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.
Institute Activities and Advances
Bone Mineral Density in Children
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 bone mineral density (BMD) reference data for monitoring bone health in growing children. Likewise, the dual-energy X-ray absorptiometry (DXA) 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. (Source: Kalkwarf, H. J., et al. . Journal of Clinical Endocrinology & Metabolism. 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.
Calcium Metabolism in Mexican American Adolescents
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 Effects of Physical Activity on the Development of Healthy Bones
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. (Source: Farr, J. N., et al. . Osteoporosis International. PMID: 20694457)
Supplemental Vitamin D and Functional Outcomes in Early Adolescence
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.
Other Activities and Advances
The NICHD is also involved with the following projects related to lactose intolerance research.
- The NICHD plays an active role in the Federal Working Group on Bone Diseases, an interagency committee led by the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). The committee focuses on osteoporosis, Paget's disease, and other bone disorders. The group offers a forum for sharing information, learning from each other and from invited speakers, and facilitating the development, early in the planning stages, of collaborative research activities based on each agency's mission.
- To review the scientific evidence on lactose intolerance and its impact on bone and overall health, the NICHD along with the NIH Office of Medical Applications of Research, convened a 3-day NIH Consensus Development Conference: Lactose Intolerance and Health in February 2010. A panel of independent experts addressed the prevalence of lactose intolerance and how occurrence differs by race, ethnicity, and age; health outcomes of dairy exclusion diets; tolerable levels of lactose; and best practices for managing lactose intolerance. The panel also identified future research needs for understanding and managing lactose intolerance. For more information, read the Consensus Statement.
- The NICHD contributes to NIH Osteoporosis and Related Bone Diseases National Resource Center, which provides patients, health professionals, and the public with an important link to resources and information on metabolic bone diseases, including osteoporosis, Paget's disease of the bone, and osteogenesis imperfecta. More information about the National Resource Center is available at: http://www.niams.nih.gov/Health_Info/Bone/.
- The NICHD played a key role in the Surgeon General's Workshop on Osteoporosis and Bone Health in 2002. A report on the workshop is available at: http://www.ncbi.nlm.nih.gov/books/NBK44687/.