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What Is a Multivitamin? (Benefits, Usage & Side Effects)

Connor Sellers
Published by Connor Sellers
Fact checked by Donald Christman, BHSc FACT CHECKED
Last updated: September 24, 2022
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While multivitamins are always trending, it's important to know what they are exactly and how we can include them in our diet ( and if we need any at all).

In the face of an increasingly crowded market of multivitamin supplements, I had to conduct extensive research to find out how to determine if they were worth buying.

Let's dive right in.

Quick Summary

  • Multivitamins are all the necessary vitamins and minerals packed into one convenient tablet or pill.
  • Overdosing multivitamins or taking them with other vitamins may be potentially dangerous.
  • People who cannot get all nutrients from food should consider taking multivitamins.

What Are Multivitamins (And What Do They Contain)?

different set of pills and capsules

Multivitamins are supplements that combine multiple vitamins and minerals, sometimes alongside other ingredients.

There are many multivitamins available on the market.

These vitamins are not strictly regulated by the Food and Drug Administration (FDA). As a result, there is no universal standard, and the nutrient components can vary by brand and product.

Most multivitamins contain:

  • Vitamin C,
  • Vitamin  B1, B2, B3, B5, B6, B7, B9, B12
  • Vitamin A (including beta carotene)
  • Vitamin E, 
  • Vitamin D 2 (or D3)
  • Vitamin  K
  • Potassium
  • Iodine
  • Selenium
  • Borate
  • Zinc
  • Calcium
  • Magnesium
  • Molybdenum
  • Iron

Additionally, certain multivitamins also contain some herbal ingredients or nutrients such as friendly bacteria, amino acids, fatty acids, or ginseng.

Health Benefits Of Taking Multivitamins

stethoscope on a heart squishy

The benefits of taking multivitamins include:

Increased Nutrition Intake

Some people cannot or do not meet their needs from food due to poor nutrition or some medical conditions. Taking multivitamins can help fill these nutritional gaps [1].

Chronic Disease Prevention

The evidence concerning multivitamins and chronic diseases is pretty mixed.

Although most research shows that taking vitamins and minerals can impact our overall health, they mostly agree that it is not directly linked to reducing the risk of developing chronic diseases such as cancer or heart disease.

A review including 47289 participants separated into five randomized controlled trials concluded that the risk of cancer in men who took multivitamins was 31% lower, but had no effect on women [2].


A recent publication also found that women taking multivitamins for more than three years are less likely to develop heart disease and have a lower risk of a heart attack [4].

Other Benefits

woman in gym clothes giving a thumbs up outdoors

Multivitamins may help improve brain function, mood, and memory (especially for older adults) [5].

Many studies serve as scientific evidence of a link between nutrition deficiency and lousy mood.

Furthermore, filling nutrition gaps with multivitamin use can also decrease the symptoms of depression and anxiety [6] [7].

In addition, antioxidant vitamins and minerals may help slow the progression of certain diseases that cause blindness [8].

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“Millions of Americans today are taking dietary supplements, practicing yoga, and integrating other natural therapies into their lives. These are all preventive measures that will keep them out of the doctor's office and drive down the costs of treating serious problems like heart disease and diabetes.”

- Andrew Weil, American Scientist

Can Multivitamins Be Harmful?

Some vitamins can cause serious side effects if taken in high doses; therefore, combining these with your daily multivitamin should be avoided [9].

Also, keep in mind that exceeding 100% of the daily value of some dietary supplements is not helpful. Excessive intakes of certain nutrients – like zinc, niacin, folic acid, or vitamins A, D, E, and K – can become toxic [10].

Pregnant women should be especially cautious with vitamin A intake since it's proven to raise the risk of certain birth defects in their babies [11].

Large intakes of beta carotene and vitamin A have proven to raise the risk of lung cancer. Therefore, smokers should avoid multivitamins containing large doses of any of these [12].

Another risk is consuming too much iron, which could impact the body's ability to absorb zinc [13].

Be careful with taking multivitamin products with an already nutrition-dense diet since it can lead to exceeding your recommended daily intake.

Who Should Take Multivitamins?

hand view of a person offering a white pill and glass of water

As we all know, certain vitamins are essential for our health [14].

Even though you can get most of these vitamins from a well-balanced diet, for some people, it may be tricky to get enough nutrition in certain circumstances.

This is where multivitamins can fill up these small but critical nutritional gaps in the diet, helping prevent the symptoms of low intakes.

These circumstances include [15]:

  • Age – our bodies find it harder to absorb some essential nutrients as we get older
  • Allergies or intolerances – difficulty to absorb certain nutrients
  • Vegetarianism and veganism – these diets could be missing certain nutrients that are mainly found in animal products
  • Pregnancy and breast-feeding – pregnancy increases your body's need for certain nutrients, such as iron and folate

Taking multivitamins with other medications or dietary supplements can cause drug interactions or affect how medicines work in your body. Ask a doctor to provide medical advice if it is safe to use multivitamins if you are on any other medication.


What Happens if I Overdose on Multivitamins?

If you overdose on multivitamins, the side effects can lead to severe complications and, in rare circumstances, even death [16]. These side effects include headaches, nausea, stomach cramps, diarrhea, and vomiting.

Do Multivitamins Cause Weight Gain?

Multivitamins don't make you gain weight, as they hardly include any calories. On the other hand,  multivitamins containing B complex may increase the appetite and trigger obesity [17].

How Would You Increase Vitamin Intake?

Dietary supplements and multivitamins can be a great way to improve health.

Adding multivitamins to your diet can help fill the nutritional gaps you may have and improve your energy levels and brain function.

When choosing your daily multivitamin, opt for ones tested by third parties that contain safe and clean ingredients, and some of the best are:

The vitamins and minerals you may need depend on your age and overall health, so be sure to talk to someone with medical education before taking supplements.


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