Nutritional Management of Disorders

D M Klurfeld, US Department of Agriculture, Beltville, MD, USA

© 2005 Elsevier Ltd. All rights reserved.

The primary functions of the colon are to absorb water and to form and store feces for excretion. The length of the large intestine in an adult is approximately 1.5 m; several divisions and landmarks of the colon are shown in Figure 1. Disturbances in colonic function are symptoms of diseases or disorders, including constipation, diarrhea, diverticular disease, irritable bowel syndrome, and inflammatory bowel diseases; due to surgical treatment of inflammatory bowel diseases, stomas are often created. Symptoms of these conditions range from mild discomfort to life-threatening emergencies, although most are chronic and can benefit from nutritional

Hepatic Splenic flexure flexure

Hepatic Splenic flexure flexure

Terminal ileum Rectum

Figure 1 Diagram of the colon showing anatomical divisions and landmarks. Intestinal chyme enters via the ileum, ferments in the proximal ascending portion of the colon, and becomes feces, which is stored in the transverse and distal descending portions for elimination.

Terminal ileum Rectum

Figure 1 Diagram of the colon showing anatomical divisions and landmarks. Intestinal chyme enters via the ileum, ferments in the proximal ascending portion of the colon, and becomes feces, which is stored in the transverse and distal descending portions for elimination.

management. Although pharmacological therapy in some of these conditions may often be indicated, nutritional management is recognized as the first choice and is particularly effective in preventing and treating some of these disorders. As in many issues related to nutrition, there is a tremendous amount of misinformation believed by many. For example, there is no basis for the claims that meat remains undigested in the colon for years or that colonic cleansing with enemas or herbal preparations is of any value.

Constipation

Constipation can be defined as the slow movement of feces through the large intestine that results in the passage of dry, hard stool. Another acceptable definition is the infrequent passage of small, dry, hard feces accompanied by discomfort or pain. Many individuals self-diagnose the condition based on perceived deviations from 'normal' bowel habits; this often leads to unnecessary use of chemical laxatives that can irritate the colon and eventually lead to dependence on such preparations for evacuation. Normal bowel habits are generally deemed as at least three stools per week to no more than three per day. Constipation is often accompanied by symptoms of distension and flatulence. Diverticular disease is characterized by thinning and outpouching of the colonic wall. The diverticula are generally asymptomatic but can become infected with the potential for rupture. The major complications of this condition are bleeding and bacterial infection; the latter may result in abscess formation or perforation of an existing diverticulum with subsequent peritonitis. Although past practices were to prescribe low-residue diets to rest the bowel, it is now known that high-fiber diets are effective in the treatment and prevention of diverticular disease as well as for reducing the complication rate.

In the early 1970s, it was proposed that reduced fiber consumption in Western countries resulted in an incidence of diverticular disease that approximated 50% beyond the age of 70 years, whereas this condition was almost nonexistent in sub-Saharan Africa. Since that time, there have been contradictory studies on this point, and it seems that dietary fiber may not be the only factor that influences the development of diverticular disease. However, several explanations for some of the contrary findings in this area are evident. First, many factors in the diet are correlated; that is, a diet low in fiber tends to be high in meat and fat. Second, the measurement of dietary fiber in many studies has not included total dietary fiber, thereby suffering from measurement bias. Third, not all sources of dietary fiber have a therapeutic effect and the benefit varies according to the specific type of food or fiber supplement along with the amount of water available.

Despite past controversy, it now seems clear that diets high in dietary fiber will prevent the development of diverticular disease, can be used successfully for symptomatic treatment, and reduce the risk of infection of the diverticula. It must be understood that once formed, diverticula do not spontaneously resolve, and surgery is the only means of removing them. Recommended dietary modifications are increases in water and dietary fiber, particularly wheat bran or psyllium. Although fruits and vegetables also contribute to the prevention or reduction of symptoms, there is controversy about including those that have seeds. Seeds often pass through the gastrointestinal tract undigested; these have been found in infected diverticula, and it was assumed that they were the nidus for infection. Therefore, many practitioners have prohibited patients from consuming foods with small seeds, such as raspberries, cranberries, and blueberries, or larger seeds, such as tomatoes, peppers, and cucumbers. In addition, seeds added to foods, such as caraway, sesame, and poppy, have been proscribed. Some do not prohibit consumption of these seed-containing foods but there is little evidence to demonstrate the safety of abandoning this advice.

Diarrhea

Diarrhea is generally defined as loose, watery stools occurring more than three times a day and is a symptom of an underlying condition. It is estimated that the average adult has four episodes of diarrhea each year. Most events are self-limited and resolve within 24-48 h; it is presumed that the majority of these are viral in etiology and numerous agents have been implicated. Bacterial causes include Campylo-bacter, Escherichia coli, and, less commonly, Salmonella or Shigella. The latter organism is prevalent in tropical areas of the world and one species of Shigella is responsible for dysentery, which is characterized by profuse, watery diarrhea particularly in children and the elderly. Parasitic infections with Giardia lamblia, Entamoeba histolytica, or Cryptosporidium are often linked to chronic diarrhea. Alterations of normal colonic flora secondary to antibiotic therapy may result in diarrhea; the best studied organisms that overgrow the normal bacteria are Clostridium species. Noninfectious causes of diarrhea may be lactose intolerance, excess consumption of sugar alcohols, irritable bowel syndrome, inflammatory bowel disease, or celiac disease.

Clearly, the underlying cause of chronic diarrhea needs to be established and proper therapy instituted. Although most episodes of diarrhea will resolve spontaneously without specific therapy, nutritional management of diarrhea is primarily concerned with replacement of lost fluid. Copious or chronic diarrhea increases the need for electrolytes. Any episode of diarrhea in young children or the elderly may require electrolytes in addition to fluid replacement; this is easily obtained from oral rehydration therapy solutions made for this purpose if diarrhea is severe or protracted. Such solutions contain starch, proteins, and electrolytes and have been shown to reduce stool volume significantly. In less severe cases, maintenance of, or return to, the usual diet after 24 h is recommended. Four foods traditionally recommended for children—bananas, rice, applesauce, and toast—and referred to as the BRAT diet were thought useful because they do not irritate the colon since they are low in fiber and residue. However, this diet is no longer recommended by some pediatrics organizations because it is low in energy density, protein, and fat. During bouts of diarrhea, it is generally recommended that individuals avoid spicy foods, fatty foods, high-sugar foods, or high-fiber foods. Milk is sometimes proscribed, but evidence suggests that 80% of children with diarrhea can tolerate full-strength milk so most do not need to avoid this food, which provides more energy and protein than alternative fluid sources. Clear broth or soup is often recommended. Although clear fruit juices or soft drinks are sometimes recommended, these should be not be used or they should be diluted to avoid an osmotic effect of the sugars drawing more fluid into the intestine. There is considerable controversy regarding the consumption of specific foods during or just after a bout of diarrhea. Some studies justify use of complex carbohydrates (rice, wheat, potatoes, bread, and cereals), lean meats, yogurt, fruits, and vegetables because they are well tolerated even during active diarrhea. Many health professionals recommend a more limited diet of toast, rice, bananas, cooked carrots, and skinless chicken until symptoms abate. The choice of specific foods will depend on the tolerance of an individual, keeping in mind the fluid and energy needs of that person. Research suggests that repopulating the colonic bacteria through consumption of yogurt may provide more healthful organisms (Lactobacilli, Bifidobacteria, and Streptococcus thermophilus) and a quicker return of the total flora to normalcy, particularly in antibiotic-induced diarrhea.

Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is also called spastic colon or mucus colitis, and it is one of the most common causes for referral to gastroenterologists. Symptoms include abdominal pain, bloating, constipation and/or diarrhea, heartburn, belching, and mucus in the stool. IBS is diagnosed by eliminating other diagnoses or organic causes and, therefore, treatment is aimed at alleviating symptoms. Women are affected twice as frequently as men, and it is estimated that as much as 8% of the US population is afflicted with this condition. Although stress and other psychological factors seem to play a significant role in IBS, a number of dietary interventions have been suggested. Although dietary fiber has been advocated for alleviation of the symptoms of IBS, it is clear that some patients will benefit but others will get worse, so individual trial and error may be the logical therapeutic plan. Patients with abdominal distension or excessive flatulence should reduce consumption of gas-provoking foods, such as beans, lentils, cabbage, broccoli, onions, garlic, raw fruits and juices, bananas, and nuts. Caffeinated, alcoholic, and carbonated beverages cause exacerbations in some patients. In addition, high-fat foods, such as deep-fried foods, processed meats, gravies, and chocolate, as well very spicy or pickled foods, may increase symptoms of IBS. Since many IBS patients are also lactose intolerant, reduction of milk products is often recommended empirically but should probably be done based on a patient's response to these food products. Sweeteners such as sorbitol and fructose are often associated with increased diarrhea, so products containing these should be tested for effects on symptoms. In patients with constipation, the addition of fiber to the diet along with increased fluid intake will help to alleviate this symptom. The most commonly recommended types of fiber are wheat bran and psy-llium. In patients with diarrhea, some have benefited from the addition of wheat bran, pectin, or kaolin to the diet, but other patients seem to do better with a low-fiber diet. Individualized trials of dietary intervention seem to be indicated for IBS. In addition to nutritional therapy, drug treatment to reduce intestinal transit and emotional or psychological support are major parts of therapy for IBS. Aerobic exercise, consumption of smaller, more frequent meals, relaxation techniques, cessation of cigarette smoking, and a variety of other environmental changes have been tried with varying degrees of efficacy.

Inflammatory Bowel Diseases

Inflammatory bowel disease (IBD) refers to a group of conditions in which inflammation involves portions of the small or large intestines. The ileum and colon are most commonly affected. The types of IBD are Crohn's disease and ulcerative colitis (UC). Although the two conditions have many common features, they can be distinguished based on clinical, x-ray, and pathological findings. Symptoms include chronic abdominal pain, cramps, rectal bleeding, or bloody stools; diarrhea and rectal bleeding are more common in UC. The diagnosis is usually made in adults younger than age 30 years and there is a preponderance of cases among whites, especially Jews. There is familial clustering of these conditions, indicating that genetic predisposition is important; approximately 20% of patients have a close relative with the same diagnosis. The onset of either disease can be acute or insidious, and the course is protracted. Both are characterized by exacerbations and remissions, sometimes of long duration. The international epidemiology of Crohn's disease suggests that it is uncommon in developing countries and has become more common in Western countries, where fiber intakes are lower and consumption of refined carbohydrates is high, but there is no direct evidence that diet plays a role in its etiology. Much research has focused on the etiology, but no clear-cut factors have been identified. Infectious and immunological mechanisms have been most thoroughly investigated with no conclusive evidence. Cigarette smoking has been strongly linked to Crohn's disease but not to UC.

As a result of chronic abdominal pain and diarrhea, many patients lose large amounts of weight. Since oral intake is often limited, there are frequently protein and multiple micronutrient deficits. It is important to replenish these nutrients, but often the early nutritional intervention for IBD relies on bowel rest. Total parenteral nutrition (TPN) accomplishes this best, but enteral liquid formulae can be used in some cases. In fact, TPN often results in short-term remission of symptoms in Crohn's disease. Unfortunately, long-term remissions are not maintained in most patients by this intervention.

Crohn's disease may involve any portion of the gastrointestinal tract but is most commonly found in the terminal ileum, often with extension to the proximal colon. In the majority of patients, multiple areas of the intestine are involved, usually separated by areas of normal intestine. The inflammatory changes are nonspecific but tend to be granuloma-tous and involve all layers of the intestinal wall. Because inflammation involves the entire thickness of the intestinal wall, there is a high propensity for development of fistulae into adjacent structures that are often infected by the bacteria from the colon. Bowel obstruction from strictures or adhesions tends to occur more frequently in Crohn's disease than in UC.

Ulcerative colitis often begins in the distal colon or rectum and progresses to involve most or all of the colon. Approximately one-fourth of cases have involvement of the terminal ileum, usually in continuity with the colonic manifestations. Ulcerative colitis involves primarily the mucosal layer. The chronic inflammation often leads to shortening and narrowing of the muscle layer in which the colon has been likened to resembling a garden hose. The ulcers tend to undermine portions of the mucosa and this frequently gives rise to pseu-dopolyps. The incidence of colon cancer is greatly increased in patients with chronic UC; tumors are often multiple and tend to have a poorer prognosis than in sporadic colon cancer. Thus, prophylactic subtotal colectomy is required in approximately 30% of patients who have persistent signs of colo-nic dysplasia. One of the surgical developments in the therapy of UC is the production of an ileoanal reservoir or 'J pouch,' which becomes a functional rectum, allowing a patient to defecate through the rectum rather than via a colostomy. Some patients with this type of surgery continue to have many bowel movements per day, so limitation of dietary fiber or fruits and vegetables is often required; gas-inducing foods should be avoided. A complication of this surgery is infection of the reservoir or pouchitis. Although no foods or food groups have been identified as contributing to this condition, it is recommended that patients pay attention to foods that may be associated with episodes of pouchitis.

In acute phases of IBD, bland low-residue or elemental diets are recommended; sometimes, total bowel rest is required and TPN is prescribed. Malabsorption of many nutrients has been documented in patients with IBD; the estimation of macronutrient needs is not difficult, but the determination of vitamin and mineral losses is problematic. In UC, elimination of milk products is often advised to reduce the amount of fermentable carbohydrate (lactose) entering the colon, which contributes to bloating, cramps, and diarrhea. In Crohn's disease, intestinal strictures are often found; these are contraindications to high-fiber diets because of the possibility of intestinal obstruction, which is a fairly common complication of the condition. The current consensus is to use low-fiber, low-milk, low-fat diets in patients with IBD; however, controlled studies have found little significant benefit of dietary intervention. This is because some dietary components are beneficial in certain patients but have no, or detrimental, effects in others. It is important for the patient to receive nutritional counseling to avoid deficiencies of calories and most nutrients. However, there is little specific nutritional therapy available for these conditions. Some patients find that spicy foods or alcoholic beverages exacerbate symptoms; in others, wheat bran or raw fruits have the same effect. The only hard and fast rule is to avoid foods that provoke symptoms while maintaining as nutritious and balanced a diet as possible.

Research studies in which UC patients were treated with short-chain fatty acid (SCFA) enemas generally showed considerable improvement in symptoms. Because dietary fiber is fermented to SCFA, this suggests that high-fiber diets may be beneficial. If this turns out to be the case, it is likely that specific types of dietary fiber will be recommended to achieve defined concentrations of one or more of the SCFAs.

Surgery and drug treatments are the mainstays of therapy, but there is no cure. In fact, surgical removal of an affected portion of the intestine must be weighed quite seriously because the disease may recur in previously normal tissue. Immunosup-pressive medications are the standard therapy for these conditions. Because fish oils, rich in n-3 fatty acids, have immunosuppressive properties, these products have been studied and found to have benefit in treating Crohn's disease that is approximately equal in effectiveness to immunosuppressive drugs, but side effects of indigestion and bad breath were major limiting factors in acceptance of the fish oil. The best study done in this area was conducted in Italy, and it is unknown if the fat types and amounts in the Italian diet play some interacting role with the fish oil treatment. In addition, because Crohn's disease is heterogeneous, it is not clear if all patients will benefit from this treatment.

Sublingual vitamin B12 has been recommended by some for patients with Crohn's disease because absorption of this vitamin occurs in the ileum, which is the segment of gut frequently affected. However, the absence of the specific transport system for absorption of the vitamin and intrinsic factor, produced in the stomach, call into question the benefit of the route of administration. The efficacy of sublingual vitamin B12 is primarily a result of swallowing the vitamin, with subsequent intestinal absorption. Patients should have regular blood counts and intramuscular injection of vitamin B12 may be necessary if macrocytic anemia develops.

One of the complications in patients with Crohn's disease who have had ileal resections is increased formation of calcium oxalate kidney stones. This is due to enhanced absorption of oxalate. Since limiting dietary sources of oxalate is considered too restrictive, calcium supplementation and increased fluid intake are recommended. The calcium will decrease oxalate absorption if taken with meals, and the increased fluids will dilute the urine. Since ascorbic acid increases urinary oxalate, supplements and dietary sources rich in vitamin C should be used judiciously, if at all.

Stomas

Although the creation of a surgical stoma is associated with some dietary restrictions, many patients find that there are fewer prohibited foods following the creation of the stoma than prior to surgical resection. Jejunostomies are usually indicated for treatment of Crohn's disease. Ileostomies are created when the colon is removed typically due to a disorder such as ulcerative colitis or bypassed due to trauma (usually short term and reversible). Continent ileostomies are made by creating an internal reservoir that is drained by the patient several times a day via a tube inserted through the stoma; this avoids the necessity of wearing an external appliance. Colostomies are made by attaching a portion of the colon to the abdominal wall, often as a treatment for cancer, IBD, or trauma. The site of the colostomy often determines the nutritional modifications a patient requires; a stoma in the proximal colon (Figure 1) produces more liquid feces, whereas one placed distally results in more solid fecal material. Intestinal excreta are collected into a plastic bag attached to a device around the stoma. Postsurgical diets reflect a transition from clear liquids through low-fiber diets to a relatively unrestricted diet. A number of concerns regarding patients with stomas are reflected in nutritional management.

One of the more important complications of bowel resection and stoma placement is the development of short bowel syndrome. Patients with this condition have reduced absorption of most nutrients, which is accompanied by diarrhea. The degree of symptoms depends on the portion and length of intestine resected. Postsurgical nutritional management usually consists of TPN to reduce an osmotic effect of food in the remaining gut. There is concern about long-term bowel rest inducing intestinal atrophy and allowing bacterial translocation; this is based almost exclusively on studies in animals but there are few data from humans. Formula diets given enterally are indicated if the length of the remaining small bowel is insufficient for adequate digestion and absorption of a normal diet. Combinations of enteral, parenteral, and normal feeding may be required. Specific advice depends on the length of remaining intestine and which portions were resected.

Since one of the primary physiological functions of the colon is reabsorption of water and electrolytes, surgical removal of this organ can result in excessive losses. Many patients voluntarily restrict their fluid intake in the mistaken belief that this will reduce effluent volume; however, excess water intake is eliminated primarily via the kidneys. In addition, the typical patient will need to be reminded to consume adequate sodium and potassium. When stomal losses exceed oral intake, par-enteral fluids and minerals are required. Absorption of most trace elements and vitamins can also be reduced and, when needed, these are also supplied parenterally. A number of foods have been found to influence the amount of effluent. Those that increase volume are beans, cabbage, broccoli, spinach, raw fruits and juices, many spicy foods, red wine, and beer. Foods that are associated with decreased effluent volume include rice, bananas, applesauce, cooked milk, and peanut butter. Limited research indicates that pectin supplements can control excessive ileal effluent. Often, there are differences in the way individuals react to specific foods or combinations of them, so a food diary is highly recommended to relate changes in effluent to diet.

Because the diameter of a surgical stoma can be less than that of the intestine, certain foods can cause problems if chewed insufficiently. Therefore, chewing food thoroughly is an important part of the nutritional advice for a patient with a stoma. Some high-fiber foods are also relatively undigested and may need to be reduced or eliminated to control fecal volume and viscosity. These include corn, popcorn, nuts, coconut, celery, and raw fruits, particularly the skins and seeds.

Foods that are associated with gas production should be avoided if the patient is concerned with odor or flatulence from the stoma, which are common problems with this type of surgery. Such foods include the cabbage family, onions, beans, nuts, peppers, chocolate, carbonated beverages, eggs, and alcoholic beverages. Habits that encourage swallowing of air should also be minimized, such as gum chewing or drinking through a straw.

Weight control is important for patients with sto-mas to avoid some of the complications involving the skin surrounding the stoma. There is also a tendency for patients to gain weight once their primary gastrointestinal disease is treated successfully. There are a number of support groups for patients that provide nutrition advice, but it is important to distinguish between claims based on hype and soundly conducted studies. Nutritionists with proper academic credentials are generally the best source of accurate information.

See also: Colon: Structure and Function; Disorders. Diarrheal Diseases. Nutritional Support: Adults, Enteral; Adults, Parenteral; Infants and Children, Parenteral.

Further Reading

Beers MH and Berkow R (eds.) (1999) The Merck Manual of Diagnosis and Therapy, 17th edn. Whitehouse Station, NJ: Merck. Coulston AM, Rock CL, and Monsen ER (eds.) (2001) Nutrition in the Prevention and Treatment ofDisease. San Diego: Academic Press.

Haubrich WS, Shaffner F, and Berk JE (1995) Bockus Gastroenterology, 5th edn. Philadelphia: WB Saunders.

Kinney JM, Jeejeebhoy KN, Hill GL et al. (eds.) (1988) Nutrition and Metabolism in Patient Care. Philadelphia: WB Saunders.

Lewis JD and Fisher RL (1994) Nutrition support in inflammatory bowel disease. Medical Clinics of North America 78: 1443-1456.

Nightingale JM (1995) The short-bowel syndrome. European Journal of Gastroenterology and Hepatology 7: 514-520.

Ozick LA, Salazar CO, and Donelson SS (1994) Pathogenesis, diagnosis, and treatment of diverticular disease of the colon. Gastroenterologist 2: 299-310.

Sax WC and Souba WW (1993) Enteral and parenteral feedings. Guidelines and recommendations. Medical Clinics of North America 77: 863-880.

Shils ME, Olson JA, Shike M etal. (eds.) (1999) Modern Nutrition in Health and Disease, 9th edn. Baltimore: Williams & Wilkins.

Spiller GA (ed.) (1993) CRC Handbook of Dietary Fiber in Human Nutrition, 2nd edn. Boca Raton, FL: CRC Press.

Zeman FJ and Ney DM (1996) Applications in Medical Nutrition Therapy, 2nd edn. Englewood Cliffs, NJ: Prentice Hall.

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