Prevention of Vitamin D Deficiency in Breastfed Infants

描述(申请人提供)：维生素D缺乏症在美国各地母乳喂养的婴儿中都会发生，但在皮肤色素沉着的婴儿和生活在美国北部地区的婴儿中尤其常见，因为那里的皮肤在冬天维生素D的合成减少或缺失。维生素D缺乏症的流行，包括其最严重的形式--软骨病，正在上升，可能是因为母乳喂养的增加。补充维生素D可以预防维生素D缺乏症。目前的建议是每天补充200IU的维生素D，然而，还不能确定这个剂量就能可靠地预防维生素D缺乏。目前也不知道高剂量的效果如何，以及对婴儿的最佳剂量是多少。这项拟议研究的目的是确定三种维生素D剂量在预防母乳喂养婴儿维生素D缺乏方面的有效性或缺乏。这项研究还将检查一系列维生素D充足的功能指标，以期确定婴儿保持良好健康所需的最佳维生素D含量。适用于此的婴儿包括不分季节皮肤黝黑的婴儿和冬季生活在北纬地区的高加索婴儿。母乳喂养的婴儿将在1个月大时被招募，并被随机分配到1至9个月大的婴儿接受每日补充200鲁/天、400鲁/天或600鲁/天。他们在9个月大之前不会收到任何补充配方奶粉。这将是一项双盲研究。婴儿将每月接受检查，并将在七个场合用脚跟棒抽血，以确定25-OHD和维生素D状态的功能指标。紫外线暴露也将被估计。骨矿含量将一次性测定(在3月或4月，即在冬季结束时)。其他端点将在多个场合进行测量。主要终点是维生素D状态，即血浆中25-OHD的浓度，缺乏定义为15 ng/ml。我们假设，每天定期服用400IU和600IU的维生素D将可靠地防止维生素D缺乏，但每天服用200Lu将不会完全有效。维生素状况的功能指标将随着补充维生素D剂量的增加而增加。这项研究具有相当大的公共卫生重要性，因为预防维生素D缺乏症的重要性不仅在于预防严重形式的软骨病，还在于预防轻度形式的维生素D缺乏。

DESCRIPTION (provided by applicant): Vitamin D deficiency occurs among breastfed infants in all parts of the U.S. but is particularly common among infants with dark skin pigmentation and infants living in the northern parts of the U.S. where synthesis of vitamin D in the skin is diminished or absent during winter. The prevalence of vitamin D deficiency, including its severest form, rickets, is on the rise, probably because of the increase in breastfeeding. Vitamin D supplementation can prevent vitamin D deficiency. Current recommendations are to provide a daily supplement of 200 IU of vitamin D. However, it is not established that this dose prevents vitamin D deficiency reliably. Nor is it known how effective higher doses are and what the optimal dose is for infants. The objective of the proposed study is to establish in definitive fashion the effectiveness, or lack thereof, of three vitamin D dosages in the prevention of vitamin D deficiency in breastfed infants. The study will also examine an array of functional indicators of vitamin D sufficiency in the hope of establishing the optimal amount of vitamin D that infants need in order to remain in good health. Infants to whom this applies include infants with dark skin regardless of season and Caucasian infants living at northern latitudes during winter. Breastfed infants will be recruited at 1 month of age and will be assigned at random to receive a daily supplement of either 200 lU/day or 400 lU/day or 600 lU/day from 1 to 9 months of age. They will receive no supplemental formula until age 9 months. This will be a double blind study. Infants will be seen monthly and blood will be drawn by heel stick on seven occasions for determination of 25-OHD and of functional indicators of vitamin D status. Ultraviolet exposure will be estimated also. Bone mineral content will be determined once (in March or April, i.e., at the end of winter). The other endpoints will be measured on multiple occasions. The primary endpoint will be vitamin D status, i.e., plasma concentration of 25-OHD, with deficiency defined as concentration <15 ng/ml. We hypothesize that regular administration of 400 IU and 600 IU of vitamin D each day will prevent vitamin D deficiency reliably but that administration of 200 lU/day will be less than completely effective. Functional indicators of vitamin status will increase with increasing doses of supplemental vitamin D. The study has considerable public health importance because of the importance of preventing vitamin D deficiency not only in its severe form, rickets, but also in its milder forms.