Lack of relationship of calcium and vitamin D intake to bone mineral density in premenopausal women with inflammatory bowel disease

Abstract

Objectives: Low bone mineral density has been widely reported in patients with inflammatory bowel disease (IBD). The exact etiology of this condition is not completely understood but is suggested to be multifactorial, possibly including low calcium and vitamin D intake. The objective of this study was to assess calcium and vitamin D intake and its relationship to bone mineral density (BMD) in premenopausal women with IBD.

Methods: A total of 70 premenopausal women with IBD (mean age 33.3 yr, range 18-44 yr) drawn from the population-based University of Manitoba IBD Research Registry participated in the study. Calcium and vitamin D intake was determined using a semiquantitative food frequency questionnaire and compared to the Dietary Reference Intake values for adequacy. BMD of total body, lumbar spine, femoral neck, and hip was measured using dual-energy x-ray absorptiometry.

Results: Of the 70 subjects, 66 successfully completed the study. Inadequate calcium intake (<1000 mg/day) was found in 69.7% of the subjects. This low intake group had a mean calcium intake of 508 mg/day. Inadequate vitamin D intake (<200 IU/day) was found in 53% of the subjects with a mean vitamin D intake of 76 IU/day in this group. Calcium and vitamin D intake correlated with each other with R2=0.57, p<0.00001. Daily calcium intake was not significantly different for subjects with T scores greater than -1 (901 mg) and for subjects with T scores less than -1 (875 mg, p=0.44). Daily vitamin D intake was not significantly different for subjects with T scores greater than -1 (297 IU) compared with subjects with T scores less than -1 was (267 IU, p=0.33). Comparing subjects with T scores greater than -1 to those with T score less than -1, there was no difference in the percentage of subjects ingesting >1 g/day calcium (14/43 vs 8/23, p=0.86) or in those with vitamin D intake >200 IU/day (21/43 vs 9/23, p=0.45).

Conclusions: The results show that, on average, premenopausal women with IBD have less than the recommended intake for calcium and vitamin D. However, this does not seem to influence BMD. Calcium and vitamin D intake is not a predictor of bone status in premenopausal women with IBD.