During a Crohn’s disease flare-up, you may not have much of an appetite, because the flare can create inflammation in the digestive tract that makes it hard to eat.?Moreover, if you’ve had surgery to remove your colon or part of your small intestine, you may have more trouble absorbing certain nutrients.?You might also adhere to certain dietary restrictions to mitigate flare-ups.
These things can lead to serious deficiencies in some essential vitamins and minerals you need to stay healthy, including iron, calcium, vitamin B12, folic acid, and vitamin D. Here’s why these vitamins and minerals are so important for maintaining your health — and what you can do about a deficiency.
1. Iron Deficiency Can Leave You Tired and Dizzy
The underlying inflammation from Crohn’s disease can make it hard to absorb iron. More specifically, the liver produces a protein called hepcidin that can prevent the body from absorbing iron, and hepcidin levels may be high when inflammation — a hallmark of Crohn’s — is present.
An iron deficiency can then lead to anemia, a condition in which you don’t have enough red blood cells to carry sufficient oxygen to tissues.?“When patients have a flare-up of Crohn’s, they can have anemia,” says William Sandborn, MD, the chief of gastroenterology and the director of the inflammatory bowel disease center at the University of California in San Diego. Anemia can result in fatigue and shortness of breath when you exercise.
People with Crohn’s can also become deficient in iron by losing blood through bowel movements. Blood loss may not always be obvious, so it might require a stool test, Dr. Sandborn adds.
An iron-rich diet full of leafy greens (such as spinach), beans, lentils, peas, and meats will help, but it’s important to be monitored by a physician to see if it’s necessary to take an iron supplement in addition.
“In some cases, your iron can’t be absorbed from the small intestine, even if you take supplements, so we sometimes have to give iron as an intravenous infusion,” says Sandborn.
When iron deficiency is chronic, your diet may not be able to keep up, so it will require taking a supplement.
2. Medication and Flare-Ups Can Affect Calcium Absorption
People with Crohn’s disease may run low on calcium. One reason may be because many individuals with Crohn's disease are also likely to be lactose intolerant.?(If you’re lactose intolerant, you may have to avoid dairy, which is rich in calcium.) Also, some drugs used to treat Crohn’s disease, such as corticosteroids, can reduce calcium absorption.
A flare-up of Crohn’s can also cause lower levels of albumin — a protein made by the liver that binds to calcium — and lead to lower calcium levels.
Calcium is essential for making and sustaining bone, as well as keeping the heart and muscles working properly.?This means people with Crohn’s can be at risk of osteoporosis, bone fractures, weak muscles, and irregular heart rhythms.
“The trick is to not restrict your diet too much or avoid dairy products,” says Sandborn. “But, if dairy is exacerbating your Crohn’s symptoms, then over-the-counter calcium supplements are good.”
Biologics can be used to treat flare-ups and ease the inflammation associated with Crohn’s disease.
3. Resection Surgery Can Make It Hard to Absorb Vitamin B12
Vitamin B12 is the most common deficiency among people with Crohn’s, says Sandborn. Severe cases can lead to anemia as well as nerve damage, resulting in tingling or numbness in the fingers and toes.
Vitamin B12 is absorbed in the ileum, the lower portion of the small intestine that leads to the large intestine. If the end portion of the ileum has been inflamed, scarred, or surgically removed, the vitamin does not properly absorb in the body, which results in a deficiency.
Like iron, this vitamin is important for maintaining a sufficient level of red blood cells.
“Your doctor needs to periodically monitor vitamin B12 in your blood,” says Sandborn. “Patients will typically need lifetime replacement if they’ve had corrective surgery for Crohn’s.”
B12 is mostly found in animal products, such as eggs, milk, fish, poultry, and other meats. Fortified breakfast cereals can also provide sufficient vitamin B12.?But if the end portion of the ileum has been removed, Sandborn says, the vitamin will have to be given as a shot (typically once a month) or an intranasal formulation, such as a nasal spray.
4. Lack of Folic Acid in the Diet Causes Folate-Deficiency Anemia
Folate deficiency is less common among people with Crohn’s and occurs most often in those taking methotrexate or sulfasalazine. When inflammatory bowel disease specialists prescribe either of these drugs, they often also prescribe a folic acid supplement to compensate for folate loss.
Folate is a B complex vitamin, found in beans, leafy green vegetables, asparagus, rice, and fruits. It is key to producing red blood cells for protein synthesis and skin health.
Pregnant women, including women with Crohn’s, are advised to take folic acid to prevent birth defects.
5. Insufficient Vitamin D Can Trigger Flare-Ups
Vitamin D deficiency is very common in people with Crohn’s. “Just having Crohn’s seems to be an additional risk factor for vitamin D deficiency, but it’s not well understood why,” says Sandborn.
The two main ways to get vitamin D are exposing your skin to sunlight and taking a supplement. (Vitamin D is also found in certain foods, including eggs, fortified milk, and fatty fish,?but not in levels high enough for optimal health.)
Vitamin D is essential for bone health, and a review found that flares create a high risk of vitamin D deficiency, while well-maintained vitamin D levels reduce the risk of flares.
Talk to your doctor if you’re concerned about vitamin D deficiency, so they can run tests and determine your current levels.
“There is still a lot of research to be done in Crohn’s disease,” Sandborn says. “[Following a] restricted diet is a common practice, but I think this does a lot of harm, because there’s not enough science behind some of these restrictions. Many patients don’t need so many restrictions. Eating a healthy, well-balanced diet is probably the best thing you can do.”
The Takeaway
Dietary restrictions, inflammation, blood loss, drug side effects, and surgery can all lead to low levels of essential vitamins and minerals, including iron, calcium, vitamin B12, folic acid, and vitamin D in people with Crohn’s disease.
When left unaddressed, certain vitamin and mineral deficiencies can result in serious health consequences such as anemia, osteoporosis, and nerve damage.
Talk to your doctor about the need to test for and monitor potential vitamin and mineral deficiencies.
Ira Daniel Breite, MD, is a board-certified internist and gastroenterologist. He is an associate professor at the Icahn School of Medicine at Mount Sinai, where he?also sees patients and helps run an ambulatory surgery center.
Dr. Breite divides his time between technical procedures, reading about new topics, and helping patients with some of their most intimate problems. He finds the deepest fulfillment in the long-term relationships he develops and is thrilled when a patient with irritable bowel syndrome or inflammatory bowel disease improves on the regimen he worked with them to create.
Breite went to Albert Einstein College of Medicine for medical school, followed by a residency at NYU and Bellevue Hospital and a gastroenterology fellowship at Memorial Sloan Kettering Cancer Center. Working in city hospitals helped him become resourceful and taught him how to interact with people from different backgrounds.
Padma has been an independent journalist and writer for 17 years and has written for a variety of media outlets in the United Kingdom and the United States. She started out as a business reporter, then covered the biotech and clean-tech industries before settling on science writing, with a focus on health, environment, and agriculture. She enjoys writing about health from the medical, policy, and research angles, and pursuing meaningful stories that make an impact. Within the health beat, she focuses on public health issues, substance abuse, the opioid crisis, cancer research, communications, disparities, and mental health issues. She lives in San Diego.
In addition to writing for Everyday Health, she has written for various publications and websites, such as California Health Care Foundation, Capital Press, Dermatology Times, MedShadow, New Scientist, Science News for Students, TakePart, Water Deeply.
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
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