A lack of vitamin D because of protection from the sun may be leading to more children developing asthma and allergies.
Auckland's Starship Hospital paediatrician Cameron Grant has published a study showing for the first time that mothers taking vitamin D supplements during their pregnancy prevent children developing allergies.
Taking the supplements also reduced the number of times children needed to be taken to the doctor.
At birth 57 percent of New Zealand newborns have low concentrations of vitamin D.
Both asthma and allergies are highly prevalent in New Zealand with 25 percent of six to seven-year-olds reported with asthma, and 35 percent of 11 to 12-year-olds having an allergic response to dust, plants or food.
Dr Grant said he could not yet say that vitamin D supplements definitely prevent asthma.