The following case presentation is for questions 15 and 16:

A 55 year old woman with scleroderma has, in addition to complaints of dysphagia to solids

and liquids, a one year history of non-bloody diarrhea. She has additional symptoms of

abdominal gas and bloating. She has lost approximately 10 lbs. In evaluating her dysphagia

an upper gastrointestinal series with barium is performed and the radiologist gives more

barium to allow examination of the small intestine. The small intestinal portion of the test is

remarkable for several small bowel diverticula. You suspect her diarrheal symptoms are due

to small intestinal bacterial overgrowth syndrome.

What is the most likely pathophysiologic mechanism that explains why vitamin D is

malabsorbed in this patient?