Excess of Vitamin D – Toxicity

Excess of Vitamin D - Toxicity

Hypervitaminosis and Vitamin D

Hypervitaminosis is a morbid condition caused by an excess of vitamins , which causes intoxication of the organism.

There are various types of hypervitaminosis, depending on the type of vitamin taken in excess; however, it should be noted that not all vitamins cause intoxication and that their excess can have very different consequences from one vitamin to another.

The discovery of hypervitaminosis morbid states is quite recent, since in the past it was ignored that these nutrients , more often deficient than in excess in the diet, could in some way harm health.

Vitamin D

Vitamin D is a fat-soluble nutritional factor , with a hormonal-like action. In nature it is widespread in various chemical forms, but the metabolically active one is calcitriol .
Vitamin D performs various functions, among which the most important is the regulation of calcium and phosphorus in the body (but it is also necessary for the differentiation of some cells , for the immune system , etc.).

Calcium and phosphorusthey are essential for the skeleton , for the teeth and also for the muscles .
A lack of vitamin D can lead to bone deformities such as rickets in children and osteomalacia in adults; the lack of vitamin D and calcium in youth, responsible for the failure to reach peak bone mass , can favor the onset of osteoporosis in old age (especially in the presence of significant hormonal alterations related to menopause ).
Most vitamin D is synthesized in the skin from cholesterol, thanks to the action of the sun’s UV rays (at mid-latitudes, from May to September, the body is capable of fully satisfying its need for vitamin D on its own).

In the autumn- winter period , or in any case in places where sun exposure is limited, it is necessary to increase the intake of vitamin D with the diet. The most relevant sources are: fatty fish , fish liver and its oil, egg yolk , certain mushrooms and fortified foods .
The dietary requirement of vitamin D is between 8.5 and 10 μg/day.

Is too much vitamin D bad for you?

Excess vitamin D can be harmful to health. Obviously. this depends on the actual extent of the excess, i.e. on the amount of vitamin D capable of triggering intoxication in the body.



Vitamin D excess and intoxication

Even if all documentary toxicity cases refer to doses higher than 1,000 μg/day (40,000 IU), it is assumed that a prolonged intake of vitamin D at doses > 250 μg/day (10,000 IU), with blood levels of the same equal to 100 ng/ml , can cause both acute and chronic phenomena.



Causes of vitamin D poisoning

The causes of vitamin D poisoning are almost exclusively pharmacological. The nutritional component also plays a fundamental role but, as often happens, only when the diet includes supplements and fortified foods .



Symptoms of vitamin D poisoning

The symptoms of vitamin D hypervitaminosis are:

  • Nausea
  • Diarrhea
  • Polyuria .


Clinical signs

The clinical signs of hypervitaminosis D are:

  • Hypercalcemia
  • Hypercalciuria
  • Soft tissue calcification.



What happens when you take too much vitamin D?

As we have said, taking drugs and/or vitamin D supplements in excess for a long period of time can lead to specific hypervitaminosis and consequent intoxication.
In correlation to the symptoms and clinical signs already described, due to the accumulation of calcium in the blood (hypercalcemia) coming from the bones , serious complications can arise, such as:

  • Weakening of the skeleton
  • Damage to certain organs such as the kidneys and heart .



Remedy for vitamin D poisoning

To cure vitamin D poisoning it is necessary to suspend or reduce its intake with drugs and supplements.
It is not necessary to modify the diet, even if the elimination of all fortified foods could help the recovery of vitamin D blood homeostasis and consequently of calcium levels.



Right dose of vitamin D with supplements

By choosing to take supplements and foods fortified with vitamin D as a supplement to the ordinary diet, it is advisable not to exceed 10 μg/day.

Maximum dose of vitamin D with supplements

With quantities greater than 100 μg/day the chances of undesirable effects are higher than normal. This applies to healthy adults, pregnant and breastfeeding women , the elderly , and children between the ages of 11 and 17.

Children between the ages of 1 and 10 must never exceed 50 μg/day.

The limit for infants under 12 months is 25 μg/day.
Note : sick subjects may have a lower tolerance and suffer intoxication at lower doses. If in doubt, consult your doctor.

Dose of vitamin D in therapy

The dose of vitamin D necessary for therapy to combat rickets is 250 μg/day (10,000 IU of vitamin D3 or cholecalciferol); consider this value as the safe upper limit for the tolerable daily intake (UL).



Recommendations of the competent bodies

Information dissemination bodies are partly responsible for the few cases of vitamin D hypervitaminosis. Vitamin D deficiency has been responsible for serious public health problems for many years. Today, aware of the diseases that can depend on its nutritional deficiency, there is a tendency to overemphasize the importance of dietary supplementation . We remind you that food supplements and fortified foods are over-the-counter products available in supermarkets, pharmacies without a medical prescription or in parapharmacies. They are therefore widely available and within everyone’s reach.
For example, the UK ‘Department of Health’ recommends the following:

  • Infants breastfed from birth to one year of age should be given a daily vitamin D supplement containing 8.5-10 μg of the active ingredient to ensure that the minimum requirement is met.
  • Infants fed synthetic formulas should not be supplemented.
  • Children between the ages of 1 and 4 should enjoy a daily supplement of 10 μg.

Furthermore, the same recommends taking a daily supplement containing 10 μg of vitamin D throughout the year if:

  • You don’t leave the house often
  • He is hospitalised
  • Clothing that covers most of the skin is worn.

Such recommendations can easily be overestimated and excessive intake of vitamin D often occurs. However, it must also be admitted that the criticality limit, already corrected for default, is about 10 times higher than the guidelines’ recommendations.



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