Constituents of Food

Nutrients in food are grouped into several categories. Macronutrients means fat, protein, and carbohydrates. Micronutrients are the minerals and vitamins. Additionally food contains water and dietary fiber.

Carbohydrates are the most important source of energy. From them we get most of energy which we need to act and move, perform work and live. They contain the elements Carbon, Hydrogen and Oxygen. The first part of the name "carbo-" means that they contain Carbon. The second part of the name "-hydr-" means that they contain Hydrogen. The third part of the name "-ate-" means that they contain Oxygen. In all carbohydrates the ratio of Hydrogen atoms to Oxygen atoms is 2:1 just like water.

We obtain most of our carbohydrate in the form of starch. This is found in potato, rice, spaghetti, bread and cereals. Our digestive system turns all this starch into another carbohydrate called glucose. Glucose is carried around the body in the blood and is used by our tissues as a source of energy. Any glucose in our food is absorbed without the need for digestion. We also get some of our carbohydrate in the form of sucrose; this is the sugar which we put in our tea and coffee. Both sucrose and glucose are sugars, but sucrose molecules are too big to get into the blood, so the digestive system turns it into glucose.

Proteins are required for growth and repair. The living tissues of plants and animals consist of protein material which is continually destroyed in the maintenance of life and must be restored. Proteins contain Carbon, Hydrogen, Oxygen, Nitrogen and sometimes Sulphur. Proteins are very large molecules, so they cannot get directly into our blood; they must be turned into amino-acids by the digestive system. There are over 20 different amino-acids. Our bodies can turn the amino-acids back into protein. When our cells do this they have to put the amino-acids together in the correct order. There are many millions of possible combinations or sequences of amino-acids; it is our DNA which contains the information about how to make proteins. Our cells get their amino-acids from the blood. Proteins can also be used as a source of energy. When excess amino-acids are removed from the body the Nitrogen is excreted as a chemical called urea. The liver makes urea and the kidney puts the urea into our urine.

Fats make our meals palatable and satisfying. Like carbohydrates, fats contain the elements Carbon, Hydrogen and Oxygen. Fats are used as a source of energy: they are also stored beneath the skin helping to insulate us against the cold. Some fats and oils are important sources of vitamins A, D, E and K. They provide various amounts of fatty acids which are essential in diet.

Vitamins are known to be exceedingly important in nutrition even though they are required only in small amounts. They are essential for good nutrition and health and for normal growth.

· Vitamin A: good for your eyes.

· Vitamin B: about 12 different chemicals.

· Vitamin C: needed for your body to repair itself.

· Vitamin D: can be made in your skin, needed for absorption of сalcium.

Minerals are inorganic elements. Most of them can be found in the body, but only fifteen of them are known to be essential and must be taken from food. The main functions of minerals are: they are constituents of the bones and teeth; they help to control the composition of body fluids and salts; they are essential adjuncts to many enzymes, and other proteins such as haemoglobin. The major minerals are calcium, phosphorus, magnesium, sodium, chlorine, potassium, iron and sulphur.

Fibre. We do not// can not digest cellulose. This is a carbohydrate used by plants to make their cell walls. It is also called roughage. If you do not eat foods materials which contain fibre you might end up with problems of the colon and rectum. The muscles of your digestive system mix food with the digestive juices and push food along the intestines by peristalsis; if there is no fibre in your diet these movements cannot work properly.

4.Answer the following questions.

1.What nutrients are found in food?

2.What reasons are carbohydrates important for?

3.What do carbohydrates contain?

4.What forms do we get carbohydrates in?

5.We need proteins for growth and repair, don’t we?

6.Can proteins get directly into our blood? Why?

7.What is DNA?

8.What role do fats play?

9.Are vitamins important for good nutrition?

10.How many minerals are essential for the body?

11.What are the functions of minerals?

12.Why is it necessary to eat foods which contain fibre?

5.Give the English equivalents to the following words and word combinations.

Поживні речовини, клітковина, виконувати роботу, у формі крохмалю, травна система, поглинатися, занадто великий, перетворювати на глюкозу, молекули цукрози, ріст та відновлення, впродовж життя, безпосередньо в кров, сполуки і послідовності, містити інформацію, надлишок амінокислот, смачний і ситний, у невеликих кількостях, складові кісток і зубів, склад рідин та солей в організмі, стінки клітин, травні соки.

6.Match the nutrients with their functions.

1) Carbohydrates 2) Fats 3) Proteins 4) Minerals 5) Vitamins 6) Fibre

a) are the constituents of the bones and teeth, help to control the composition of body fluids and salts. b) is required to help your intestines function correctly, it is not digested. c) are essential for health and for normal growth, regulate the body processes. d) give energy which we need to act, move, perform work, and live. e) provide amino acids for growth and repair. f) make food palatable and satisfying; provide essential fatty acids.

7.Arrange the words into the groups.

Carbohydrates, calcium, liver, potato, Carbon, proteins, rice, blood, phosphorus, Oxygen, bread, skin, fats, colon, Nitrogen, magnesium, spaghetti, eyes, iron, vitamins, coffee, teeth, minerals, Sulphur, cereals, kidney, potassium, rice, bones, tea, sodium, intestines.

Food	Nutrients	Chemical elements	Minerals	Parts of the body
…	…	…	…	…

8.Read the following sentences choosing the correct word.

1.People get carbohydrates in the form of glucose/starch.

2.Sugar which we put into tea or coffee is called glucose/sucrose.

3.Sucrose molecules are too big/small to get into the blood.

4.Proteins must be turned into amino-acids/fatty acids.

5.Fats are stored beneath the skin/in the intestines.

6.Vitamins are required in big/small amounts.

7. Vitamin C/Vitamin A is good for eyes.

8.People can/can’t digest cellulose.

9.You are going to read a newspaper article about unhealthy food. Six paragraphs have been removed from the article. Choose from paragraph A-G the one which fits each gap (1-5). There is one extra paragraph which you do not need to use. There is an example at the beginning (0).