Summary: Low calcium intake hampers bone mineral acquisition in adolescent girls. This study explores dietary calcium sources and nutrients possibly associated with vertebral mass. Milk intake is not influenced by genetic variants of the lactase gene and is positively associated with serum IGF-1 and with lumbar vertebrae mineral content and density.
Introduction: Low calcium intake hampers bone mineral acquisition during adolescence. We identified calcium sources and nutrients possibly associated with lumbar bone mineralization and calcium metabolism in adolescent girls and evaluated the possible influence of a genetic polymorphic trait associated with adult-type hypolactasia.
Methods: Lumbar bone mineral content (BMC), bone mineral density (BMD), and area, circulating IGF-1, markers of bone metabolism, and -13910 LCT (lactase gene) polymorphism; and intakes of milk, dairy products, calcium, phosphorus, magnesium, proteins, and energy were evaluated in 192 healthy adolescent girls.
Results: After menarche, BMC, BMD, serum IGF-1, and serum PTH were tightly associated with milk consumption, but not with other calcium sources. All four parameters were also associated with phosphorus, magnesium, protein, and energy from milk, but not from other sources. Girls with milk intakes below 55 mL/day have significantly lower BMD, BMC, and IGF-1 and higher PTH compared to girls consuming over 260 mL/day. Neither BMC, BMD, calcium intakes, nor milk consumption were associated with -13910 LCT polymorphism.
Conclusions: Milk consumption, preferably to other calcium sources, is associated with lumbar BMC and BMD in postmenarcheal girls. Aside from being a major source of calcium, milk provides phosphates, magnesium, proteins, and as yet unidentified nutrients likely to favor bone health.