Vitamin D Research Today is a free monthly online journal that collates and summarizes the latest research about Vitamin D, including details on sources, melanin, benefits, deficiency, supplements, calcium absorption.

Seasonality of vitamin D status and bone turnover in patients with Crohn's disease.

McCarthy D, Duggan P, O'Brien M, Kiely M, McCarthy J, Shanahan F, Cashman KD

Department of Food and Nutritional Sciences, University College, Cork, Ireland.

BACKGROUND: While winter-time vitamin D deficiency has been well-documented in Crohn's disease patients, less is known about vitamin D status during summertime and whether a seasonal variation exists in bone turnover. AIMS: To compare vitamin D status and bone turnover markers in Crohn's disease patients with age- and sex-matched controls during late-summer and late-winter. SUBJECTS: Crohn's disease patients (n = 44; mean age 36.9 years, currently in remission) and matched controls (n = 44) were recruited from Cork University Hospital and Cork City area, respectively. METHODS: Bloods were analysed for 25-hydroxyvitamin D, parathyroid hormone, bone-specific alkaline phosphatase, osteocalcin and urine analysed for N-telopeptides of type 1 collagen. RESULTS: Serum 25-hydroxyvitamin D concentrations were significantly (P < 0.003) lower in Crohn's disease patients than in control subjects during both seasons. In Crohn's disease patients, serum 25-hydroxyvitamin D concentrations were lower (P < 0.0001) whereas serum parathyroid hormone, osteocalcin and bone-specific alkaline phosphatase and urinary N-telopeptides of type 1 collagen levels were higher (P < 0.001) during late-winter than late-summer. CONCLUSION: There were notable seasonal variations in vitamin D status and bone turnover markers in Crohn's disease patients. The impact of winter decline in vitamin D status and increase in bone turnover on long-term risk of osteopenia/osteoporosis in Crohn's disease patients is unclear.

Published 27 April 2005 in Aliment Pharmacol Ther, 21(9): 1073-83.
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