Lee Swanson Research Update

Vitamin D is Needed by Both Mother and Baby

September 2010

Feeding children vitamin D-rich foods and supplements after birth may be too late to ensure optimal bone health if mom’s intake was inadequate during pregnancy, new data has revealed.

A study with guinea pigs has revealed that sufficient vitamin D for a newborn may not be sufficient to reverse vitamin D deficiency in the womb, researchers from McGill University in Quebec, Canada, report in the Journal of Nutrition.

"This study demonstrates the importance of vitamin D in bone health as well as the implications that a mother’s nutrient deficiency has a profound effect on her offspring during gestation and infancy," wrote the researchers, led by Dr. Hope Weiler. "This study is highly suggestive that efforts to optimize maternal vitamin D status in pregnancy are needed along with maintenance in infancy rather than relying on postnatal supplementation to restore vitamin D status and bone mass."

In the U.S. and Canada there are currently no specific recommendations for pregnant women, and adequate intakes are in line with the general population (five mcg per day). On the other side of the Atlantic in the United Kingdom, pregnant women are recommended by the Food Standards Agency (FSA) to take supplements with a daily dose of 10 mcg vitamin D.

"Although vitamin D deficiency can be reversed in human infants through supplementation, it is unclear if deficiency in utero and neonatally continues to manifest as low bone mass and altered bone metabolism despite correction of vitamin D status," explained Dr. Weiler and her co-workers.

In order to assess the effects of vitamin D in utero and neonatally, the McGill scientists studied pregnant guinea pigs fed either a diet containing adequate vitamin D levels or a diet with deficient levels of the sunshine vitamin.

Newborn pups from both groups were then randomized to receive a daily oral vitamin D supplement providing 0.25 mcg per day or placebo supplement for 28 days. This dose is equivalent to a four kg infant receiving 10 mcg of the vitamin per day, the researchers said.

The results showed that pups of mothers in the deficient group had lower bone mineral content, 6.2% lower blood levels of osteocalcin (a protein that is essential for the body to utilize calcium in bone tissue), lower body weight, and the animals were shorter in length, regardless of the pups’ own supplementation.

"Although postnatal vitamin D supplementation was in part successful in restoring vitamin D status, supplementation did not have a significant effect on bone mass or markers of bone modeling," the researchers wrote.

"Longer-term studies are required to establish the implications to bone later in life," the authors concluded.

Journal of Nutrition 140(9):1574-1581, 2010

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