The Truth About Taking Vitamins
Many of us do this every day. But is it a good idea?
Multivitamins and single vitamins are some of the most popular supplements in the U.S. In a summer 2022 nationally representative Consumer Reports survey (PDF) of 3,070 U.S. adults, about half of people said they take multivitamins and 42 percent said they take individual vitamins— for everything from improving general health and boosting immunity to preventing COVID-19.
While experts agree that most Americans don’t eat enough vitamin-rich foods, research shows that vitamin supplements might not be a great way to bridge the gap. And people who take higher doses of certain vitamin supplements actually have a higher risk of adverse health outcomes. In the U.S., the days of widespread vitamin deficiencies causing conditions like scurvy and rickets are long gone. If you have a deficiency, a doctor may recommend a vitamin. But many ailments, including certain cancers, heart disease, and diabetes, stem from multiple factors and don’t seem to be prevented or treated with vitamins.
Unless you have certain medical conditions or a restrictive diet, vitamin supplements are generally not helpful, says Fang Fang Zhang, MD, chair of the division of nutrition epidemiology and data science at Tufts University in Boston. Still, there are some exceptions. One key caution: If you take vitamins, avoid mega-dosing, Zhang says. That could cause stomach upset or organ damage, or even increase cancer risk. “More isn’t always better,” Zhang says.
Here’s what to consider.
The Research on Multivitamins
“A lot of my patients take multivitamins because they see them almost as an insurance policy to guarantee they get all the nutrients they need,” says Kenneth Koncilja, MD, a geriatrician at the Cleveland Clinic.
A 2020 study published in the journal BMJ Open found that people who took these over-the-counter (OTC) products—which contain all or most recognized vitamins and minerals—reported better overall well-being. But most research doesn’t bear this out. The BMJ study found no measurable health benefits for users.
Special Situations
A multi may be helpful in a few cases—say, after gastric bypass surgery or for severe malnutrition due to cancer—but most of the time you’re best off getting nutrients from a balanced diet, Koncilja says. Still, evidence suggests that some adults may benefit from certain single-ingredient supplements. If your doctor recommends one, check the product for certification or verification from a third-party group like the U.S. Pharmacopeia or NSF International. These include:
Vitamin B12
Adults older than 60 may have difficulty absorbing this vitamin (found in fish, meat, poultry, eggs, and dairy), so they’re more likely to be deficient, says Nisha Rughwani, MD, an associate professor of geriatrics and palliative care medicine at the Icahn School of Medicine at Mount Sinai in New York City. If tests show that your blood levels are under 300 picograms per milliliter (pg/mL), you’ll probably need a supplement, she says. Extremely low levels may call for temporary B12 injections.
People with autoimmune disorders, like rheumatoid arthritis, or those with alcoholism might also need extra B vitamins. And during pregnancy, doctors recommend folic acid (vitamin B9) to help prevent birth defects.
Vitamin D
Fatty fish and fortified milk have vitamin D, and exposure to sunlight triggers your skin to produce it. But it’s hard to get the recommended daily amount for adults older than 70 (800 international units, or IU) this way, Koncilja says. If you take a vitamin D supplement, be aware that a significantly higher intake can hike kidney stone risk. If you use a combined vitamin D and calcium supplement, be aware that supplemental calcium has been linked to a higher risk of colon polyps, kidney stones, and calcium buildup in the heart’s arteries, Miller says.
Iron
A bit more than 10 percent of people older than 65 have anemia. If you suspect you have it (signs are weakness, headache, fatigue, shortness of breath and rapid heartbeat during exercise, and brittle nails) ask your doctor about testing to determine whether you need an iron supplement. “You don’t just want to take it on your own, as iron tablets can cause constipation and stomach pain, nausea, and vomiting,” Rughwani says.
Vitamin C
This antioxidant supports immune system function. Most people get enough by eating produce. But smokers or people exposed to secondhand smoke, people with renal disease, and others who have issues with vitamin absorption tend to have lower levels and may need a supplement.
Vitamin E
An antioxidant, vitamin E helps the immune system fight off certain illnesses and infections. It’s in vegetable oils, nuts, and green vegetables. Though most people don’t get enough, supplementing hasn’t proved to be beneficial in healthy people. People with rare disorders that impede fat absorption, and premature infants under the care of a physician may benefit from a supplement, however.
Can You Trust Label Claims?
OTC supplements aren’t regulated by the Food and Drug Administration the way that prescription medications are. And 12 of the 27 multivitamin and mineral supplements analyzed in 2020 by ConsumerLab.com were found to have quality problems, such as having more or less of the vitamins and minerals than their labels claimed. Some may also contain contaminants.
@consumerreports CR science journalist Catherine Roberts explains why you should reconsider buying yet another bottle of multivitamins. Learn more through the link in our bio. #healthtok #multivitamin #sciencetok #sciencetiktok
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Editor’s Note: A version of this article also appeared in the June 2021 issue of Consumer Reports On Health. It was updated with content from the January 2023 issue of Consumer Reports magazine.
