Through its intramural and extramural organizational units, the NICHD conducts and supports a broad range of research related to lactose intolerance and bone health. Brief descriptions of this research are included below.
To address the lack of solid, reliably collected reference data on bone density, the Pediatric Growth and Nutrition Branch (PGNB) initiated the Bone Mineral Density in Children Study (BMDCS), a population-based longitudinal, observational study of bone accretion in 2,000 healthy children and adolescents ranging from 5 years to 22 years in age. Collected data from the BMDCS provide BMD reference data for monitoring bone health in growing children. Likewise, the dual-energy X-ray absorptiometry data that the study generated enable researchers and health care providers to assess changes of other body-composition components during childhood, puberty, and adolescence.
To date, results of the BMDCS show that bone mineral accretion in childhood occurs at a slow and consistent pace, with a sharp increase associated with the rise in sex steroids during the pubertal growth spurt. After puberty, bone accretion continues gradually until peak bone mass is achieved in early adulthood. Interestingly, the data indicate that BMD continues to rise into early in the third decade, even though an individual reaches peak height several years earlier. BMDCS investigators also observed that boys continue to accrue BMD for several years longer than do girls. (PMID: 17311856)
Patterns of bone mineral accretion in childhood during the various stages of linear growth and sexual maturation suggest a separate heritable component distinct from body size as measured by height and weight. To further understand this process and to identify genetic variants associated with BMD and bone mineral accretion, a genome-wide association study (GWAS) is currently under way using BMDCS data. The investigators anticipate that the GWAS techniques will reveal genetic variants associated with bone mineral accretion and bone mineral status (for example, bone mineral content or BMD relative to age) and should indicate whether the effects of genetic variants differ in childhood and young adulthood.
In this project, PGNB-supported researchers are investigating the role of dietary calcium in skeletal calcium retention in Mexican American adolescents and will compare these results with those from previous studies of other racial groups to identify mechanisms responsible for racial differences in skeletal calcium retention. Collectively, the results of these studies will inform calcium intake requirements to optimize calcium retention during adolescence, which is a key nutritional strategy to build peak bone mass and reduce lifelong risk of osteoporosis.
The PGNB supports several school-based exercise interventions to test the hypothesis that weight-bearing physical activity is osteotrophic and will elicit positive adaptations in bone macro-architectural structure in children. An intervention of 560 elementary school girls in Arizona assessed the effects of weight-bearing physical activity on bone accrual and structure after 2 years of exercise intervention. The study showed that physical activity duration, frequency, and load were all independently associated with bone parameters in young girls and that increased physical activity duration, frequency, and load are all important osteogenic stimuli. (PMID: 20694457)
While a large percentage of children have low blood vitamin D levels, the significance of these low levels and the impact on health is unclear. Researchers funded by the PGNB are investigating the effects of varying doses of vitamin D supplementation over 12 weeks on blood vitamin D concentrations and other bone health indicators in early pubertal white and black children.
The NICHD is also involved with the following projects related to lactose intolerance research.
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