Malnutrition

Malnutrition occurs when you do not get enough of 1 or more nutrients that your body needs to thrive. There are many reasons why people with inflammatory bowel disease are at risk of malnutrition:1,2

  • You may avoid eating to limit unpleasant symptoms.
  • Your appetite may be poor.
  • You may not be able to absorb nutrients because of damage to your intestine.
  • You may have had surgery to remove parts of your intestine where nutrients are absorbed.
  • You may be burning more calories than you can eat because of inflammation in your body.
  • You may be losing nutrients because of diarrhea or intestinal bleeding.
  • Your medications may cause taste changes. They may also change the way you absorb and process nutrients.3
  • You may eat less because you feel depressed. Depression is common among people with chronic illnesses, such as Crohn’s disease and ulcerative colitis.

You can be malnourished if you do not get enough calories (energy) every day. You can also be malnourished if the foods you eat do not provide enough vitamins or minerals.1 There are some people who get enough calories, but not enough of certain vitamins or minerals. Iron deficiency is common in people with Crohn’s disease.1 Other nutrients that tend to be low in the typical diet are starches and sugars (carbohydrates), healthy (monounsaturated) fats, fiber, calcium, and vitamins C, D, E, and K.2


It is hard to know how many people with inflammatory bowel disease are malnourished. The estimates range from 20% to 85%.1 If you have Crohn’s disease that has affected your small intestine, you are especially likely to have malnutrition.1 Most nutrients are absorbed in the small intestine. Malnutrition is also more likely in people with tunneling (fistulas) or people who have had digestive tract surgery.1 During periods of recovery from inflammatory bowel disease (remission), most people are in good nutritional status.2

What are signs and symptoms of malnutrition?

Weight loss is a sign of malnutrition caused by not getting enough calories. Up to 80% of people in the hospital for Crohn’s disease lose weight. About 20% to 40% of outpatients with Crohn’s disease also have weight loss.2

Most children with inflammatory bowel disease lose weight.2 They may grow more slowly than expected. Slow growth may start years before being diagnosed with inflammatory bowel disease.2

Body mass index (BMI) is not always a good way to measure malnutrition. BMI is an estimate of body fat based on your weight and height. (In children, BMI-for-age is used to estimate body fat.) Recent research shows that about one-third of people with inflammatory bowel disease are overweight or obese.2 However, many of these people have low muscle mass and handgrip strength, which are signs of malnutrition.4 People with inflammatory bowel disease often avoid foods that make their symptoms worse or increase their risk of a blockage. As a result, may not be able to get all the vitamins and minerals they need through their diet.5

Symptoms of malnutrition are not very specific. You might feel tired or depressed. You may notice that wounds heal slowly.3 However, most vitamin and mineral deficiencies do not cause symptoms.6

How is malnutrition evaluated?

Your health care provider or dietitian will weigh and measure you regularly. One way to check for malnutrition is to keep track of how much and how quickly you lose weight. Height is an important sign of how well children are growing. Blood tests can check for anemia, as well as low levels of certain vitamins and minerals.

Your provider or dietitian may evaluate your diet in many different ways. There are simple questionnaires with questions about weight changes, what you have been eating, symptoms that interfere with eating, and changes in activity level. More complicated questionnaires may have questions about how frequently you eat certain foods. Keeping a food diary can help your provider or dietitian to understand what your normal diet is like. It can also help you figure out what foods you can tolerate. The best diet for inflammatory bowel disease varies from person to person and even from one flare to the next.7 This variation is one of the reasons inflammatory bowel disease is so challenging for patients and providers.

How is malnutrition treated?

Dietary counseling can be useful to improve nutrient intake.1 Working with a dietitian may be helpful to identify dietary gaps and work with you to find foods that meet your needs.

In some cases, supplements of certain vitamins or minerals might be helpful. If you are having a hard time eating enough calories, your health care provider might recommend oral nutritional supplements.1 These are high-calorie, nutrient-dense powdered or liquid products that you consume in addition to regular foods.

Tube feeding and intravenous (IV) nutrition have been used to start remission and improve nutritional status in people with inflammatory bowel disease. Tube feeding (enteral nutrition) can be done by inserting a thin, hollow tube from your nose into your stomach or small intestine. A nutrient-rich formula flows through the tube. Studies have shown that tube feeding can decrease inflammation and help patients recover during active inflammatory bowel disease.2,8 Eight-five percent of children with active inflammatory bowel disease who receive all their nutrition through tube feeds go into remission.2 Therefore, tube feeds may be used instead of corticosteroids for children. In adults, tube feeding is less effective than corticosteroids for starting remission. However, it also has fewer side effects and can be a good choice in certain situations.2

When the digestive system is not working, IV nutrition can be used. Other terms for IV nutrition are parenteral nutrition or TPN. TPN bypasses your digestive system. A special liquid of broken down nutrients is given directly into the blood through a catheter. TPN is mainly used for severe malnutrition and people with short bowel syndrome.2,8 Short bowel syndrome occurs when a large section of the small intestine is surgically removed.8 People with short bowel syndrome have a difficult time digesting and absorbing nutrients from food.

What are consequences of malnutrition?

Long-term malnutrition can cause a number of conditions (Table).1 Malnutrition can increase your hospital stay by an average of 6 days. Studies have also shown that malnourished patients are 3.5 times more likely than well nourished patients to die while in the hospital.

Table. Nutrient Deficiency Syndromes

Deficiency Syndrome Nutrient(s)
Anemia Iron, B12, folate
Osteomalacia (softening of the bones) Vitamin D
Peripheral neuropathy (nerve damage, usually in the hands or feet) Vitamin E
Night blindness Vitamin A
Beriberi (damage to the heart and nervous system) Thiamine
Stomatitis or glossitis (Inflammation or soreness of the mouth and tongue) B vitamins

Source: Donnellan CF, et al. Therap Adv Gastroenterol. 2013;6:231-242.

Written by: Sarah O'Brien and Emily Downward | Last Reviewed: January 2018.
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