Is it reasonable to ignore vitamin D status for musculoskeletal health?

Effects of Vitamin D3 Fortified Low-fat Dairy Products on Bone Density Measures in Adults with Abdominal Obesity: A Randomized Clinical Trial

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.

Vitamin D in Osteosarcopenic Obesity

Osteosarcopenic obesity is a unique clinical condition where low bone and muscle mass coexist in individuals with obesity. Alterations in adipose tissue, skeletal muscle and bone are strictly interconnected, and vitamin D plays key roles in several metabolic pathways that are involved in maintaining musculoskeletal health and glucose homeostasis. We reviewed the available literature on mechanisms underlying osteosarcopenic obesity, with a focus on the role of vitamin D in the pathogenesis and treatment of the condition. We found that, although evidence from large observational studies and pre-clinical experiments strongly supports a role of vitamin D deficiency in the pathogenesis of osteosarcopenic obesity, the common belief that vitamin D improves musculoskeletal health lacks solid clinical evidence, as trials specifically aimed at assessing the effects of vitamin D supplementation in patients with osteosarcopenic obesity are not available, and trials that investigated the role of vitamin D on muscle and bone health in other patient populations either showed no or even detrimental effects. We conclude that large observational and interventional studies including individuals with osteosarcopenic obesity representative of different sex, age and race are needed to better define the role of vitamin D in the pathogenesis and treatment of this condition.