Postmenopausal women did not experience beneficial effects on bone mineral density, muscle function, muscle mass or falls with high-dose vitamin D, according to a study published in JAMA Internal Medicine.
Some experts support the view that optimal serum 25-hydroxyvitamin D levels are ≥30ng/mL whereas the Institute of Medicine recommends levels of ≥20ng/mL. Researchers from the University of Wisconsin School of Medicine compared the effect of high-dose cholecalciferol, low-dose cholecalciferol, and placebo at one year changes on total fractional calcium absorption (TFCA), bone mineral density, sit-to-stand tests, and muscle mass in 230 postmenopausal women (age ≤75) with vitamin D insufficiency. The high-dose vitamin D regimen achieved and kept 25-hydroxyvitamin D levels at ≥30ng/mL.
Study results showed that calcium absorption increased 1% in the high-dose group but decreased 2% in the low-dose group and 1.3% in the placebo group. The increase was not considered beneficial because there were no differences found between the three groups regarding changes in spine, average total-hip, average femoral neck or total-body bone mineral density, trabecular bone score, muscle mass or sit-to-stand tests. In addition, there were no differences between the groups for number of falls or fallers, physical activity or functional status.
The authors noted that the study is limited in its ability to identify different responses to cholecalciferol based on race. Since participants only took cholecalciferol for one year, longer exposure to high-dose cholecalciferol may lead to greater effects on bone mineral density, they added.
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