Seasonal vitamin D deficiency was prevalent and those affected had low bone mineral density. - GreenMedInfo Summary
Sun exposure behavior, seasonal vitamin D deficiency and relationship to bone health in adolescents.
J Clin Endocrinol Metab. 2016 May 26:jc20161559. Epub 2016 May 26. PMID: 27228370
Mark D Farrar
CONTEXT: Vitamin D is essential for bone health in adolescence, where there is rapid bone mineral content accrual. As cutaneous sun-exposure provides vitamin D, there is no recommended oral intake for UK adolescents.
OBJECTIVE: Assess seasonal vitamin D status and its contributors in white Caucasian adolescents, and examine bone health in those found deficient.
DESIGN: Prospective cohort study.
SETTING: Six schools in Greater Manchester, UK.
PARTICIPANTS: 131 adolescents, 12-15 years.
INTERVENTION(S): Seasonal assessment of circulating 25-hydroxyvitamin D (25OHD), personal sun-exposure and dietary vitamin D. Adolescents deficient (25OHD<10 ng/mL/25 nmol/L) in≥one season underwent dual-energy X-ray absorptiometry (lumbar spine, femoral neck), with bone mineral apparent density (BMAD) correction for size, and peripheral quantitative computed tomography (distal radius) for volumetric (v)BMD.
MAIN OUTCOME MEASURE: Serum 25OHD; BMD.
RESULTS: Mean 25OHD was highest in September: 24.1 (SD 6.9) ng/mL and lowest in January: 15.5 (5.9) ng/mL. Over the year, 16% were deficient in≥one season and 79% insufficient (25OHD<20 ng/mL/50 nmol/L) including 28% in September. Dietary vitamin D was low year-round while personal sun-exposure was seasonal and predominantly across the school week. Holidays accounted for 17% variation in peak 25OHD (p<0.001). Nineteen adolescents underwent bone assessment, which showed low femoral neck BMAD versus matched reference data (p=0.0002), 3 with Z≤ -2.0 distal radius trabecular vBMD.
CONCLUSIONS: Sun-exposure levels failed to provide adequate vitamin D,∼one-quarter adolescents insufficient even at summer-peak. Seasonal vitamin D deficiency was prevalent and those affected had low BMD. Recommendations on vitamin D acquisition are indicated in this age-group.