The Betterment Project

Multivitamin Side Effects You Should Know About

Pharmaceuticals are known for their side effects. The comically sped-up disclaimers at the end of drug ads listing all the possible side effects and disclaimers is not an unfamiliar concept for people who are old enough to remember the times when you actually had to watch full-length commercials during a TV broadcast. 

It seems like a natural thing to assume that drugs are going to have side effects. To assume that, it is okay to do harm to one part of your body while trying to relieve symptoms in another. To even assume that, multivitamins and dietary supplements will have their side effects too. And, that’s what we are going to take a deeper look at today… What are the multivitamin side effects you should know about?

Usefulness of Multivitamins


Over the next decade, the vitamin industry is positioned to double in size, so it seems that more and more people are beginning to take vitamins in order to optimize their health. With so much data out there on each different vitamin, it can be difficult to know just what your body needs. 

One common misconception that people tend to make is that they need everything, but this simply is not true. Most healthy people are not vitamin deficient in any way. As long as they continue to eat a healthy diet and get some sun then they should not develop a significant vitamin deficiency either. 

But, let’s say a person gets their annual blood tests back and they have a vitamin D deficiency, or they begin taking a drug that reduces the amount of a particular enzyme, like a statin’s effect on CoQ10

These people will need an extra boost to these nutrients! Is the best way to get vitamin D with a multivitamin? Of course not, this is why there are targeted supplements. So then what’s the fascination with multivitamins?

The answer is simple. Multivitamins provide a baseline optimization of bodily nutrients. This prevents deficiencies from happening in the first place, but it does leave you with the possibility of taking extra vitamins that maybe your body might not need. 

The important factor here is whether you are taking a drug or may have other underlying conditions that ensure that you will have developed negative symptoms that could be lessened by the inclusion of a multivitamin. 

Too Many Vitamins

Normally when people think about taking something for their body they might go back to those pharmaceutical commercials that go on and on with side effects and disclaimers. 

To think about the fact that they would put themselves at the same risk when their body does not even need all those vitamins in the first palace is off-putting. They think to themselves: I don’t need to take those. I am as healthy as can be.

However, the reality is that the side effects of multivitamins are nothing like the side effects of pharmaceuticals. Pharmaceuticals are generally chemicals that are foreign to your body. They are powerful and disrupt the natural order of your system in order to achieve your specific goal. 

Meanwhile, vitamins are natural compounds that the body needs, but is constantly being exposed to. For instance, every time that you eat natural whole foods you are making plenty of nutrients available to your body through digestion. Chances are that you will max out on your daily intake for each nutrient before you know it. 

For example, if you were to only eat 3.5 oysters (about 100 grams) then you would supply your body with 600% of the recommended daily intake for zinc, 200% of the recommended daily intake for copper, and supply your body with lots of B12, Vitamin D, and many other nutrients. 

Your body goes above and beyond the intake of certain vitamins all the time with virtually no consequences. Usually, if you do develop vitamin toxicity then it is due to an underlying health condition and not from your eating habits. 

Meaning that, if you decide to take a multivitamin then you can expect not to have any serious side effects due to the number of vitamins that you are consuming. 

Vitamin Interactions

Another plausible concern when it comes to multivitamins is the interactions they may cause. One constant reminder in the pharmaceutical commercials is to avoid taking that medication with a number of other specified medications due to their interactions, often causing amplified negative side effects. 

But, remember vitamins behave differently from your traditional pharmaceutical. In your body, hundreds of chemical reactions are happening all the time and vitamins are a big part of that, so they do react. 

However, many of the reactions that vitamins are involved in do not traditionally involve other vitamins but specific molecules made by your body. This is why multivitamins are safe to be packaged up together in a single capsule or gummy up until the moment you consume them. 

To look at the interactions present in multivitamins, one study measured the levels of a number of essential nutrients in athletes. These athletes were given a multivitamin supplement for three months and the researchers monitored the nutrient levels throughout the three months. 

As a result, they found that there were very few effects that arise due to vitamin interactions. The only effects that did arise only created changes in the absorption of particular supplements. 

Solubility - The Final Consideration

One final consideration that must be made about the potential side effects of multivitamins comes in the form of solubility. Solubility refers to how a compound will associate in the body. If a compound is polar, having unevenly charged parts, then it can mix well with water. It is water-soluble. If a compound is nonpolar, having evenly charged or uncharged parts, then it can mix well with fats. It is fat-soluble. 

This distinction is important because water-soluble vitamins have a higher tendency to be discarded when the body has enough of them. Vitamins like vitamin C and the various B vitamins are all water-soluble and are extremely difficult to have an abundance of. Meanwhile, vitamins that are fat-soluble like A, D, E, and K do have a higher toxicity rate since they can be stored in the body. 


Although pharmaceutical commercials have conditioned our brains to think that every health consumable will have strenuous side effects for our bodies, this is far from the case. Vitamins are natural nutrients that have virtually no negative effects on the body when there are no underlying conditions present. 

Multivitamins provide a baseline optimization of bodily nutrients and most healthy people might not need them to remain healthy. The most important factors when considering a multivitamin have nothing to do with what side effects you might experience since there are no significant ones, but rather if a multivitamin might be of benefit to your health.

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Gummy Vitamins Market by Type, Demographics, and Sales Channel: Global Opportunity Analysis and Industry Forecast 2019-2026 | Allied Market Research

The Role of Coenzyme Q10 in Statin-Associated Myopathy: A Systematic Review | Journal of the American College of Cardiology

Vitamin and mineral status of trained athletes including the effects of supplementation | The American Journal of Clinical Nutrition

The effect of multivitamin supplements on continuation rate and side effects of combined oral contraceptives: A randomized controlled trial | The European Journal of Contraception & Reproductive Health Care

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This article has been reviewed by members of our Scientific Advisory Board.

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