2007 Annual Report 1a.Objectives (from AD-416) Enhance the quality of life through establishing mineral intakes that support optimal bone health. Specifically, determine the amount of dietary calcium needed to maximize calcium retention and minimize bone resorption in postmenopausal women; determine the extent to which dietary protein, specific mineral elements (zinc, copper, magnesium, and boron) and prebiotics (inulin) interact with dietary calcium to affect bone metabolism. 1b.Approach (from AD-416) Studies will utilize human subjects and animal models. Human studies will use the Mobile Nutrition Research Laboratory, the in-house Community Studies Unit, and the Metabolic Research Unit to conduct epidemiological supplementation, fortification, and controlled feeding experiments, respectively. In each case, subjects will be fed diets containing marginal to high amounts of mineral elements to determine how specific minerals, and interactions among them, affect bone structure (as determined by light microscopy, biomechanical assessment, and densiotometry) and biomarkers [urinary deoxypyridinoline, hemoglobin A1c, and C-reactive protein]). When relevant, the modifying influence of selected hormonal (e.g., estrogen deficiency) or diet compositional (e.g., inulin) factors will be examined. 3.Progress Report None. 4.Accomplishments New Estimation of the Calcium Requirement for Men and Women: Calcium is an element that may be a risk factor for osteoporosis and current recommendations regarding the amount of calcium needed to support health and optimal biological function are based on sparse balance data. ARS scientists at Grand Forks, ND, established a new estimation of the average calcium requirement of healthy men and women by conducting secondary analyses of calcium balance data generated in 19 human controlled feeding studies at the Grand Forks Human Nutrition Research Center over the last three decades. The findings suggest a calcium requirement for healthy men and women (741 mg/d) that is lower than that estimated previously. This work will be very useful in setting the next Dietary Reference Intake for calcium. This accomplishment was conducted under National Program 107 Human Nutrition; goal 4 of IMPROVING THE NATION’S NUTRITION AND HEALTH; and part of performance standard 4.1.2 related to defining human requirements for known classes of nutrients. Bone Loss Caused by Calcium Deficiency During Adolescence Can be Restored by Subsequent Adequate Calcium Intake: Because women are at increased risk for bone fracture after menopause, it is recommended typically that teenage girls consume amounts of calcium during puberty sufficient to maximize their peak bone mass and thereby reduce the risk for later bone fracture. However, there is little information available whether poor calcium nutrition during adolescence has permanent effects on bone structure and strength. A cooperative study between scientists at the Grand Forks Human Nutrition Research Center, and the University of Oklahoma showed that the damaging effects of severe calcium deficiency on bone structure and strength during adolescence in female rats can be reversed completely by subsequent adequate calcium nutriture during early adulthood. This finding suggests that young women who consumed inadequate amounts of calcium during adolescence may be able to repair damage to their bones by increasing consumption of calcium-rich foods in early adulthood and thereby reduce their risk for bone fracture after menopause. This accomplishment was conducted under National Program 107 Human Nutrition; goal 4 of IMPROVING THE NATION’S NUTRITION AND HEALTH; and part of performance standard 4.1.2 related to defining human requirements for known classes of nutrients. New Methodology Developed for Quantification of Normal Cell Death in Human White Blood Cells: The ability of white blood cells to undergo controlled cell death is an essential feature in the maintenance and regulation of the immune response. ARS scientists at the Grand Forks Human Nutrition Research Center developed a method to assess the potential of white blood cells to undergo cell death in the intact whole blood sample. Whole blood collected from 30 free-living individuals was mixed with chemicals known to stimulate cell death. As cells begin to die, their DNA starts to break at characteristic points. Antibodies that target these broken ends were added and the blood sample was passed through an analyzer that counted each cell and the amount of attached antibody. This method appears capable of measuring the potential of white blood cells to go through a normal life cycle while minimizing unintentional physical damage to the cells during the assessment process. This accomplishment was conducted under National Program 107 Human Nutrition; goal 4 of IMPROVING THE NATION’S NUTRITION AND HEALTH; and part of performance standard 4.1.2 related to defining human requirements for known classes of nutrients. 5.Significant Activities that Support Special Target Populations None. 6.Technology Transfer Number of non-peer reviewed presentations and proceedings 7 Number of newspaper articles and other presentations for non-science audiences 1 Review Publications Hunt, C. 2006. Boron in the typical diet: a physiological role for bone health, reproduction and insulin metabolism. Nutrition and the MD. 32(11):1-8. Hunt, C., Johnson, L.K. 2006. Magnesium requirements: new estimations for men and women by cross-sectional statistical analyses of metabolic magnesium balance data. American Journal of Clinical Nutrition. 84:843-52. Nielsen, F.H., Milne, D.B., Gallagher, S., Johnson, L.K., Hoverson, B. 2007. Moderate magnesium deprivation results in calcium retention and altered potassium and phosphorus excretion by postmenopausal women. Magnesium Research. 20(1):19-31. Roughead, Z.K. 2005. Influence of total diet on calcium homeostasis. Book Chapter. In: Weaver, C.M., Heaney, R.P., editors. Calcium in Human Health. New Jersey: Humana Press. p.191-208.