Below normal levels of vitamin D, due to low sun exposure, have been associated with increased incidence of food allergy and eczema in children, say researchers.
The study – published in Journal of Allergy and Clinical Immunology – reports that increased exposure to sunlight could reduce the risk of both food allergies and eczema in children. The researchers, led by Dr Nick Osborne from the European Centre for Environment & Human Health, at the Peninsula College of Medicine and Dentistry, UK, with several Australian institutions, found that children living in areas with lower levels of sunlight, and thus with low vitamin D status, are at greater risk of developing food allergies for egg and peanuts and the skin condition eczema, compared to those in areas with higher levels.
Speaking with NutraIngredients, Dr Osborne explained that the data used in the new research comes from two separate studies in Australia – a particularly good place for this type of study as it spans nearly 3000 miles from North to South – in both four-to-five year-olds and in eight-to-nine year-olds.
“To our surprise we found that allergy incidence changed from the Northern states that are closer to the equator where there was a low rate of incidence, and as we moved down towards the middle and then Southern states we found incidence was higher,” explained Osborne.
As well as finding a link between latitude and allergies to peanut and egg, the results showed that on average children in the South of the country are twice as likely to develop eczema as those in the North, he said.
Osborne noted that such findings build on existing evidence that suggests vitamin D status may play a role in rising levels of food allergy and eczema.
The research team used the Australian study data to analyse how rates of food allergy, eczema and asthma varied throughout the country. Osborne added that the study was the first to utilise population data from a large scale epidemiological study to investigate such an association.
“We found that a latitude gradient existed for both food allergy (peanut and egg allergy) and eczema, but not for asthma, in both age groups assessed,” wrote the researchers.
They added that in the eight-to-nine year-old cohort, the odds of having a peanut allergy were six times greater in Southernmost regions when compared to the Northernmost areas, whilst the odds of having eczema doubled.
“Similar to asthma, we found no latitudinal gradient for cow’s milk, wheat, and combined other food allergies,” they said.
Osborne said he believes these findings provide us with an important insight into the prevalence of food allergies and eczema, which appear to be on the increase. However he cautioned that – as with many areas of vitamin D research – further research is needed before policies that advocate supplementation could be given credence.
"Its an interesting area of research, but there are still quite a few unknowns out there," said Osborne.
“Vitamin D supplement may be appropriate for some people, but on the flip side getting out into the great outdoors also has great benefits,” he added.
Source: Journal of Allergy and Clinical Immunology
Published online ahead of print, doi: 10.1016/j.jaci.2012.01.037
“Prevalence of eczema and food allergy is associated with latitude in Australia”
Authors: N.J. Osborne, O.C. Ukoumunne, M. Wake, K.J. Allen,