Vitamin A.

Vitamin A belongs to the group of vitamins that the human body absolutely cannot synthesize. Therefore, the person himself must take care of replenishing the daily supply of vitamin A, the daily dose of which is:

For newborns and up to 6 months: 400 mcg / day (the permissible upper limit of the daily dose is 600)
For infants from 7 to 12 months: 500 mcg / day (acceptable upper limit of the daily dose is 600)
For children from 1 year to 3 years: 300 mcg / day (the permissible upper limit of the daily dose is 600)
For children from 4 years old to 8 years old: 400 mcg / day (the permissible upper limit of the daily dose is 900)
For boys from 9 to 13 years old: 600 mcg / day (permissible upper limit of the daily dose - 1700)
For girls from 9 to 13 years old: 600 mcg / day (permissible upper limit of the daily dose - 1700)
For men 14 and older: 900 mcg / day (the permissible upper limit of the daily dose is 2800)
For women 14 and older: 700 mcg / day (the allowed upper limit of the daily dose is 2800)
For pregnant women: 750-770 mcg / day (the permissible upper limit of the daily dose is 2800)
For breastfeeding: 1200-1300 mcg / day (the permissible upper limit of the daily dose is 2800)

The source of vitamin A can be food products of plant and animal origin, pharmaceuticals of vitamin A, produced in the form of separate compositions and in the form of vitamin complexes.

In plant products, vitamin A is found in the form of its precursors - carotenoids (alpha, beta, gamma - carotenes) and xanthophylls (beta-cryptoxanthin). Plants (vegetables and fruits) containing carotenoids have an expressive orange-red hue due to the fact that carotene itself is a yellow-orange coloring matter (with the exception of greens and legumes, which also contain carotenoids). Vitamin A is synthesized from beta-carotene only when necessary in a ratio of 6 mg of beta-carotene = 1 mg of vitamin A; in other cases, beta-carotene is involved in metabolic processes by itself as an antioxidant.

Vegetables containing provitamins A:

Carrots (9 mg / 100g of product)
Sweet red pepper (2 mg / 100g product)
Pumpkin (1.5 mg / 100g product)
Tomato (1.2 mg / 100g product)
Sweet green pepper (1 mg / 100g product)
Brussels sprouts (0.3 mg / 100g product)
Red cabbage (0.1 mg / 100g of product)
Potatoes (0.02 mg / 100g product)

Fruits containing provitamins A:

Sea buckthorn fruit (7 mg / 100 g of product)
Rosehip fruit (5 mg / 100g product)
Mango (2.9 mg / 100g product)
Melon (2 mg / 100g product)
Apricots (1.6 mg / 100g of product)
Aronia fruit (1.2 mg / 100g of product)
Peaches (0.5 mg / 100g product)
Apples (0.02mg / 100g product)
Cherry (0.1 mg / 100g product)
Plum (0.1 mg / 100g product)
Watermelon (0.1 mg / 100g product)

Legumes containing provitamin A:

Soy (0.07mg / 100g product)
Green peas (0.4 mg / 100g of product)
Green beans (0.4 mg / 100g product)

Greens containing provitamin A:

Sorrel (7 mg / 100g product)
Parsley leaves (5.7 mg / 100g product)
Watercress (5.6 mg / 100g product)
Spinach (4.5 mg / 100g product)
Celery leaves (4.5 mg / 100g product)
Ramson (4.2 mg / 100g product)
Garlic (2.4 mg / 100g product)
Green onions (2 mg / 100g of product)
Lettuce (1.8 mg / 100g product)
Broccoli (1.5 mg / 100g product)
Dill (1 mg / 100g product)

Animal products contain ready-made vitamin A in the form of retinoids (retinol or axeroftol, dehydroretinol, retinal, retinoic acid).

Foods containing vitamin A:

Fish oil (19 mg / 100g product)
Chicken liver (12 mg / 100g product)
Beef liver (8.2 mg / 100g product)
other types of animal liver (3.6 mg / 100 g of product)
Cod liver (4.4 mg / 100g product)
Beluga fish roe (1 mg / 100g product)
Egg yolk (1.26 mg / 100g product)
Dairy products (milk - 0.025 mg / 100g of product, fat cottage cheese - 0.10 mg / 100g of product)
Animal oils (0.5 mg / 100g product)
Cheese (0.25 - 0.30 mg / 100g product)

Pharmaceutical forms of vitamin A preparation:

Cod fish oil
Retinol acetate (tablets, dragees)
Retinol acetate solution in oil
Retinol palmitate (tablets, dragees)
Retinol palmitate solution in oil
Vetoron

A feature of vitamin A and its carotenoid precursors is their insolubility in water, but good solubility in oils. It is for this reason that, for example, it is recommended, for example, to mix salads containing vegetables with carotenoids with vegetable oil (to increase the percentage of assimilation of provitamins A), vitamin A itself (as a pharmaceutical) should be used in combination with vitamin E or in the form of oil solutions.

From the point of view of medical significance, the role of vitamin A in maintaining the health of the human body cannot be underestimated. Obtained by any means (ingested in the form of retinoids or synthesized from carotenoids), vitamin A is responsible for many processes in the body:

stimulates the growth of the body,
constitutes an important component in the structure of cell membranes,
participates in the antioxidant defense of the body along with other substances,
provides the synthesis of rhodopsin, a component of the retina that provides us with twilight vision,
stimulates T-cell immunity ,
participates in the synthesis of the enzyme lysozyme, interferon ,
is an intermediate in the synthesis of structural chemical compounds for the formation of cartilage, bones, connective tissue, muscle tissue,
prevents premature keratinization of skin cells,
the health of the skin and mucous membranes depends on vitamin A, since it is involved in regeneration processes,
participates in the synthesis of sex hormones,
blocks the processes of carcinogenesis.

An overdose of vitamin A is terrible for the liver (causes its toxic damage), since it is in it that it accumulates in 90% of its volume and is deposited in the form of palmitic acid.