Vitamins

A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. In other words, an organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. If a molecule can be synthesized in the body, it is not a vitamin. The single exception to this rule is vitamin D which can be synthesized in the skin, but only when exposed to sunlight and Niacin (B3) which itself can be synthesized in the liver in small amounts. The term vitamin does not also include other essential nutrients such as minerals, fatty acids, or amino acids (which are needed in larger amounts than vitamins).

Vitamins are classified as either water-soluble or fat-soluble. There are 13 universally recognized vitamins: 4 fat-soluble (A, D, E, and K) and 9 water-soluble (8 B vitamins and vitamin C). Fat-soluble vitamins are stored in the body's fatty tissue, so they do not need to be ingested every day. Water soluble vitamins cannot be stored, with the exceptions of В₁₂ and Folic Acid and must be ingested frequently for optimal health. They are easily excreted through the urine.

Vitamins have diverse biochemical functions. For example, vitamin A helps to develop and maintain body tissues such as bone and skin; it also helps the body’s vision, nervous system functioning, reproduction, and growth. The B vitamins are responsible for increasing the production of fats, proteins, and carbohydrates as well as assisting with metabolism, building red blood cells, and maintaining the protection of the nervous system. Vitamin C helps form tissues, cells, bones and teeth; heals wounds; and improves the immune system’s performance. Vitamin E protects the outer cell membranes from harm, thus assisting the immune system in fighting off diseases.

A diet naturally high in vitamins and minerals can be the best defense against many diseases. You can develop health problems (deficiency disease) if you do not get enough of a particular vitamin. But it is also important to remember that high doses of certain vitamins can cause vitamin poisoning.

POST-TEXT ASSIGNMENTS:

Exercise 6. Answer the following questions:

1. What vitamins can be synthesized in the body?

2. How are vitamins classified?

3. How many vitamins are universally recognized?

4. Why is it unnecessary to ingest fat-soluble vitamins daily?

5. How are water-soluble vitamins excreted out of the body?

6. What functions do vitamins have?

7. What are B vitamins responsible for?

8. What can high doses of certain vitamins cause?

Exercise 7. Find words or word combinations in the text denoting the following:

1. a condition, such as pellagra, beriberi, or scurvy, produced by a lack of vitamins or other essential substances;

2. a condition of high storage levels of vitamins, which can lead to toxic symptoms;

3. an organic compound required as a nutrient in tiny amounts by an organism, which cannot be synthesized in sufficient quantities within the body;

4. a chemical compound whose molecules contain carbon;

5. a group of vitamins stored in the body's fatty tissue;

6. a group of vitamins which cannot be stored in the body.

Exercise 8. Translate the following word combinations into English:

Різноманітні біохімічні функції, викликати отруєння вітамінами, захищати зовнішню клітинну оболонку від пошкодження, органічна сполука, покращувати продуктивність імунної системи, розвивати авітаміноз, виділяти з сечею, допомагати підтримувати тканини тіла, у достатній кількості, єдиний виняток з цього правила, жирні кислоти та амінокислоти, потрібно споживати щоденно, необхідні поживні речовини, накопичуватися у жировій тканині, водорозчинні вітаміни, жиророзчинні вітаміни.

Exercise 9. Match the terms with their definitions:

vitamin	any vitamin that is soluble in water
fat-soluble vitamin	any of a large group of organic compounds, including sugars, such as sucrose, and polysaccharides, such as cellulose, glycogen, and starch, that contain carbon, hydrogen, and oxygen; an important source of food and energy for animals.
water-soluble vitamin	any substance that nourishes an organism
nutrient	any of various organic compounds that are needed in small amounts for normal growth and activity of the body.
carbohydrate	an injury, especially one in which the skin or another external surface is torn, pierced, cut, or otherwise broken.
wound	any vitamin that is soluble in fats

Дата добавления: 2015-10-21