High risk of vitamin D toxicity due to self-prescribing

There is a common advice, as soon as the winter comes, especially in countries with the lack of sunshine. Taking vitamin D, also known a sunshine vitamin, is a must. As we know, vitamin D is produced in the skin when it is exposed to the sun. Everyone is aware of vitamin D benefits and also of consequences in case of deficiency. Bone loss, muscle pain, hair loss, depression, fatigue, tiredness or getting sick often can be some of symptoms of low vitamin D levels. But, what about if someone has too much of it? What are the side effects?


Morning sun
Sun rising in the morning

Although it is very rare, Vitamin D toxicity can happen especially in people who supplement with high doses. It is also known as hypervitaminosis D. There are not reported cases of toxicity by diet or sun exposure.

Hypervitaminosis can easily provoke hypercalcemia – elevated levels of calcium in the blood. Some other direct symptoms are gastrointestinal disorders like anorexia, diarrhoea, constipation, nausea, and vomiting. Bone pain, drowsiness, continuous headaches, irregular heartbeat and loss of appetite are other side effects that are likely to appear within a few days or weeks. Even frequent urination, especially at night, excessive thirst, weakness or nervousness. But what is the major problem? In many cases people have been taking large dose of vitamin D for months without any symptoms. It was only when they were tested that tests showed severe hypercalcemia and symptom of kidney failure (1).

Many strong campaigns pro this sunshine supplement come from many angles every day, from doctors, nutritionists, grandmothers and even instagram gurus. They all may confuse people. Everyone agrees that, at some point, Vitamin D is necessary before or during winter months. That unique message can persuade the population and do more harm than good.

Vit d flyer
NHS campaign about vitamin D benefits

Do you really need the “sun” pills? Have you been tested? Have you checked your vitamin D levels before supplementation? Is the diet enough? Why is it so hard to find a message that advises people to test for vitamin D levels before taking supplements? Obviously, supplements and pharmaceutical companies don’t really encourage people to test first. Aggressive advertising and sales of great quantities for supplementation may be dangerous if someone decides to self-prescribe these sunshine pills.

Why vitamin D can build up in the body?

Vitamins are classified in two types: water-soluble and fat-soluble. Water-soluble vitamins do not store in the body and they are vitamins B and C. On the other hand, fat-soluble vitamins are A, D, E and K. They are stored in the liver and adipose (fat) tissue when not used.

As vitamin D is almost in every cell in the body, it is so important to have optimal levels. But, how much is enough to ensure the right level for most people? The exact number is debatable but many health organisations recommend daily intake of 400-4000 International Unit (IU). It is between 10 and 100 micrograms, obviously the age and the status will determinate how much is required exactly.


Vit d supplements
Different types and forms of vitamin D supplements

When are my vitamin D levels right? Following vitamin D guidelines (2) will help you understand where you levels  are:

  • Sufficient: 20-30ng/ml or 50-75nmol/L
  • Safe upper limit: 60ng/ml, or 150 nmol/L
  • Toxic: Above 150 ng/mL, or 375 nmol/L

So before you start taking pills visit your doctor and ask for the vitamin D test. You may need or you may not need sunshine pills. Testing is the only way to know for sure.




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