Vitamin D Dose-Response Study to Establish Dietary Requirements in Infants
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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.
Vitamin D plasma concentrations [ Time Frame: 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.
Secondary Outcome Measures
Bone mineral content [ Time Frame: 12 months ]
Bone mineral content will be assessed at 1, 3, 6, 9 and 12 months of age. Using DXA technology which provides measures of bone mineral content as well as body composition measurements the investigators will be able to correlate these changes with vitamin D concentrations.
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Ages Eligible for Study:
up to 5 Weeks (Child)
Sexes Eligible for Study:
Accepts Healthy Volunteers:
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.
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.