Low levels of vitamin D in newborns may increase the risk of respiratory infections and wheezing in children, but not asthma, according to an international study.

In some previous studies, a link has been found between vitamin D deficiency and increased risk of cognitive impairment and memory robbing condition dementia later in life.

Some other studies also touted the 'sunshine' vitamin as an effective and trustworthy nutrient packed with numerous health benefits, including warding off heart disease.

An earlier research has showed that women who take vitamin D supplements during pregnancy are less likely to have offspring who develop wheezing during childhood.

Vitamin D deficiency linked to wheezing, respiratory infections
Now researchers at the Massachusetts General Hospital (MGH) have suggested that newborn babies who are deficient in vitamin D seem to be more vulnerable to respiratory infections in their first few months of life, and wheezing during early childhood.

Carlos Camargo, MD, DrPH, of the Massachusetts General Hospital (MGH) in Boston, who led the study, said that acute respiratory infections make children prone to health risks.

"For example, bronchiolitis - a viral illness that affects small airway passages in the lungs - is the leading cause of hospitalization in U.S. infants," he said.

Study details:

To reach findings, Camargo and researchers from New Zealand analyzed data from the New Zealand Asthma and Allergy Cohort Study, which followed 922 children in the cities of Wellington and Christchurch, for whom umbilical cord [The flexible cordlike structure connecting a fetus at the abdomen with the placenta and containing two umbilical arteries and one vein that transport nourishment to the fetus and remove its wastes.] blood was available.

According to WebMD.com, of the study infants, most were born at term, 40 weeks, with an average weight of about 3.6 kilograms.

As per the health website, the participants' mothers were also frequently asked about their children's history of asthma, wheezing, respiratory infection and other infectious diseases from age 3 months until the children were 5-years-old.

The children's umbilical chord blood was measured for levels of 25-hydroxyvitamin D (25OHD) that is reflective of vitamin D status.

Study findings:

After testing the blood for 25-hydroxyvitamin D (25[OH]D) and comparing with parental reports of wheezing, asthma diagnoses and respiratory infection five years later, the researchers found that the overall average cord-blood level of 25(OH)-vitamin D was 44 nanomoles per liter (nmol/L), which was considered low.

Also 20 percent or slightly fewer than one in five had 25-hydroxyvitamin D levels below 25 nmol/L, which is considered insufficient.

Vitamin D deficiency was more common among children born in the winter, infants and children from lower socioeconomic status, and children who had family histories of asthma and smoking and who had been exposed to secondhand smoke at an early age.

Compared with infants whose cord blood levels were at least 75 nmol/L, those with levels between 25 and 74 nmol/L had a 39 percent increased risk of infection, and those with levels below 25 nmol/L were twice at risk.

"Or 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 Camargo.

"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. That idea needs to be tested in a randomized clinical trial, which we hope to do next year."

The study findings appear in the January issue of the journal 'Pediatrics.'

A little about vitamin D
Vitamin D is also called the "sunshine vitamin" because of its exceptional quality of being produced by the body by just basking in the warm sun.

It is a fat-soluble vitamin that is naturally present in very few foods but is available as a dietary supplement.

As little as 30 minutes of early morning or late afternoon sunlight on the face, hands and arms two or three times a week can supply the entire Vitamin D one needs.

In addition, many experts recommend 400-600 IU a day for people over the age of 50, and 800 IU for those over the age of 70. For younger adults, 200-400 IU a day is probably sufficient.