CBSE Notes Class 6 Science - Components of Food

We know the importance of food, it is required for growth, maintenance of the body and also to protect us from diseases. We eat a large variety of food, and people from different parts of our country have different food habits. Some people prefer rice, others take chapatis or meat and fish.

1.0Components of Food

• Nutrients are the substances in the food that every living organism needs to make energy, grow, develop and reproduce. 
• There are seven essential components or substances called nutrients in our food.
• Carbohydrates  
• Fats  
• Proteins 
• Mineral salts 
• Vitamins  
• Water 
• Fiber (also called roughage) 

There are two main types of nutrients. 

• Macronutrient : It consists of carbohydrates, fats and proteins which are required in large amounts. 
• Micronutrient : It consists of vitamins and minerals which are required in small amounts. 

1. Carbohydrates 

• Carbohydrates are as important to the body as fuel is to cars. 
• These are the common energy-giving compounds. 
• There are two major types of carbohydrates in food : sugar and starch. Sugar is used to provide energy immediately. Starch releases energy more slowly than sugar..
• Foods rich in carbohydrates are potato, sweet potato, bread, rice, wheat, honey, common sugar, jaggery (gur) and milk.

2. Fats

• Fats too provide us energy, producing more energy than carbohydrates. Fat- rich foods are 
• milk products such as butter and cheese
• vegetable oils such as coconut oil, groundnut oil
• nuts,  
• milk
• animal fat from meat. 
• Fats provide more than double the energy provided by carbohydrates or proteins but still carbohydrates are the preferred source of energy because fats make energy available at a slower pace. 

Functions of fat 

• Efficient source of energy
• Forms an insulating layer beneath the skin to prevent excessive heat loss. e.g. Blubber in whales
• Formation of fat soluble vitamins and various hormones.

3. Proteins

• These are body-building foods. 
• Proteins help the body in its growth, repair of body cells and tissues, protect and help the body to fight against infections and regulate body functions. 
• Protein sources of plant origin include pulses, soybeans, peas, and to a lesser extent cereals. 
• Meat, eggs, cheese, milk and fish provide proteins of animal origin. 

4. Mineral salts 

• Mineral salts are important for various body functions. 
• They are required in small quantities and are obtained from the food we take in. Minerals have no energy value. 
• Rich sources are milk, cheese, green leafy vegetables (like spinach), pulses, meat and eggs. 

5. Vitamins 

• Vitamins are neither body building nor energy giving food, but are very important for proper functioning of our bodies. 
• Some vitamins can be produced by our body, but most have to be supplied through food. Vitamins are classified into two types 
• Fat soluble vitamins - A, D, E, K. 
• Water soluble vitamins - B and C

6. Water 

• Water is indispensable. 
• About 70 percent of our body weight is that of water. 
• It helps the body in various functions. 
• It is a means of transporting substances in the organism. 
• It helps to maintain a constant body temperature. 
• Water helps in the absorption of food and excretion of waste products from the body in the form of urine and sweat. 
• Our body needs 2-3 liters of water every day. 

7. Dietary fibers / Roughage

• Roughage is the fibrous indigestible material in food that promotes the elimination of wastes from the large intestine. 
• Fibers come from plants. 
• Fiber is the substance that gives plants their form. 
• The fibers that we eat are known as dietary fibers. 
• Whole grains and pulses, potatoes, fresh fruits and vegetables are main sources of roughage. 

2.0Balanced Diet 

• A diet that contains an adequate amount of different components of food required for the healthy functioning of our body is called a balanced diet. 
• According to scientists, a balanced diet must include foodstuffs from the following four basic food groups: 
• Milk group : Includes milk and milk products. 
• Meat group: Includes meat (chicken, fish, lamb, etc.) and meat substitutes (beans, peas, nuts, and seeds). 
• Fruit and vegetable group: Includes fruits and vegetables. 
• Grain group: Includes breads and cereals.

Effect of cooking on nutrients

• Selecting and eating the right kind of food is not enough. 
• It should be cooked properly. 
• Cooking improves the taste of food and makes it easily digestible. 
• Cooking results in loss of certain nutrients. 
• For example, Vitamin C gets easily destroyed by heat during cooking. 
• It is, therefore, advised to include fruits and raw vegetables in our diet. In the case of rice, it is a common practice to use excess water during cooking and then throw off the extra water. 
• This results in loss of nutrients. 

3.0Diseases due to imbalance in the diet 

• Many diseases are known to occur just because of imbalances in the diet. Imbalances in the diet may be due to following three reasons : 
• Inadequate quantity of food (under-nourishment or undernutrition)
• Excess of food (overnutrition)