Key takeaways

  • Chronic inflammation in Crohn’s disease can prevent proper nutrient absorption and lead to symptoms like diarrhea, which can cause nutrient loss. Deficiencies in nutrients such as iron, zinc, magnesium, calcium, and some vitamins are possible.
  • While there is no single best diet for Crohn’s, eating nutrient-dense foods, especially during flare-ups, may help you manage the symptoms. It’s important to identify your trigger foods through trial and error.
  • A dietitian specializing in inflammatory bowel disease (IBD) can provide personalized guidance on aspects of your diet such as meal timing, portion sizes, appropriate supplementation, and hydration.

Getting proper nutrition from the food you eat is essential to your overall health. But if you have Crohn’s disease, your body may not absorb enough nutrients, and the foods you eat may affect your symptoms.

In Crohn’s disease, which is a type of inflammatory bowel disease (IBD), inflammation of your gastrointestinal tract — most commonly the upper colon and the lower small bowel — can cause a range of symptoms that may lead to malnutrition.

The condition is manageable, and your healthcare team can offer the most appropriate advice on all aspects of your care.

Chronic bowel inflammation can prevent your body from absorbing vitamins and minerals from the foods you eat. More specifically, small intestine inflammation can make digestion and nutrient absorption more difficult, while large intestine inflammation can affect the absorption of water and electrolytes.

The symptoms of Crohn’s disease, such as diarrhea, abdominal pain, rectal bleeding, nausea, and frequent bowel movements, can also contribute to malnutrition.

People with Crohn’s disease have a higher risk of developing deficiencies in certain vitamins and other nutrients, including those below.

Most of these deficiencies can be detected through simple blood tests.

Iron

Crohn’s disease can sometimes cause ulcers, anal fissures, or hemorrhoids that lead to rectal bleeding. That bleeding, in turn, can affect your iron levels.

Possible symptoms of an iron deficiency include:

  • gastrointestinal symptoms, such as abdominal pain, nausea, diarrhea, and vomiting
  • weakness and fatigue
  • lack of concentration
  • memory issues
  • more frequent infections
  • sensitivity to cold temperatures

Zinc

Zinc deficiency can develop in people with Crohn’s disease as a result of factors such as a limited diet and persistent diarrhea.

Zinc deficiency can cause symptoms such as:

  • loss of taste and smell
  • hair loss
  • diarrhea
  • weight loss
  • slow growth and loss of appetite (in children)
  • difficulties with wound healing, memory, and clear thinking (in older adults)

Magnesium

Magnesium plays an important role in your body, helping to regulate muscle and nerve function, blood sugar levels, and blood pressure.

Symptoms of magnesium deficiency are sometimes difficult to detect, but early symptoms can include:

  • vomiting
  • nausea
  • loss of appetite
  • fatigue
  • weakness

As magnesium deficiency progresses, you may experience numbness, muscle tightening or cramping, seizures, or irregular heart rhythms.

Vitamin A

You may experience vitamin A deficiency in Crohn’s disease as a result of insufficient nutrient absorption and low food intake.

Vitamin A is essential to your body as an antioxidant nutrient for your immune system. It also contributes to cell growth and the maintenance of your heart, lungs, eyes, and other organs.

Symptoms of vitamin A deficiency can include dry eyes, difficulty seeing in low light or darkness, and more frequent infections.

B vitamins

B vitamins help your body use energy from food. They also play a role in the development of red blood cells. There are eight B vitamins:

When living with Crohn’s disease, you may develop B vitamin deficiencies if your body does not properly absorb nutrients or if you have trouble eating enough. A small bowel resection — a procedure sometimes used to treat Crohn’s — can also cause B12 deficiency.

Symptoms of a deficiency vary depending on the specific B vitamin but may include fatigue, irritability, headaches, and unexpected weight loss.

Vitamin D and calcium

Vitamin D plays an important role in calcium absorption and bone strength and growth. It also reduces inflammation and helps prevent muscle cramps and spasms.

Calcium forms much of the structure of your bones and teeth and helps maintain the rigidity, strength, and flexibility of tissues in your body. It also plays a role in blood vessel and muscle function, blood clotting, nerve communication, and hormone secretion.

Vitamin D deficiency can result from insufficient nutrient absorption or corticosteroid use and can lead to low calcium levels.

You may develop a calcium deficiency if you have low vitamin D levels, if you use corticosteroids, or if you have hypoparathyroidism (a condition in which your parathyroid glands do not produce enough parathyroid hormone).

Vitamin K

Vitamin K is essential for bone health, blood clotting, and other bodily functions.

You may experience a vitamin K deficiency as a result of antibiotic use, insufficient absorption, or a limited diet.

Severe vitamin K deficiency can lead to blood clotting disorders, bruising, and reduced bone strength.

Electrolytes: Sodium and potassium

Electrolytes are minerals that play several important roles in your body, such as regulating your blood pressure and heart rate, helping your muscles and nerves work as they should, and helping to regulate the amount of water in your body.

Some of the most important electrolytes are:

  • sodium
  • potassium
  • calcium
  • chloride
  • bicarbonates
  • magnesium
  • phosphate

Severe diarrhea in Crohn’s disease can cause dehydration and electrolyte depletion, leading to low levels of sodium and potassium.

It’s especially important to replenish your levels of these two electrolytes, which are essential for nerve and muscle function. Sodium also helps maintain your body’s fluid balance, and potassium supports a regular heartbeat.

If your potassium levels are too low, you may experience:

  • increased blood pressure
  • increased risk of kidney stones
  • muscle weakness
  • fatigue
  • constipation
  • a general feeling of being unwell
  • increased urination
  • high blood sugar levels
  • irregular heartbeat

If you are low on electrolytes, a healthcare professional may recommend drinking a premade electrolyte drink or adding an electrolyte powder to water.

While there is no specific diet for Crohn’s disease, you may find it helpful to eat nutrient-rich meals, particularly during a flare-up when certain foods may irritate your gastrointestinal tract and your body may absorb fewer nutrients.

Foods can affect each person differently, so it may take some trial and error to find foods that work for you.

If you can eat only small amounts, it may be helpful to include nutrient-dense foods such as these in your meals:

  • Fish high in omega-3 fatty acids: Salmon and sardines are high in omega-3 fatty acids, which have been associated with immune system health, decreased inflammation, and lower blood pressure.
  • Shellfish: Shellfish can be a good source of vital nutrients such as vitamin B12 and zinc. Clams are a particularly good source of vitamin B12, among other nutrients.
  • Kale and wild cabbage: Kale and cabbage are part of the Brassica family of vegetables. They are rich in vitamins and minerals, and extracts of these vegetables are also thought to display anticancer activity.
  • Garlic: Garlic has many health benefits and provides nutrients such as vitamins C, B1, and B6; calcium; and potassium.
  • Potatoes: Potatoes contain good amounts of nutrients, including potassium, magnesium, iron, vitamin C, and almost all B vitamins. But during a flare, you may want to avoid eating the skins of potatoes, which can be harder to digest.
  • Eggs: Eggs are high in protein and healthy fats. They can be a great choice for breakfast and may help you feel full longer than some other breakfast options. Egg yolks in particular contain many nutrients.

If a healthcare professional has confirmed that you have a vitamin or mineral deficiency, they may suggest that you consume supplements or nutritional drinks to help restore your nutrient levels and manage any related health conditions that may arise.

Your healthcare team can best advise you on what supplements to take and how they may affect your overall health while living with Crohn’s disease.

Some supplements can cause gastrointestinal symptoms, and some can interact with medications, so it’s important to speak with medical professionals before taking them.

If you experience diarrhea and weight loss in Crohn’s disease, you might also become dehydrated. You might not be able to consume enough fluids, or you may lose fluids and electrolytes before your body can absorb them.

Your entire body relies on water to function, so staying hydrated is essential. Medical experts recommend that adults consume 2 to 3 liters of water daily to stay hydrated, but this can be challenging when you’re experiencing Crohn’s disease symptoms.

Drinking small amounts more often may be the most manageable option if you find it difficult to consume larger amounts at a time.

It’s a good idea to avoid drinks that contain caffeine, as well as alcohol and some sodas, as these can cause dehydration. While drinks other than water may help with hydration, a 2022 study showed that people who preferred water over juices and other drinks had a reduced risk of active IBD symptoms.

Eating foods with high water content, such as cucumber and watermelon, can also contribute to proper hydration.

If you find it difficult to eat a full breakfast, lunch, and dinner, you can try eating smaller portions, such as appetizer-sized dishes or half portions.

Alternatively, having small, nutrient-dense snacks at regular intervals may be a good way to keep your energy levels up throughout the day.

Try to include foods such as fresh fruits and vegetables, complex carbohydrates (oats, brown rice, lentils, beans), monounsaturated fats (avocado, nuts, seeds), and lean proteins in your meals or snacks.

If you’re having trouble meeting your nutritional needs while living with Crohn’s disease, a registered dietitian who specializes in IBD may be able to help.

  • screen for and address malnutrition
  • check for and manage nutrient deficiencies
  • recommend specific diets
  • introduce you to more varied foods
  • help you manage IBD symptoms
  • answer IBD-specific questions on nutrition
  • help you improve your relationship with food, if necessary

A primary care physician or gastroenterologist can help you find a registered dietitian.

If you have Crohn’s disease, talking with your healthcare team about your nutritional needs is essential to ensure that you get the right support.

Adjusting the size and timing of your meals, prioritizing nutrient-rich foods, and staying hydrated can help you manage symptoms when Crohn’s disease is active.