Having an intestinal disorder that affects the absorption of nutrients in your small intestine - such as Crohn's disease and celiac disease - puts you at risk of anemia.

But we also have the highest rates of inflammatory bowel disease, or ibd-when the immune system mistakenly attacks intestinal cells and friendly gut bacteria.

He wondered if the absence of intestinal parasites was causing Crohn's disease — if our bodies missed their worms' parasitic presence so badly they were increasingly attacking themselves.