Bone Abstracts

Objectives: Anorexia nervosa (AN) is a life-threatening eating disorder often associated with reduced bone mass. The aim of the present study was to investigate vitamin D status and the association with BMI, fat mass and bone mineral density (BMD) during a novel intensive nutrition therapy in young AN women.

Methods: Twenty-five female AN patients (20.1±2.3 years, BMI 15.5±0.9 kg/m²) admitted to a specialised inpatient eating disorder unit were included. 11 patients had vitamin D supplements daily before study entry. Patients underwent a novel nutritional therapy during 12 weeks with an extra high-energy diet from start, median 75 kcal/kg per day, which gradually decreased to 54 kcal/kg per day over the study period. The diet contained an average of 15 μg per day vitamin D and 2120 mg per day calcium. Serum 25-hydroxyvitamin D (25 (OH) D), calcium, phosphate and parathyroid hormone (PTH) were measured. BMD and body composition were assessed by dual-energy x-ray absorptiometry (DXA) (Lunar Prodigy).

Results: 22 patients completed the 12-week treatment period, and the mean weight gain was 9.9 kg and the mean BMI increased to 19.0±0.9 kg/m², P<0.0001. One patient was vitamin D deficient (<25 nmol/l) and three patients had vitamin D levels <50 nmol/l at baseline. The median serum 25(OH) D was 84 nmol/l at baseline, which decreased to 76 nmol/l after 12 weeks (P=0.033). PTH increased from median 2.3–3.2 pmol/l (P<0.0001), but serum calcium and phosphate remained unchanged. Fat mass increased from median 12.4–26.7%. We found no significant associations between 25(OH) D and BMI, fat mass or total body BMD.

Conclusion: On a positive note, only one out of 25 patients was vitamin D deficient at baseline. The adequate vitamin D levels before study entry is likely caused by the widespread use of dietary supplements. The reduction in vitamin D levels during the study, despite an adequate intake, could be explained by low sunlight exposure during the treatment period and possibly due to an increased storage of vitamin D related to the increase in fat mass since vitamin D is sequestered in adipose tissue.

Disclosure: The authors declared no competing interests.