Carbohydrates

The tern carbohydrate refers to a large family of organic compounds essentially made of three elements i.e. carbon, hydrogen and oxygen. If you are not familiar with the terms element Carbohydrates are widely distributed in plant foods. They are mainly present in these foods in the form of three types of compounds called sugars, starches and fiber. All these carbohydrates are made up of some basic .simple units. One prominent example of a basic unit is glucose. Other examples are fructose and lactose.

Table sugar (cane sugar) which we commonly use in our houses is a carbohydrate made up of two basic units i.e. one unit of glucose and one unit of fructose. On the other hand, a starch molecule is very large. It is made up of several basic units of glucose linked together. These chains of glucose can be straight or branched. Examples of foods rich in starch are rice, wheat, maize and tapioca.

Fiber. like starch, is made up of a number of basic units. The term fiber includes several substances. Cellulose is one example. It is a substance made up of several glucose units. How, then, is it different from starch? It is the type of linkage between glucose units in cellulose that makes all the difference.

All these types of carbohydrates i.e. sugars, starches and fiber can also be classified as.available and non-available carbohydrates. Carbohydrates like sugars and starches are digestible in the human digestive tract and hence can be made available to the body for its functioning. These carbohydrates are termed as available carbohydrates.Cellulose and certain other large carbohydrate molecules that cannot be digested in the human digestive tract are collectively referred to as fiber or non-available carbohydrates.

Available Carbohydrates

You will now learn various aspects relating to sugars and starches i.e. the available carbohydrates

Food Sources: Which foods provide good amounts of carbohydrate? The list includes cereals and mullets, roots and tubers, some fruits, sweeteners like cane sugar, jaggery and honey.  Cereals and mullets are 

the main source of carbohydrates in Indian diets. All cereals like wheat, rice, and millets e.g. jowar, bajra and ragi contain considerable amounts of starch. So do roots and tubers like potato, tapioca, sweet potato, yam and collocation. Fruits like mango, banana, sapota are, however rich in carbohydrates in the sugar form, Cane sugar or cube sugar and other sweeteners Eke honey and jaggery are 95 per cent to

100 per cent carbohydrate (sugar form).

Pulses also contain substantial amounts of carbohydrates. However. pulses are more important in our diet as sources of protein.

Categories of carbohydrates

Functions : Some of the important functions of carbohydrates are listed below

Energy-giving function: The chief function of carbohydrates is to furnish energy for the working of the body. One gram of carbohydrate provides approximately 4 kilo calories (Kcal). Carbohydrate foods are widely distributed in nature and are the cheapest sources of energy. They usually provide 60-70 per cent of the total calories in our diets. The kilo calorie is the unit of measurement of energy. One kilo calorie is the amount of heat required to raise I the temperature of I kilogram of water by I degree centigrade (OC). Do note that in nutrition. kilo calorie and calorie mean one and the same thing.

Protein-sparing action : Though proteins can be broken down in the body to meet the energy need, this is not their chief function. You will learn more about the functions of proteins in Unit 3. An insufficient amount of carbohydrates in the diet will force the body to break down proteins for releasing energy instead 1 of using them for the body's growth and development. Carbohydrates. if taken I in sufficient amounts to meet the energy needs of the body, spare proteins for I their important basic role in the body i.e. supporting growth and body-I building. This particular act of sparing proteins for other functions is termed as t the protein-sparing action of carbohydrates.

Utilization of fats: Some amount of carbohydrate is needed for the proper utilization of fat in the body. Presence of carbohydrates in the diet prevents the body from breaking down too much fat for energy. In case of deficiency of carbohydrates in the diet. more fat will be broken down to meet the energy requirements of the body. Why is this harmful? The reason is that excessive fat breakdown can result in accumulation of by-products of fat metabolism. this accumulation clauses a problem and can affect health.

Non available Carbohydrates

If you have gone through the health columns of leading newspapers or magazines, I you may have come across the term fiber. Fiber is nothing but nonavailability carbohydrate. Is fiber a nutrient? What role does it play in our body? Le! us try to answer these questions. Fiber, as you are aware, refers to a number of indigestible carbohydrates like cellulose present in plant foods. Research in this field shews that though these indigestible components oi food are not available to the body, yet they play an important role in the regulator of some body processes. This is the reason why they arc considered regulatory substances

Functions : Let us now study the role of fiber in some detail.

Satiety value : You know fiber cannot be broken down chemically in the body. However, in the digestive tract some components of fiber absorb water. They swell up and make the food residue bulky which gives a feeling of fullness or satisfaction.

Elimination : Fiber also helps in the easy elimination of  absorbed food in the form of stools or farces from the body. Fiber  present in stools holds water, makes them softer and hence helps in their easy elimination. This particular function of  fiber makes it useful for preventing or relieving constipation. Hence, it is a good idea to eat a diet that has generous amounts of fiber sources like cereals, pulses and vegetables.

Prevention of diseases like cancer, diabetes and heart disease : Some  research studies have indicated that fiber does play a role in prevention of diseases like heart disease, diabetes. cancer of the colon i.e. the large intestine.

Food Sources : Fiber is present in the outer covering of cereals and pulses. The wheat grain, whole  wheat flour and whole pulses (with outer husk) like black gram,  rajmah, lobia, contain appreciable amounts of fibre. fined cereals like maida and suji and washed dals (without outer covering or husk) do not contain much fiber

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What do we mean by the terms "whole cereal" and "refined areal"  You will find that all grains have a common structure . They have three main partsthe outer covering or the bran, the germ or the embryo (the part which grows into a new plant) and the endosperm (which stores food for the growing embryo). The I grain with the outer covering (or its product having the outer covering in it) is  termed whole grain cereal (or whole cereal product). For example: when wkde wheat is milled (ground in machines) to form atta, most of the bran rrmains in it. Thus, atta or whole wheat flour is a whole cereal product.

Maida and suji arc produced by further cleaning or refining (removal of coarse particles of bran and germ) of atta and arc thus known as refined cereals. 

Fiber is also present in the outer skin and seeds of most vegetables and fruits. However, some of the vegetables and fruits are particularly rich in fiber. Some examples are lotus stem. green leafy vegetables, ladies finger, peas, beans, brinjal guava. oranges and amla. Animal foods like milk, milk products. meat, fish, poultry ,do not contain fiber.

Parts of the cereal  grain