Too Much Vitamin D May be a Factor

It is commonly understood that low levels of calcium and vitamin D can lead to a lower bone mineral density (BMD). However, according to a recent report in the medical journal Gut, this does not hold true for a sub-set of Crohn’s patients. It seems that these patients have a low BMD, but have an excessively high level of vitamin D in their blood.

A team of researchers, led by Dr. M. T. Abreu of the Inflammatory Bowel Disease Centre at Cedars-Sinai Medical Centre in Los Angeles, examined 167 individuals with Crohn’s disease and ulcerative colitis, two forms of inflammatory bowel disease (IBD), measuring their levels of vitamin D metabolites, and comparing these to available BMD results.

Low BMD, and the resulting increased bone fracture risk, is a fairly common complication of IBD. Some studies have found rates of osteopenia, a reduced bone mass condition, to be as high as 59%, and osteoporosis rates of 41% among IBD sufferers. While it has generally been accepted that steroid therapy is the principal cause of bone loss in Crohn’s disease (CD) patients, a number of other causative factors have been suggested including, malabsorp-tion of nutrients; intestinal resections; smoking; inflammatory cytokines; and vitamin D deficiency.

While a vitamin D deficiency can be detrimental to the bones, under certain circumstances, ‘inappropriately high’ levels of vitamin D in the blood can also lead to lowered bone mineral density.

These researchers believe that, “High vitamin D levels are most likely a manifestation of the underlying gut inflammation.” And that, when inflammation is reduced, the problematically high levels of vitamin D will also decrease.

The results of this study showed that patients with Crohn’s disease had a lower BDM than those with ulcerative colitis and that levels of hormonally active vitamin D were significantly elevated in the CD patients (42%) compared with ulcerative colitis patients (7%). The data demonstrated that “calcium excretion was significantly higher in CD patients”, and the researchers concluded that together with steroid treatment, high levels of active vitamin D are “an important risk factor for the development of osteoporosis in patients with CD”.

While a standard treatment practice for IBD patients is to supplement their diets with calcium and vitamin D, these researchers suggest that, “Based on our work, measuring vitamin D metabolites is important in identifying those patients with an additional risk factor for developing low BMD.”

The researchers suggest that treatment of the underlying inflammation, “may improve metabolic bone disease.”

If you are concerned that this may be a factor for you, ask your doctor about having the vitamin D level in your blood checked, especially if you are taking supplements. It seems that better management of the inflammation may bring the excessively high vitamin D levels down.

First published in the Inside Tract® newsletter issue 146 – November/December 2004
M T Abreu, V Kantorovich, E A Vasiliauskas, et al. Measurement of vitamin D levels in inflammatory bowel disease patients reveals a subset of Crohn’s disease patients with elevated 1,25-dihydroxyvitamin D and low bone mineral density. Gut. 2004;53(8):1129-1136