What Happens When You Take Too Many Vitamins?

Colourful vitamins arranged in a blister pack

For the most part, it is best for people to consume the vitamins they need through nutritious foods and beverages. Based on your quality of diet and health, it may be necessary to take supplements to achieve the recommended daily amount of vitamins. The need to take vitamin supplements could be for many reasons. Certain illnesses make vitamin absorption difficult, and supplements help achieve an ideal intake. Certain diets such as a plant-based or vegan diet do not naturally include vitamin B12 (available through animal sources only), and thus can be supplemented instead. But what happens if you take too many vitamins? In some cases, it is not that harmful, but in others, there can be dangerous side effects.

Are you taking too many vitamins?

Before taking any vitamin or supplement, discuss your plan with your doctor or healthcare provider. Though vitamins and supplements can be key for rounding out your existing diet, it’s always best to stick with the recommended dosage. Something to keep in mind when calculating vitamin intake is to include all sources of vitamins. This could include fortified foods, regular foods, and also vitamins and supplements.

Fortified foods

In addition to naturally occurring vitamins, many foods are now fortified with vitamins. This makes it easier for all people to achieve ideal vitamin intake from diet alone. It has also helped curb health issues that were historically common in America, such rickets (soft bones) and pellagra (characterized by dermatitis, dementia, and diarrhea). Vitamins commonly added to fortified foods include:

  • Iodine in salt (iodized salt)
  • B vitamins and folic acid (iron) in grain products
  • Vitamin A and vitamin D in milk
  • Omega-3 fatty acids in eggs
  • Calcium, vitamin D, and vitamin A in dairy-alternative milks such as soy and almond milk
  • Calcium and vitamin D in orange juice
  • B vitamins in cereal

Which vitamins can be toxic?

Though it is possible to take too much of almost any vitamin, in general fat-soluble vitamins pose a greater risk of toxicity than water-soluble vitamins. This is because the body stores fat-soluble vitamins for longer periods of time than water-soluble vitamins. When vitamins aren’t easily eliminated from the body, the potential that they will build up to unsafe levels increases. Fat-soluble vitamins include vitamin A, D, E, and K. Because water-soluble vitamins are flushed more easily out of the body, it’s more difficult to attain dangerous levels of intake. In fact, people are generally more at risk of being deficient of water-soluble vitamins than they are of taking too much.

Fat-soluble vitamins

Vitamin A

Vitamin A is essential for many functions in the body, but primarily vision health. It also assists with immunity, reproduction, and the proper functioning of many organs. To avoid risks associated with ingesting too much vitamin A, stick to the recommended daily intake. This varies based on age and other factors, but is 700 micrograms per day for adult women and 900 micrograms per day for adult men. People who are pregnant should be especially cautious about their vitamin A intake, as higher levels of this vitamin have been linked to birth defects. Taking too much vitamin A can also result in a rare but serious condition called hypervitaminosis A. This can lead to liver damage, as well as bone and hair loss. In extreme cases, too much vitamin A can be fatal.

Vitamin D

Vitamin D keeps bones, muscles, and teeth healthy. It is also integrated into the health of your brain and immune system. It is almost impossible to absorb dangerous levels of vitamin D through sunlight or food sources. Because of this, extreme levels are generally associated with taking too much through supplements. Though toxicity through too much vitamin D is rare, it is recommended to avoid any risks by limiting intake to the recommended daily amount. For adults, this is 10-20 micrograms per day. Because vitamin D is essential for absorbing calcium, an excess of vitamin D can result in too much calcium in the blood. This condition is called hypercalcemia. If hypercalcemia persists, the excess of calcium can cause damage to the kidneys and heart. To learn more about vitamin D risks and deficiency, you can read more here.

Vitamin E

Vitamin E is essential for our immune health. It is an antioxidant that protects the body from free radicals, a by-product synthesizing energy from food. The recommended daily intake of vitamin E is 15 milligrams for adults. Taken in excessive amounts, vitamin E can thin the blood. At these higher levels, it can also inhibit blood clotting. Though an excessive amount of vitamin E is not as dangerous as some other vitamins, it can be hazardous for people who are already taking blood thinners.

Vitamin K

Vitamin K is essential for blood clotting. Though this vitamin is fat-soluble, there has been no reported incidents of toxicity from taking too much. Because of the lack of data on the subject, there is no established dangerous amount. To avoid any ill-effects of this fat-soluble vitamin, the best course of action is to stick to the recommended daily intake. For adults, this is 90 micrograms per day for women and 120 micrograms per day for men.

Other vitamins that can be toxic

As previously mentioned, other vitamins that are water soluble tend to be less dangerous than fat-soluble vitamins. However, taking too much of certain vitamins can still lead to risks and unpleasant symptoms. Too much vitamin B3 can cause liver damage in those who have pre-existing liver conditions, and can also cause birth defects in pregnant people. Too much vitamin B6 can cause neurological symptoms such as numbness and loss of coordination. Vitamin C, if taken in extreme doses, can cause digestive problems such as cramping, diarrhea, and nausea.  

Worried about your vitamin and mineral levels?

Worried about your vitamin and mineral levels? Speak with your doctor or healthcare provider. At Your Health Lab, we offer many diagnostic tests that can give you a clear idea of your current vitamin levels. Check out our list of over 3,500 tests available, or speak to your healthcare provider to discuss the many options for monitoring and optimizing your vitamin intake.


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