Low vitamin D levels increase respiratory infections in newborns

A new study has suggested that newborns with low levels of vitamin D levels are at a higher risk of respiratory infections and the occurrence of wheezing during early childhood.

"Our data suggest that the association between vitamin D and wheezing, which can be a symptom of many respiratory diseases and not just asthma, is largely due to respiratory infections," said Carlos Camargo, lead author of the study.

Although vitamin D is commonly associated with its role in developing and maintaining strong bones, recent evidence suggests that it is also critical to the immune system.

The researchers analysed data from the New Zealand Asthma and Allergy Cohort Study, which followed more than 1,000 children in the cities of Wellington and Christchurch

Survey results covering the first five years of the participants' lives showed that, the lower the neonatal 25OHD level, the higher the cumulative risk of wheezing during that period. But no significant association was seen between 25OHD levels and a physician diagnosis of asthma at age 5 years.

Some previous studies had suggested that particularly high levels of vitamin D might increase the risk for allergies, but no such association was seen among study participants with the highest 25OHD levels.

Camargo noted that very few children in this study took supplements; their vitamin D status was determined primarily by exposure to sunlight.

Camargo said that the study results do not mean that vitamin D levels are unimportant for people with asthma.

"There's a likely difference here between what causes asthma and what causes existing asthma to get worse. Since respiratory infections are the most common cause of asthma exacerbations, vitamin D supplements may help to prevent those events, particularly during the fall and winter when vitamin D levels decline and exacerbations are more common," he said.

The findings were reported in the journal Pediatrics.