Management of nutritional problems
Protein–energy malnutrition
Decisions about the dietary rehabilitation of malnourished patients with Crohn's disease require a review of the patient's gastrointestinal investigations: What is the extent of the disease? Is there intestinal obstruction? Is there a significantly short bowel? From this information, a decision should be made to determine whether the patient can eat a normal or modified oral diet. If so, a dietitian should be consulted to prescribe suitable protein and energy intakes and to modify the diet to account for food intolerances or allergies and adjust vegetable and fruit intake for bowel obstruction. It is generally believed that fruit and vegetables may not pass through strictures and may cause a bolus obstruction behind a stricture. Hence, patients with symptoms suggestive of mild or partial bowel obstruction, consisting of severe abdominal pain associated with vomiting and the inability to pass stools or flatus, should avoid the intake of raw fruit and vegetables. In general, intestinal obstruction due to vegetable matter often occurs in patients who have had gastric surgery,6 but this has also been seen in patients with an intact bowel,7 including those with Crohn's disease.8 On the other hand, in controlled trials fibre made of fine particles, such as bran in unrefined cereal, is tolerated quite well.9
The target protein–energy intake should be 126–146 kJ/kg per day, with 1.5–1.7 g/kg of protein per day. However, patients with a short bowel (such as those who have had a previous bowel resection for obstructions) and malabsorption should increase both their protein and energy intake to compensate for the reduced absorption.
Fluid and electrolyte deficiencies
These usually occur in patients with a short bowel. This is best treated by using an oral rehydration solution (ORS), which was first described by Harrison as a treatment for infantile diarrhea.10 Since then the composition has evolved so that the composition for adults should approximate the following: glucose 90 mmol/L, sodium chloride 45 mmol/L, sodium citrate 45 mmol/L and potassium chloride 20 mmol/L. The sodium concentration must be at least 90 mmol/L.11 Sports drinks designed to replace losses due to sweating, such as Gatorade, are often prescribed as a substitute for ORS. This is inappropriate, because these drinks contain a very low concentration of sodium, are rich in soluble carbohydrates and have high osmolality, characteristics that may even increase the volume and frequency of diarrhea.
Iron deficiency
Iron deficiency is treated with iron supplements, such as ferrous sulfate or gluconate starting with doses of 300 mg once a day and increasing to 300 mg 3 times a day, but patients with inflammatory bowel disease often do not tolerate oral iron. In addition, there is some evidence that iron in the colon increases oxidative stress and may exacerbate inflammation.12 For these reasons, it is sometimes necessary to administer iron by intravenous infusion or intramuscular injection.12 Even if oral iron is tolerated, the degree of deficiency may be such that ferritin levels do not rise and the hemoglobin level remains low. Under these circumstances, after suitable observation for about a month showing no change in hemoglobin, parenteral iron should be given.
Other mineral deficiencies
Magnesium deficiency is common in Crohn's disease, especially in patients who have had an intestinal resection. The best treatment consists of oral supplements with magnesium heptogluconate (Magnesium-Rougier) or magnesium pyroglutamate (Mag 2). The other salts of magnesium will cause more diarrhea. The total dose of elemental magnesium required to ensure normal serum magnesium varies between 5 and 20 mmol/day. To avoid causing diarrhea with magnesium supplements, I recommend that the total dose be mixed in the ORS and sipped throughout the day, ice cold and flavoured with non–sugar-containing agents.
Although difficult to diagnose biochemically, zinc deficiency occurs in patients with inflammatory diarrhea owing to considerable losses in the stools.13 All patients with Crohn's disease who have significant diarrhea, passing more than 300 g of stool per day, should receive zinc supplements for as long as their diarrhea continues. Zinc deficiency can be treated by the administration of zinc gluconate, 20–40 mg/day.
Calcium supplements usually consist of calcium carbonate, providing 1000–1500 mg of elemental calcium per day in divided doses.
Vitamin deficiencies
Adequate folic acid nutrition is important in light of recent data indicating that folate supplementation may provide protection against colon cancer.14 Patients with Crohn's disease should routinely take folic acid, 1 mg/day. Owing to the high prevalence of biochemical vitamin deficiency even in patients with inactive disease, supplementation with thiamine, riboflavin, pyridoxine, niacin and ascorbate should be recommended using a standard decavitamin preparation. The treatment of vitamin D deficiency depends on the cause. If it is the result of malabsorption, large doses (2000–4000 IU/day), or even calcitriol (0.25–0.5 μ/day), may be necessary.
