Malnutrition and IBDs

Managing your diet with Crohn's disease or ulcerative colitis is critical.  We can help you get you started on the path to a healthier life by understanding how inflammatory bowel disease (IBD) affects your body’s nutrition.

 Crohn’s disease and ulcerative colitis can impact your body’s ability to properly digest food and absorb nutrients, which may lead to serious vitamin deficiencies and malnutrition.

Malnutrition and the GI Tract

Intestinal inflammations and certain medications can make it difficult for you to maintain healthy nutrition. For example:

  • Small intestine inflammation can cause problems digesting food and absorbing nutrients.

  • Large intestine (including colon and rectum) inflammation can cause problems absorbing water and electrolytes.


Signs You May Be Malnourished

Even mild cases of malnutrition can make it more difficult for your body to bounce back after an illness. Signs of malnourishment include:

  • Under-eating and/or severely restricting the variety and types of foods eaten

  • Weight loss

  • General fatigue and low energy

  • Weakness

  • Loss of muscle mass

  • Vitamin and mineral deficiency


Causes of Malnutrition

In addition to intestinal inflammation, symptoms of Crohn's and Colitis can contribute to malnutrition.

  • Severe diarrhea can cause dehydration, which means your body may be depleted of fluids, nutrients, and necessary electrolytes such as  sodium, potassium, magnesium, phosphorus, and zinc. It can also lead to weight loss.

  • Abdominal pain and nausea can reduce your appetite, making it difficult for you to consume enough calories and sufficient nutrients.

  • Rectal bleeding from ulcers in your intestines can lead to iron deficiencies and anemia.

  • Frequent bowel movements can cause you to cut back on eating to avoid diarrhea or excessive trips to the restroom. Eating too little puts you at risk for becoming malnourished.

While medication can help with Crohn's and Colitis symptoms, certain IBD medications may interfere with your ability to maintain a healthy nutritional status:

  • Corticosteroids, such as prednisone, may cause weight gain and increase your risk for diabetes. Long-term use can also cause a decrease in healthy muscle mass, as well as bone and skin strength.

  • Sulfasalazine and methotrexate may interfere with the absorption of folic acid, a vitamin that promotes healthy cell growth.


Complications of Malnutrition

IBD-related malnutrition can cause serious complications if not treated and resolved. If you suspect that you or your loved one are experiencing malnutrition due to Crohn’s disease or ulcerative colitis, make an appointment with your doctor as soon as possible.


Malabsorption makes it difficult to absorb necessary nutrients in the small intestine, such as proteins, fats, sugars, vitamins, and minerals. It can be caused by inflammation in the intestines.

The degree of malabsorption depends on how much of the small intestine is affected. Malabsorption and nutrient deficiencies are often more significant if larger sections of your small intestine are inflamed or have been surgically removed. If a significant portion of your  ileum, or the end section of your small intestine, is inflamed or removed, the absorption of fat-soluble vitamins A, D, E, K, and B12 will likely be affected.

Patients with ulcerative colitis may have less significant nutrient deficiencies, though severe diarrhea and blood loss can cause weight loss and anemia.


A stricture is a narrowing of your intestine, created when scar tissue builds up after repeated cycles of inflammation and healing in the lining of the intestine. Strictures can make it difficult for digested food to pass through your intestine, and can eventually lead to a blockage.

High-fiber foods, such as fresh fruits and vegetables, may become stuck in the narrowed intestine, causing pain, bloating, or nausea. Low-fiber foods or liquid diets may be needed to reduce your symptoms if the stricture is mostly inflammatory. Your doctor may also prescribe medication to reduce inflammation or recommend surgery.

Decreased Bone Strength

Decreased bone strength is a common complication for people with IBD. This puts you at an increased risk of fractures.

Causes of decreased bone strength include:

  • Poor absorption of calcium

  • Vitamin D deficiency

  • Decreased physical activity

  • Inflammation

  • Long-term use of certain medications, including corticosteroids

Growth Delays

This complication may occur in some children with IBD who experience chronic inflammation and malnutrition, or who take long-term corticosteroids. In approximately one-third of children with Crohn’s disease and one-tenth of children with ulcerative colitis, their final adult height is less than expected because of their IBD.

Good eating habits, adequate calorie intake, and control of the underlying disease are essential to minimize the negative effects of IBD on your child’s growth. Consult your child’s doctor or a registered dietitian if your child is not staying on their typical growth curve. It may be necessary to evaluate your child’s calorie and nutrient intake.

How to Avoid Malnutrition

There are steps you can take to maintain healthy nutrition even if your diet is limited by IBD.

  • Get tested for vitamin and mineral deficiencies even if you aren’t showing symptoms of malnutrition.

  • C-Reactive protein test 

  • Stool ova and parasites (O&P test)
  • Stool Culture 
  • Take vitamins and supplements daily
  • Work with your healthcare team to identify a list of foods that may help you maintain well-balanced nutrition.