Research Findings On Gastrointestinal Diseases

The gastrointestinal system extracts essential vitamins and minerals from diverse plant and animal foods and breaks down the carbohydrate, protein, and fat molecules to smaller subunits that can be absorbed. It accomplishes these tasks by means of the various digestive organs of the body and the enzymes. (See Digestive System.)

The diet must provide, sufficient nutrients and energy to synthesize the rapidly renewing cells that line the gastrointestinal tract, the enzymes that digest and transport nutrients across the intestinal walls, and other hormones that control these processes. Digestive function can be seriously disrupted by inadequate nutrition.

Diseases of the gastrointestinal tract will unavoidably have profound effects on nutritional and metabolic processes. Loss of body weight is often an indication of gastrointestinal disease and a diet history may reveal obvious nutritional deficiencies associated with the underlying disease, eating problems, and psychological problems.

Dietary fat, fiber, and alcohol are significant factors associated with gastrointestinal diseases. Higher intakes of dietary fiber can prevent or relieve symptoms of constipation and chronic diverticular disease. Individuals with celiac disease should obtain information on foods free of wheat gluten. Those with inflammatory bowel disease, heart-burn, and ulcers should follow diets appropriate to their conditions.

Diseases of the Mouth

Dental caries result from demineralization of the enamel surface of the tooth by acids produced from sugars. Initially mineral disappears from the sub-surface of the tooth and if this process is not addressed a cavity will develop in which more bacterial growth can occur causing further dissolution of enamel. Eventually the tooth may be lost.

The presence in the mouth of fermentable sugars is essential for the development of dental caries. Within minutes of consumption sugars cause the pH in dental plaque to fall below the critical pH for enamel dissolution. This fall in pH will occur irrespective of the amount of sugar consumed or whether it comes from fruit or chocolate. The normal oral pH of 7.0 will only be restored about 30 minutes after the sugar has finally been swallowed. Normally the pH will return sooner if the item is consumed quickly rather than if eaten slowly over a long period of time.

Acidic foods, such as citrus fruits and cola drinks, lower the mouth pH and hence produce cariogenic conditions. Finishing a meal with an alkaline food, such as cheese, milk, or peanuts can help to raise the pH of the mouth.

Fluoride can increase enamel resistance by the formation of fluorhydroxyapatite crystals in the tooth which are more resistant to acid erosion. The maximum benefit from fluoride is obtained if it is available during tooth formation. Once the tooth has emerged, further protection can be obtained from topical or dietary fluoride.

Deficiency of certain vitamins may produce inflammation of the gums and the teeth may become loose from the lack of cement which normally holds them to the jaw. A lack of vitamin C causes scurvy, a weakening of periodontal fibers and the teeth may become loose and fall out. The gums become tender and bleed easily. Treatment is by vitamin therapy and sources of vitamin C should be included in the diet regularly.

Deficiency of vitamin D causes defective calcification of the dentine of the teeth and may increase susceptibility to dental caries. Eruption of the teeth may be delayed in children with rickets. Vitamin D therapy should be given and good sources of vitamin D taken in the diet, together with exposure to sunlight where possible.

Disorders of the esophagus

The diaphragm has several openings through which the abdominal viscera can enter the thorax. The opening for the esophagus, the hiatus, is loosely attached to the esophagus. In middle age this attachment weakens and in overweight people additional abdominal weight puts extra strain on the hiatus which herniates. A low fiber diet which results in constipation causes straining when the bowels are opened and weakening of the hiatus. The major symptoms of hiatus hernia are those of reflux and esophagitis and the sensation of food 'sticking'.

The refluxed contents of the stomach may contain partly digested foods, acids and enzymes. It is possibly this combination which causes mucosal damage and esophagitis. Symptoms develop if reflux becomes frequent and the mucosa of the esophagus becomes sensitive to the acidic reflux. Fatty foods, chocolate, coffee, alcohol, spicy foods and citrus juices lower sphincter pressure and may induce reflux.

Cystic fibrosis

Cystic fibrosis (CF) is a generalized hereditary condition characterized by chronic pulmonary disease, reduced secretion of water and bicarbonate, pancreatic enzyme deficiency and abnormally high concentrations of electrolytes in the sweat.

Progressive malnutrition and poor growth are common features of CF and need to be addressed by diet therapy. It is important to provide the CF patient with the optimum diet for the potential for growth to be fulfilled and resistance to infection maximized.

Energy intake is generally increased by 50% more than the Recommended Daily Requirement. In order to achieve an adequate energy intake, effective use should be made of suitable energysupplements such as glucose polymers and glucose drinks. Fat intake should be normal and frequent snacks should be encouraged.

Deficiencies of vitamins A, D, E and K are well documented. Daily supplementation of 8000 IU of vitamin A, 20 mg of vitamin D, and 200 mg of vitamin E is currently advised. Deficiency of vitamin K has been noted in patients with liver disease and in young infants with CF. A supplementation is only necessary if deficiency has been demonstrated.

Lactose Intolerance

Lactose (milk sugar) is digested in the small intestine by the enzyme lactase. An insufficiency of lactase, in the small intestine, results in undigested lactose to pass into the large intestine where it is fermented by bacteria with the production of lactic acid. This accumulation of lactic acid is characterized by abdominal discomfort, pain, and diarrhea, the condition known as lactose intolerance.

After the age of 5 the genetic absence of lactase occurs among remarkably high proportions of Asians (95 percent), Africans (99 percent), American Indians (95 percent), and black Americans (75 percent), as well as among a significant proportion of healthy Caucasians. The origin of racial lactose intolerance is not entirely clear. It may be a genetic difference or it may be that the custom of drinking milk, which is common among Caucasians, results in the continued production of lactase. Many other races do not take much milk after infancy, so the enzyme diminishes or disappears completely.

For practical purposes, no differentiation is usually made between cows milk and goats or sheeps milk. For people who are milk intolerant a wide range of soya based foods are available.

Nutrition Programs and Services

Food Labels:
Evidence related to the role of dietary factors in gastrointestinal disease suggests that food manufacturers should include on package labels information about nutrient content of the food, especially for fat and carbohydrate components (including fiber).

Food Services:
Evidence related to the role of dietary factors in gastrointestinal diseases suggests that food services should include provisions for adequate intake of high-fiber and low-fat foods.

Food Products:
Evidence related to the role of dietary factors in gastrointestinal diseases suggests that the public would be benefit from additional products that are low in fat and calories and high in fiber. [The Surgeon General's Report on Nutrition & Health, 1988]

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