Vitamin D Dose-Response Study to Establish Dietary Requirements in Infants
试验速览
- 阶段
- 2 期
- 状态
- 已完成
- 入组人数
- 132
- 试验地点
- 1
- 主要终点
- Vitamin D plasma concentrations
研究概览
简要总结
The research team is comprised of an expert nutrition scientist and a pediatrician with expertise in endocrinology. Both have world-class experience in assessing bone mass in infancy. Together they have designed a study to determine how much dietary vitamin D is needed to optimize health in infants. This is important since many infants are born with vitamin D deficiency. At present the dosage of vitamin D that is optimal for infant health is unclear and recent research suggests that vitamin D status very early in life has long lasting effects on bone mass and other health issues. Therefore, in a group of healthy infants, this research team will test which dosage of vitamin D is needed to achieve optimal vitamin D status. Optimal vitamin D status will be based on growth, biomarkers of vitamin D and bone status in blood and also general health. The infants will all be breastfed and begin the study at about 2 weeks of age. At 3 months intervals over the first year of life, each infant will be measured for growth, duration of breastfeeding and supplement use plus have a bone density scan to determine changes in bone growth. The data will be helpful to guide health care professionals in providing the best care possible for their infants. It will also be important to the health of populations since dietary recommendations for vitamin D are used to guide fortification of foods and development of evidence based policy around nutrient recommendations and their implementation.
详细描述
Vitamin D status is currently judged by serum 25(OH)D and the parathyroid hormone (PTH)-25(OH)D dynamic (1). The ultimate effect of vitamin D on human health is a healthy skeleton, which is characterized in infancy by normal linear growth and bone mineral accretion and absence of bone related disease, such as rickets (1). The importance of these indicators is illustrated in epidemiological research, where linear growth in infancy is positively related to peak bone mass as an adult (2). Moreover, both vitamin D status (3) and intake (4) in infancy are related to bone mass in children.
In 2004, Health Canada reaffirmed its population health policy that all breastfed, healthy term infants in Canada receive a daily vitamin D3 supplement of 400 IU (5). This policy recommendation was made in consultation with the Canadian Expert Advisory Committee on Dietary Reference Intakes (DRI). They determined that the 1997 DRI value for vitamin D of 200 IU was too low for Canadians based on Canadian studies (6, 7) and surveillance systems (1) that indicated a high rate of vitamin D deficiency and vitamin D deficient rickets continued in Canada.
Both the Health Canada committee (5) and Institute of Medicine Committee on Dietary Recommended Intakes (1) acknowledged that there was considerable uncertainty regarding what defines optimal vitamin D intake in infancy based on functional outcomes.
In adults, a minimum serum 25(OH)D value of 75 nmol/L now defines optimal vitamin D status (8). This concentration is derived from dose-response studies of the relationship between 25(OH)D and PTH, where PTH plateaus in approximately the mid-normal range and also from studies where 25(OH)D concentrations between 90 and 100 nmol/L are positively related to bone mineral density (BMD) in young adults (9). A dose-response study to determine the physiological and functional response to vitamin D3 supplementation has not been conducted in infants and is necessary to confidently set DRI values for Canadian infants.
In summary, health care professionals are faced with major gaps in knowledge of: a) what constitutes optimal vitamin D status in infancy based on the physiological and functional outcomes, 25(OH)D, PTH and bone mass; and b) what oral dosage of vitamin D supplement is required to elevate serum 25(OH)D to optimal values as the key biomarker of optimal vitamin D status.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Treatment
- 盲法
- Triple (Participant, Care Provider, Investigator)
入排标准
- 年龄范围
- 2 Weeks 至 5 Weeks（Child）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Healthy singleton term born infants of appropriate size for gestational age (AGA) according to the Centers for Disease Control growth charts based on weight at birth between the 5th and 95th percentiles for sex; and born to healthy breastfeeding women. This allows us to assess growth and bone mineral accretion without bias of intrauterine growth restriction.
排除标准
- •Infants of mothers with history of gestational diabetes or hypertension in pregnancy; chronic alcohol use; malabsorption syndromes due to malabsorption of vitamin D (celiac disease, Crohn's etc.); and multiple births.
- •Should any exclusion criteria be identified after recruitment, the infant will be excluded from the main analyzes, but followed in a separate arm as intent-to-treat.
研究组 & 干预措施
1
400 IU / day vitamin D
干预措施: Vitamin D (Drug)
2
800 IU / day vitamin D
干预措施: Vitamin D (Drug)
3
1200 IU / day vitamin D
干预措施: Vitamin D (Drug)
结局指标
主要结局
Vitamin D plasma concentrations
时间窗: 12 months
25(OH)D concentrations will me measured in infants over the first year of life. The blood sampling will be done at 1, 2, 3, 6, 9 and 12 months of age. Monitoring the vitamin D concentrations will allow the investigators to determine the best dose of vitamin D for breast fed infants receiving one of three vitamin D dosages.
次要结局
- Bone mineral content(12 months)
研究者
Hope Weiler
Associate Professor
McGill University