Not everyone should be taking a multivitamin
In some situations, they can be helpful. In others, they can lead to dangerous nutrient deficiencies or imbalances. Experts weigh in on how to make an informed decision.
Do multivitamins ensure your body gets everything it needs? It's a complicated question without a one-size-fits-all answer.
While there’s no doubt taking multivitamins may benefit some people, experts suggest assessing your nutritional needs before popping a daily multivitamin.
“A large amount of vitamins can cause nausea, vomiting, dehydration, confusion, and organ damage, such as [to the] liver or kidney,” says medical oncologist Liudmila Schafer. “Additionally, multivitamins containing certain minerals like calcium, magnesium, or zinc can interfere with the absorption of certain medications, such as antibiotics or thyroid medications.”
(How these two vitamin supplements could do more harm than good.)
That said, there are some situations in which a multivitamin may be helpful. Experts explain who may benefit from taking multivitamins and how we can make an informed decision about whether or not to include them in our daily routine.
Who should take multivitamins?
According to the National Institutes of Health (NIH), approximately one-third of all adults in the United States and one-quarter of adolescents take multivitamins. However, only a portion of them have received a recommendation from a healthcare professional to do so.
Whether you should actually take a multivitamin is still a controversial topic, though the general consensus is that most people don’t need them. One 2024 study from the National Cancer Institute found no association between daily multivitamin use and a lower risk of death for healthy adults.
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Still, in some cases, carefully considered supplementation can address specific nutrient gaps in certain populations.
“Multivitamins aren’t magic pills or meant to replace a nutrient-rich diet—they’re support tools,” says registered dietitian and holistic health expert Samantha Peterson. “They won’t prevent death or replace lifestyle habits like whole foods, sleep, movement, or stress regulation, but they can help bridge gaps that are nearly inevitable with today’s food system, aging, or modern stress loads.”
People who are pregnant or planning to become pregnant are one population who are recommended to take vitamin supplements. The Centers for Disease Control and Prevention (CDC) recommends they get up to 400 mcg of folic acid daily to help prevent neural tube defects, or birth defects that occur when the neural tube doesn’t close properly in newborns.
“A multivitamin is recommended for pregnant people because it can be difficult to eat a healthy and well-balanced diet to meet the nutritional needs of the pregnancy and the mother,” says OB-GYN Brittany Noel Robles. “This is especially true if a person develops food aversions or has nausea throughout the pregnancy.”
The Office of Disease Prevention and Health Promotion also recommends older adults take vitamins like B12 and D, as they may have trouble getting enough nutrients from their diets. Often older adults have decreased appetites and don’t eat as much, so their bodies can also have trouble absorbing these nutrients.
According to a 2023 randomized clinical trial, daily multivitamin supplementation improved immediate recall memory in men older than 60 and women older than 65, with benefits lasting for up to three years. This suggests that multivitamins may also offer a potential cognitive benefit in older adults.
Peterson says individuals with limited nutrient diets (like vegan and low FODMAP), busy professionals who skip meals or rely on convenience foods, or people with malabsorption issues—either due to a health condition (cystic fibrosis, celiac disease, or other digestive disorders) or medications (metformin, statins)—may also benefit from taking multivitamins.
Who shouldn’t take multivitamins?
While taking a multivitamin may benefit some individuals, experts warn against taking multivitamins without consulting a healthcare professional.
Individuals who take certain medications, such as blood thinners, antibiotics, or diuretics, may require targeted supplementation rather than a multivitamin, says dietician Susan Schachter.
Multivitamins may contain ingredients that can interact with other medications, making them less effective or ineffective, or even causing serious side effects. Multivitamins containing vitamin K, for example, can interfere with the effectiveness of blood thinning medications such as warfarin (sold under the brand Coumadin) and increase the risk of blood clots.
“Coumadin is prescribed to prevent blood clot formation and stroke, and taking vitamin K could counter the effect of Coumadin and potentially put a patient taking Coumadin at risk,” says Rand McClain, physician and regenerative sports medicine specialist.
Multivitamins with active ingredients, such as herbs to promote weight loss or extracts to improve sleep or muscle development, should be carefully considered, as these may interact with prescribed medications, according to registered dietitian Theresa Moutafis.
Other examples of drug-nutrient interactions include calcium or magnesium, which can interfere with the absorption of thyroid hormones like levothyroxine if taken too closely together.
Additionally, multivitamins often contain higher levels of vitamins and minerals than the recommended daily intake. People with kidney or liver disease may not be able to clear these nutrients from their bodies, which can lead to excess buildup and damage to their organs.
(Liver problems linked to supplement use are on the rise—here’s why.)
For example, taking too much vitamin A can cause nausea, dizziness, headaches, and even liver damage. Additionally, while uncommon with standard multivitamin use, excessive daily doses of vitamin B6—typically above 200 mg per day and often from long-term self-treatment with high-dose supplements—have been associated with nerve function issues, like tingling or numbness.
“Fat-soluble vitamins in particular are prone to cause toxicity, as they ‘stick around’ for longer in the body,” says Moutafis. These include vitamins A, D, E, and K. “For individual nutrients, a lab test is typically helpful to know when you need to supplement, particularly with high doses.”
Taking multivitamins can even cause nutrient deficiency or imbalances, as taking too much of one nutrient can interfere with the absorption or use of other nutrients in the body (too much vitamin C, for example, can interfere with iron absorption).
“You can think about nutrients as a team playing a game,” says orthopedic surgeon Wang Lushun. “For the team to do well, every player has to perform their role. If one player takes over, it might cause an imbalance. In the same way, when taking multivitamins, some nutrients can overshadow others. For example, taking high doses of zinc can inhibit copper absorption, leading to a possible copper deficiency.”
What’s in a multivitamin?
Multivitamins are supplements, and the Food and Drug Administration (FDA) does not regulate their content. This means there’s a risk of inaccurate labeling or contamination, which can result in consuming harmful ingredients. Another growing concern is the rise of counterfeit multivitamins and supplements sold online making it even harder to know exactly what you’re putting in your body.
(What’s in melatonin? And is it giving you nightmares?)
“Unlike medications prescribed by medical doctors, vitamins do not undergo the same rigorous evaluation of appropriate dosages and potential interactions for each individual patient,” says emergency medicine physician Mary Valvano. “This is where an individualized approach becomes crucial—patients who mistakenly believe they’re pursuing a healthy path by taking multivitamins often find themselves deficient due to a lack of understanding regarding their specific nutritional needs and how to meet their health goals.”
If you take multivitamins, Schachter recommends looking for products certified by a third-party organization, such as the US Pharmacopeia (USP), which verifies supplements' quality, purity, and potency. Those certified by the National Science Foundation or Informed Choice also undergo testing for contaminants and label accuracy.
Peterson also notes that “more expensive” doesn’t necessarily mean better. “It’s not true for all, but you should use a ‘cautious eye’ when introducing a new supplement, and ask your attending provider if it’s right for you,” she adds.
(Supplements may contain more than what's on the label.)
Ideally, your multivitamin should “fill in the cracks,” like known deficiencies, and work as a supportive tool that complements your overall nutritional health, Peterson notes. “We use supplements to augment, not replace, food-based nutrition,” she says.
The bottom line? Food is a true nutritional powerhouse, offering a spectrum of vitamins, minerals, and other essential nutrients that support our well-being. These nutrients keep us healthy and boost our immune system. Beyond nutrients, food contains fiber, antioxidants, and phytochemicals that can help protect against chronic diseases and improve our overall health.
