Higher levels of vitamin D in newborns may reduce the risk of obesity in childhood, as it is linked to better sensitivity to insulin, according to a study presented at the Obesity Society's 28th annual scientific meeting in San Diego. Susanna Y. Huh, MD, MPH, a doctor at Children's Hospital Boston and instructor of pediatrics at Harvard Medical School, says that higher levels of vitamin D may protect the children against insulin resistance, one of main risk factors for obesity.
The hypothesis that vitamin D levels affect obesity was recently developed and many studies have accumulated evidences towards the same, says Huh. In this study, the researchers measured the vitamin D levels in the cord blood of 629 newborns and 990 pregnant women during their second trimester. When the children were 3-years-old, their body mass index and other factors were measured. To evaluate their sensitivity to insulin, the researchers measured the amount of adiponectin, a hormone, in the blood.
Huh explains that high levels of adiponectin made the individual leaner. Thus, measure of adiponectin indicates how sensitive an individual is to insulin. Sensitivity to insulin reduces the chances of obesity. Results of the study showed that higher levels of vitamin D in the cord blood were associated with higher levels of adiponectin in the children. This correlation between adiponectin and vitamin D was found only in the cord blood of newborns, says Huh. No correlation was noted between the two during pregnancy. “This may show that higher levels of vitamin D are more important around the time of birth when compared to pregnancy”, she adds. There is no designated amount required for an individual to have regarding this hormone, according to researchers. Therefore, one cannot say that a child may require ‘X’ amount of adiponectin to prevent obesity.
About a half of the women in the study had very low levels of vitamin D. Huh feels that the link between vitamin D and adiponectin requires more study. Even though adiponectin is an established marker of insulin sensitivity, the presence of this compound has not been studied extensively in young children.
The link between vitamin D and obesity is under focus now and more and more studies are being done in this field, according to Connie Diekman, RD, director of university nutrition for Washington University in St. Louis. Diekman, who is immediate past president of the American Dietetic Association and on the advisory panel for the National Dairy Council, says that pregnant women have already been recommended to watch the intake of vitamin D. According to the Institute of Medicine (IOM), adults should ideally have 200 international units (IU) a day, which according to Huh is too low a value. Huh echoes what experts in the field of vitamin D feel — adults should have at least 800 IU per day.