Vitamin D Intervention and Bone: A Randomized Clinical Trial in Fair- and Dark-skinned Children at Northern Latitudes

Area of Science:

• Pediatrics
• Nutritional Science
• Dermatology

Background:

• Vitamin D status is crucial for bone health, particularly in regions with limited sunlight exposure.
• Skin pigmentation affects vitamin D synthesis, potentially leading to disparities in status and bone health outcomes.
• Understanding these differences is vital for targeted public health interventions.

Purpose of the Study:

• To assess vitamin D status in fair- and dark-skinned children in Sweden.
• To investigate the impact of vitamin D supplementation on bone mineral density (BMD) and bone mineral content (BMC).
• To evaluate potential differences in response based on skin pigmentation.

Main Methods:

• A prospective, double-blinded, randomized intervention study involving 206 children aged 5-7 years.
• Children received daily vitamin D supplements (25 μg, 10 μg) or placebo over 3 winter months.
• BMD and BMC were measured at baseline and follow-up; vitamin D intake, serum 25-hydroxyvitamin D (S-25[OH]D), and related parameters were analyzed.

Main Results:

• Dark-skinned children had higher baseline and follow-up BMD and BMC despite lower S-25(OH)D levels.
• Vitamin D intervention did not significantly alter general BMD or BMC between groups.
• Femoral neck bone mineral content (FN-BMC) increased more in dark-skinned children receiving 25 μg or 10 μg vitamin D compared to placebo.

Conclusions:

• Higher BMD and BMC persist in dark-skinned children, irrespective of lower vitamin D status.
• While general BMD/BMC responses to vitamin D intervention were not significant, increased FN-BMC in dark-skinned children suggests a potential localized benefit.
• Findings indicate a complex interplay between skin pigmentation, vitamin D status, and bone health, warranting further investigation into targeted supplementation strategies.