Understanding the Biological Evidence and Emerging Research Gaps in Nutrition That Impact the Health of School-Aged Children-a Report from the "Biomarkers of Nutrition for Development: Knowledge Indicating Dietary Sufficiency (BOND-KIDS)" Project Working Group 1.

The biology of nutrition is essential and inextricably involved in all aspects of human growth and development. Nutritional status is governed by an ecology consisting of internal (biology, genetics, metabolism, health status, developmental stage, and nutrient intake) and external (home, community, school, and physical environment) inputs. The application of an ecological perspective considers internal and external components that may influence the effect of nutrition on growth and development. These interactions will differ across various stages of human development. The importance of diet and nutritional status and health during the "first 1000 d," which is inclusive of pregnancy through 2 y of postnatal life, is well recognized. However, significant gaps exist in our understanding of the importance of nutrition during the "next 7000 d" through adolescence (2-21 y). The community expends substantial resources to ensure nutritional adequacy during this critical developmental period, but not on improved precision of assessment of the need for or impact of these efforts. The "Biomarkers of Nutrition for Development: Knowledge Indicating Dietary Sufficiency (BOND-KIDS)" Project applied an ecological approach to understand both the need for, and impact of, programs and interventions intended to address nutrition in school-aged children. This paper summarizes the findings of Working Group 1 of the BOND-KIDS Project, which focuses on the biological evidence underlying nutritional needs and responses to interventions. Specifically, based on a review of the role of nutrition in the development of key functional systems (the musculoskeletal system, brain, metabolic processes, and immune system in school-aged children), we examined the importance of nutrition and physical activity for body size and composition, bone health, neurobehavioral function, and risk of noncommunicable diseases both in childhood and in later life. This work provides the biological underpinning upon which the other 3 BOND-KIDS Working Groups built their reports.