| dc.description.abstract | Abstract Background: The low mechanical loading of bones among wheelchair users leads to an increased risk of osteoporotic fractures and associated complications related to low bone mineral density (BMD). Low bone mineral density can also be related to insufficient energy intake and suboptimal dietary intake of the micronutrient vitamin D and calcium. Vitamin D deficiency is common in this population. Objectives: The primary outcome was to investigate the associations between energy, vitamin D and calcium intake and BMD (Z-scores) of the lumbar spine, hip, and femoral neck among wheelchair users. The secondary outcome was to investigate the associations between dietary intakes of vitamin D and the corresponding blood level, as well as associations between dietary intake and blood bone markers including CTX-1, P1NP and bALP. The main hypothesis is that energy availability, vitamin D and/or calcium status among wheelchair users will be positively associated with BMD (Z-score) of the spine, hip and/or femoral neck. Methods: Dietary intake was assessed with 3 unannounced 24-hour dietary recalls within a 2-week period. Bone mineral density and body composition were measured by Dual-Energy X-ray Absorptiometry and S-vitamin D, S-PTH, S-CTX-1, S-P1NP and S-bALP by a fasted, venous blood sample. Differences between groups were tested with Mann Whitney U, and Pearson and Spearman correlation analyses were performed with a significance level α=0.05. Results: Both the median vitamin D and calcium intake were above the Nordic Nutrition Recommendations (NNR), 14.6 μg/day and 1021 mg/day, respectively, and the subjects presented sufficient energy intakes. However, suboptimal S-vitamin D levels were present in 3 of 4 wheelchair users and 83 % of the subjects presented a Z-score ≤ - 2.0 at lumbar spine, hip, or femoral neck. None of the EI parameters or vitamin D intake was significantly correlated with measurements of BMD, but the relationship between calcium intake and Z-score of the hip was significantly correlated (rsp=0.606, P=0.037). In addition, there was a significant correlation between S-vitamin D and the blood bone marker CTX-1. Conclusion: Despite an overall sufficient energy, vitamin D and calcium intake, low BMD were prevalent in this thesis, which might indicate that the lack of mechanical loading of bones is the main determinant for bone loss in this population. Further research is needed to determine whether the daily recommendations of vitamin D and calcium are adequate for this population and whether insufficient intakes and/or low energy availability further magnifies the impaired bone health among wheelchair users. | eng |