Born with less vitamin D?

LOS ANGELES — Even as a high-profile panel of experts recently disputed the conventional wisdom that Americans don't get enough vitamin D — and that vitamin D deficiencies create greater risk of disease — new research shows that newborns with low levels of vitamin D have higher rates of respiratory infection and wheezing than infants born with more vitamin D in their systems.

There was no correlation, however, between low vitamin D levels and asthma.

The study, published Monday in the journal Pediatrics, expanded on earlier work by Dr. Carlos Camargo of the Massachusetts General Hospital in Boston that had shown that babies born to mothers who took vitamin D supplements were less likely to develop wheezing during childhood.

This time around, instead of focusing on supplement intake, Camargo and his team looked at the levels of vitamin D in newborn cord blood samples collected from a group of 922 children in New Zealand who had participated in a study on asthma and allergies between 1997 and 2001.

In addition to allowing researchers to collect cord blood, the babies' mothers had filled out periodic questionnaires about their children's health up until the children turned 5. The researchers mined these data to determine rates of wheezing, infections and asthma in the group and correlate them with vitamin D levels in the cord blood.

They found that the lower the amount of vitamin D, the higher the risk of wheezing. Newborns with particularly low levels of the vitamin — about one in five — were twice as likely to develop respiratory infections such as colds, coughs and ear infections during the first three months of life, the team reported. Those babies also had an increased risk of other types of infections.

The researchers found higher levels of vitamin D in children born to slightly older mothers and to mothers of European ethnicity. They observed lower levels in kids born in winter and in children of lower socioeconomic status.

The paper reported that the team was surprised that children with less vitamin D in their cord blood didn't also develop asthma at a higher rate than other babies. In the past, some had speculated that vitamin D deficiency might be a cause of the high incidence of asthma in the world today.

But even though asthma doesn't appear to result directly from low vitamin D levels, treating asthmatic kids with vitamin D could still be effective because it might reduce respiratory infections that can exacerbate the condition, the authors wrote.