Overdose of vitamin A
"Everything should be in moderation," says the wise saying. Even the consumption of vitamins, the reserves of which we strive to replenish, has reasonable limits. Separate vigilance is caused by vitamins A and D, folic and ascorbic acid. There is an ancient Greek saying about them: the position of their dosing is between threatening hypovitaminosis and no less threatening hypervitaminosis.
This is especially true for vitamin A, an 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 toxic dose and how to prevent it.
Daily dose of vitamin A
The composition of vitamin A includes retinol, retinal and retinoic acid. All of them are unstable, therefore, to achieve stability, they are connected with ethers. Retinol acetate or palmitate is a "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?
- The daily dose for men is 900 μg or 0.9 mg.
- The daily dose for women is 700 μg (0.7 mg).
The maximum daily allowable dose for adults is 3000 μg (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 - 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 a hyperdose comes in - an overestimate of normal indicators by 3-10 times or megadoses - an increase of 10-100 times or more.
For comparison, you can give a dose of vitamin A in the drug "Aevit." The retinol acetate content in this preparation is 35 mg (more than 100 000 ME)! This is more than 10 times the maximum allowable daily dose.
When there is a poisoning with vitamin A
The traditional place of vitamin A accumulation 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, cod liver craze, pet pepper paste, vitamin accumulation takes place and its toxic effect is manifested.
The indigenous inhabitants of the north do not consume the liver of a seal, walrus or a 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 they designate "Roaccutane", "Tigazon". And also in the treatment of eye diseases in order to improve vision. The appointment of "Aevit" in the treatment of infertility or problems with skin, nails, hair. There are cases of poisoning with prolonged intake of fish oil. Do not take vitamin A with estrogen-containing drugs, this leads to an increase in its absorption and 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
When an overdose of vitamin A symptoms are:
Taking megadoses (from 50 to 300 mg), even once, will cause acute poisoning. Due to diarrhea and indomitable vomiting, severe dehydration occurs. From the side of the nervous system, confused consciousness, severe headache, visual disturbances and convulsions are observed. The next day there is a profuse rash with signs of peeling. The rash covers the face, trunk and especially the limbs. Because of a hemorrhage in the periosteum, there are pains in the large bones of the extremities.
A sign of an overdose of vitamin A is the coloration of the palms and feet in yellow.
Normally, free vitamin A in the blood is not detected. It is bound to a transport protein. His appearance in the blood in a loose state indicates an overdose. If it persists for a long time, it will lead to chronic poisoning. Beat on the liver, because free retinol - hepatotoxic. Violation of protein synthesis, which will affect the coagulating system of blood and detoxification. There is an elevated calcium content in the blood, which is fraught with an increase in intracranial pressure. Signs of increased intracranial pressure:
- nausea, vomiting;
- edema of the papilla of the optic nerve;
- on the skin appears peeling;
- in the corners of the mouth of the crack;
- pain in the bones;
- to increased activity (excitation);
- increase in temperature;
- lack of appetite;
- hair begins to fall out;
- appears seborrhea.
The most formidable complication of increased intake of vitamin A in the child's body is the bulging of fontanelles and the appearance of fluid in the brain (hydrocephalus). There are spontaneous bleeding due to liver damage, bleeding gums appear, nosebleeds are characteristic.
An overdose of vitamin A in children leads to:
Overdose of vitamin A in pregnancy
Of particular concern should be the appointment of unreasonably high doses of vitamin A in pregnancy. With a normal diet, an overdose of food is unlikely, because it has low bioavailability. This makes me happy. But in total consumption in combination with additional doses there is a risk of teratogenesis - congenital deformities.
Thus, the drug "Aevit" is 10 times higher than the threshold of teratogenesis. An overdose of vitamin A during pregnancy threatens to violate the formation of the facial skeleton of the child, heart, stomach and other serious consequences.
During pregnancy, the daily norm is 1 mg.
What to do if an overdose of vitamin A
If you suspect a severe poisoning with vitamin A, you should induce vomiting, rinse the stomach with a suspension of activated charcoal. 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 in a dose of 5.0 milliliters is better to enter intravenously or intramuscularly.
- To begin reception of hepatoprotectors: "Karsil", "Essentiale", "Heptral".
- Glucocorticoids: dexamethasone, prednisolone.
When combined, glucocorticoids and ascorbic acid show antagonism and reduce manifestations of hypervitaminosis.
Hepatoprotectors are necessary because vitamin A is toxic to the liver. Of folk remedies - will have a good therapeutic effect of milk thistle.
Treatment if symptoms of poisoning increase
Washing was carried out, sorbents were taken, but vomiting and diarrhea persisted. Moreover, there were cramps. Immediately call an ambulance! Urgent measures are necessary to reduce intracranial pressure in a hospital:
- mannitol intravenously;
- Glucocorticoids in large doses intravenously drip.
Vitamin A is fat-soluble, with a long excretion period of 21 days. Its effect on the body is comparable to the action of hormones. The desire to be treated with high doses for vitamin A is unacceptable and such carelessness turns into serious consequences. It is better not to experiment with him. The load of carotene, which is contained in plant foods, is not dangerous. You can consume carotene in large quantities without the risk of overdose. But in case of coloring the palms and feet in yellow, the reception should be stopped. Women planning a pregnancy should finish taking high doses of vitamin A for a year or a half before pregnancy in order not to give birth to a sick child.