What are Carbohydrates?

Our bodies are powered by a significant energy source known as carbohydrates. The basic unit of all carbohydrates is a substance called glucose. Some carbohydrates consist of long or complex chains of glucose units—these are called starches. Other carbohydrates contain very few glucose units—these are sugars. We get starches from plants, such as potatoes, grains, beans, and sugars from foods such as honey, fruit, and milk, and processed foods such as candy, cake, and cookies. Whatever type of carbohydrate we eat, the body always breaks it down into glucose. This is the fuel that we burn to power the entire body from the muscles to the brain.

Carbohydrates include monosaccharide, disaccharide and polysaccharide, and many other types of carbohydrates. Different types of carbohydrates have different chemical makeup and can significantly different effects on your body when ingested. After we eat carbohydrate food, glucose enters our cells and is burned to produce energy. Our body can carry enough glucose to supply us with about an hour’s worth of power at a time. The excess is turned into a substance called glycogen, stored in the liver until it is needed.

The basic structural unit of a carbohydrate is a single sugar unit called a monosaccharide. The three most common monosaccharides in the diet are glucose, fructose, and galactose. Glucose is the monosaccharide that travels in our bloodstream and is often called blood sugar. Fructose is a sugar found in fruit and is sometimes called fruit sugar. Galactose is a component of the sugar that is found in milk.

When two monosaccharides are linked together, they form a disaccharide. The most common disaccharides in the diet are lactose, maltose, and sucrose. Lactose is milk sugar. It is the only sugar found naturally in an animal product. It is made up of glucose linked to galactose. Maltose consists of two molecules of glucose and is formed when starch is broken down during digestion. Sucrose is what we know as common white sugar or table sugar; it is created by linking glucose to fructose.

The monosaccharides and disaccharides are simple carbohydrates. When many sugar molecules are linked together, they form a polysaccharide. Polysaccharides are complex carbohydrates. They include starch, fiber, and glycogen. Starch is an energy storage molecule for plants. It is made up of straight or branching chains of glucose molecules. Grains such as wheat and oats and starchy vegetables such as potatoes, beans, and corn, are sources of dietary starch. Fiber is also found in plant foods, such as grains, fruits, and vegetables. Fiber cannot be digested by human enzymes. Glycogen, which is sometimes called animal starch, is a polysaccharide that is the storage form of glucose found in humans and other animals. It is made of glucose molecules linked together in highly branched chains. This branched structure allows it to be broken down quickly to release glucose into the blood when it is needed. We do not consume glycogen in our diets because it breaks down quickly after an animal dies.

Lentils, rice, and beans are all excellent sources of starch, also known as complex carbohydrates (due to the number and arrangement of glucose units). They are a highly nutritious food source and form the basis of many dishes in different cultures all over the world. Eating large amounts of complex carbohydrates means that the body benefits from a gradual release of energy over time.  Carbohydrates have formed the bulk of our diet since people first started farming carbohydrate-rich grain crops about 10,000 years ago. We know that the ancient Egyptians grew wheat and barley on the fertile banks of the Nile River. Once harvested, the grains were made into bread, soup, and beer.

Source of Carbohydrate

BREAD
Bread is the primary source of carbohydrate made from wheat or other grains. If grain husks are left on when the grain is ground into flour, the bread is whole-grain. Products such as croissants and white pita bread are less nutritious because they contain refined flour—this means the husk is removed.

PASTA
Like bread, pasta is usually made from ground wheat. It is found in both whole-grain and refined forms, depending on how much of the husk is retained in the flour. Pasta comes in an enormous variety of shapes—from the thin strands of spaghetti to the seashell-shaped conchiglie. Pasta is often combined with meat or vegetable-based sauce to create a nutritious, carbohydrate-rich meal.

STARCH GRAINS
Starch exists in plants in the form of grains. The exact size and shape of the grains differ according to the plant. Starch is often indigestible in its natural way, but the grains swell and soften when it is cooked. This is why foods such as pasta, rice, and potato are challenging to eat when raw, but soft and edible after being boiled in water.

SUGAR
The carbohydrates in chocolate and cola are sugars or simple carbohydrates. The body digests them quickly, which causes a rapid rise in the level of blood glucose—many nutritionists believe this to be unhealthy. This is one reason why it is sensible to limit sugary snacks in the diet.

Roots of Plants
Some plants store starch in the form of thickened underground organs called tubers. Potatoes, sweet potatoes, and yams are all examples of tubers. As well as being an excellent source of starch, they also contain vitamin C. The way tubers are cooked affects how quickly they release glucose into the body. For example, boiled potatoes release glucose at a medium rate, whereas baked potatoes release glucose quickly, giving us a fast burst of energy.

Health effects of dietary carbohydrate restriction

Low-carbohydrate diets may miss the health advantages – such as increased intake of dietary fiber (why we need dietary fiber? click here)– afforded by high-quality carbohydrates found in legumes and pulses, whole grains, fruits, and vegetables. Disadvantages of the diet might include halitosis, headache and constipation, and in general the potential adverse effects of carbohydrate-restricted diets are under-researched, particularly for possible risks of osteoporosis and cancer incidence.

Carbohydrate-restricted diets can be as effective as low-fat diets in helping achieve weight loss over the short term when overall calorie intake is reduced. body-fat accumulation does not appear to be affected by even very pronounced changes in the amount of fat vs carbohydrate in the diet." In the long term, effective weight loss or maintenance depends on calorie restriction, not the ratio of macronutrients in a diet. The reasoning of diet advocates that carbohydrates cause undue fat accumulation by increasing blood insulin levels, and that low-carbohydrate diets have a "metabolic advantage", is not supported by clinical evidence. Further, it is not clear how low-carbohydrate dieting affects cardiovascular health, although two reviews showed that carbohydrate restriction may improve lipid markers of cardiovascular disease risk.