Don’t assume that all vitamins are so good for your health that you can never take too much.

Vitamin toxicity is real, and it can be dangerous, especially in the case of vitamin D toxicity.

Many of us might be concerned about getting the recommended daily allowance (RDA) of all the essential vitamins and minerals the body needs. We’ve been taught that if we don’t get enough from the diet, supplements are a safe way to provide the extra help our bodies need.

But keep in mind that when it comes to supplementation, not all nutrients are created equal. Loading up on and exceeding those recommended amounts is safe for most vitamins without negative consequences. The exceptions are the fat-soluble vitamins – A, D, E, and K. The body uses these vitamins slowly and stores them in the liver. But because the body holds on to these vitamins, taking larger amounts than needed for prolonged periods can be dangerous, particularly with vitamin D.


Why You Need Vitamin D

Vitamin D plays an important role in normal bone health, as it aids in the absorption of calcium, a prominent component in bone mineralization. Vitamin D also plays key roles in muscle function, brain development, cell growth, immune system support, hormone regulation, and cardiovascular function.

Vitamin D exists in two forms: D2 (ergocalciferol) and D3 (cholecalciferol). Traditionally, both forms have been regarded as equal in their ability to support optimal health, although vitamin D3 is the more bioavailable form for humans.

The body is engineered to make its own supply of vitamin D3 from sun exposure. It’s the result of a chemical reaction triggered by the sun’s ultraviolet B rays hitting the skin. Vitamin D needs are typically met by 10-15 minutes of sun exposure three times a week.1 People who don’t live in sunny locations or those who are housebound may not make enough vitamin D naturally. Having darker skin color can also inhibit the body’s ability to make enough vitamin D from sun exposure. In these cases, consult with your doctor for the proper amount of vitamin D that should be taken in supplement form.

For most adults the RDA for vitamin D is 600 IU per day.2


The Dangers of Vitamin D Toxicity

Vitamin D toxicity is nearly always linked to supplement over use. Don’t think you have to limit your vitamin D intake from food or limit your sun exposure. In fact, as a whole we’re eating less nutrient dense foods and spending less time in the sun thanks to our growing dependence on electronic devices for work, school, and entertainment that keep us indoors. More than ever, health professionals are concerned about the increase of vitamin D deficiency.

But this is no excuse to be careless about using vitamin D supplements. Too much accumulated vitamin D causes the intestines to absorb excess calcium. High levels of blood calcium (hypercalcemia) can cause a number of ailments.3

Symptoms of hypercalcemia:

Confusion Nausea Fatigue
Dizziness Vomiting Weight loss
Excessive urination    Poor appetite High blood pressure
Dehydration Muscle weakness      Irregular heartbeat    

Long-term complications of untreated hypercalcemia:

Excessive bone loss    Calcified arteries and soft tissues   
Kidney damage Organ failure
Kidney stones  

Vitamin D toxicity can develop after prolonged intake of 40,000 IU daily.


Test Your Vitamin D Levels

Because vitamin D intake can be from a combination of sun exposure, food, and supplements, it’s important to know your levels to prevent toxicity. As a cautionary measure, it is strongly advised that you have your vitamin D levels tested prior to taking any vitamin D supplements. It’s also a good idea to re-test your levels after two months of regular vitamin D supplementation, and make dosage adjustments if needed.

Testing the blood is the best way to know if you’re getting enough vitamin D. The test needed is called the 25(OH)D test, measuring for 25-hydroxyvitamin D.

Serum concentration of 25(OH)D is the most accurate indicator of vitamin D status, as it reflects vitamin D obtained from sunlight, food and supplements and has a long half-life of approximately 15 days.

Ask your primary care physician about getting the 25(OH)D test done. If the test cannot be done through your doctor, in-home test kits are available, or you can get the test done at an independent testing laboratory.

Vitamin D serum concentrations and health status


Avoiding Vitamin Toxicity

Hypervitaminosis is the clinical term for abnormally high storage levels of vitamins. The condition is typically achieved through high supplement intake and not from food sources, and pertains more to the fat-soluble vitamins (A, D, E, and K).

As with any dietary or herbal supplement, always consult a qualified healthcare professional before use and especially if:

  • You are pregnant or lactating.
  • You have a medical condition that may be affected by dietary supplements.
  • You are taking prescription or over-the-counter medications that may interfere with dietary supplements.
  • You are administering dietary supplements to a minor.

Pay attention to manufacturer Suggested Use directions and consult with your doctor before taking a higher dose.

If you suspect adverse effects as a result from taking a dietary supplement, immediately discontinue using the product and consult with a doctor. If symptoms are severe or life threatening, seek medical attention immediately.

To avoid possible vitamin toxicity, be informed before you dose. It’s best to take the Goldilocks approach—you need to find the amount that’s “just right” for your body’s needs – not too much, not too little.



  1. University of Maryland Medical Center http://umm.edu/health/medical/ency/articles/vitamin-d
  2. National Institutes of Health Office of Dietary Supplements http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
  3. Vitamin D Council https://www.vitamindcouncil.org/about-vitamin-d/am-i-getting-too-much-vitamin-d/


*Disclaimer Notice: This information is for educational purposes only and should not be used in the place of advice from a qualified healthcare professional. These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure or prevent any disease. Please read full disclaimer here.