How to choose a multivitamin tablet

What if you could take one pill and get all of the vitamins and minerals you need? That's the general idea behind daily multivitamins—a one-a-day pill to help you overcome any possible vitamin deficiencies from your diet. It sounds like a dream, but there's been some controversy about whether multivitamins are worth taking. What's the deal? Should you be taking a daily multi? 

In this article, we'll explore the pros and cons of taking a multivitamin, which ingredients are most important in a daily multi, which you should watch out for, and other vitamins to consider. Let's dive in. 

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The research is a bit mixed, but most studies seem to show that multivitamins are generally safe (with some precautions) and may have some real benefits. In an ideal world, we'd get all of the vitamins and minerals we need from the food we eat. In the United States, most of us have abundant access to food, yet many of us don't eat the nutrient-rich diets we probably should. Vitamin deficiencies—yes, even here in the U.S.—are quite common, so a good multivitamin may be useful (Bird, 2017). 

Multivitamins come in different forms, including tablets, capsules, gel caps, and even chewable gummy vitamins. 

Here are some possible benefits of taking a complete multivitamin: 

• One study showed taking a daily multivitamin may improve mood, along with certain markers in the blood (namely, an amino acid called homocysteine) (White, 2015).

• Another study showed promising effects of multivitamins on energy and exercise performance (Dodd, 2020).  

• There's some evidence that multivitamins may be especially useful in older adults (over the age of 50) in curbing iron-deficiency anemia and neurological damage. Multivitamins that contain iron, folic acid, vitamin B12, and vitamin D can help fight against bone disease (Ward, 2014).

Not all researchers see multivitamins in such a rosy light, though. One group of researchers warns against taking multivitamins with high doses of certain vitamins and minerals (Hamishehkar, 2016). (These are valid concerns that we'll cover in the next section). There seems to be a consensus that multivitamins don't have much impact on heart health (Kim 2018). And, while people who take multivitamins tend to see themselves as healthier than average, that doesn't necessarily correlate with improved health outcomes (Paranjpe, 2020). 

Bottom line? As long as you're careful about which multivitamins you take, they're likely safe to take and may be beneficial for your health and wellness. Just don't expect them to be a cure-all. 

Not all multivitamins are created equal. Before you run to the drugstore and buy the first multivitamin/multimineral supplement you grab off the shelf, take a few minutes to learn about what to look for in a multi. This includes which ingredients are most important, as well as which ingredients you need to be careful about in high doses. 

Most important multivitamin ingredients

Most multivitamins will have a whole slew of ingredients, but more isn't necessarily better when it comes to vitamins and minerals. The following vitamins and minerals are probably the most important ingredients in a multivitamin since they have the best evidence:

• Vitamin D3—Vitamin D is essential for bone health (and possibly for other health outcomes, too). Even though we should be able to get all of our daily vitamin D requirements from the sun and diet, vitamin D deficiency is common, especially in older adults. Generally, 600 IU daily is recommended for adults, with that recommendation going up to 800 IU per day for people over 75 (Bouillon, 2017). Some multivitamins include vitamin D2 instead of D3. Vitamin D2 works fine, but D3 is generally more potent, so it's better to look for a multi with D3 (Logan, 2013).  

• Vitamin B12 (cobalamin)—Vitamin B12 is important for many areas of health, including helping the body form red blood cells and facilitating neurological function. Vitamin B12 deficiency is particularly common in older adults and vegetarians/vegans (since one of the natural sources of vitamin B12 is meat) (Bird, 2017). People who take metformin are also at some risk of developing a vitamin B12 deficiency that can be fixed with supplementation (Yang, 2019). The recommended daily intake is 2.4 mcg (Ward, 2014). 

• Folic acid (folate)—Folic acid is another B-vitamin that's especially important for women who may get pregnant since folate is essential for normal fetal brain development. For women who may get pregnant, the recommended daily dose is 400–800 mcg. For everyone else, 240 mcg daily is sufficient (Merrell, 2020). 

• Magnesium—It's estimated that two-thirds of adults in western countries are deficient in magnesium. Magnesium plays a big role in many health processes, including depression, migraines, muscle cramps, asthma, and bone health, among others. It's recommended that adult men consume 400–420 mg of magnesium per day, while women should consume 310–320 mg daily (Schwalfenberg, 2017). 

We recommend looking carefully at your multivitamin label to make sure it contains the recommended level of these vitamins and minerals. If not, you may want to take a separate, stand-alone supplement for these ingredients as needed. 

Ingredients to watch out for

One of the potential dangers of taking a multivitamin without looking carefully at the label is that some multivitamins include extremely high levels of certain vitamins and minerals. Some specific vitamins and minerals can be toxic in high doses, so it's important to follow the recommended daily allowances for these ingredients. Remember that your recommended daily allowance (RDA) for vitamins and minerals includes both what you consume through food and supplementation.  

• Vitamin A—Vitamin A is important for health, but it can have detrimental effects in high doses. It's associated with bone loss, and it's also a teratogenic drug, which means it can cause birth defects. Some multivitamins also contain beta-carotene, which can convert into vitamin A in the body. In smokers, beta carotene may increase the risk of lung cancer. Make sure your multivitamin doesn't exceed the RDA for vitamin A—700 mcg for women and 900 mcg for men (Hamishehkar, 2016).  

• Calcium—We all know calcium is important for bone health (think back to those old milk commercials). In high doses, though, calcium can cause gastrointestinal side effects, like constipation, diarrhea, and stomach pain. It's also been linked to an increased risk of kidney stones in postmenopausal women. Stick with the daily RDA of 1,000 mg per day of calcium (including what you eat) (Li, 2018). 

• Magnesium—Although magnesium is also on our list above of most important minerals, it's important to stay within the recommended daily intake. Excessive doses of magnesium can result in diarrhea, dizziness, muscle weakness, and other symptoms. Check that your multivitamin does not exceed the RDA for magnesium of 400–420 mg per day for men, and 310–320 mg per day for women (and slightly higher for women who are pregnant or breastfeeding) (Schwalfenberg, 2017).  

• Vitamin K— Vitamin K may be contraindicated in some people. In particular, if you're on blood thinners (like warfarin) or if you have kidney disease, be sure to discuss any multivitamin with your healthcare provider before taking it to make sure the vitamin K contents are safe for you (Imbrescia, 2020). You don't need much vitamin K, anyway. 90–120 mcg per day is sufficient for most people (Ward, 2014). 

• Iron—Iron is included in many multivitamins, which may be useful for menstruating or pregnant women or the elderly (all of whom are at risk of iron deficiency anemia). It's probably not necessary for most men, though, unless there's a specific reason to believe they need it. For instance, vegetarians are at higher risk of developing iron deficiency, so men who are vegetarians should get their iron levels checked. If they are deficient, an iron supplement may help (Nguyen, 2020). 

In general, when taking a multivitamin, it's a good idea to avoid going over daily recommended intakes, especially if you are taking multiple supplements with similar ingredients. Even if one dietary supplement doesn't exceed the daily limits, you may be taking too much of a given vitamin or mineral if you're taking it in multiple supplements. Many vitamins and minerals are totally fine in somewhat higher doses, but be especially careful with vitamins A and K.

Multivitamins often contain dozens of different vitamins and minerals. If you are taking a high-quality daily multivitamin with safe ingredient levels, you probably don't need to take much else. There are three other supplements worth mentioning, though. 

B-complex

If your multivitamin doesn't have high enough levels of B-vitamins, you might consider taking a B-complex. A B-complex is a combination of multiple B-vitamins. This can include any combination of vitamin B1 (thiamine), vitamin B2 (riboflavin), vitamin B3 (niacin), vitamin B5 (pantothenic acid), vitamin b6, vitamin b7 (biotin), vitamin b12, and folic acid. 

B-vitamins are coenzymes, which help the body's enzymes function properly. There's good evidence that taking a combination B-vitamin may help reduce oxidative stress in the body, which is an important part of the aging process (Ford, 2018). And speaking of stress, B-vitamins seem to work well for reducing mental stress and improving overall mood (though it doesn't do much for more specific clinical diagnoses, such as depression or anxiety) (Young, 2019). 

Resveratrol 

If you've ever heard that drinking red wine may be good for your health, it's because of resveratrol, a substance found in grapes, berries, and peanuts. The alcohol in red wine may cancel out those benefits, but luckily, you can take resveratrol in a pill. It's shown promising effects on heart disease, inflammation, certain types of cancer, and neurological disorders. We still don't know a lot about resveratrol, but it may be a worthwhile addition to your supplement regimen (Berman, 2017). 

CoQ10

Taking a coenzymeQ10 (CoQ10) supplement may be useful for improving the way the mitochondria in our cells function. It has anti-inflammatory and antioxidant effects and is safe and well-tolerated. We need more research to know for sure how beneficial it is, though (Hernández-Camacho, 2018). 

Even though multivitamins are readily available online or at the drugstore, it's important to speak with your healthcare provider before starting on a new dietary supplement. There may be certain interactions with other medications you're taking, or certain vitamins or minerals may require extra caution if you have a particular medical condition. For most healthy people who aren't taking any medications, multivitamins are safe and possibly beneficial. Just read those labels carefully! And, like any medication or supplement, keep those bottles out of reach of children.

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Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

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Current version

February 25, 2021

Written by

Rachel Honeyman

Fact checked by

Steve Silvestro, MD

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About the medical reviewer

Steve Silvestro, MD, Ro

Dr. Steve Silvestro is a board-certified pediatrician and Associate Director, Clinical Content & Education at Ro.