Nutritional Support in Patients with Intestinal Stoma "Q: doctor, what can I eat after this surgery?"

Provides answers to the most frequent question from patients who have undergone GI surgery: “What can I eat from now?”

 Pathophysiologic Implications 

Left colostomy: left (distal) colostomy has minimal implication on the pathophysiology of nutrition in these patients, since the only organ bypassed is the rectum which normally is devoted to storage of the feces, minor effects on the final dehydration of the stools, and control of the defecation. 

Nevertheless, the nutritionists should be aware of the profound changes in the microbiota induced by the mechanical bowel preparation and prolonged antibiotic therapy which normally occur in patients undergoing colorectal surgery and suggest pre/probiotic treatments. 

The output through the stoma is formed stools, and the frequency of the bowel movement and consistency of the feces strongly depends on the preoperative bowel habit (patients with slow transit constipation remain constipated) and type of diet and drinking. 

Coecostomy: from a pathophysiologic point of view, it must be considered like a terminal ileostomy (see later). Ileostomy: the pathophysiologic consequences of an ileostomy strongly depend on the level of the ileostomy. In any case the role of the colon on the absorption of water, electrolytes, and biliary salts is lacking; therefore the stools will be fluid and irritating on the skin for the presence of biliary salts and residual activated pancreatic enzymes. Furthermore, the output from the stoma is frequent following the migrating motor complex of the small bowel that occur approximately every 90 min in fasting state. Furthermore, the passage of liquid stools often follows the oral feeding after few minutes. 

This condition can cause dehydration and electrolyte imbalance leading to hypotension and kidney failure. 

Hopefully this high output from the ileostomy tends to decrease within 2–3 months, and the stool becomes more consistent and dehydrated. 

When the stoma involves the proximal part of the ileum or the jejunum, the pathophysiologic consequences may be devastating, and often the patients need to be hospitalized for a parenteral nutrition and rehydration. In the long term, these patients can gain weight because the absorption of most of the nutrients is maintained, nevertheless they are predisposed to develop gallbladder stones because of the altered enterohepatic recirculation of the biliary salts absorbed in the cecum. 

Approximately 8500  mL of fluid is added to the gastrointestinal tract daily, 1500 mL coming from the diet and 7000 mL coming from endogenous secretions from the salivary glands, stomach, small intestine, pancreas, and biliary tree. Of this amount, roughly 7000 mL is absorbed in the small intestine, leaving 1500 mL of fluid for the cecum to handle. In the cecum and proximal colon, a further 1400 mL is absorbed, leaving approximately 100 mL of fluid to be expelled with the solid fecal material in the stool. In contrast to the relatively leaky mucosal resistance of the jejunum and ileum, resistance in the colon becomes much tighter, thus preventing back diffusion of electrolytes and water. Associated with this prevention is an increase in the spontaneous membrane potential difference, which further restricts ionic movement into the lumen. The absorptive processes are different in the distinct regions of the gastrointestinal tract, with absorption of sodium, chloride, and short chain fatty acids (SCFA) predominantly in the colon.

Pathophysiology of Ileostomy and Nutritional Support in Patients with Ileostomy

• The ileus is the most important part of the GI tract involved in the absorption of nutrients, such as carbohydrates, lipids, proteins, mineral salts, and vitamins, and in the reabsorption of the biliary salts. Therefore, following surgery on the ileus, it is important to know the length of the residual small bowel in order to estimate its ability to allow adequate absorption of nutrients and fluids: the higher the site of the ostomy, the higher the risk associated with nutritional impairment and malabsorption. 
• If the resection involves the jejunum, the possible deficiencies are iron, calcium, magnesium, and all the three macronutrients (protein, carbohydrate, and fat). 
• In case of distal resection of the ileus, the absorption of lipids, bile, and vitamin B12 might be significantly impaired [6]. Thereafter, the postoperative diet and possible need of supplements depend on the spared tract of gut, its physiological conditions, and the presence of associated diseases. In the first months after the surgery, it is necessary to have a high caloric diet (40–60 kcal/kg of weight) with high protein content (1.5 g/kg of weight) in order to provide enough energy and nutrients to restore the muscle mass and promote early recovery. 
• In case of obese patients, the diet should include a high percentage of proteins (22–25%) and a low quantity of carbohydrates, with a low glycemic index (do not overcome a glycemic load of 20 g per meal and 80 g daily). Lipid supplementation should be low in order to prevent steatorrhea and to decrease the overall calories during meals. High biological protein value with low fat presence should be preferred (low-fat meat, egg white, low-fat fishes, bresaola, low-fat ham, low lactose and lactose-free cheese). The digestion of the lactose is often difficult even in patients without lactose intolerance, and therefore patients with intestinal stomas should prefer lactose-free foods.
• In the presence of weight loss higher than 1 kg per week or irresponsive diarrhea (>600 g output per day), the need for parenteral nutrition for a limited period should be considered.
• The control of the hydroelectrolytic balance is of pivotal importance in the presence of an ileostomy.
• The estimated loss of NaCl through an ileostomy is about 30–40 mEql/die; however the small bowel adapts, over time, to reabsorb water, so the patient will decrease the stoma output from 1000/1200 mL/die to about 750 mL/die within 1–2 months from surgery; this adaption is easier and faster in distal ileostomy.
• The most frequent cause of new hospitalization is dehydration with some cases of renal insufficiency. This risk is greater in patients under diuretic therapy for other reasons, including arterial hypertension. Symptoms of dehydration must be recognized as soon as possible (increased thirst, dry mouth, dry skin, decreased urine production, fatigue, shortness of breath, headache, dry eyes, and abdominal cramps) in order to be able to correct them promptly. To compensate for urinary and saline losses, the urine is more concentrated, predisposing to the calcium and uric acid precipitation and stone formation. Hypomagnesemia can also occur because of ileostomy loss, and therefore the support of magnesium-rich foods should be encouraged (almonds, sunflower seeds, fish, tofu, avocado). Vitamin B12 is mainly absorbed into the ileum, and therefore the risk of vitamin B12 deficiency must be considered in these patients leading to macrocytic anemias and possible repercussions on the folate cycle and hyperhomocysteinemia.
• The passage of the chimo in the terminal part of the small intestine stimulates the release of entero-hormones like the Pyy and GLP2, with a modulating function on the appetite and gastric motility and secretion. This mechanism is known as ileal brake, decreases gastric emptying, increases pyloric contraction, slows postprandial transit, decreases pancreatic exocrine secretion, and modulates the appetite reducing food intake. As a consequence, resection of the terminal ileum can result in increased gastric motility and transit time. The ileal brake mechanism is completely lost in proximal ileostomies, while it is quite maintained in distal ileostomies.
• In ostomy patients, particularly in the first 2–3 postoperative months, it is important to keep solid meals separate from liquids. Each meal must be composed by small portions of food and must have at least 3 h interval between meals.
• To decrease the volume of feces and frequency of bowel movements, meals should be based on refined cereals in order to avoid the whole fiber intake, peel the fruit, and avoid the foods with the seeds (eggplant, zucchini, tomatoes, kiwi), which can speed up the transit. From the 6th to 8th°week, depending on the stoma output and individual response, the patient can switch to a semi-solid diet but with low amount of fiber and few fats.
• It should be remembered that the small intestine secretes about 100 mmoles/L of sodium in the intestinal lumen; therefore it is necessary to consider as an integral part of the feeding also 90 mmol/L of sodium, which roughly corresponds to about 5 g of cooking salt, favoring an easy water absorption.
• It should be remembered that the small intestine secretes about 100 mmoles/L of sodium in the intestinal lumen; therefore it is necessary to consider as an integral part of the feeding also 90 mmol/L of sodium, which roughly corresponds to about 5 g of cooking salt, favoring an easy water absorption
• These 5 g of sodium chloride are in addition to the preoperative meals. Water intake too must be increased compared to the usual diet to prevent dehydration; the consumption of at least 500–700 mL of water per day should be added to normal preoperative water intake. 
• Isotonic solutions must be preferred, and drinking hypotonic solutions should be limited to no more than 500 mL per day. 
• Examples of suggested drinks can be a mix of orange juice, about half a liter, one teaspoon of sodium chloride, one teaspoon of baking soda, and sugar, which increases the absorption of sodium and should be added depending on the patient’s glucose tolerance, and water up to a liter to be drunk away from meals . 
• Patient with jejunostomy may exhibit supervisory changes due to hyperammonemia, since the residual intestine does not produce an appropriate amount of citrulline to detoxify the ammonium, through the urea cycle. Prescription of arginine assumption may be able to decrease the serum levels of ammonium, thanks to the activation of the urea cycle. 
• Calcium oxalate lithiasis is also common in patients with ileostomy (in the colonostomy patients, instead, uric acid lithiasis is favored) due to a decrease in diuresis. Alkalization of the urine (pH > 6.5) can help preventing urolithiasis. This may be achieved using negative PRAL foods (potential renal acid load) (vegetables, beans, barbet, milk, bananas). 
• Patients presenting steatorrhea are at risk of developing hyperoxaluria due to increased permeability of the oxalate. In this case the aim of the diet is to reduce fatty acids and oxalates and/or increase calcium intake to bind oxalates in the intestinal lumen and in urine. Foods rich in oxalate are rhubarb, spinach, beets, cocoa and chocolate, sweet potatoes, strawberries, celery, and peanuts, which should be removed or reduced to a minimum. 
• Magnesium citrate can also be prescribed to decrease the risk of urolithiasis. Patient with ileostomy should chew the food completely; chewing allows a better digestion and a more efficient absorption of nutrients, decreasing the possibility of obstruction of the stoma. 
• The evening meal must be taken at least 3 h before going to bed and must be of small quantity in order to decrease the stoma output during the night limiting the necessity to change the bag during the night. 
• Insoluble fiber, like bran, makes the stool more voluminous and accelerates the transit; it causes a greater loss of bile and a lower absorption of cholesterol; therefore it can be recommended when the patient has a hypercholesterolemia. 
• While soluble fibers, such as pectin, decrease gastric emptying and transit time, it slows the absorption of carbohydrates and can be therefore recommended in patients with diabetes.
• In the first weeks after ileostomy, the fibers should be reduced to a minimum in order to decrease the fecal volume, and then it must be reintroduced progressively by choosing the right fiber-rich foods in relation to the intestinal transit and stool consistency. The absorption of trace elements may be decreased by 10–20% in phytate-rich diets [13]. Phytate-rich foods include whole grains, legumes, soy, peanuts, sesame, and cocoa powder, which should be eliminated from the diet of patients bearing proximal ileostomies. 

Nutritional Support in Patients with Colostomies 

• One of the main aims of the colon is the resorption of the water contained in the feces that leave the ileum. It is estimated that only 40–400 mL of fluids are found in the feces out of 800–1800 mL that enter the colon daily. In addition, it also has the function of reabsorbing electrolytes, especially sodium, vitamin B12, and vitamin K, particularly in the right colon. 
• Consequently, in the left colon ostomies, the colonic functions are almost completely preserved. Therefore, minimal nutritional advices are required in the daily diet. 
• In order to have regular bowel movements, these patient should drink adequate quantity of water (1500–2000 mL) and high fiber diet; the amount of fibers to be ingested, however, should be adjusted case by case in order to prevent the passage of high volume stools requiring frequent changes of the bag. 
• Soluble fibers could be added in the diet in order to reduce the absorption of carbohydrates and to provide nutrients to the microbiota. Soluble fibers are found mainly in fruit eaten with peel (the richest part of pectin is the white layer below the peel, called albedo, then removing the peel often eliminates pectin), in legumes, in chicory, and in oily fruit. Insoluble fiber-rich foods are present in whole foods, in the outer part of legumes, and in fibrous vegetables. 
• The choice of one type or the other type of fibers will depend on the occurrence of concomitant diseases (diabetes, dyslipidemia, use of anticoagulants) and the transit time, by the state of hydration of the patient and the amount of oil assumed. Therefore, sometimes the introduction of the fibers alone cannot correct constipation. 
• Stomas performed on the cecum or right colon should be managed like patients with distal ileostomies. However, this type of colostomy is going to be abandoned in favor of a terminal ileostomy. 
• In patients with documented lactose intolerance, the consumption of containing lactose foods like milk should be limited or better replaced with “milk” of vegetable origin (soy, rice, oats, almonds or other), while soy derivatives can be used instead of cheeses. 
• In any case, it is necessary to suggest the patient to make a good chewing of all the foods, in order to make the nutrients more easily absorbable, while the fibers, both insoluble and soluble, are reduced to pulp and do not increase gas production or alterations of the bowel motility. 
• Water intake should be preferred between meals, in small and frequent portions, about 80–120 mL for 12–10 times a day; this quantity should be increased if the feces become fluid and abundant. 
• Another problem related to the nutritional support in patients with a colostomy is the occurrence of abnormal meteorism with consequent inflate of the stoma bag. In these cases, chewing gum, carbonated drinks, and foods that induce the production of gases such as brassicas (cabbage, cauliflower, turnips, broccoli, etc.) should be avoided. 
• If consumed with a complementary food such as cereals, legumes are a good source of high biological value proteins and contain both soluble and insoluble fibers, however, the indegestible sugars contained into the legumes (raffinose, stachyose, and verbascose) reach unaltered the terminal part of the small intestine and, if present, the large intestine where they are fermented by the local bacterial flora with gas production. A prolonged soaking, at least 48  h, allows the germination of legumes with the use by the same legumes of their indigestible sugars; therefore this would lead to a lower presence in cooked ones. In addition, germination makes the minerals and vitamins present in the legume more available for absorption.