Vitamin D in Infancy Can Help Support Healthy Body Composition

Vitamin D is an essential fat-soluble vitamin that is not typically present in most natural foods. The best dietary sources include cod liver oil, sword fish, salmon, vitamin D fortified foods and dietary supplements. Vitamin D is also produced endogenously when ultraviolet rays from sunlight strike the skin and trigger vitamin D synthesis. However, due to increased sunscreen use, inadequate dietary intake, geographical locations (latitude and altitude), atmospheric conditions that impact UVB radiation intensity on the ground (air pollution) and seasonal changes, the quality and quantity of vitamin D production in skin has greatly decreased, making it common to have some degree of vitamin D deficiency.

Human milk commonly provides 10-80 IU of vitamin D per liter (L), which corresponds to 0.2-1.5 μg/day (8-60 IU/day), falling short of the 400 IU/day recommended by many health experts. Older infants and toddlers exclusively fed milk substitutes and weaning foods that are not vitamin D fortified, are also at a greater risk for vitamin D deficiency. For this reason, vitamin D supplementation is routinely recommended for babies until they can get an adequate amount through diet.

A study published in the journal Pediatric Obesity has shown that a healthy supplemental intake of vitamin D during the first year of life provides children with more muscle mass and less body fat as toddlers. These findings emerged from an initial double-blind randomized trial of 132 healthy, breastfed infants (one month of age at the start of the study) living in Quebec Canada randomly assigned to receive a daily oral vitamin D3 supplement of 400, 800, 1200 or 1600 IU  (10, 20, 30, 40 micrograms) for 11 months. The infants returned for a follow-up at 3 years of age for a further evaluation of vitamin D blood levels and body composition. The additional benefit of a leaner body composition came as somewhat of a surprise for the research team. “We were very intrigued by the higher lean mass, the possibility that vitamin D can help infants to not only grow healthy skeletons but also healthy amounts of muscle and less fat,” said Hope Weiler, one of the study’s authors and Director of the Mary Emily Clinical Nutrition Research Unit at McGill University.

This study confirms the importance of a higher vitamin D status beginning in early infancy for the development of strong bones and healthy lean muscle mass. The only other factor known to make a significant difference to child’s body fat level is the amount of physical activity.

Hazell TJ, Gallo S, Vanstone CA, Agellon S, Rodd C, Weiler HA. Vitamin D supplementation trial in infancy: body composition effects at 3 years of age in a prospective follow-up study from Montréal. Pediatr Obes. 2016; Feb 4.