Not everyone should be taking a multivitamin

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.” 

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 or not you should take multivitamins depends on your individual nutritional needs, which can vary depending on factors such as age, gender, health status, and dietary habits,” says dietitian Johna Burdeos. “It's important to consult with a healthcare professional before starting any supplement regimen to determine if it’s necessary and safe for you. While multivitamins can be a convenient way to help fill nutrient gaps, they shouldn’t replace a healthy diet and lifestyle.”

For example, 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 (NTDs) or birth defects that occur when the neural tube doesn’t close properly in newborns, like spina bifida. 

“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 CDC 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, but also, their bodies can have trouble absorbing the nutrients.

Burdeos says individuals with nutrient deficiencies or absorption problems (people with cystic fibrosis, celiac disease, or other digestive disorders) and those who follow strict dietary restrictions (vegans, for example) also may 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.

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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 your other medications, making them less effective, ineffective, or even cause 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.

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 an excess buildup and damage to their organs. For example, taking too much vitamin A can cause nausea, dizziness, headaches, and even liver damage. 

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. 

(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.

(Supplements may contain more than what's on the label.)

While multivitamins can be tempting, the best way to obtain nutrients is via food consumption rather than supplements, says McClain, highlighting the importance of identifying potential deficiencies and adjusting our diets accordingly. 

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.