This makes sense, since most nutritional absorption occurs in the small intestine.

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Aside from immediate symptoms, like abdominal pain and diarrhea, celiac disease can cause serious damage to the small intestine over time, leading to poor absorption of nutrients and vitamins.

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This may be due to surgery to your stomach or small intestine (such as gastric bypass surgery), abnormal bacterial growth in your small intestine, or an intestinal disease, such as Crohn's disease or celiac disease, that interferes with absorption of the vitamin.

CNN: Vitamin deficiency anemia