Genetic factors could explain the difference in the association between low vitamin D and food allergy risk in different populations.
In many studies low vitamin D has been found to increase the likelihood of food allergy, however results have varied depending on the studies’ location around the world. Researchers from Murdoch Children's Research Institute have found an explanation as to why this may be the case.
Researchers studied over 600 infants and found that gene changes in the vitamin D binding protein can control the impact of vitamin D on food allergy risk. The study showed Asian infants have more gene changes, which is why low vitamin D does not increase their risk of food allergy.
In the study vitamin D levels and vitamin D binding protein levels were measured in one-year-old infants with and without food allergy. Infants with food allergy were followed up at two years of age to determine persistence or resolution of food allergy.
The study found persistently low vitamin D levels increased the likelihood of food allergy persisting to at least two years of age. However, this effect was found to be population specific. Conversely researchers also found infant vitamin D levels appear to be important in predicting the resolution of food allergy.
Maternal use of vitamin D supplementation during pregnancy was also found to be associated with a reduced risk of food allergy.
“Our findings may explain population differences in the association between vitamin D and allergic disease and explain why some previous studies found a protective association with vitamin D supplementation and food sensitisation or allergy while others did not,” said lead researcher Dr Jen Koplin.
“We found evidence that genes modify the association between vitamin D insufficiency and food allergy. Our results could explain our previous finding that infants with parents born outside Australia showed no association between vitamin D and food allergy, while low vitamin D was a risk factor for food allergy among infants with parents born in Australia.”
Co-lead researcher Professor Katie Allen said these results will have implications for both the prevention and treatment of food allergy.
“Future trials to determine whether supplementation in infants with low vitamin D decreases the risk of food allergy or increases tolerance development in allergic infants is necessary. Vitamin D reference ranges may need to account for either ethnicity or genetic factors.”
Researchers at the Institute are currently recruiting for a vitamin D study which will investigate whether vitamin D supplementation in infants can prevent food allergy in the first year of life. The study, which will recruit 3000 infants, will compare the immune responses and vitamin D levels of children who receive a vitamin D supplement in the first six months of life with those who do not.