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Dangerous Things That Can Happen If You Take a Multivitamin Every Day

8 in 10 Americans take supplements on a daily basis, but experts say they could be doing more harm than good.

Polls show that roughly 80% of Americans take vitamins or supplements. You would think that something that so many people do in the name of health would be good for you, right? Not so fast. There may not be as many benefits of taking vitamin supplements—and multivitamins, in particular—as you've been led to believe.

An Annals of Internal Medicine study by Johns Hopkins researchers concluded that multivitamins don't reduce the risk for heart disease, cancer, cognitive decline, or early death. The researchers also noted that vitamin E and beta-carotene supplements actually appear to be harmful, especially at high doses.

Based on this study, it appears that taking a multivitamin doesn't have to be a part of your health routine, and nutrition experts agree.

"A generally healthy person most likely does not need to take a multivitamin! Unless my clients have dietary restrictions, food allergies, or a health condition that interferes with the absorption of food, I tell them to get their vitamins from whole foods first," says registered dietitian Danielle Gaffen, MS, RDN.

"Multivitamins might sound convenient, but you get much more value and health benefits from just focusing on one type of supplement at a time," says Nikola Djordjevic, MD, a medical advisor at HealthCareers

Rather than opt for a one-size-fits-all solution in the form of a multivitamin, Ilene Ruhoy, MD, PhD, a doctor trained in both pediatric and adult neurology at Seattle Children's Hospital and the University of Washington, suggests a more targeted approach. "If there is a nutrient deficiency, an illness, or a health struggle, then appropriate choices of particular supplements can be of great use and benefit. But this calls for specific supplement choices. Please see your physician for guidance on supplement use," she urges.

If you shouldn't take a multivitamin, what should you do? Ask any nutrition expert and they'll tell you the same thing: it's best to naturally source your vitamins from fresh fruit and vegetables when you can.

To learn more about why we shouldn't be wasting our money on multivitamins, we asked registered dietitians and doctors to share the dangers of taking a multivitamin every day. Read on to learn more, and for more on healthy eating, don't miss 7 Healthiest Foods to Eat Right Now.

You may overdose on certain vitamins


"When you take a multivitamin, you are giving your body an unnatural cocktail of vitamins that you wouldn't normally have present in such high concentrations," says Dr. Djordjevic. "An overdose of certain vitamins including vitamins A, D, K, or E can have serious and life-threatening effects. The side effects of using excessive vitamin A include vision disturbances, poor appetite, hair loss, headache, and sunlight sensitivity. Similarly, Vitamin D overdose can cause weakness, fatigue, nausea, sleepiness, and loss of appetite. Taking vitamin E daily without any reported deficiency can result in blood thinning that can lead to problems with blood clotting and hemorrhaging."

Abbey Sharp, RD, registered dietitian and blogger at Abbey's Kitchen notes that fat-soluble vitamins aren't the only ones you should worry about: "Most water-soluble vitamins are excreted in excess but can still cause digestive issues and also can interfere with medication and blood work results. It's always important to have blood work done to determine which vitamins and supplements you could benefit from, and which you're already getting enough of through diet."

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You may be misled into thinking you don't have to get as many nutrients from whole foods


"Obtaining your nutrients from food is always the best first-line approach to ensuring adequate nutrient intake. The purpose of a nutrition supplement is to fill in nutrient gaps that you may not be getting from your food, but it should never be considered a replacement or 'free pass' to fix a nutrient-depleted diet," says Ansley Hill, RDN, LD, a nutrition contributor at Clean Green Simple.

Dr. Jinan Banna, PhD, RD, a registered dietitian and professor of nutrition shares that getting nutrients from whole foods provides you with nutrients that multivitamins can't: "Food contains lots of other important compounds for our body, such as those that function as antioxidants. If we try to get most of what we need from supplements, we may be missing many other important components of the diet we need for optimal health."

"Eat a wide variety of foods, especially plant-based foods, as they are not only great sources of vitamins and minerals, but also provide fiber, antioxidants, and phytochemicals, which a nutritional supplement does not have," adds Melissa Nieves, RD, a registered dietitian at Kemtai, the virtual personal trainer company.

RELATED: What Taking a Multivitamin Every Day Does to Your Body

You may not end up getting enough of the nutrients you're deficient in

taking vitamins

In contrast to the potential of overdosing on certain vitamins in multivitamins, it's also entirely possible to miss out on getting the targeted supplement that your body really needs. "Generic multivitamins often contain insufficient doses of important vitamins such as vitamin D. Most of us are deficient in this important vitamin, but the standard 400 IU daily found in many multivitamins is most often not sufficient," says Arielle Levitan, MD, co-founder of Vous Vitamin LLC and author of The Vitamin Solution: Two Doctors Clear the Confusion About Vitamins and Your Health.

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It could have dangerous interactions with existing medications

taking medicine

"Experiencing negative side effects of taking a multivitamin depends if a consumer has a pre-existing health condition, or is taking certain medications," says Nieves. "For example, people who are on the anticoagulant medication Warfarin should be careful of supplements that contain vitamin K, as it can interfere with the medication."

You may suffer from indigestion

woman suffering from stomach pain

"If you must buy a multivitamin, try and find the most expensive and naturally-sourced one at the health food store. The ones you should never buy are any multivitamins that cost less than $6 per bottle. Cheaply sourced multivitamins have been known to cause indigestion and even exit partially undigested in your stool. So try and avoid those altogether, as they are not good for you," says Dr. Djordjevic.

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You may expose yourself to heavy metals.

Shot of woman nutritionist doctor writes the medical prescription for a correct diet on a desk with fruits, pills and supplements.

"Many generic multivitamins contain many heavy metals. These can deposit in your body and have been associated with dementia and other issues," says Dr. Levitan.

Hill agrees, underscoring that ingesting these harmful contaminants is even more dangerous since you're consuming them every day. Hill suggests that "if you can, opt for supplements that have been third-party tested for purity and potency so you know you're getting exactly what you've paid for."

RELATED: Popular Supplements That May Be Dangerous, Say Experts

Multivitamins may interact with underlying health issues

woman Having Spinal Or Kidney Pain

"Medications and certain disease states can cause issues with multivitamins. If you have certain conditions like kidney disease, then your body may have more trouble eliminating nutrients," notes registered dietitian Amanda A. Kostro Miller, RD, LDN, who serves on the advisory board for Fitter Living.

Supplements You're Taking Too Much Of, Say Dietitians

You may not be able to tell how much of any nutrient is actually present in the multivitamin

Steroids for physical development of human body as medical's pills.

"While mainstream supplement brands found in health food stores or major retail outlets are likely to be legitimate and safe, due to a lack of regulation, lesser-known nutritional supplements may not actually be composed of what they're advertised to contain (such as containing greater or lesser quantities of a vitamin)," says Gaffen.

You won't get as many beneficial nutrients as you'd think

vitamins and supplements on white background with a brown bottle.

Dr. Ruhoy underscores that the vast majority of us do not need to take multivitamins: "if we regularly eat a healthy diet, there is minimal benefit from the addition of multivitamins to our regimen." She adds that not only can we get the nutrients included in multivitamins from food, but that they're also more bioavailable sources of them: "Vitamins and nutrients from food are the form our body prefers as opposed to encapsulated with excipients. When extracted from our foods, it is much more bioavailable for assimilation into the variety of functions the nutrient compound performs, including as substrates and co-factors for enzymatic reactions." Why not start with The Healthiest Foods You Should Be Eating Every Day, According to Experts?

Read more:

5 Dangers of Multivitamins, Says Science

The Best Supplements for Your Hair, According to Dietitians

Warning Signs You're Not Getting Enough Vitamin D

Olivia Tarantino
Olivia Tarantino is the Managing Editor of Eat This, Not That!, specializing in nutrition, health, and food product coverage. Read more about Olivia