Vitamin A overdose
Vitamin A (retinol, A 1, vitamin A) - a fat-soluble vitamin, which opened in 1913. In 1931, the Swiss chemist Paul Carrer (awarded for the discovery of the Nobel Prize) was the first to fully describe its chemical structure, and in 1937, vitamin A was crystallized. Retinol and its derivatives (retinal (vitamin A 1 aldehyde), dehydroretinol (A 2) and retinoic acid, esters of these compounds and their spatial isomers) are combined into the retinoid group.
Source: depositphotos.com
Vitamin A and other retinoids are found in some plant foods, but mostly in animal products: fish oil, liver (mostly beef), caviar, milk, butter, margarine, sour cream, cottage cheese, cheese, egg yolk.
The precursors of retinoids, the so-called provitamins, are carotenoids - natural pigments of yellow, orange or red color, found mainly in plant products. To date, more than 600 carotenoids have been described, the most common are α-, β- and δ-carotenes, lutein, lycopene, zeaxanthin. Once in the body, they are partially metabolized to retinoids. The main sources of provitamins A are green and yellow vegetables (carrots, pumpkin, bell peppers, spinach, broccoli, green onions, parsley), legumes (soybeans, peas), peaches, apricots, apples, grapes, watermelon, melon, rose hips, sea buckthorn, cherries.
Vitamin A has many functions in the body:
- indirectly stimulates the synthesis of bone, cartilage and connective tissue proper;
- is part of enzymes that enhance the synthesis of hyaluronic acid;
- is a component of sex hormones;
- participates in the formation of taurine (sulfonic acid, plays the role of a neurotransmitter, stimulates energy processes, improves metabolism in the tissues of the eye);
- participates in the synthesis of liver enzymes;
- involved in redox processes;
- ensures the normal functioning of the visual analyzer;
- supports the activity of the immune system;
- accelerates healing processes, stimulates collagen synthesis, improves the quality of newly formed epithelial tissue;
- contributes to the normal development of the embryo during pregnancy;
- being a powerful antioxidant, it has an antitumor effect, including helping to prevent the recurrence of cancer.
With excessive use of retinoids, an overdose develops, manifested by acute or chronic intoxication.
How much vitamin A is needed for an overdose?
1 mcg of retinol is equivalent to 3.33 IU (international units).
The daily intake of vitamin A varies depending on the situation (prophylactic or therapeutic intake) from 10,000 (3,000 μg) to 50,000 (15,000 μg) IU for an adult. For a child, the daily rate is calculated depending on age.
A dose of vitamin A at the rate of 25,000 IU per 1 kg of body weight provokes acute poisoning, daily consumption of 4,000 IU per 1 kg of body weight for six months or more causes chronic poisoning.
Signs of overdose
Acute overdose is manifested by the following symptoms:
- motor and speech excitement or, conversely, drowsiness, depression of consciousness;
- headache;
- development of seizures, paralysis is possible;
- loss of appetite, nausea and vomiting;
- abdominal pain, diarrhea;
- fever;
- photophobia.
Chronic overdose of vitamin A and other retinoids has a wide range of symptoms:
- the appearance of various shapes and colors of rashes, itching and flaking of the skin, hair loss, brittle nails, dryness of the oral mucosa, seizures in the corners of the mouth
- a decrease in the general tone of the body, loss of appetite, drowsiness, irritability, dizziness, frequent headaches, torrential night sweats;
- joint and bone pain, degeneration of cartilage tissue, the development of osteoporosis (bone loss), which provokes spontaneous fractures;
- in pregnant women, the systematic long-term intake of excessive doses of retinol can lead to the formation of congenital abnormalities in the development of the fetus;
- keratitis (inflammation of the cornea), visual impairment (photophobia, decreased acuity, twilight vision disorder);
- dyspeptic disorders (pain in the epigastric and umbilical region, nausea, vomiting, stool disorders), enlargement of the liver and spleen, exacerbation of chronic diseases of the gastrointestinal tract.
Source: depositphotos.com
First aid for an overdose of vitamin A
If a chronic overdose is diagnosed, it is necessary to immediately stop taking the vitamin and correct the developed disorders in a hospital setting.
In case of acute overdose with retinol, it is necessary:
- Rinse the stomach, for which drink 1-1.5 liters of water or a weak solution of potassium permanganate and, by pressing on the root of the tongue, induce a gag reflex.
- Take a saline laxative (magnesium sulfate).
- Take enterosorbent (Enterosgel, Polysorb, Laktofiltrum or any other).
Antidote
There is no specific antidote for vitamin A.
When is medical attention required?
Medical assistance is needed in a number of cases:
- a child, pregnant woman, or elderly patient is injured;
- violent neurological symptoms (paralysis, paresis, convulsions, stupor, stupor, coma);
- high fever resistant to antipyretic drugs;
- indomitable vomiting and diarrhea;
- traces of blood in vomit or stool;
- intense headache.
Treatment is carried out in stationary conditions:
- a diet low in vitamin A and carotenoids;
- the introduction of enterosorbents;
- intravenous administration of electrolyte solutions (sodium chloride, Lactasol, polarizing mixture) or plasma substitutes (Reomakrodex, Reopolyglyukin, Polyglyukin);
- forced diuresis (diuretic drugs (usually Furosemide) in combination with a water load of up to 5 l / day);
- oxygen therapy for the prevention of hypoxic damage to organs and tissues;
- hepatoprotectors (Karsil, Essentiale);
- in severe cases - exchange blood transfusion, hemodialysis.
With adequate therapy, the consequences of acute poisoning are stopped within a few days, chronic - in a period from a week to a month.
Possible consequences
The consequences of an overdose of vitamin A are observed, as a rule, in the case of long-term use of high doses, an acute overdose is usually resolved without serious complications:
- renal and / or hepatic impairment;
- inflammation of the pancreas (pancreatitis);
- in children - the development of hypertensive-CSF syndrome;
- in women - impaired reproductive function, menstrual cycle, up to amenorrhea;
- coma, when taking an ultra-high dose of vitamin - death.
Olesya Smolnyakova Therapy, clinical pharmacology and pharmacotherapy About the author
Education: higher, 2004 (GOU VPO "Kursk State Medical University"), specialty "General Medicine", qualification "Doctor". 2008-2012 - Postgraduate student of the Department of Clinical Pharmacology, KSMU, Candidate of Medical Sciences (2013, specialty "Pharmacology, Clinical Pharmacology"). 2014-2015 - professional retraining, specialty "Management in education", FSBEI HPE "KSU".
The information is generalized and provided for informational purposes only. At the first sign of illness, see your doctor. Self-medication is hazardous to health!
