Vitamins

Vitamins are substances that are essential in certain chemical transformations in the human body. They help the body process proteins, carbohydrates, and fats. Certain vitamins also contribute to the production of blood cells, hormones, genetic material, and chemicals of the nervous system.

Vitamins exist in minute quantities in food. Most vitamins cannot be produced by the body and must be obtained through the diet. Since no single food item or nutrient class provides all the essential vitamins, it is necessary to eat a variety of foods. For example, vitamin A is needed for the eyes and to keep the linings of the bronchial, urinary, and intestinal tracts healthy; vitamin C is needed for the development of bones, teeth, blood vessels, and other tissues; vitamin K is necessary for blood clotting; and vitamin D is also needed for the development of bones and teeth.

The principal vitamins are: vitamin A, vitamin B₁, vitamin B₂, pantothenic acid (part of the B₂ complex), vitamin B₃, vitamin B₆, folic acid, vitamin B₁₂, vitamin C, vitamin D, vitamin E, vitamin H (often considered part of the B-vitamin group), and vitamin K.

Some vitamins (e.g., vitamin K) are produced by intestinal bacteria, and a few can be formed by the body from substances called provitamins (portions of vitamins that can be assembled or modified by the body into functional vitamins). Carotene is an example of a provitamin that can be modified by the body to form vitamin A. Vitamins are used by the body in their original or slightly modified forms. Once the chemical structure of a vitamin is destroyed, its function is usually lost. The chemical structure of many vitamins is destroyed by heat (e.g., when food is overcooked).

There are two major classes of vitamins: fat soluble and water soluble. Fat-soluble vitamins such as vitamins A, D, E, and K are absorbed from the intestine along with lipids, and some of them can be stored in the body for a long period of time. Because they can be stored, it is possible to accumulate an overdose of these vitamins in the body (hypervitaminosis) to the point of toxicity. Water-soluble vitamins such as the B complex and C are absorbed with water from the intestinal tract and remain in the body only a short time before excreted.

The absence of a specific vitamin in the diet can result in a specific deficiency disease.

Ex. 11. Translate the following words and word-combinations into English:

Зберігати; сприяти; живлення|харчування|, їжа; пантотенова кислота; збирати; кількість; неістотний|несуттєвий|, незначний; брак|нестача|, дефіцит; компонент їжі; фолієва| кислота; згортання; розчинний.

Ex. 12. Translate the text “Vitamins” into Ukrainian:

Ex. 13. Insert the missing words:

1. Vitamins are _ that are essential in certain chemical transformations in the human body. 2. They help the body process _, carbohydrates, and fats. 3. Most vitamins cannot be produced by the body and must be obtained through the _. 4. Vitamin A is needed for the eyes and to keep the _ of the bronchial, urinary, and intestinal tracts healthy; vitamin C is needed for the development of bones, teeth, blood vessels, and other tissues; and vitamin D is also needed for the development of _ and teeth. 5. Some vitamins are produced by intestinal bacteria, and a few can be formed by the _ from substances called provitamins. 6. Once the chemical structure of a vitamin is _, its function is usually lost. 7. There are two major classes of vitamins: _ -soluble and _ -soluble. 8. _-soluble vitamins are vitamins A, D, E, and K. 9. _-soluble vitamins are the B complex and C.

Ex. 14. Answer the following questions:

1. What are vitamins? 2. What is the function of vitamins? 3. What principal vitamins do you know? 4. How are some vitamins produced by the body? 5. In what form are vitamins used by the body? 6. What classes are the vitamins divided into?

Ex. 15. Insert the prepositions:

1. Vitamins A and D are stored _ the liver. 2. Reserves of vitamins A and D may be sufficient _ 6 months. 3. Vitamins A and D can produce toxic effects when taken _ excessive amounts. 4. Although it is popularly believed that the water-soluble vitamins are harmless when taken _ large amounts, this is not always true. 5. Some of the water-soluble vitamins may have strong medicinal effects – good and bad – when taken _ large amounts. 6. _ large doses, B vitamin can cause nerve damage.

Ex. 16. Write out key sentences of the text “Vitamins”.

Ex. 17. Make up a plan of the text “Vitamins”.

Ex. 18. Give a summary of the text “Vitamins”.