What are carbohydrates
Our bodies use carbohydrates as their main source of energy. Most carbohydrates come from plant sources. Your body either uses the carbohydrates right away, or converts it to fat to use later. There are three different types of carbohydrates-sugars and starches which we can digest and fiber which we don??™t digest.
Chemical Structure and Composition
All carbohydrates are made up of the same basic components, carbon, hydrogen and oxygen. The dietary carbohydrates are found in three main types monosaccharide??™s, disaccharides and polysaccharides.
The simplest form of carbohydrate, otherwise known as a monosaccharide, is made up of six carbon atoms, twelve hydrogens and six oxygens. The three monosaccharides important in nutrition all have the same numbers and kinds of atoms, but in different arrangements.
Glucose is commonly known as blood sugar and serves as an essential energy source for all the body??™s activities.
* Essentially the base of every other kind of carbohydrate.
Fructose is the sweetest of the sugars and occurs naturally in fruit and honey. It is also used commercially in soft drinks, breakfast cereals and desserts.
Galactose rarely occurs naturally as a single sugar and has the same number and kinds of atoms as glucose and fructose, but in a different arrangement.
Disaccharides are pairs of the three monosaccharides listed above. Glucose occurs in all three and the second member of the pair is either fructose, galactose or an additional glucose.
Maltose consists of two glucose atoms. Maltose is produced whenever starch breaks down. Maltose is only a minor component of a few foods and is most notably found in barley.
Sucrose is made up of fructose and glucose. Due to the fructose sucrose tastes sweet. When refined from the juices of sugarcane and sugar beets and after being granulated, sucrose forms table sugar.
Lactose is the combination of glucose and galactose and is the principal carbohydrate of milk. It is also known as milk sugar and, depending on the milk??™s fat content, can contribute 30 to 50 percent of milk??™s energy.
Here are two examples of two simple sugars in their basic form. Fructose being a monosaccharide and sucrose a disaccharide. While they look the same and have the same number of calories, a simple change to their genetic makeup has made fructose noticeably sweeter.

Complex carbohydrates contain many glucose units and, in some cases, a few other monosaccharides strung together to form polysaccharides. Three types of polysaccharides are important in nutrition: glycogen, starches and fibers.
Glycogen molecules contain hundreds of glucose in long, highly branched chains. It is found in small amounts in meat and not found at all in plants. The main important role the glycogen plays is how the human body stores much of its glucose as glycogen. It is stored in muscles and liver.
Starch molecule contains hundreds of glucose molecules in either occasionally branched chains or unbranched chains. In our bodies glucose is stored as glycogen, while plants store it as starch.
Fibers are another type of polysaccharide but they differ from starches because they cannot be digested by our digestive system.
Glucose is the carbohydrate molecule that is used to fuel the body cells. Digestion of disaccharides and polysaccharides can also yield fructose and galactose but these monosaccharides are converted to glucose by the liver before they can be used. Once in the blood, the monosaccharides are either used for energy, stored in the liver and muscles as glycogen, or if there is an excess of energy it is converted to fat. Even though fiber isn??™t used as fuel it still plays an important role in assisting digestion.
The body is able to make glucose from extra dietary protein and fats you may eat, but it is recommended that half of your daily calories come from carbohydrates. The body needs a certain amount of carbohydrates in order to properly function. Without carbohydrates the body may experience fatigue, muscle cramps and poor mental function.
Carbohydrates have other uses including:
The body stores glycogen in the muscles and the liver and uses it later for muscle developement.
Store energy in the form of starch (photosynthesis in plants) or glycogen (in animals and humans).
Provide energy through metabolism pathways and cycles.
Supply carbon for synthesis of other compounds.
Form structural components in cells and tissues.

Interrelationships with other nutrients
In nature, carbohydrates don??™t exist in isolation. They are usually found in a form that is a combination of all the macronutrients, including protein and fat and often contain vitamins and minerals as well. For example a banana contains one percent fat, ninety one percent carbohydrate, eight percent protein as well as calcium and potassium. It??™s also a good source of dietary fiber.
Whereas sugar is one hundred percent carbohydrate. This is why it is a far more preferable for us to obtain carbohydrates from a natural sources rather than concentrated manufactured sources. Also, carbohydrates found in fruits and vegetables are complex carbohydrates, meaning they take longer to digest and keep us feeling full for longer.
Food sources
Food sources of complex carbohydrates are more natural sources like milk, fruits and vegetables and a very small amount in meat. Sugars come from fruits, sugar cane, sugar beets, honey and milk. The polysaccharide starch is found in grains, legumes and root vegetables. More processed carbohydrates are found in manufactured foods such as carbonated drinks, lollies, ice-cream, pudding, pastries, pasta and bread.
Recommended daily allowance
The recommended daily intake of carbohydrates is 125-175g or 55-60% of the total caloric intake of one day. Carbohydrates are a vital source of fuel for the bodies of every human being. Carbohydrates can be of particular importance to athletes as they are regularly pushing their bodies to perform and using up energy. Carb loading is a change to training and nutrition designed to maximize the amount of muscle glycogen stores prior to endurance competition.
Diabetics must be more aware of the types of carbohydrates they consume. Simple sugars or refined grains can cause their blood sugar to rise rapidly. Natural sources of carbohydrate such as fruits, vegetables and whole grains are slower to break down and less likely to cause problems.
Current thinking on the role that this nutrient plays in a healthy lifestyle and diet.
The Australian guide of healthy eating promotes the consumption of plenty of carbohydrates. Vegetables and legumes, fruits and bread, cereals, rice, pasta and noodles make up about two thirds of what is believed to be the healthy daily intake of food and all of these foods are a good source of both complex and simple carbohydrates.
Carbohydrates are essential to a functional, healthy body and without them people wouldn??™t have the energy to exercise and keep themselves healthy. They are the fuel that keeps the body going and without carbohydrates we wouldn??™t have the ability to perform even the simplest of day to day tasks.