MedicalResearch.com Interview with:
Hope Weiler, RD (CDO), PhD
Canada Research Chair tier I, Nutrition and Health Across the Lifespan,
Director, Mary Emily Clinical Nutrition Research Unit
School of Dietetics and Human Nutrition
McGill University Macdonald Campus
Ste Anne de Bellevue, QC
MedicalResearch.com: What is the background for this study? What are the main findings?
Dr. Weiler: Vitamin D is a fat soluble with important functions in growth during infancy and childhood, especially for the skeleton. It is for this reason that many policy recommendations for infants stipulate that newborn infants receive a supplemental form of vitamin D. In Canada, it is recommended by Health Canada (www.hc-sc.gc.ca) that newborn infants receive 400 international units of vitamin D from birth to a year of age or until that amount can be obtained from diet. In Canada, older children and adults can make vitamin D when their skin is exposed to direct sunlight between April and October; however, parents are advised to avoid placing their infants in direct sunlight. Thus supplemental vitamin D is particularly important in infancy.
Often newborn infants begin life with low body stores of vitamin D (Weiler and colleagues, CMAJ 2005). This prompted Dr. Weiler’s research group at McGill University to test how much vitamin D is needed by newborn infants in Canada. They learned that 400 to 1200 international units of vitamin D given daily to healthy term born infants is enough to support healthy bone growth and mineral deposition (Gallo and colleagues, JAMA 2013). In conducting tests of bone health, they also learned that the amount of muscle was enhanced and fat reduced when infants had very good vitamin D stores. Vitamin D stores are reflected in the blood. Blood concentrations of a vitamin D form called 25-hydroxyvitamin D are used to establish if stores are in a healthy range. In the recent study published in Pediatric Obesity by Hazell et al, values above 75 nanomoles per litre of blood plasma were linked to lower amounts of body fat (~450 g) at 3 years of age. The 450 g difference is almost a pound of fat. This is a meaningful amount to young children where typical amounts of body fat are 10-times that equating to 4.5 kg (almost 10 pounds). Thus the lower fat is still in a healthy range.
MedicalResearch.com: What should clinicians and patients take away from your report?
Dr. Weiler: Even though the results need to be confirmed and better explained by future studies, it is a remarkable observation that suggests vitamin D nutrition early in infancy is important to how muscle and fat develop in addition to the skeleton. The study by Hazell and colleagues is complemented by other studies in older children and in adults that also show when vitamin D stores are improved from low to healthy, muscle mass or function may also improve.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Dr. Weiler: As a result of the novel observations made by Dr. Hazell and colleagues, the research team lead by Dr. Weiler is now studying the importance of building vitamin D stores quickly after birth in attempt to improve quality of growth. The new study is focused on infants born with very low vitamin D stores and will test whether improving body stores more quickly will help to improve the amount of muscle and reduce excess fat during infancy. The infants will be studied across infancy and then followed again at 2 and 3 years of age to learn if the intervention was meaningful. The researchers will also explore various reasons for the improved quality of growth and establish if vitamin D has a role to play in prevention of childhood obesity. Vitamin D would not be the only factor in obesity, but learning about its role is important to better understand the various contributing factors in the risk of developing obesity.
MedicalResearch.com: Is there anything else you would like to add?
Dr. Weiler: Readers should also take away the message that adhering to recommendations is important to achieving healthy vitamin D status; in the case of infants, giving the supplement as prescribed on a daily basis is important. In Canada, the recommended dosage is 400 international units of vitamin D daily for infants. It is not routine to test for vitamin D stores, we know from our previous research that the recommended dosage will help to build vitamin D stores in infancy when given daily.
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Hazell, T. J., Gallo, S., Vanstone, C. A., Agellon, S., Rodd, C., and Weiler, H. A. (2016) Vitamin D supplementation trial in infancy: body composition effects at 3 years of age in a prospective follow-up study from Montréal. Pediatric Obesity,
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