Description

Similar to the fuel of a car, carbohydrates are the primary source of energy and one of the three major nutrients in the human diet. The other two being fat and proteins. Carbohydrates are classified according to their structure. The basic carbohydrate consist of one unit, called a saccharide.

A monosaccharide (a single saccharide) is the simplest carbohydrate and called a simple sugar. They include glucose (the form in which sugar circulates in the blood), fructose (found in fruit and honey), and galactose (produced by the digestion of milk). These simple sugars are readily absorbed by the small intestine without the aid of enzymes. Now, if two single sugars are linked together, they make a disaccharide. The disaccharide sugars present in the diet are maltose (a product of the digestion of starch), sucrose (table sugar), and lactose (the sugar in milk). The intestine us unable to absorb them because they are too bid to go through, hence enzymes produced in the small intestine break down the enzymes into two monosaccharides. Polysaccharides are much more complex carbohydrates made up of many simple sugars, the most important of which are glycogen, which is stored in the liver, and starch (such as that found in rice and potatoes).

Digestion of Sugars

Digestion of food begins in the mouth, moves on to the stomach, and then into the small intestine. Along the way, specific enzymes are needed to process different types of sugars. An enzyme is a substance that acts as a catalyst to produce chemical changes without being changed itself. The enzymes lactase, maltase, sucrase are needed to break down the disaccharides; when one or more is inadequate, the result is carbohydrate intolerance.

Types

Carbohydrate intolerance can be primary or secondary. Primary deficiency is caused by an enzyme defect present at birth or developed over time. Secondary deficiencies are caused by a disease or disorder of the intestinal tract, and disappear when the disease is treated. These include protein deficiency, celiac disease, and some intestinal infections.

Adult lactose intolerance is the most common of all enzyme deficiencies, and it is estimated that 70% of the world population have this condition. Some racial and ethnic populations are affected more than others. Some people feel the symptoms after having certain foods. For example, consumption of rice and/or potatoes may lead to bloating and cramps due to inadequate amount of amylase to break down the starch present in these foods.

Causes & Symptoms

Enzymes play an important role in breaking down carbohydrates into forms that can pass through the intestine and be used by the body. Usually they are named by adding ase to the name of the substance they act on, so lactase is the enzyme needed to process lactose. Cooked starch is broken down in the mouth to a disaccharide by amylase, an enzyme in the saliva. The disaccharides maltose, sucrose, and lactose cannot be absorbed until they have been separated into simple sugar molecules by their corresponding enzymes present in the cells lining the intestinal tract. If this process is not completed, digestion is interrupted.

Carbohydrate intolerance plays a factor in many obese people, especially men.

Although not common, a deficiency in the enzymes needed to digest lactose, maltose, and sucrose is sometimes present at birth. Intestinal lactase enzymes usually decrease naturally with age, but this happens to varying degrees. Because of the uneven distribution of enzyme deficiency based on race and ethnic heritage, especially in lactose intolerance, genetics are believed to play a role in the cause of primary carbohydrate intolerance.

Digestive diseases such as celiac disease and tropical sprue (which affect absorption in the intestine), as well as intestinal infections and injuries, can reduce the amount of enzymes produced. In cancer patients, treatment with radiation therapy or chemotherapy may affect the cells in the intestine that normally secrete lactase, leading to intolerance.

The severity of the symptoms depends on the extent of the enzyme deficiency, and range from a feeling of mild bloating to severe diarrhoea. Undigested sugars remain in the intestine, which is then fermented by the bacteria normally present in the intestine. These bacteria produce gas, cramping, bloating, a "gurgly" feeling in the abdomen, and flatulence. In a growing child, the main symptoms are diarrhoea and a failure to gain weight. In an individual with enzyme deficiency, gastrointestinal distress begins about 30 minutes to two hours after eating or drinking foods containing the offending sugar, such as lactose in the case of lactose intolerance. Food intolerances can be confused with food allergies, since the symptoms of nausea, cramps, bloating, and diarrhoea are similar.

Sugars that aren't broken down into one of the simplest forms cause the body to push fluid into the intestines, which results in watery diarrhoea (osmotic diarrhoea). Diarrhoea may sweep other nutrients out of the intestine before they can be absorbed, causing malnutrition.

Treatment and Cure

In primary conditions, no cure exists to improve the body's ability to produce the enzymes, but symptoms can be controlled by diet. Commercially available digestive enzymes (see Carbozyme) are the only present solution to treat those who either do not wish to diet or cannot help avoid the offending carbohydrates e.g. those added and hidden in so many foods. On the other hand, carbohydrate intolerance caused by temporary intestinal diseases disappears when the condition is successfully treated.

The degree of carbohydrate intolerance varies in different people, hence treatment should be tailored for the individual. Young children showing signs of lactose intolerance should avoid milk products; infants should switch to soy-based formula, or even better drink milk treated with lactase enzymes. Older children and adults can adjust their intake of lactose depending on how much and what they can tolerate. For some, a small glass of milk will not cause problems, while others may be able to handle ice cream or aged cheeses such as cheddar or Swiss, but not other dairy products. Generally, small amounts of lactose-containing foods taken throughout the day are better tolerated than a large amount consumed all at once.

For those individuals who are sensitive to even very small amounts of lactose, the lactase enzyme is available without a prescription. It comes in liquid form for use with milk or in capsules for dairy products. The addition of a few drops to milk will reduce the lactose content by 90% after 24 hours in the refrigerator. Heating the milk speeds up the process, and doubling the amount of lactase liquid will result in milk that is 98% lactose free. Chewable lactase enzyme tablets (Lactaid) are also available. Three to six tablets taken before a meal or snack will aid in the digestion of solid foods, alternatively one capsule of Prolactazyme Forte is sufficient to do the job. Lactose-reduced milk and other products are also available in some stores.

Diagnosis

Carbohydrate intolerance can be diagnosed using oral tolerance tests. The carbohydrate being investigated is given by mouth in liquid form and several blood levels are measured and compared to normal values. This helps evaluate the individual's ability to digest the sugar.

Prognosis & Prevention

Since the cause of the enzyme deficiency leading to carbohydrate intolerance is unknown, there is no way to prevent this condition. With good dietary management, individuals with carbohydrate intolerance can lead normal lives. The existence of specific commercially available digestive enzymes to break down carbohydrates make life easier and may help individuals with carbohydrate intolerance being able to eat food containing carbohydrates without suffering the related symptoms.

Carbohydrate Intolerance & Obesity

Studies have shown that Carbohydrate Intolerance plays part in obese people. Moreover it was also found that obese men may not process carbohydrates as efficiently as obese women, a condition that can, ultimately, lead to a decrease in fitness level and the development of metabolic disorders.

Carbohydrate intolerance can explain why some people find it more difficult to lose weight.

A new study published in the CHEST, a journal of the American College of Chest Physicians (ACCP), showed that severely obese men were more carbohydrate intolerant and had less physical endurance than severely obese women, leading researchers to believe that gender plays a strong role in physical fitness and a person's ability to metabolize carbohydrates.

“Carbohydrate intolerance, the inability to metabolize sugar found in carbohydrates, may lead to a build-up of fat deposits on muscle tissue, which can cause a person to gain weight and, eventually, impair physical endurance,” said study co-author Emile F. L. Dubois, MD, PhD, FCCP, Department of Pulmonary Diseases, Hospital Reinier de Graaf Groep, Delft-Voorburg, Netherlands.

“It appears that carbohydrate intolerance is more common in obese men, which would cause them to be less physically fit than obese women.” Researchers also assessed patients for carbohydrate intolerance, according to American Diabetes Society Guidelines. 59 percent of men had overt diabetes or were carbohydrate intolerant, as compared to 35 percent of women. Researchers note that patients with carbohydrate intolerance usually suffer from metabolic syndrome, a group of medical conditions, including obesity, diabetes, and hypertension, that can lead to cardiovascular disease.