When we assess whether a patient needs nutritional support, we often use the phrase: “If the gut is functional, make the most of it.” However, in adult CD patients, especially when the disease is in its acute phase, this becomes a controversial topic.
CD is a widespread inflammatory disease of the intestine with varying degrees of severity. Some patients present with mildly active lesions or lesions limited to a small segment of the intestine with good results with medication, while others present with persistent moderately to severely active lesions requiring multiple hospital admissions for treatment and even surgical intervention to remove the diseased segment of the intestine. These patients also often present with malnutrition and require nutritional support.
The need for nutritional support in CD patients usually requires consideration of several factors: disease activity and severity, effectiveness of drug therapy, presence and extent of malnutrition. In the following, we will provide reasonable guidance for nutritional support in the treatment of CD by briefly reviewing some of the relevant rationale and evidence.
CD and malnutrition
Malnutrition occurs in approximately 65-75% of patients with CD. Causes of malnutrition include the following.
1. decreased transoral intake due to abdominal pain, nausea, and diarrhea.
2. impaired nutrient absorption associated with mucosal inflammation or intestinal resection.
3. intestinal inflammation leading to nutrient loss.
4. acute chronic inflammation leading to altered organismal metabolism.
5, drug-nutrition interactions.
Micronutrient or vitamin deficiencies such as calcium, iron, folic acid, vitamin D, and vitamin B12 in patients with CD can lead to reduced quality of life.
Choosing a pathway for nutritional support
The primary goal of nutritional intervention is to correct any underlying malnutrition and to maintain nutrients at normal levels. Enteral nutrition is the preferred route for patients with inflammatory bowel disease. Extreme nausea and vomiting, severe diarrhea or impaired intestinal absorption, high-flow parenteral fistulas and intestinal obstruction can prevent effective adoption of enteral nutrition.
However, complete cessation of enteral nutrition is usually not necessary in patients with acute CD. In addition, attention should be paid to coexisting digestive dysfunctions, as they can exacerbate the patient’s clinical symptoms and also affect the effectiveness of enteral nutrition. These disorders include: lactose intolerance, irritable bowel syndrome (IBS), and intestinal bacterial overgrowth due to intestinal obstruction.
Enteral nutrition as supportive therapy
Enteral nutrition is a priority for patients with CD. A healthy, balanced diet is encouraged for all patients. For patients with moderate to severe malnutrition with CD, a high-protein, high-calorie nutritional supplement should be added to the diet. In severely malnourished patients, there is a risk of re-feeding syndrome (re-feeding syndrome is a group of manifestations associated with metabolic abnormalities, including severe water-electrolyte imbalance, decreased glucose tolerance and vitamin deficiency, caused by the provision of re-feeding (including oral intake, enteral or parenteral nutrition) after prolonged starvation).
These patients require hospitalization for nutritional support and electrolyte monitoring. If patients are unable to eat or drink by mouth due to fear of eating, anorexia, or nausea, enteral nutrition can be given by nasogastric or nasojejunal tube. In patients with Crohn’s disease who have intestinal strictures, a low residue diet has been shown to reduce the incidence of small bowel obstruction.
Enteral nutrition as primary therapy
In acute exacerbations of CD, enteral nutrition as primary therapy can lead to a decrease in disease activity in patients. Studies have found that enteral nutrition using an elemental formula (consisting of free amino acids, glucose oligomers, and low concentrations of fat) has a high rate of remission in patients with hormone-resistant or dependent CD, with most patients having improved nutritional status and being able to reduce or discontinue hormone use.
However, enteral nutrition has a slow onset of action, usually taking 4-6 weeks, so enteral nutrition for adult CD is generally used in patients in whom immunomodulatory therapy has failed or produced side effects. Patients should understand the advantages and disadvantages of enteral nutrition and communicate fully. Enteral nutrition formulas are not as tasty as the usual diet; and they are slower to take effect. Placement of enteral feeding tubes may improve patient compliance and increase response rates to therapy.
Although enteral nutrition can lead to disease remission, it does not guarantee maintenance of remission. Patients in remission with enteral nutrition have a 1-year relapse rate of 65% to 100%, and continued pharmacologic therapy is required after remission.
Parenteral nutrition as supportive therapy
Preoperative parenteral nutrition support is beneficial for patients with Crohn’s disease. Prospective randomized controlled studies have shown that perioperative parenteral nutrition given for at least 7-10 days in severely malnourished CD patients can reduce the incidence of postoperative complications.
In addition to this, a retrospective study also showed that preoperative parenteral nutrition reduced postoperative complications in CD patients and was able to reduce the length of bowel segment resection.
Indications for parenteral nutrition in CD.
1.Short bowel syndrome
2.Severe absorption disorders
3, high-flow parenteral fistula
4, intestinal obstruction
5.Severe vomiting and diarrhea
6.Gastrointestinal bleeding
7.Severe colitis
8.Intestinal ischemia
Parenteral nutrition as primary treatment
The consensus of American Society for Parenteral Nutrition (ASPEN) is that parenteral nutrition does not play an important role in the induction of remission of CD. Parenteral nutrition poses many risks to the patient and therefore it is not an appropriate treatment. The indication for bowel rest and the use of parenteral nutrition as the primary treatment is a high-flow parenteral fistula, which can result from CD or from surgical complications.
Patients with parenteral fistulas can reduce fistula volume by not eating, which facilitates fistula closure. After fistula closure in patients with parenteral fistula, it is recommended to continue maintaining parenteral nutrition for 7 days before resuming transoral feeding. The treatment of parenteral fistulas after surgery is better than that of parenteral fistulas caused by CD itself.
Summary
The primary goal of nutritional support is to correct nutritional deficiencies in patients with CD, and the enteral route is the preferred route for providing this support. Modification through diet and use of dietary supplements is a more common practice, especially for those patients with mild to moderate malnutrition. Enteral nutrition, as the primary means of nutritional support during acute exacerbations of CD, is effective in reducing the use of immunosuppressive drugs in patients, while being able to correct malnutrition in patients.
Parenteral nutrition is less important than enteral nutrition in the treatment of CD. the indications for parenteral nutrition in CD are similar to other patients with non-inflammatory bowel disease. The application of nutritional support, either enteral or parenteral nutrition, requires good communication between the physician and the patient.
Nutritional support intolerance and side effects occur frequently, and when these occur they need to be addressed promptly by the clinician to avoid further exacerbation. Nutritional therapy is very important for most people with CD and is an important part of treatment. If used appropriately, nutritional support can effectively improve patient outcomes and quality of life.