DIETARY MINERAL BIOAVAILABILITY IN PREMATURE INFANTS

胎儿宫内生长率已成为衡量出生后 早产儿的生长进行了比较，和身体成分的 足月婴儿的营养需求已经成为 已经计算过了。 代谢平衡研究，对早产儿进行 婴儿，以确定是否保留的膳食营养素的量， 每单位时间内体内的营养物质与子宫内营养物质的积累相匹配 在相当的时间内，经常表现出消极的 营养平衡，并建议身体营养不足， study. 这尤其体现在矿物方面， 钙锌和铜 此外，由于技术上的困难， 可能低估或高估吸收和保留， 代谢平衡研究产生不同的结果。 因此，在这 我们建议直接测量膳食的生物利用度， 早产儿稳定性同位素钙、锌、铜测定 浓缩技术 60个适合胎龄婴儿， 出生体重小于或等于1，500克，可耐受全肠内营养 到7日龄至少100千卡/千克/天的营养将形成最终的 研究人群。 这些婴儿将被分为3个喂养组， 20. 第一组将获得一种专有配方， 为成长中的早产儿设计，第二组将接受他们自己的 母乳（PTHM），第III组将接受强化PTHM（混合物 他们自己的母亲的PTHM与粉状矿物质补充剂）。 十 每组婴儿的出生体重将小于1，250 gm（亚组 A）和10的出生体重在1，250和1，500 gm之间（亚组B）。 钙、锌和铜的生物利用度将通过增加 含有示踪量的稳定的，非放射性的， 这些矿物的天然同位素，46 Ca，70 Zn和65 Cu， 一次喂食，然后收集粪便和尿液72小时。 同位素 粪便和尿液样本的矿物质分析将允许 准确计算每种给药药物的吸收分数 稳定同位素。 将对每种药物进行两项生物利用度研究 婴儿;第一个年龄在10至14天之间，第二个在身体上 亚组A的婴儿体重约为1，500克，亚组B的婴儿体重约为1，750克， 对于亚组B的婴儿。 因此，本研究将确定 对膳食钙、锌和铜生物利用度的影响， 同时比较它们的生物利用度从PTHM，公式， 强化PTHM。

The intrauterine growth rate has become the standard to which postnatal growth of premature infants is compared, and the body composition of the full-term infant has become the standard from which nutrient requirements have been calculated. Metabolic balance studies, performed with premature infants to determine whether the amount of the dietary nutrient retained by the body per unit time matched the in utero accumulation of that nutrient over an equivalent period of time, have often demonstrated negative nutrient balances and have suggested body deficits of the nutrient under study. This has been particularly the experience with minerals such as calcium, zinc, and copper. Furthermore, due to technical difficulties that can either underestimate or overestimate both absorption and retention, metabolic balance studies produce variable results. Therefore in this investigation we propose to directly measure the bioavailability of dietary calcium, zinc, and copper in premature infants with stable isotope enrichment technology. Sixty appropriate for gestational age infants with birthweights less than or equal to 1,500 gm that tolerate full enteral nutrition of at least 100 kcal/kg/day by 7 days of age will form the final study population. These infants will be divided into 3 feeding groups of 20. Group I will receive a proprietary formula that has been specifically designed for the growing premature infant, Group II will receive their own mother's milk (PTHM), and Group III will receive fortified-PTHM (a mixture of their own mother's PTHM with a powdered mineral supplement). Ten infants in each group will have a birthweight less than 1,250 gm (Subgroup A) and 10 will have a birthweight between 1,250 and 1,500 gm (Subgroup B). Calcium, zinc, and copper bioavailability will be assessed by the addition of a solution containing tracer amounts of stable, non-radioactive, naturally occurring isotopes of those minerals, 46Ca, 70Zn, and 65Cu, to one feeding, followed by a 72 hour collection of stool and urine. Isotopic and mineral analyses of the stool and urine samples will then permit an accurate calculation of the fractional absorption of each administered stable isotope. Two bioavailability studies will be performed with each infant; the first between 10 and 14 days of age and the second at a body weight of about 1,500 gm for the infants in Subgroup A and about 1,750 gm for the infants in Subgroup B. Thus, this study will determine the effect of post-natal age on dietary calcium, zinc, and copper bioavailability, while comparing their bioavailability from PTHM, formula, and fortified-PTHM.