The Effects of Vitamin D Fortified Products on Bone B-omarkers: A Systematic Review and Meta-Analysis

Background: Vitamin D plays an essential role in the regulation of bone metabolism. The current meta-analysis aimed to assess the effectiveness of vitamin D fortification on special bone biomarkers. Methods: Five main databases (PubMed/Medline, ISI Web of Knowledge, Science Direct, Scopus, Cochrane Library as well as Science Direct, and Scopus) were considered for this systematic review, until Jan 2020. All randomized controlled trials were included to evaluate the probable relationship between consumption of vitamin D fortification products and bone biomarkers profile in this review. Results: Among serum bone biomarkers (osteocalcin and telopeptides of type-1 collagen) investigated, only the level of telopeptides of type-1 collagen significantly decreased after fortification of vitamin D in the intervention group. A significant increase in vitamin D was seen in those older than 18 yr old, while the increase in younger children was not statistically significant between intervention and control groups. Conclusion: Vitamin D fortification was not associated with a significant improvement in bone mass density (BMD), while it resulted in decreased PTH levels. Vitamin D fortified foods have some benefits on bone health due to increase in the level of vitamin D and IGF-1; and decreasing PTH and CTx levels.