2006 Annual Report 1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? Why does it matter? This CRIS research unit addresses the absorption and metabolism of essential mineral nutrients and is composed of two individual research projects: 1)Evaluation of the absorption and utilization of minerals in the diets of toddlers, and. 2)Physiological and molecular consequences of mild and moderate zinc deficiency. This research is relevant to ARS National Program 107, specificaly Component 1 Nutrient Requirements. A need for the understanding of nutrient requirements throughout the life cycle is imperative. The nutrient requirements of the fetus, infants, children, adolescents, pregnant and lactating women, and adults, especially the elderly, differ. Thus, there is a need to understand the effects of nutrition at different points in the life cycle. Learning nutrient requirements early in life may lead to the prevention of chronic disease. Research is needed to define borderline deficiencies and to identify biomarkers of deficiency. Project 1: Evaluation of the absorption and utilization of minerals in the diets of toddlers By understanding mineral absorption and utilization, evidence-based dietary recommendations can be made for children in this age group, which has important implications for consumers and public policy planners. If increasing mineral intake does not increase the total amount of minerals absorbed, then further discretionary fortification of foods intended for consumption with these minerals is unlikely to be in the public interest. Furthermore, having more accurate dietary requirement information is of value in planning diets by parents and by governmental agencies for small children (e.g., the school lunch and Women Infants and Children programs). Understanding mineral absorption and utilization in this age group will allow more accurate, evidence-based dietary recommendations to be made. Project 2: Physiological and molecular consequences of mild and moderate zinc deficiency Zinc deficiency is a major nutritional challenge; however, the current methods of diagnosing zinc deficiency are inadequate. The main objective of this study is to identify novel potential markers of zinc status using changes in RNA expression in response to zinc deficiency. Potential biomarkers will be identified in zinc-deficient animal models, and their utility as measures of zinc status tested in human models of zinc deficiency. This research will assess the effect of mild and moderate zinc deficiency on gene expression using state of the art methods such as DNA microarrays and real time quantitative PCR. The identification of new markers of zinc status will be useful in the study of zinc deficiency, and will allow better understanding of zinc requirements in health and disease. The project will also develop an animal model to identify biomarkers of marginal zinc status, and validate their effectiveness in experimental human zinc deficiency. 2.List by year the currently approved milestones (indicators of research progress) Project 1: Evaluation of the absorption and utilization of minerals in the diets of toddlers Year 1 (2005) Enroll 24 subjects to evaluate three different levels of dietary mineral intake. Begin comparisons of TIMS vs. HR ICP-MS for calcium, magnesium, and zinc. Year 2 (2006) Enroll an additional 24 subjects to evaluate three different levels of dietary mineral intake. Complete comparisons of TIMS vs. HR ICP-MS for calcium, magnesium, and zinc. Year 3 (2007) Begin enrolling subjects by the end of year 3 to evaluate the enhancers and inhibitors of mineral absorption. Begin enrolling 32 subjects for the evaluation of high Fe/Zn ratio study. Complete sample analyses of the evaluation of three different levels of dietary mineral intake. Year 4 (2008) Enroll all subjects by the end of year 4 to evaluate the enhancers and inhibitors of mineral absorption. Begin evaluation of copper and iron by the end of year 4. Year 5 (2009) Complete the sample analysis of the enhancers and inhibitors of mineral absorption by the end of year 5. Complete analysis of the high Fe/Zn ratio study. Project 2: Physiological and molecular consequences of mild and moderate zinc deficiency Year 1 (2005) Complete animal studies, initiate compartmental modeling, and start DNA microarray analysis for the identification of novel biomarkers in an animal model. Year 2 (2006) Complete microarray analysis. (added milestone) Complete recruitment of subjects for the use of biomarkers in zinc deficienty paradigm research study. Select most promising biomarkers to be studied in the disease model of zinc deficiency study, and in the zinc depletion/repletion research study. (added milestone) Q-PCR analysis will be conducted to better understand the expression of biomarkers in healthy humans. Recruit healthy subjects in order to screen for biomarkers, and sample collection will be accomplished. Year 3 (2007) The final subjects in the disease model of zinc deficiency study will be recruited and studied. Data analysis for the disease model of zinc deficiency study will be started. Year 4 (2008) Conduct and finish Q-PCR and data analyses on the use of biomarkers in zinc deficiency paradigm. Begin recruitment of subjects for the use of biomarkers in zinc depletion/repletion research study. The dietary intervention to better understand the effects of zinc supplementation/depletion will have begun. Year 5 (2009) Data samples will be collected to determine outcome measurements. Q-PCR analysis of the effects of zinc depletion/repletion research study will be concluded. Effects of zinc supplementation/depletion data will be analyzed. 4a.List the single most significant research accomplishment during FY 2006. Project 1: Evaluation of the absorption and utilization of minerals in the diets of toddlers Effect of Mineral Intake on Calcium, Magnesium, Zinc, and Iron Absorption Identifying the method of regulation of absorption of key nutrients is a considerable problem of childhood nutrition. Researchers at the Children's Nutrition Research Center in Houston, TX, found that calcium behaves as a threshold mineral in toddlers, and that at the usual dietary intakes, intestinal absorption of zinc and magnesium is not a primary source of regulation of total absorption. Additionally, researchers learned that iron absorption is more closely related to iron status than iron intake. These findings were accomplished in our lab using stable isotope iron absorption measurements. Data obtained as a result of this research will be essential in developing evidence-based dietary guidelines for this critical age group. [NP107 - Component 1 Nutrient Requirements] 4b.List other significant research accomplishment(s), if any. Project 2: Physiological and molecular consequences of mild and moderate zinc deficiency Identification of Potential Novel Biomarkers of Zinc Status Identifying reliable markers of zinc status in humans has proven to be difficult. Researchers at the Children's Nutrition Research Center in Houston, TX, have identified 882 potential biomarkers that changed significantly during zinc deficiency in animal models. Of these, 226 increased by more than 2-fold and 182 decreased by more than 2-fold. They were measured from RNA extracted from skin samples by microarray analysis. These transcripts are potential biomarkers that could be used to assess zinc status in humans. [NP107 - Component 1 Nutrient Requirments] Understanding Growth Failure Growth failure accompanies zinc deficiency; however, the degree of growth failure due to anorexia and decreased food intake versus the amount due to zinc deficiency per se was not known. Scientists at the Children's Nutrition Research Center in Houston, TX, conducted research studies where animal models were fed a zinc-adequate diet at the same intake level as the zinc-deficient animals, in order to mimic the growth of the zinc-deficient animals. Results from this study permitted our researchers to estimate that about 60% of the growth failure observed in zinc deficiency can be explained by anorexia and poor feed intake. The remaining 40% is unexplained and may be due to changes in body composition, energy expenditure, or nutrient absorption. Such findings are important in understanding the promoters of growth failure and minimizing such contributors. [NP107 - Component 1 Nutrient Requirements] 4c.List significant activities that support special target populations. None. 5.Describe the major accomplishments to date and their predicted or actual impact. This research is relevant to ARS National Program 107, specificaly Component 1 Nutrient Requirements. A need for the understanding of nutrient requirements throughout the life cycle is imperative. The nutrient requirements of the fetus, infants, children, adolescents, pregnant and lactating women, and adults, especially the elderly, differ. Thus, there is a need to understand the effects of nutrition at different points in the life cycle. Learning nutrient requirements early in life may lead to the prevention of chronic disease. Research is needed to define borderline deficiencies and to identify biomarkers of deficiency. Project 1: Evaluation of the absorption and utilization of minerals in the diets of toddlers Information in the area of children's mineral requirements is lacking. Scientists at the Children's Nutrition Research Center, Houston, TX, have developed, tested, and verified that studies of calcium, magnesium, iron, copper, and zinc absorption could simultaneously be performed in toddlers. This has not been successfully accomplished in this age group before. It is expected that this method will be highly useful in evaluating the mineral requirements of children. Project 2: Physiological and molecular consequences of mild and moderate zinc deficiency The animal models of zinc deficiency have been completed, and tissues collected for mRNA extraction and microarray analysis. Additionally, the effect of zinc supplementation in children with cystic fibrosis will be evaluated. Buccal cells are being collected from these children for mRNA extraction before and after randomization to zinc supplementation or placebo. The study of the disease model of zinc deficiency (cystic fibrosis) continues. Samples are being collected to analyze the effect of zinc supplementation on the potential biomarkers from this study. We have been able to identify the relative contributions of anorexia on the growth failure associated with zinc deficiency. Although anorexia explains most of the growth failure of zinc deficiency, a significant proportion remains unexplained suggesting that other factors, in addition to anorexia, are responsible for growth failure in zinc deficiency. 6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? None. 7.List your most important publications in the popular press and presentations to organizations and articles written about your work. (NOTE: List your peer reviewed publications below). Project 1: Evaluation of the absorption and utilization of minerals in the diets of toddlers Abrams, S.A. Presented "Determination of Calcium Absorption in Young Adolescents" at the 18th International Congress of Nutrition, Durban, South Africa, Sept. 21, 2005. Abrams, S.A. Visiting Professor, "Bone Mineral Metabolism in Young Adolescents Studied Using Stable Isotopes". Department of Anatomy and Cell Biology, University of North Dakota and USDA/ARS Grand Forks Human Nutrition Research Center, Grand Forks, North Dakota, May 8-9, 2006.