Contrary to expectations, people with the inflammatory bowel condition Crohn’s disease are likely to have excessive levels of the active form of vitamin D in their blood, researchers have found. This is associated with low bone mineral density, they report.

Dr. Maria T. Abreu from the Inflammatory Bowel Disease Center at Cedars-Sinai Medical Center in Los Angeles led the study. She told Reuters Health, “Most doctors think that Crohn’s patients automatically have decreased vitamin D levels and encourage supplementation with vitamin D. We would like to urge doctors to check vitamin D levels before making that recommendation.”

As Abreu’s team explains in the medical journal Gut, under certain circumstances too much active vitamin D can actually contribute to the breakdown of bone, leading to osteoporosis.

The researchers found “inappropriately high” blood levels of the active form of vitamin D in 42 percent of the 138 people they studied with Crohn’s disease. This was true of only 7 percent of 29 patients with ulcerative colitis, another type of inflammatory bowel disease.

Also, the higher the blood levels of active vitamin D in Crohn’s patients, the lower was their bone density - regardless of whether they were treated with steroids - the investigators found.

“We believe that high vitamin D levels are most likely a manifestation of the underlying gut inflammation,” Abreu said.

A high vitamin D level is “an additional risk factor predisposing to development of osteoporosis” for some Crohn’s disease patients, the team concludes. Treatment of the underlying inflammation, “may improve metabolic bone disease.”

SOURCE: Gut, August 2004.