Vitamin D recommendations for Canadian elderly: an evaluation of adequacy of current clinical practices for nutrition and skeletal health
Bibliographic record
Abstract
Vitamin D is a key nutrient in bone health. Seniors living in long-term care (LTC) facilities in Canada face a higher risk of deficiency as menus are often deficient in vitamin D and sunlight exposure is limited. Vitamin D status can be measured by serum 25-hydroxyvitamin D concentration (25(OH)D). Many seniors in Canada have low vitamin D status. The global objectives of this thesis were to: (1) assess vitamin D intake and association with biomarkers of bone health in older men in a LTC facility of the Montréal region (latitude: 46°N); (2) assess the impact of an 8-wk supplementation regimen of 2000 IU/d of vitamin D3 on 25(OH)D and markers of bone metabolism; (3) determine how much vitamin D3 is needed to sustain vitamin D status using vitamin D3 fortified foods. Study 1 tested the first objective. Food intake and sunlight exposure of 30 men were measured for 1 year. Food intake was measured with 3-d weighed food records. Biomarkers of bone metabolism (serum 25(OH)D, parathyroid hormone (PTH), calcium, phosphate, osteocalcin (OC) and C-terminal telopeptide of collagen type 1 (CTX)) were tested. Descriptive statistics and change over time were analyzed. A mean of 280±120 IU/d of vitamin D was consumed. In the winter months, over 30% of participants were below the 50 nmol/L of serum 25(OH)D concentrations suggested by the Institute of Medicine. Serum 25(OH)D rose by summer and declined in the fall. PTH was lower in the spring. CTX and OC were unchanged. Study 2 tested the second and third objectives with a 2 phase trial. First, a Loading Phase used 2000 IU/d vitamin D3 tablet supplementation (October to December; 8 weeks; RCT –8). A randomized controlled trial (RCT) followed (January to July; 24 weeks; RCT0–RCT24). Participants were randomized to 3 groups: Placebo group, 500 IU/d group or 1000 IU/d of vitamin D3. Vitamin D3 was given as bite size fortified foods. The Placebo group received identical unfortified foods. Biomarkers of bone metabolism (serum 25(OH)D, PTH, calcium, phosphate, OC, CTX, osteoprotegerin and RANKL) were measured at RCT –8, RCT0 and RCT24. At RCT0 and RCT24, peripheral dual-energy X-ray absorptiometry, peripheral quantitative computed tomography (pQCT) and handgrip strength were measured on the non-dominant forearm. Differences were tested using mixed model ANOVA for fixed effects of time and group and interactions of time by group.At RCT –8, mean vitamin D intakes and mean 25(OH)D concentrations were 494±380 IU/d and 56.9±13.3 nmol/L for the Placebo group, 769±526 IU/d and 54.6±15.0 nmol/L for the 500 IU/d group and 562±383 IU/d and 56.9±9.7 nmol/L for the 1000 IU/d group. The 2000 IU/d of vitamin D3 raised serum 25(OH)D to a mean value of 65 nmol/L in all groups. During the RCT, the 500 IU/d and 1000 IU/d groups maintained serum 25(OH)D above 65 nmol/L. In 8 weeks, the 25(OH)D concentration values of the Placebo group reverted back to the values of RCT –8. Biomarkers of bone metabolism were stable. The pQCT values declined over time in trabecular volumetric bone mineral density (vBMD) for the 500 IU/d group and in vBMD at the diaphysis for the 1000 IU/d group. Total bone area in the diaphysis improved and areal bone mineral density improved in the 1000 IU/d group. For all groups, muscle area declined over time and muscle density did not change. Handgrip strength was stable in the 1000 IU/d group. In conclusion, these studies suggest that vitamin D supplementation is needed to achieve and maintain healthy vitamin D status. The group getting 1000 IU/d of vitamin D3 improved cross-sectional bone area at 66% of the forearm diaphysis suggesting remodeling with incomplete mineralization. As handgrip strength was improved in the 1000 IU/d group, vitamin D3 could positively influence muscle strength and, possibly reduce the risk of falls and fractures. More research is needed to understand the relationships among vitamin D and musculoskeletal health in older men living in LTC.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.004 | 0.012 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.003 | 0.005 |
| Science and technology studies | 0.003 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".