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Diet and nutrition

What would explain a craving to eat chalk?

Ask the doctor

By , Chief Medical Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing
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A pile of pieces of chalk in assorted colors and different lengths rests on a white background.

Q. Why would someone crave and eat chalk? I have been eating large amounts of chalk (sidewalk chalk) since my pregnancy. My baby is now four months old and I am still craving it.

A. The craving for chalk is most likely related to iron deficiency. The general medical term for craving certain items is pica. With iron deficiency, you can have cravings other than chalk, including ice, paper, coffee grains, and seeds. It's not known why iron deficiency causes pica. But once a person has replenished his or her iron stores, the craving disappears.

Women, especially pregnant women, commonly have iron deficiency anemia. So this problem is seen most often in women.

The usual treatment for iron deficiency is iron sulfate. But iron can be constipating. So I recommend that people start with one tablet per day. Each dose is 325 milligrams. If possible, try to increase it to one tablet twice per day. Once your iron levels are restored, you might only need one pill every other day.

In addition to constipation, some people find that iron sulfate irritates their stomach, causing upper abdominal discomfort. If that becomes a problem, you can switch to iron gluconate at the same doses. In general, less iron gets into the body with iron gluconate compared to iron sulfate, so it will take longer to build up your iron levels.

One more thing: you can expect very dark (even black) stools from iron.

Image: © Creative Images Lab/Getty Images

About the Author

photo of Howard E. LeWine, MD

Howard E. LeWine, MD, Chief Medical Editor, Harvard Health Publishing; Editorial Advisory Board Member, Harvard Health Publishing

Dr. Howard LeWine is a practicing internist at Brigham and Women’s Hospital in Boston, Chief Medical Editor at Harvard Health Publishing, and editor in chief of Harvard Men’s Health Watch. See Full Bio
View all posts by Howard E. LeWine, MD
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