Abstract
BACKGROUND: Bone disease-related fractures constitute a heavy burden on the healthcare systems and economy. Vitamin D is an important regulator of bone health and its deficiency is a global problem. This study aimed to evaluate the effect of the 1,500 IU nano-encapsulated vitamin D used for fortifying low-fat dairy products (milk and yogurt) on bone health parameters. METHODS: This parallel totally blinded, randomized controlled trial was part of the Ultraviolet Intake by Nutritional Approach study and conducted on 306 individuals with abdominal obesity. Individuals were randomly assigned to four groups, including fortified low-fat milk (1,500 IU nano-encapsulated vitamin D3 per 200 g/d), non-fortified low-fat milk, fortified low-fat yogurt (1,500 IU nano-encapsulated vitamin D3 per 150 g/d), and non-fortified low-fat yogurt, for 10 weeks between January and March 2019. Bone mineral density (BMD) and trabecular bone score (TBS) were measured at the baseline and end of the trial. Trabecular bone score and BMD were defined as primary and secondary outcomes. RESULTS: There were no significant differences in TBS and BMD between the intervention and control groups at the end of the trial (P>0.05). CONCLUSION: This trial demonstrated no significant effect of nano-encapsulated vitamin D fortified milk and yogurt on BMD and TBS. There remains a need for longer-term trials regarding bone health outcomes to establish optimal doses of fortification.