Production of normal amounts of blood depends in part on the body’s iron reserves, which can be depleted because of bleeding and malabsorption but supplemented with increased iron intake. Because inflammatory bowel disease (IBD) is associated with both bleeding and malabsorption, iron levels must be measured regularly and deficiencies treated when necessary.
How the Body Uses Iron
Iron is absorbed in the first part of the small intestine, called the duodenum. Hemoglobin (a protein in red blood cells) carries about 70% of the iron found in the body. Hemoglobin is vital to the body, as it supplies tissues and organs with oxygen. The body keeps a small reserve of iron (in the liver, bone marrow, spleen, and muscles), about 15% of its total iron content, in case iron levels start to get low. The remaining 15% of iron is used in proteins in various body tissues.
As the body's store of iron gets low (which can lead to a condition known as anemia) it begins to take more iron from food sources. When iron is at more normal levels, the body absorbs less iron from foods.
People With IBD Who May Develop Iron Deficiency
People with Crohn's disease and ulcerative colitis often experience some blood loss in their stool. The amount of blood varies widely from person to person. Bleeding is more common when the large intestine is involved rather than the small intestine.
Malabsorption also may contribute to a lack of iron. This is particularly true for those who have Crohn's disease of the small intestine, because the small intestine is where most vitamins and minerals are absorbed by the body.
What to Do About Iron Deficiency
When iron levels are low, a diet high in iron may help correct the problem. Iron is found in two forms: heme, which is found in meat, and non-heme, which is found in plants. The body more readily absorbs heme iron, which is why iron deficiency is more common among vegetarians and vegans. Consuming non-heme iron sources along with foods that have high levels of vitamin C will help in absorbing non-heme iron. Foods that are high in iron include:
- Beef (chuck and tenderloin) (heme)
- Chicken liver (heme)
- Clams (heme)
- Oysters (heme)
- Turkey (heme)
- Grits (non-heme)
- Lentils (non-heme)
- Soybeans (non-heme)
For people with IBD, iron supplements may be necessary. Supplements are usually given in a dose of 325 mg taken from one to three times per day. Iron supplements should be used with care because they can cause cramping and constipation and cause stool to turn black. Taking iron supplements with food may lessen these side effects. Iron supplements come in either ferrous or ferric form. The body more readily absorbs the ferrous form.
Too much iron can be toxic, especially to children. A physician should closely supervise anyone with IBD who needs iron supplementation.
Office of Dietary Supplements, National Institutes of Health. "Dietary Supplement Fact Sheet: Iron." National Institutes of Health 24 Aug 2007. 18 May 2014.
Gomollón F, Gisbert JP. "Anemia and inflammatory bowel diseases." World J Gastroenterol 2009 Oct 7;15: 4659-4665. 18 May 2014.