(NaturalNews) Obese women are more likely to give birth to children with low blood levels of vitamin D that women of healthy weight, according to a study conducted by researchers from Northwestern University and published in the Journal of Clinical Endocrinology and Metabolism.
Vitamin D is produced naturally by the body upon exposure to the ultraviolet radiation from sunlight. It plays an important role in bone synthesis and maintenance, and recent studies have suggested that it also helps maintain a healthy immune system. Insufficient levels of vitamin D have been linked with a higher risk of obesity, inflammation and autoimmune diseases in adults; it remains unknown what effect low vitamin D levels might have in infants.
Because vitamin D is fat soluble, it tends to accumulate in body fat. As a consequence, obese people may be consuming or producing the same amount of vitamin D as thinner people, but still have lower levels in their blood.
The new study was conducted as part of a longer-term study into whether body fat at birth is predictive of body fat later in life. As part of this study, the researchers also collected and analyzed data on vitamin D levels at birth.
The vitamin D analysis was conducted on 61 women who gave birth at Prentice Women's Hospital of Northwestern Memorial Hospital in Chicago. All the participating women had body mass indexes classified as either normal or obese. Their vitamin D levels were measured from blood taken some time between the 36th and 38th weeks of pregnancy. Infant vitamin D levels were measured from an umbilical blood sample taken right after birth. Infants' body fat, weight and volume were all measured, as well.
Less vitamin D transferred to infants
The researchers found that regardless of weight, women tended to have similar (healthy) levels of vitamin D in their blood. Yet infants born to thinner women had a third more vitamin D in their blood than infants born to obese women. This suggests that obese women transfer less vitamin D to their babies.
"Nearly all of mothers in this study reported taking prenatal vitamins, which may be the reason why their own vitamin D levels were sufficient, but the babies born to the obese mothers had reduced levels of vitamin D," lead researcher Jami L. Josefson said. "It's possible that vitamin D may get sequestered in excess fat and not transferred sufficiently from an obese pregnant woman to her baby."
Surprisingly, however, babies with the most body fat also had the highest levels of vitamin D.
"The range of body fat of the babies in this study was similar to other studies reporting neonatal body fat," Josefson said. "What was novel about this study was that we found babies born with higher vitamin D levels had more body fat. That's in contrast to studies in children and adults who have an inverse relationship between levels of vitamin D and body fat, where the higher their vitamin D, the lower their fat."