What does it mean to have a level of vitamin D that is too high?

The term ‘vitamin D’ actually refers to two different molecules: vitamin D2 and vitamin D3 (or cholecalciferol). The first is found in some foods of plant origin, while the second is produced by the body following exposure of the skin to sunlight and can be found in some foods of animal origin.

Vitamin D deficiency can cause some disorders, but high vitamin D levels can also be harmful to the body.


Hypervitaminosis occurs when a certain vitamin is present in excessive amounts in the body. Usually, vitamins taken in doses that exceed requirements are excreted through urine. Fat-soluble vitamin D, however, like other lipophilic substances, when present in excess, is accumulated and then released in small doses according to the body’s needs. If the levels are too high, a state of intoxication occurs.

Vitamin D synthesis can occur within the human body when ultraviolet rays from sunlight penetrate the skin, triggering the production of pre-vitamin D3, the precursor to vitamin D3. To a lesser extent, vitamin D can be taken with food. In both cases, these are inactive forms that must undergo two transformations (in the liver and then in the kidney) before becoming the physiologically active vitamin D.

In any case, exposure to the sun, however prolonged and protracted, does not lead to hypervitaminosis because our body is able to regulate the amount of vitamin D produced in the skin. The same applies to diet, as there are very few vitamin D-rich foods and even fortified foods don’t contain high amounts of the vitamin. In most cases, the cause of hypervitaminosis D is therefore the intake of excessive amounts of supplements containing this vitamin. Vitamin D hypervitaminosis is caused by prolonged and/or excessive intake of the vitamin. Hypervitaminosis D – the presence of excess vitamin D in our bodies – is a rare but potentially serious condition that can undermine the body’s wellbeing.

Toxicity caused by high vitamin D levels is uncommon, occurring almost exclusively in people who take high-dose, long-term supplements without following a medical prescription or monitoring their blood values. Because vitamin D is stored in body fat and released slowly into the bloodstream, the effects of toxicity can still last for several months after stopping taking supplements.

What foods are best avoided during this time period? It may help to reduce consumption of foods that contain significant portions of vitamin D, including fatty fish, such as salmon and tuna, beef liver, cheese, egg yolk and some mushrooms. This is the case even if vitamin D through the diet is unlikely to have a significant effect on its excessive values. Of course, it’s advisable to avoid taking cod liver oil. When shopping, pay attention to labels, as vitamin D-fortified foods including milk and dairy products, orange juice and yoghurt can be found in shops. It’s also important to limit calcium in the diet, avoiding milk, yoghurt, cheese and butter; but also, for example, aromatic herbs (such as rosemary, basil, parsley, mint, thyme, sage, marjoram and oregano), seeds, dried fruit and chocolate.

Vitamin D deficiency

Vitamin D and sunshine

Vitamin supplements

Vitamin D and bones

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