Enhancing Dietary Iron and Zinc Bioavailability in Indian Children

背景：铁和锌缺乏症经常同时发生，因为影响铁吸收的饮食因素也会影响锌的吸收。在印度没有推荐锌的每日摄入量。有了铁和锌的稳定同位素，现在可以精确地测量铁和锌的吸收率。具体目标是(1)测量具有代表性的印度饮食中铁和锌的生物利用度(2)测量具有代表性的印度饮食的可行多样化所实现的铁和锌的生物利用度变化(3)确定可行的饮食修改的耐受性。方法：本研究采用交叉设计，选取寄宿学校13-15.9岁的健康儿童（男16名，女16名）为研究对象。将评估铁和锌的基线状态。所有儿童将被随机分配，接受代表性饮食或多样化饮食。建议的修改是从每餐的水果和蔬菜中加入~ 20毫克的抗坏血酸。儿童将连续5天在各自的饮食中添加57Fe（仅3天，两次主餐），第4天口服58Fe（含抗坏血酸）作为参考剂量。将在基线和第18天采集血样。第一餐同时给予67Zn，同日静脉注射参考剂量70Zn。从第3天到第6天收集尿液。吸收将通过血红蛋白中57Fe和58Fe的相对富集来定量铁或通过ICP-MS通过尿中67Zn和70Zn来定量锌。然后，参与者将在第19天按照相同的方案切换到另一种饮食。通过对参与者使用5分享乐量表进行感官评估问卷，对多样化饮食的耐受性进行为期6周的评估。结果：该项目将产生有关青少年铁和锌吸收的数据，为确定RDA和膳食调整作为预防铁和锌缺乏症策略的可行性提供基础。在贝勒医学院的稳定同位素实验室和国家营养研究所之间建立长期合作，以评估印度儿童的营养问题，将是这个项目的一个重要成果。

DESCRIPTION (provided by applicant): Background: Iron and zinc deficiencies frequently occur together because the dietary factors that impair iron absorption also affect zinc absorption. There is no recommended daily intake for zinc in India. With stable isotopes of iron and zinc it is now possible to measure precisely iron and zinc absorption. The specific objectives are (1) To measure the bioavailability of iron and zinc from a representative Indian diet (2) To measure the change in bioavailability of iron and zinc achievable by feasible diversification of a representative Indian diet (3) to determine the tolerability of the feasible dietary modifications. Methods: The proposed program uses a cross-over design to study healthy children aged 13-15.9 years (16 boys and 16 girls) selected from residential schools. Baseline iron and zinc status will be assessed. All children will be randomly assigned to receive either the representative diet or the diversified diet. The proposed modification is the inclusion of ~ 20 mg ascorbic acid from fruits and vegetables which will be served with each meal. Children will be fed their respective diets for 5 consecutive days labeled with 57Fe (for 3 days only, two main meals) with an oral reference dose of 58Fe (with ascorbic acid) on day 4. Blood samples will be collected at baseline and on day 18. Simultaneously 67Zn will be given with the first meal and a reference dose of 70Zn injected intravenously on the same day. Urine will be collected from day 3 to day 6. Absorption will be quantitated by the relative enrichment of 57Fe and 58Fe in hemoglobin for iron or by 67Zn and 70Zn in urine for zinc using ICP-MS. The participants will then crossover to the other diet on day 19, following the same protocol. Tolerability of the diversified diet will be assessed for 6 weeks by administering a sensory evaluation questionnaire to the participants using a 5-point hedonic scale. Outcomes: This project will generate data on the absorption of iron and zinc in adolescents to provide a basis for determining the RDA's and the feasibility of dietary modification as a strategy to prevent iron and zinc deficiencies. The establishment of a long term collaboration between the stable isotope laboratories at Baylor College of Medicine and the National Institute of Nutrition to evaluate nutritional problems among children in India will be an important outcome of this project. PUBLIC HEALTH RELEVANCE: This study will provide evidence that achievable dietary changes in a very "at-risk" group, adolescents, in India can have important benefits in improving the amount of iron and zinc absorbed from the diet. Improving the intake of bioavailable minerals would be crucial to enhancing the health of the Indian population as it will improve school and work performance in both boys and girls. These benefits will lead to larger population-based studies and an enhanced understanding of using nutritional interventions in developing countries to improve health.