When people eat, most of the food is broken down in the stomach and absorbed in the small intestine. However, in many people with Crohn’s disease — and in nearly all of those with small bowel Crohn’s disease — the small intestine is unable to absorb nutrients properly, resulting in what is known as malabsorption.

People with Crohn’s disease have an inflamed intestinal tract. The inflammation or irritation can occur in any part of the intestinal tract, but it most commonly affects the lower section of the small intestine, which is known as the ileum. The small intestine is where critical nutrient absorption takes place, so many people with Crohn’s disease don’t digest and absorb nutrients well. This can result in various problems, including malabsorption of important vitamins and minerals. These vitamin and mineral deficiencies may eventually lead to additional health complications, such as dehydration and malnutrition.

Fortunately, blood tests can help doctors determine whether people with Crohn’s disease are getting the vitamins and nutrients they need. If they’re not, they may be referred to a gastroenterologist for evaluation. A gastroenterologist is someone who specializes in diseases affecting the intestinal tract and liver. They can recommend a treatment plan for someone who has nutritional deficiencies due to Crohn’s disease.

People with Crohn’s disease may have trouble absorbing a large number of vitamins and nutrients, including:


Calories are derived from macronutrients, such as carbohydrates, protein, and fat. When someone isn’t absorbing enough calories due to malabsorption, they often lose a significant amount of weight very quickly.


People with Crohn’s disease may need to supplement their protein intake due to:

  • the use of high-dose steroids, such as prednisone
  • prolonged blood loss or diarrhea
  • wounds or fistulas affecting the small intestine


People who have severe Crohn’s disease and who have had more than 3 feet of their ileum removed may need to incorporate more healthy fats into their diets.


Anemia, or a lack of healthy red blood cells, is a common side effect of Crohn’s disease. The condition can lead to iron deficiency, so many people with Crohn’s require additional supplementation of iron.

Vitamin B-12

People who have severe inflammation and who have had their ileum removed often require regular injections of vitamin B-12.

Folic Acid

Many people with Crohn’s disease take sulfasalazine to treat their symptoms. However, this medication may affect the body’s ability to metabolize folate, making folic acid supplements necessary. People who have extensive Crohn’s disease of the jejunum, or middle section of the small intestine, may also need to supplement their folic acid intake.

Vitamins A, D, E, and K

Deficiencies of these fat-soluble vitamins are often associated with fat malabsorption and inflammation of the small intestine. They may also be related to the removal of large sections of either the ileum or the jejunum. The risk of vitamin D deficiency is also believed to be higher in people who take cholestyramine, as this medication can interfere with the absorption of vitamin D.


People with Crohn’s disease may need to take zinc supplements if they:

  • have extensive inflammation
  • have chronic diarrhea
  • have had their jejunum removed
  • are taking prednisone

These factors can interfere with the body’s ability to absorb zinc.

Potassium and Sodium

The colon, or large intestine is responsible for processing fluids and electrolytes. People who have had this organ surgically removed will therefore need to increase their intake of both potassium and sodium. There is an increased risk of potassium loss in people who take prednisone and who frequently experience diarrhea or vomiting.


Steroids interfere with the absorption of calcium, so people who take these medications to treat symptoms of Crohn’s disease will likely need to incorporate more calcium into their diet.


People who have chronic diarrhea or who have had their ileum or jejunum removed may not be able to properly absorb magnesium. This is a key mineral for bone growth and other body processes.

Many people with Crohn’s disease don’t experience symptoms of malabsorption, so it’s important to undergo regular testing for nutritional deficiencies. When malabsorption symptoms do appear, they may include:

  • bloating
  • gas
  • stomach cramping
  • bulky or fatty stools
  • chronic diarrhea

In severe cases of malabsorption, fatigue or sudden weight loss may also occur.

A number of factors related to Crohn’s disease may contribute to malabsorption:

  • Inflammation: Persistent, long-term inflammation of the small intestine in people with small bowel Crohn’s disease often leads to damage of the intestinal lining. This can interfere with the organ’s ability to absorb nutrients properly.
  • Medications: Certain medications used to treat Crohn’s disease, such as corticosteroids, may also affect the body’s ability to absorb nutrients.
  • Surgery: Some people who’ve had a portion of their small intestine surgically removed may simply have less of the intestine left to absorb food. This condition, known as short bowel syndrome, is rare. It is usually only found in people who have less than 40 inches of the small intestine remaining after multiple surgeries.

Replacement of nutrients is usually an effective treatment for people who have nutritional deficiencies due to Crohn’s disease. Lost nutrients may be replaced with certain foods and dietary supplements. Supplements may be taken orally or given through a vein (intravenously).

Avoiding certain foods is also critical for treating malabsorption. Various foods may make gas or diarrhea much worse, especially during flare-ups, but responses are individual. Potential problematic foods include:

  • beans
  • seeds
  • broccoli
  • cabbage
  • citrus foods
  • butter and margarine
  • heavy cream
  • fried foods
  • spicy foods
  • foods high in fat

People with an intestinal blockage may need to completely avoid eating high-fiber foods, such as raw fruits and vegetables.

People with Crohn’s disease are encouraged to eat a healthy, well-balanced diet to promote the absorption of vitamins and minerals. It’s also recommended to eat small amounts of food throughout the day and to drink plenty of water. Dairy may need to be avoided, as some with Crohn’s disease become intolerant to dairy.


Can certain foods help prevent nutritional deficiencies in people with Crohn’s disease? If so, which ones?

Anonymous patient


Yes, certain foods can help. Avocado is an easily digestible fat and rich in folate, oysters are iron- and zinc-rich, and cooked dark leafy greens are rich in folate, calcium, and iron (pair with a vitamin C food like citrus or berries). Canned salmon with bones, calcium-fortified plant milks, beans, and lentils are also excellent sources of nutrients that are often malabsorbed.

Natalie Butler, RD, LDAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.