Carbohydrates are the chief sources of energy (Providing 4 Kcals/gm). Carbohydrates are cheap and readily available from food. There are three different kinds of carbohydrates. They include starch, sugar, and fibre. We do not get calories from fibre because our bodies do not break down fibre during digestion.
Classification of Carbohydrates
1. Monosaccharides: These are the simplest form of carbohydrates containing simple sugar molecule. Example: Glucose, Fructose and Galactose.
2. Disaccharides: These carbohydrates composed of two units of Monosaccharides. Example: Sucrose, Lactose and Maltose.
3. Polysaccharides: These are the complex sugars containing numerous units of monosaccharide molecules. Example: Glycogen, Cellulose and Pectins.
Carbohydrate intake should be in the range of 300-500gm (50%- 70%) out of the total energy intake for adults and 40-60% for children. Sources: All sugars, jaggery, honey, pulses, whole grains, cereals, grains, rice, fruits, milk, yogurt, beans, roots and tubers such as potatoes, beet root etc.
Functions of Carbohydrates
1. Supplies energy
2. Protein sparing function
3. Oxidation of fats
4. Regulating blood glucose
5. Facilitates bowel movements
Digestion and absorption of Carbohydrates
Salivary amylase aids digestion of starch in the mouth. Most of the digestion of carbohydrates takes place in the small intestine. Carbohydrates are absorbed into the blood stream as glucose, Galactose and fructose. By way of the capillaries of the villi, the simple sugars enter the portal circulation and transported to the liver.
The carbohydrates (E.g, pectin, cellulose, hemicellulose) and some non carbohydrates substances (e.g. lignin) are collectively called as dietary fibre. Fibre is found in vegetables, fruits and grains. It resists digestion.
Significance of Fibre
High fibre diet plays an important role in prevention and management of constipation (Inability to pass motion/ lack of bowel movement) Fibre also helps to reduce blood cholesterol Helps to prevent blood glucose level after food (Post prandial blood glucose)