Study conducted by researchers from Boston University have shown that vitamin D absorption is reduced in patients with Crohn's disease (CD). This reduced absorption may be the cause for increased risk of vitamin D deficiency in Crohn's disease patients.
The findings have shown that the only way to determine absorption efficiency is to perform a vitamin D bio-availability test.
Ten normal subjects (50 percent female) and 37 CD patients with quiescent disease (51 percent female) were included in this study. A vitamin D bio-availability test was performed on all subjects.
The researchers found that CD patients had on average a 30 percent decrease in their ability to absorb vitamin D2 when compared to normal subjects.
According to the researchers, this study emphasized the important role of an oral vitamin D absorption test, which may be an excellent means to assess for the malabsorption of fat-soluble vitamin.
"We demonstrated that neither disease activity nor prior surgery or location of disease predicts the ability to absorb vitamin D," said lead author Francis Farraye, a professor of medicine at BUSM.
Senior author Michael Holick, added, "Since the ability to absorb vitamin D in CD patients is unpredictable, the only way to determine absorption efficiency is to perform a vitamin D bioavailability test. This test is convenient and its use may guide clinicians in administering the appropriate therapeutic dose of vitamin D for treating vitamin D deficiency in patients with CD."
Additionally, the researchers performed vitamin D absorption tests in four patients with ulcerative colitis (UC) and found a wide variability of vitamin D2 bio-availability in patients with UC as well as in 17 patients with CD, which was unexpected since vitamin D is absorbed in the small intestine and not in the colon.
The results, if confirmed by others may merit the development of a vitamin D assay by reference laboratories as a clinical test. "Our data support the use of an oral vitamin D absorption test in CD patients, especially in those patients who could not correct in the vitamin D deficiency by either dietary or pharmacologic means," added Farraye.
The findings appeared online in Inflammatory Bowel Diseases.