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Carbohydrates
Carbohydrates which are available in the forms of muscle glycogen and blood glucose greatly influence the human nutrition and health. Certain food items like bread, beans, milk, popcorn, potatoes, cookies, spaghetti, corn, and cherry pie supply carbohydrates to our bodies.
The amount of carbohydrate in body should be sufficient to fuel workouts. Taking less amount may lower muscle glycogen levels and cause early fatigue in the gym, reduction in the intensity of training and slower gains. Whereas excess carbohydrate may cause accumulation of unwanted body fat and generalized vascular disease. Researchers recommend consumption of 5-7 g/ carbohydrate/kg body weight/day.
Importance of Carbohydrates
Carbohydrates are present in human body in the forms of sugars, oligosaccharides, starches and fibres. Carbohydrates like other macro-nutrients including fat and protein, are major energy sources for the body. According to a study, the requirement for 55% of our daily calories should be fulfilled with supply of carbohydrates.
However, there should be a balance between calorie intake and expenditure. According to a scientific study a diet with an optimum level of carbohydrates may check accumulation of body fat. Starch and sugars supply fuel for physical activities. Dietary fibre, which is also a carbohydrate ensures correct bowel functioning. Moreover carbohydrates add to the taste, texture and appearance of the foods making the diet varied and enjoyable.
What Are Carbohydrates?
The carbohydrates for which sugars are the building blocks can be classified in accordance with the number of sugar units that are linked together in one molecule.
- Sugars
- Oligosaccharides
- Polysaccharides
Glucose and fructose are the types of simple sugars (also called monosaccharides) that are available in fruits, berries, vegetables and honey. The combination of simple sugars combine constitutes disaccharides. Glucose and fructose together form table sugar or sucrose both of which are naturally present in sugar beet, sugar cane and fruits. Lactose is the main sugar which is found in milk and other dairy products whereas maltose is a disaccharide which is available in malt.
Polyols are the naturally occurring sugar alcohols. However, most of polyols are prepared through transformation of sugars for commercial purposes. Isomalt (a type of polyol) is used most commonly and is extracted from sucrose. Polyols which taste sweet are used in foods similar to sugars. Polyols can have a laxative effect on body if they are taken in large quantities.
Oligosaccharides is a combination of three to nine sugar units. Maltodextrins having 9 glucose units are commercially produced with partial hydrolysis of starch. A small amount of raffinose, stachyose and fructo-oligosaccharides are available in certain pulses, grains and vegetables.
Polysaccharides are the combination of over 10 sugar units. Sometimes several thousand sugar units form polysaccharides which are insoluble and serve as a energy store such as starch and glycogen. Polysaccharides can also serve as a structural component such as cellulose which is available in the cell walls of plants.
Carbohydrates in the body
Carbohydrates diversely function in human body and play significant role the structure and function of the body organs and nerve cells thus promoting good health.
Energy source and storage
Starches and sugars are the main sources of energy-supplying carbohydrates. They supply 4 kilocalories (17 kilojoules) per gram. In order to ensure utilisation of this energy all carbohydrates have to be broken down to glucose before being transported to their place of use. The digestive enzymes break down disachharides into simple sugars. Digestive enzymes also help the body to break down the long chains of starches into their constituent sugars for their absorption into the blood stream.
Glycogen, a polysaccharide like starch that is stored in the liver and the muscles is the changed form of glucose. It is also available in body as energy source.
Since glucose acts as energy source for brain it is necessary to constantly maintain the minimum glucose level in the blood. Glucose may be released directly from dietary carbohydrates or glycogen stores. Insulin and several other hormones not only control the flow of glucose in the blood but also maintain glucose level.
The glycaemic index (GI)
The eating of the food containing carbohydrate leads to a corresponding rise and subsequent fall in the level of blood glucose as a glycaemic response. All the carbohydrate foods are not equally created as they respond quite differently in our bodies. The carbohydrates are ranked in accordance with their effects on the levels of blood glucose in the body. The difference in the ranking of the carbohydrates is called glycemic index or GI. The rate and duration of the glycemic response are influenced by various factors such as food, individual metabolism and the time of ingesting the carbohydrate.
Carbohydrate recommendation
Carbohydrates are good for health irrespective of their shapes and forms. The weight of the body can be controlled with the help of carbohydrates particularly when the diet is combined with exercise. Carbohydrates are needed for proper function of gut and are crucial in fueling the brain and active muscles. According to researchers, the diet containing at least 55 per cent of energy from carbohydrates can be considered optimum. This optimum diet can be recommended to all those above two years of age.
The requirement of carbohydrate can accurately be calculated in accordance with the muscles' needs and not the total calorie intake. Carbohydrate for strength trainers should be recommended in terms of grams per unit of body weight and hours of training. Researchers recommend 5 to 7 grams carbohydrate per kg body weight every day for those undergoing moderate-intensity training lasting upto an hour. This range of carbohydrate requirement has been mostly found to be suitable for those following weight lifting programs. However, 7-10 grams carbohydrate per kg body weight should be consumed per day by those who do additional training for a specific sport or reach an average of two to four hours of moderately intense training daily. For example a male weight trainer with a body weight of 75 kg will require 375-525 grams of carbohydrate per day.