Prevention of Vitamin D Deficiency in Breastfed Infants

描述（由申请人提供）：维生素D缺乏症发生在美国所有地区的母乳喂养婴儿中，但在深色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，因为在冬季皮肤中维生素D的合成减少或缺乏。维生素D缺乏症的患病率，包括最严重的佝偻病，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。目前的建议是每天补充200国际单位的维生素D。然而，并没有确定这个剂量可以可靠地预防维生素D缺乏症。也不知道高剂量的效果如何，以及婴儿的最佳剂量是多少。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缺乏症方面的有效性或缺乏有效性。该研究还将检查一系列维生素D充足性的功能指标，以期确定婴儿保持良好健康所需的维生素D的最佳量。适用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，并将被随机分配，从1到9个月大每天接受200、400或600卢/天的补充。他们在9个月大之前不会接受补充配方奶粉。这将是一项双盲研究。婴儿将每月检查一次，并用足跟棒抽血7次，以测定25-OHD和维生素D状态的功能指标。紫外线照射也将被估计。骨矿物质含量将测定一次（三月或四月，即冬季结束时）。其他端点将在多个场合测量。主要终点将是维生素D状态，即25-OHD的血浆浓度，缺乏定义为浓度<15 ng/ml。我们假设每天定期服用400 IU和600 IU的维生素D可以可靠地预防维生素D缺乏症，但每天服用200 lU的维生素D将不是完全有效的。维生素状态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缺乏不仅对严重形式的佝偻病很重要，而且对轻度形式的维生素D也很重要。

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.