Adverse Interaction of Low-Calcium Diet and Low 25(OH)D Levels on Lumbar Spine Mineralization in Late-Pubertal Girls

No consensus has been reached on the serum 25 hydroxyvitamin D [25(OH)D] levels required to ensure optimal bone health around menarche We searched for a possible interaction of 25(OH)D levels and calcium intake on lumbar spine mineralization and on biologic features of bone metabolism in healthy late pubertal girls Lumbar spine parameters (ie area mineral content and density) and calcium intake were evaluated in 211 healthy white adolescent girls at pubertal stages IV-V (11 to 169 years) together with biologic markers of calcium and bone metabolism and with International External Quality Assessment Scheme for Vitamin D Metabolite (DEQAS)-validated serum 25(OH)D levels A high prevalence of 25(OH)D levels <= 30 nmol/L (41%) <= 40 nmol/L (61%) and <= 50 nmol/L (70%) was found during winter-spring Parathyroid hormone (PTH) levels were inversely associated with 25(OH)D levels (p = 0021) In contrast, lumbar spine mineral content and density were not associated with 25(OH)D excepted when calcium intake was below 600 mg/day (p = 0081) Girls with such low calcium intake and 25(OH)D levels of 40 nmol/L or less (9% of the cohort) had a 04 to 07 SD lower mean areal bone mineral density Z-score than girls with higher calcium intake and/or higher 25(OH)D status The adverse association between lumbar spine mineralization and combined calcium deficiency-low 25(OH)D levels remained significant in the 91 girls who could be followed over 4 years after their initial evaluation We conclude that low 25(OH)D levels (<= 40 nmol/L) are observed frequently during winter-spring in late pubertal European girls which may exacerbate the negative impact of calcium deficiency on lumbar spine mineralization (C) 2010 American Society for Bone and Mineral Research