Can You Actually Overdose on Vitamins and What Would Happen if You Did?

While it’s important to make sure you’re getting the necessary vitamin and mineral intake all year round, in winter, when the days are dark, cold, and wet, this need only increases.

The best source for these vitamins comes from fruit and vegetables, and yet a study from the Centers for Disease Control and Prevention (CDC), found that 76 percent of adults don’t eat enough fruit while 87 percent aren’t consuming enough veggies. So while it’s always best to up your intake through whole foods, a multivitamin supplement can become a necessity.

Think of your daily multivitamin like taking out an insurance policy. It’s essentially a guarantee to ensure your body gets the vitamins and minerals it needs and can make up for the shortfalls that happen when you don’t get what you need through food.

But can you overdo it? Is it possible to take too many? Can you overdose on vitamins? Here we look at the different categories vitamins lie in as well as outlining the potential side effects and reviewing the overall safety of taking vitamin supplements.

Can You Overdose On Vitamins?

Fat Soluble vs Water Soluble Vitamins

So, let’s begin by splitting the vitamins up into two categories: water-soluble and fat-soluble.

Most vitamins are water-soluble, which are not easily stored in body tissues and can be readily excreted. Examples of water-soluble vitamins include vitamin C which is necessary for the growth, development and repair of all body tissues, and the proper functioning of the immune system and eight of the B vitamins. Because they’re readily excreted you’re extremely unlikely to overdose on these vitamins. However, mega-doses can potentially lead to dangerous side effects.

It’s a slightly different case with fat-soluble vitamins though. As they do not dissolve in water, your body can more readily retain and accumulate fat-soluble vitamins and as such it’s easier to overdose on them. Fat-soluble vitamins include vitamin A, which is important for normal vision and a healthy immune system, vitamin D, which helps to keep your bones healthy and ward of depression and disease, vitamin K, which is important for blood clotting, and vitamin E, which helps maintain healthy skin and eyes.

While rare, taking too much vitamin A, D, or E can lead to potentially harmful side effects. Because of these side effects, upper intake levels are given to show the maximum dose of a nutrient, and adhering to these upper intake levels is unlikely to cause harm for most people.

Taking high doses of non-synthetic vitamin K seems to be relatively harmless though, which is probably why an upper intake level has not been set for this nutrient. This overview of tolerable upper intake levels as set out by the European Food Safety Authority is a useful guide for those looking to supplement their diet with vitamin supplements.

The Side Effects Of Over-Consumption

Water-Soluble Vitamins

What happens if you do over consume or overdose on vitamins though? Well, let’s start with the water-soluble vitamins again.

Although relatively low in toxicity, high doses of vitamin C can cause gastrointestinal disturbances, while migraines can occur at doses of 6 grams per day. To put this into perspective, the average dose of vitamin C in a multivitamin is around 90mg.

Long-term overconsumption of vitamin B6 can also cause severe neurological symptoms, skin lesions, sensitivity to light, and nausea with some of these symptoms occurring at intakes of 1 – 6 grams per day. Taking too much folic acid aka Vitamin B9, may affect mental function and negatively impact the immune system.

Fat-Soluble Vitamins

As previously stated much more harm can come from high doses of fat-soluble vitamins. While vitamin A toxicity, or hypervitaminosis A, can occur from eating vitamin-A-rich foods, it’s mostly associated with supplements. Symptoms can include nausea, increased intracranial pressure, coma, and even death.

“There’s two forms of vitamin A that come from food,” explains Vanessa Rohmig, our certified naturopathic nutritionist here at Form. “These are preformed vitamin A also known as retinol which is found in animal products, and provitamin A, which is mainly beta-carotene found in plant foods. Your body converts beta-carotene from food to vitamin A according to its needs so you can’t have too much of it. The animal source, like cod liver oil for example, is the only way you could really have too much vitamin A in food form.”

Toxicity from taking high doses or overdosing on vitamin D supplements can lead to a loss of appetite and an irregular heartbeat, while high-dose vitamin E supplements may interfere with blood clotting, cause hemorrhages, and eventually lead to hemorrhagic stroke.

These are all potentially harmful side effects in normal, healthy people. Different problems can arise if you have certain underlying conditions. For example, while vitamin C is unlikely to cause toxicity in healthy people, it can lead to tissue damage and fatal heart abnormalities in those with an iron storage disorder known as hemochromatosis. Anyone who is already taking medication or has a chronic disease should consult with a nutritionist or dietician before turning to supplementation.

Vitamin Intake For Pregnant Women

Pregnant women are more at risk from fat-soluble vitamins, and as such it pays to be more wary. Large doses of vitamin A as retinol has been known to cause birth defects in animals, and so the safest option for pregnant women is to only take prenatal vitamins, so as not to risk any adverse side effects.

Our Superblend contains 50 percent of the RDA for Vitamin A, and as such we advise against pregnant women using it to supplement their vitamin intake. Alternatively, our Performance and Pureblend contain no added nutrients and are perfectly safe for pregnant women to continue to use.

Once again, we must stress, overdosing on vitamins is rare. But as with everything in life, it pays to be careful. So check the nutritional information, and make sure you educate yourself properly.