Higher milk requirements for bone mineral accrual in adolescent girls bearing specific Caucasian genotypes in the VDR promoter

Abstract

Low milk intakes hamper bone mineral acquisition during adolescence, especially in European girls. We hypothesized that ethnic-specific polymorphisms of the vitamin D receptor gene promoter (VDRp) influence this milk/bone association. We evaluated lumbar spine BMC and BMD, milk/dairy products and calcium intakes, markers of P-Ca metabolism, and VDRp polymorphisms at the Cdx-2 binding (rs11568820) and -1012 (rs4516035) loci in 117 healthy European peri- and postmenarcheal girls (14.9 ± 1.6 yr) during a 4-yr follow-up. Calcium intakes from milk, nonmilk dairy products, and nondairy products averaged 199, 243, and 443 mg/d at the initiation of the study. Results show no association between milk intakes and bone mass accrual in girls bearing an A/A genotype at the -1012 VDRp locus (30% of the cohort). In contrast, A/G or G/G girls had lower spine BMC (-13%, p = 0.031), BMD (-10%, p = 0.004), and BMD Z-score (-0.84 SD, p = 0.0003) when their milk intakes were <260 ml/d compared with genotype-matched girls with higher milk intakes and with girls with an A/A genotype. The negative impact of low milk intake persisted up to 19.0 ± 1.7 yr. These findings suggest that European girls bearing a -1012 A/G or G/G VDRp genotype should have higher milk/calcium intakes for optimal vertebral mass accrual during adolescence than girls bearing an A/A genotype, a genotype found in 30% of European and 98% of Asian and Sub-Saharan African populations. VDRp genotype diversity may contribute to the ethnic differences observed in milk requirements for bone health during adolescence. © 2009 American Society for Bone and Mineral Research.