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Vitamine D tegen allergieën*
Uit een Europees-Australische studie onder Australische kinderen blijkt dat voedselallergieën, eczeem en astma wel de helft minder voorkomen in de noordelijke delen van Australië dan in het zuiden. Kinderen in het noorden (tot wel 4.500 km verschil met het zuiden) krijgen duidelijk meer zonlicht als gevolg van hun ligging dichter bij de evenaar en zonlicht zorgt voor de aanmaak van vitamine D in het lichaam. Vervolgonderzoek zal nog moeten uitwijzen welke factoren, zoals temperatuur, infectieziekten en vitamine D, een bepalende rol spelen binnen deze relatie.
Sunshine may help to prevent allergies and eczema
Increased exposure to sunlight may reduce the risk of both food allergies and eczema in children, according to a new scientific study.
Researchers from the Centre, along with several Australian institutions, have found that children living in areas with lower levels of sunlight are at greater risk of developing food allergies and the skin condition eczema, compared to those in areas with higher UV.
The research team used data from a study of Australian children and analysed how rates of food allergy, eczema and asthma varied throughout the country. 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.
The report builds upon existing evidence that suggests exposure to the sun may play a role in rising levels of food allergy and eczema. Sunlight is important because it provides our body with the fuel to create vitamin D in the skin, and locations closer to the equator typically receive higher levels of sunshine. Australia is a particularly good place for this type of study as it spans nearly 3000 miles from north to south, with a large variation in climate, day length and sun strength - from Queensland in the north to Tasmania in the south.
Dr Nick Osborne, who led the research, believes these findings provide us with an important insight into the prevalence of food allergies and eczema, which appear to be on the increase. Dr Osborne also cautioned that exposure to sunlight can vary for a host of reasons beyond latitude, such as local climate variations and behaviours, and these factors will also need to be considered.
He said “This investigation has further underlined the association between food allergies, eczema and where you live. We’re now hoping to study these effects at a much finer scale and examine which factors such as temperature, infectious disease or vitamin D are the main drivers of this relationship. As always, care has to be taken we are not exposed to too much sunlight, increasing the risk of skin cancer.”
Dr Osborne will be presenting the findings of the study at the American Academy of Allergy, Asthma & Immunology in Orlando on March 6th 2012.
The study is published in the Journal of Allergy and Clinical Immunology.
Prevalence of eczema and food allergy is associated with latitude in Australia
Recent reports from both Australia and the US suggest that vitamin D might play a role in the recent rise in allergic disease, in particular food allergy.
We examined this using the nationally-representative epidemiological study - the Longitudinal Study of Australian Children (LSAC) - containing information about two cohorts of children on State of domicile, parental report of food allergy, eczema and asthma, and potential confounders.
We found that a latitude gradient existed for both food allergy (peanut and egg allergy) and eczema, but not for asthma, in the two age groups assessed. In the 4-5 year old cohort, the southernmost children, i.e. those residing furthest from the Equator, were more likely to have each of food allergy and eczema. In the 8-9 year old cohort, the odds of having a peanut allergy were 6 times greater and the odds of having eczema were twice as great in southernmost children as those residing in the North.
This provides stimulus for research into possible causal roles of ambient UVR and vitamin D levels in this disease group.
This study is published in the Journal of Allergy and Clinical Immunology (Februari 2012)