Carbohydrate provide the most easily accessible energy source for your body. The other main sources of energy are protein and fats. However, carbohydrate are efficiently converted into glucose which will be used for energy. Glucose is used directly by your muscles and brain. Excess glucose is stored as glycogen in your muscles. Where a supply of glucose is not available, your muscles will burn fat as a source of energy.
By being converted into glucose, levels of carbohydrate will affect your blood sugar levels. Your blood sugar levels are important because your brain uses glucose from your blood. This explains why people often get depressed and down beat whilst on diets. Your blood sugar levels are not something that should be neglected!
Carbohydrate come in two forms: Simple carbohydrate and complex carbohydrate. Simple carbohydrate contain naturally occurring sugars, such as those found in fruit (fructose) for example. The sugars that make up simple carbohydrate also include table sugar (sucrose) and a variety of syrups.
Because simple carbohydrate are already simple sugars they can rapidly be converted into glucose and enter the bloodstream very soon after consumption. This where the term "sugar fix" comes from. After drinking a sugary cup of tea, for example, you may notice a sudden release of energy and an accompanying lift in your mood. However, have too much and your body will produce insulin to counteract the effect and, depending on how much sugar you've ingested, this will likely result in a rapid drop in blood sugar level and leave you feeling more tired than before!
So what are complex carbohydrate then? Complex carbohydrate are present in most grain products, vegetables and potatoes. Unlike simple carbohydrate, complex carbs are digested at a much slower rate. As a result of this, the conversion to glucose also happens at a slower rate and your blood sugar levels will not fluctuate as rapidly as they do when digesting simple carbohydrates.
Many people will try and avoid all types of carbohydrates where possible, particularly when on weight loss diets. This is not a good idea. Carbohydrate in general are not normally a problem. It's the quality of carbohydrates that should be taken into account. Highly processed foods should be avoided. This is because they normally contain a higher proportion of simple carbohydrate. For example, whole grain bread (complex carbs) should be eaten instead of white bread which uses refined white flour (simple carbs).
Complex carbohydrate are often also lower in fat and provide higher amounts of other essential nutrients like dietary fiber. It is for the above reasons that a diet of complex carbohydrate is preferable.
Pure carbohydrates contain carbon, hydrogen, and oxygen atoms, in a 1:2:1 molar ratio, giving the general formula Cn(H2O)n. (This applies only to monosaccharides, see below, although all carbohydrates have the more general formula Cn(H2O)n.) However, many important "carbohydrates" deviate from this, such as deoxyribose and glycerol, although they are not, in the strict sense, carbohydrates. Sometimes compounds containing other elements are also counted as carbohydrates (e.g. chitin, which contains nitrogen).
The simplest carbohydrates are monosaccharides, which are small straight-chain aldehydes and ketones with many hydroxyl groups added, usually one on each carbon except the functional group. Other carbohydrates are composed of monosaccharide units and break down under hydrolysis. These may be classified as disaccharides, oligosaccharides, or polysaccharides, depending on whether they have two, several, or many monosaccharide units.
Monosaccharides may be divided into aldoses, which have an aldehyde group on the first carbon atom, and ketoses, which typically have a ketone group on the second. They may also be divided into trioses, tetroses, pentoses, hexoses, and so forth, depending on how many carbon atoms they contain. For instance, glucose is an aldohexose, fructose a ketohexose, and ribose an aldopentose.
Further, each carbon atom that supports a hydroxyl group (except for the first and last) is optically active, allowing a number of different carbohydrates with the same basic structure. For instance, galactose is an aldohexose but has different properties from glucose because the atoms are arranged differently.
The straight-chain structure described here is only one of the forms a monosaccharide may take. The aldehyde or ketone group may react with a hydroxyl group on a different carbon atom to form a hemiacetal or hemiketal, in which case there is an oxygen bridge between the two carbon atoms, forming a heterocyclic ring. Rings with five and six atoms are called furanose and pyranose forms and exist in equilibrium with the straight-chain form.
It should be noted that the ring form has one more optically active carbon than the straight-chain form, and so has both an alpha and a beta form, which interconvert in equilibrium. However, the carbohydrate may further react with an alcohol to form an acetal or ketal, in which case the two forms become distinct. This is the basic type of link between the monosaccharide units of larger carbohydrates. Tiagabine
Disaccharides are composed of two monosaccharide units bound together by a covalent glycosidic bond. The binding between the two sugars results in the loss of a hydrogen atom (H) from one molecule and a hydroxyl group (OH) from the other. Tacrolimus, Fk506.
The most common disaccharides are sucrose (cane or beet sugar - made from one glucose and one fructose), lactose (milk sugar - made from one glucose and one galactose) and maltose (made of two glucoses). The formula of these disaccharides is C12H22O11.
Oligosaccharides and polysaccharides are composed of longer chains of monosaccharide units bound together by glycosidic bonds. The distinction between the two is based upon the number of monosaccharide units present in the chain. Oligosaccharides typically contain between three and nine monosaccharide units, and polysaccharides contain greater than ten monosaccharide units. Definitions of how large a carbohydrate must be to fall into each category vary however.
Oligosaccharides are found as a common form of protein posttranslational modification. Polysaccharides represent an important class of biological polymer. Examples include starch, cellulose and chitin.
Strictly speaking, carbohydrates are not necessary for human nutrition because proteins can be converted to carbohydrates¡ªthe traditional diet of some peoples consists of nearly zero percent carbohydrate, and they are perfectly healthy. However, carbohydrates require less water to digest than proteins or fats and are an important source of energy.
Some problems have been cited for the long term effects of a no-carbohydrate diet for some individuals. Athletes, for instance, or those that participate in high intensity activities, will have a considerable reduction in performance, due to having little to no glycogen supplies stored in muscle tissue. Additionally, nephrotoxicity may occur, particularly in persons that are not very well hydrated.
Complex carbohydrates have been implicated in intercellular communication. Because of their high variability and elaborate branched structures, little has been understood about the method of action. In 2001, the National Institutes of General Medicine (NIGMS) established a long-term goal of understading the underlying biological processes and awarded roughly $34 million to a constortium of US universities. Solviolence.org