Carbohydrates are the Main source of energy to human body as much as fat and protein. They are classified according to their structure based on the number of basic sugar; whereas exist in forms of monosaccharide, disaccharides and polysaccharides.

Digestion of carbohydrates starts in the mouth, passing the stomach, then to be completed in the small intestine. This process needs specific enzymes to break bonds between sugar molecules. If these factors are not available in an enough amount, carbs remain without final processing.

Most clinical manifestations for this condition appear as digestive symptoms, like indigestion and diarrhea. The case may be detected by some tests, such as lactose tolerance test and hydrogen breath test.

Although there is no curable treatment for carbohydrates intolerance, diet based on avoiding intolerable food component can help in keeping of symptoms and preventing complications that mainly result from malnutrition.

Carbohydrate Intolerance is the inability of the body to digest types of carbohydrate component into simple sugar molecule because of deficient enzymes responsible for digestion of it, which may lead to the development of symptoms each time the person eat food contains this material.

A monosaccharide is the least complicated carbohydrates so called a simple sugar that include glucose, fructose and galactose. These sugars are important because they are in a form enable them to be absorbed by the small intestine.

When two monosaccharaides linked together, they produce a disaccharide. This kind presents in the diet are maltose (a product of starch digestion), sucrose (table sugar), and lactose (milk sugar). These disaccharides must be broken down by enzymes into two simple sugars so that they can be absorbed by the intestine.

Polysaccharides are much more complex form of carbohydrates as it is made up of many simple sugars. The most important forms of polysaccharides are starch in foods and glycogen that stored in the liver and muscles.

The deficiency of carbohydrate digestive enzymes emerges from multiple causes:

• Congenital, such as “lactase” deficiency; the enzyme that digest disaccharide lactose, and the enzyme “sucrase-isomaltase”, which break down starch and isomaltose disaccharide.
•  Acquired, like acquired lactose intolerance that usually develop with age.
• Secondary, which happens as a result of damaged intestinal mucosa due to some diseases like “tropical sprue”, Celiac disease, and acute intestinal infection.

• Increasing age: The condition is uncommon in babies and young children. It usually appears in adulthood.
• Ethnicity: commonly affects people of African, Asian, Hispanic and American Indian descent.
• Premature birth: the small intestine doesn't develop lactase-producing cells until late in the third trimester.
• Small intestine affecting diseases: these problems that can cause lactose intolerance include bacterial overgrowth, celiac disease and Crohn's disease.
• Some cancer treatments: receiving radiation therapy for cancer in the abdomen or having intestinal complications from chemotherapy putting the patient under greater risk of lactose intolerance.

Carbohydrates are a major energy source for the body. They are digested by specific enzymes in the gastrointestinal tract until finally breaking disaccharides into simple sugars to become fordable through intestinal mucosa. But in cases of enzymes deficiency, the body are unable to benefit from certain carbohydrates, which stay in the gut and lead to more problems, especially with colonic bacteria that ferment disaccharides and producing gases as a byproduct which cause annoying symptoms.

Complains and clinical manifestations of carbohydrate intolerance are similar in all disaccharides deficiencies. They include:

• Diarrhea, sometimes watery.
• Bloating and flatulence.
• Abdominal pain and distention.
• Weight loss or malnutrition.

Usually these cases are diagnosed after careful history taking and physical examination, supported by food tolerance tests. The condition may be suspected based on the symptoms and response to reducing specific carbohydrate food intake. To confirm the diagnosis, the person needs to undergo one or more of the following tests: (lactose intolerance as an example)

• Lactose tolerance test: The body is exposed to a liquid that contains high levels of lactose. After Two hours, blood tests done to measure the amount of glucose in the bloodstream. If your glucose level doesn't rise, it means the body isn't properly digesting and absorbing the lactose-filled drink.
• Hydrogen breath test. The doctor measures the amount of hydrogen gas in breath at regular intervals after giving a liquid that contains high levels of lactose. Normally, very little hydrogen is detectable. However, if your body doesn't digest the lactose, it will ferment in the colon, releasing hydrogen and other gases that are absorbed by intestines and eventually exhaled in a larger amount.
• Stool acidity test: this test is done to infants and children who can't undergo other tests. The fermenting of undigested lactose creates lactic acid and other acids that can be detected in a stool sample. pH level is less than 6.

There is no complete cure for this condition. The best way to deal with the problem is by modifying diet to limit products that contain intolerant disaccharides or reduce its effect by such steps:

• Mixing these products along with other foods, as combining cereal with milk for lactose intolerance condition.
• Eating small amounts of intolerant disaccharide-containing products throughout the day instead of larger amounts all at one time.
• Choosing -if present- products that have reduced disaccharide, like milk reduced lactose. However, diabetic patients may find this milk raises blood sugar levels higher than normal.
• Resorting to foods substitutes, such as soy milk and soy cheese instead of usual milk and milk products for lactose intolerance cases.
• Taking deficient enzymes as supplements because they can compensate the loss and help digest then absorb disaccharides.

Carbohydrate containing Foods combine beside carbs a variety of other compositions needed for the body. These include vitamins, minerals, proteins and fats. The abstinence from having these foods could prevent the body from obtaining its requirement of some components and may lead to malnutrition and weight loss, thus their fallouts. For instance, a person with lactose intolerance may face Osteopenia as he doesn’t get the recommended amount of calcium that condense in dairy products. If untreated, the problem could develop to osteoporosis, then the bones are more prone to fracture.

As this condition is not able to cure completely, it is up to the person to be careful among what he eats and drinks in order to obviate the upsetting symptoms. Sometimes he can feel with frustration as he need to deal with this problem for the remnant of his life, but it is worth mentioning that there are many affected people who live with the condition without facing the symptoms after they accept their situation and control their condition with the appropriate ways.