic acid, a vitamin women of reproductive age need to prevent birth defects, but if you don’t fall into this category, proceed with caution. Research has linked getting folic acid through vitamin supplements with an increased risk for breast and prostate cancer. Plus, folic acid is a synthetic form of the B vitamin, folate, your body uses. It’s better to get this B vitamin by eating green, leafy vegetables than by taking folic acid. Unlike folic acid in supplement form, green, leafy vegetables may offer protection against breast and prostate cancer.

Just as concerning is taking mega-doses of a single vitamin. At one time, it was fashionable to swallow vitamin C pills in high doses in hopes of warding off colds, but don’t be too quick to embrace this practice. Megadoses of vitamin C can lead to diarrhea and an increased risk for kidney stones. Plus, vitamin C can interact with some medications. Keep it simple. You can meet your vitamin C requirement by eating a medium orange every day or a cup of strawberries – no supplement needed.

Another problem with taking a multivitamin is the false sense of security it gives. Rather than focusing on eating a healthy diet, vitamin takers think their morning multivitamin has them covered. Unfortunately, a multivitamin can’t supply the multitude of phytochemicals that are in whole foods such as fruits, vegetables, and whole grains.

There Are Exceptions

In some situations, you may NEED to supplement with specific vitamins. For example, low vitamin D levels are common especially among people who get little sunlight or have a dark skin pigment and can’t absorb ultraviolet rays as easily. If you have a low vitamin D level, you’ll need to take a vitamin D supplement. Multivitamins don’t contain enough vitamin D to make up for a vitamin D shortfall. If you eat a vegan diet, you’ll likely need a calcium and vitamin B12 supplement since it’s hard to get adequate amounts of calcium and almost impossible to get enough vitamin B12 when you don’t eat meat or dairy.

The Bottom Line

Don’t take the easy route of getting your vitamins and minerals from a multivitamin supplement. The vitamins and minerals you get from food are in a balanced form and linked with other healthful components like fiber and beneficial phytochemicals. Instead of reaching for a pill bottle, fill your grocery cart with more nutrient-dense whole foods and chuck the foods with lots of empty calories. Read and learn about the nutrient content of the foods you eat, so you’ll make smarter choices. Plan your diet around foods with a high nutrient content.



JAMA Internal Medicine. October 10, 2011, Vol 171, No. 18.

U.S. Preventive Task Force. “Vitamin Supplementation to Prevent Cancer and CVD: Counseling”

Cleveland Clinic. “Antioxidants, Vitamin E, Beta Carotene, and Cardiovascular Disease”

N Engl J Med 1994; 330:1029-1035April 14, 1994DOI: 10.1056/NEJM199404143301501.

Nut Rev; 2006; 64(10PT1) 468-75.

J Natl Cancer Inst. 2009 Mar 18;101(6):432-5. Epub 2009 Mar 10.

Nutraingredients.com. “Copper Levels in Supplements Should Be Reduced”


Related Articles By Cathe:

Vitamins, Minerals, & Athletic Performance: Which Micronutrients Are of Greatest Concern?

Why Whole Foods Are Better Than Supplements

Do Micronutrient Deficiencies Increase the Risk of Cancer?

Do You Need More of Certain Vitamins as You Age?

Immune Health: Are You Getting Enough of These Micronutrients?


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