What are carbohydrates and it's functions?

Carbohydrate are organic compounds made of carbon, hydrogen and oxygen. They are called carbohydrates because hydrogen and oxygen are present is same proportion as found in water 2:1 .

They are macronutrient and normal staple diet of people includes 70 - 80 % carbohydrates. They are Caloriegenic food and quick energy food. They can  be obtained from plant as well as animal source but the primary producer is plant. Small units of carbohydrates are saccharide.

Classification of carbohydrates 

1. Monosaccharides :- They are simple Carbohydrate s composed of single sugar units and cannot be further broken down.

  • Glucose :- Glucose is also known as dextrose . It is the most important of all mono saccharides as it is primary carbohydrates used by our body. It is building block of carbohydrates and is moderately sweet.

  • Fructose :- It is the sweetest of all sugar and also known as fruit sugar because it is found in fruits and honey . It is Soluble in water and twice as sweets as glucose.

  • Galactose :- It is of animal origin and building block of lactose . They are moderately sweet and fairly soluble in water.  It is found in milk, gum ,mucilage

2. Disaccharide :-

It is formed by condensations of two mono saccharides with a lost of one water molecule.when breakdown they split into Monosaccharide.

  • Sucrose :- It is also known as Table sugar and soluble in water. It is made of 1 molecule of glucose and 1 molecule of fructose. it is break by enzyme sucrase. It is prepared from sugarcane , beetroot . 

  • Lactose :- It is also known as Milk sugar and made of 1 molecule of glucose and 1 molecule of galactose. It is least sweet of all sugar and is easily fermented to lactic acid by lactic acid bacteria. It is breakdown by enzyme lactase

  • Maltose :- It is also known as malt sugar which is composed of 2 Molecule of glucose. They are obtained from sprouted grain like barley, Millet and rice . It is breakdown by enzyme Maltase 


1. The chief Function of carbohydrate is to provide energy to the body . It is the cheapest source of energy available.

2 All carbohydrates except fibre provides 4 kcal/g of energy

3. Glucose is the only form of energy used by central nervous system 

4. Carbohydrate spare proteins from being broken down for energy

5. Fibre helps in lowering blood cholesterol level

6. They are required for complete oxidation of fat. 

Excess of carbohydrates :-

1. Cause of tooth decay

2. Excessive fibre could irritate intestinal lining causing cramps.

3. Depress the appetite and cause malnutrition

4. obesity.

Main source of carbohydrates are cereal , Rice , vegetables , pasta . One gram of carbohydrates gives 4 kcal / gram of energy

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