Crohn’s disease and ulcerative colitis are both inflammatory bowel diseases (IBD). They cause inflammation in the digestive tract that interferes with the body’s ability to break down and use food.

IBD increases the risk of iron deficiency anemia. An estimated 45 percent of people with IBD also have iron deficiency anemia.

Hemoglobin is a protein that makes up part of a red blood cell. Its job is to bring oxygen around the body. Iron is required to make hemoglobin. When you don’t have enough iron in your body, you can’t make hemoglobin and your red blood cell count goes down.

Anemia occurs when your level of red blood cells drops below a normal range and your hemoglobin level is less than 12 grams per deciliter. Anemia can cause you to feel tired, weak, and short of breath. It may also cause dizziness, headaches, or an irregular heartbeat.

There are several reasons people with Crohn’s disease and ulcerative colitis are more likely to have anemia:

  • It may be hard to get enough iron in your diet. You may not tolerate some food sources of iron, or your appetite may be low.
  • IBD causes inflammation in the digestive tract. This affects your body’s ability to absorb iron and other nutrients from your food.
  • Inflammation in active IBD causes ongoing blood loss from the digestive tract. Blood loss is considered the most significant cause of anemia in IBD.

Crohn’s disease can cause inflammation anywhere in the digestive tract. Most nutrient absorption happens in the small intestine. Active Crohn’s disease in the small intestine affects the body’s nutrient absorption sites.

The small intestine includes three parts: the duodenum, jejunum, and ileum. Most iron gets absorbed in the duodenum. Some iron is also absorbed in the jejunum and ileum.

If these areas are inflamed, iron can’t be absorbed normally. This can lead to anemia. About 70 percent of people with Crohn’s disease require surgery to remove affected areas in the digestive tract. Surgery can put the disease into remission to reduce future blood loss.

Active disease comes back within 5 years in 33 percent of people who have surgery for Crohn’s disease. This can cause anemia if iron levels drop again.

Ulcerative colitis can occur throughout the large intestine (colon) as well as the rectum. Blood loss from a colitis flare is a significant contributor to anemia.

Even if your symptoms are in remission, it’s still worth getting your iron levels checked. One small study suggested that more than half of people with ulcerative colitis in remission have anemia.

About a third of people with ulcerative colitis require surgery. The most common surgery removes the colon and rectum. This surgery is considered a cure because it removes the area that the disease affects.

Without ongoing inflammation and blood loss, it can be easier to maintain normal iron levels.

Low iron can affect your health in many ways. Some studies show it can affect your overall sense of well-being. If you’re admitted to the hospital for IBD, research suggests anemia is associated with a longer stay.

Signs and symptoms of anemia include:

  • pale skin
  • fatigue
  • difficulty concentrating
  • headaches
  • dizziness
  • shortness of breath

Some people don’t feel or show signs of low iron. It’s still a good idea to check for anemia.

It’s recommended that people with IBD have their iron levels checked every 6 to 12 months. You should get blood work every 3 months if you’re having an IBD flare.

There are several reasons why someone may have iron deficiency. The most likely causes for anemia in someone with Crohn’s disease or ulcerative colitis include:

  • Low iron intake. When you have a condition of the digestive tract, it may be hard to get enough nutrients in your diet. Some foods aren’t well tolerated or may be unappealing when you’re not feeling well.
  • Poor iron absorption. It’s hard for your body to absorb nutrients when your digestive tract is inflamed. Even if you’re getting enough iron in your diet, your body may not be able to use it.
  • Blood loss. During an IBD flare, the digestive tract becomes inflamed. This inflammation causes bleeding. Blood loss reduces levels of red blood cells and iron in the body.

Depending on your iron levels and stage of IBD, your doctor may suggest different treatments for anemia.

Iron-rich foods

Getting more iron in your diet may help if you’re in remission and can tolerate iron-rich foods. Good sources of iron include meat, chicken, fish, seafood, beans, soy, nuts, and seeds.

If your iron levels are very low, you may also need to supplement iron. Eating more iron during an IBD flare won’t help. Inflammation reduces the amount of iron your body can absorb.

Oral supplements

Oral iron supplements are only recommended if you’re in remission. Studies show iron supplements can worsen inflammation in the digestive tract. This makes Crohn’s disease and ulcerative colitis symptoms worse.

Iron supplements can cause digestive side effects, including cramping, nausea, diarrhea, and constipation, even if you’re in remission. Some iron supplements are better tolerated than others. Your doctor can recommend a type and dose that’s best for you.

Intravenous (IV) iron

Your doctor may recommend delivering iron right into your veins. An IV doesn’t involve the digestive tract, so it won’t cause the same side effects as oral supplements.

IV iron is also more effective than supplements at getting iron levels into a better range. Research suggests IV iron is the best way to improve anemia in someone with active IBD. IV iron may also be a good option if you’re in remission from Crohn’s disease or ulcerative colitis but your iron levels are very low.

Keeping in regular contact with your healthcare team is important. Your treatment plan can be adjusted as needed, depending on your symptoms and how you’re feeling.

You may want to schedule an earlier appointment with your doctor if:

  • you’re taking your medications as directed and still have Crohn’s disease or ulcerative colitis symptoms
  • there’s any change in your symptoms, especially if you’re bleeding more
  • you notice a decrease in your energy level or ability to focus
  • you just don’t feel quite right

Having Crohn’s disease or ulcerative colitis puts you at greater risk of iron deficiency anemia. Anemia can be caused by low iron intake, reduced iron absorption, and blood loss. Treating iron deficiency anemia can greatly improve how you feel.

If it’s been more than 6 months since you’ve had blood work to check your iron levels, ask your doctor about getting tested.