Vitamin A overdose
“Everything should be in moderation” - says a wise saying. Even the consumption of vitamins, the reserves of which we strive to persevere, has reasonable limits. Separate vigilance is caused by vitamins A and D, folic and ascorbic acid. In relation to them there is an ancient Greek statement: the position of their dosing is between threatening hypovitaminosis and no less threatening hypervitaminosis.
This is especially applicable to vitamin A, overdose of which is extremely rare, but can occur in the treatment of certain diseases. Let's consider what conditions can cause an overdose, the magnitude of its poisoning dose and how to prevent it.
Daily dose of vitamin A
Vitamin A contains retinol, retinal and retinoic acid. All of them are unstable, therefore, in order to achieve stability, they are combined with ethers. Retinol acetate or palmitate is the “sealed” form of vitamin A. Its most active part is retinol.
High content of retinol in the liver, eggs, dairy products. And in herbal products contains the precursor of vitamin A - carotene. They are rich in carrots, peppers, tomatoes.
What is the daily rate for a person?
- Daily dose for men - 900 mg or 0.9 mg.
- The daily dose for women is 700 mcg (0.7 mg).
The maximum daily dose for adults is 3000 mcg (3 mg).
Daily allowance for children:
- from 0 to 12 months - 0.4 mg;
- from one year to three years - 0.45 mg;
- from four to six years - 0.5 mg;
- from seven to ten years old - 0.7 mg.
It becomes clear at what doses the toxic effect of vitamin A on the body is observed — the excess is guaranteed when the hyperdose is administered — the overestimation of normal values is 3–10 times or megadoses — an increase of 10–100 times or more.
For comparison, you can bring the dose of vitamin A in the drug "Aevit". The content of retinol acetate in this preparation is 35 mg (more than 100 000 ME)! This is more than 10 times the maximum daily dose.
When vitamin A poisoning comes
The traditional place of accumulation of vitamin A is the liver. It can contain it from 100 mg to 750 mg. In the liver of animals, its content is even higher. In cases of unusual diets, for example, a preoccupation with cod liver, pet liver, an accumulation of vitamin occurs and its toxic effect is manifested.
Natives of the north do not consume liver of a seal, walrus or polar bear. Even a single dose will give an excess of vitamin A and the consequences will be fatal.
Excess vitamin A is often observed in the treatment of acne when Roaccutane and Thigazon are prescribed. And also in the treatment of eye diseases in order to improve vision. Appointment "Aevit" in the treatment of infertility or problems with the skin, nails, hair. There are cases of poisoning during prolonged use of fish oil. You can not take vitamin A with estrogen preparations, this leads to an increase in its absorption and the risk of overdose.
Treatment of rickets and infectious diseases requires the appointment of large doses. Gradual accumulation of vitamin A will give a picture of poisoning.
Symptoms of an overdose of vitamin A
With an overdose of vitamin A symptoms are:
Acceptance of megadoses (from 50 to 300 mg), even once, will cause acute poisoning. Due to diarrhea and indomitable vomiting, severe dehydration occurs. On the part of the nervous system, confusion, severe headache, visual impairment and convulsions are observed. The next day, a profuse rash appears with signs of scaling. The rash covers the face, torso and especially the limbs. Due to hemorrhage in the periosteum, pain is noted in the large bones of the limbs.
A sign of an overdose of vitamin A is staining of the palms and feet in yellow.
Normally, free vitamin A is not detected in the blood. It is associated with transport protein. His appearance in the blood in a free state indicates an overdose. If it persists for a long time, it will lead to chronic poisoning. Blow will have on the liver, because free retinol is hepatotoxic. Protein synthesis is impaired, which affects the blood coagulation and detoxification system. There is an increased content of calcium in the blood, which is fraught with increased intracranial pressure. Signs of increased intracranial pressure:
- nausea, vomiting;
- swollen papilla of the optic nerve;
- peeling appears on the skin;
- in the corners of the mouth crack;
- bone pain;
- to increased activity (arousal);
- temperature increase;
- lack of appetite;
- hair starts to fall out;
- seborrhea appears.
The most terrible complication of the increased intake of vitamin A in the body of a child is the bulging of springings and the appearance of fluid in the brain (hydrocephalus). There are spontaneous bleeding due to liver damage, bleeding gums appear, nasal bleeding is characteristic.
An overdose of vitamin A in children leads to:
Vitamin A overdose during pregnancy
Of particular concern should be the appointment of unnecessarily high doses of vitamin A during pregnancy. Under normal dietary nutritional overdose is unlikely because of its low bioavailability. This makes me happy. But in total consumption in combination with additional doses there is a risk of teratogenesis - congenital malformations.
Thus, the drug "Aevit" is 10 times higher than the teratogenesis threshold. An overdose of vitamin A during pregnancy threatens a violation in the formation of the facial skeleton of the child, heart defects, stomach and other serious consequences.
During pregnancy, the daily rate - 1 mg.
What to do when overdose of vitamin A
If acute poisoning with vitamin A is suspected, it is necessary to induce vomiting, wash the stomach with a suspension of activated carbon. To do this, crush 8-10 tablets of activated carbon, dissolve in a glass of water and drink. Additional treatment consists of the following procedures.
- Vitamin C at a dose of 5.0 milliliter is better to be administered intravenously or intramuscularly.
- Start taking hepatoprotectors: "Kars", "Essentiale", "Heptral".
- Glucocorticoids: dexamethasone, prednisone.
When used together, glucocorticoids and ascorbic acid show antagonism and reduce the manifestations of hypervitaminosis.
Hepatoprotectors are necessary because vitamin A is toxic to the liver. From folk remedies - thistle meal will have a good therapeutic effect.
Treatment if symptoms of poisoning increase
Washed, taken sorbents, but vomiting and diarrhea persist. Moreover, there were convulsions. Immediately call an ambulance! Urgent measures are needed to reduce intracranial pressure in the hospital:
- mannitol intravenously;
- glucocorticoids in large doses intravenously.
Vitamin A is fat soluble, with a long period of elimination - 21 days. Its effect on the body is comparable to the action of hormones. The desire to be treated with high doses of vitamin A is unacceptable and such carelessness turns into serious consequences. It is better not to experiment with it. Carotene load that is found in plant foods is not dangerous. Carotene can be consumed in large quantities without the risk of overdose. But in the case of staining the palms and feet in yellow, the reception must be stopped. Women planning a pregnancy should finish taking higher doses of vitamin A a year or one and a half before pregnancy in order not to give birth to a sick child.