Published Online: August 15, 2015
People who live furthest from the Equator (and who have less exposure to UV) are more likely to develop food allergy, which suggests that vitamin D may play a role in the development of this condition. In the HealthNuts food allergy study, Caucasian infants with peanut and egg allergy were 11 and 3 times, respectively, more likely to have vitamin D insufficiency. However, the association between low vitamin D and food allergy risk was not found in infants of Asian descent.
In an article recently published in The Journal of Allergy and Clinical Immunology (JACI), Koplin and colleagues explored whether genetic factors could explain the difference in the association between vitamin D insufficiency and food allergy risk in different populations. Gene changes (polymorphisms) that encode for a decrease in vitamin D binding protein levels increase the biological availability of serum vitamin D. Asian infants have higher rates of these polymorphisms, thus providing a potential mechanism for why low vitamin D does not increase their risk of food allergy. Serum vitamin D (25OHD3) levels and vitamin D binding protein genetic polymorphisms were measured in 1-year-old infants with and without food allergy participating in the HealthNuts population-based cohort study. Infants with food allergy were followed up at age 2 years to determine persistence or resolution of food allergy.
In the whole cohort, persistently low vitamin D increased the likelihood of food allergy persisting to at least age 2 years, providing support for a potential role of vitamin D in disease resolution as well as disease development. However, Asian infants seemed to be protected from this association. This may have been due to their higher levels of polymorphisms in Vitamin D binding protein, which enhance utilization of low levels of serum vitamin D. These findings increase the biological plausibility of a role for vitamin D in the development of food allergy
Gene polymorphisms in the vitamin D binding protein can modulate the impact of vitamin D on food allergy risk. Vitamin D reference ranges may need to account for either vitamin D binding protein levels or ethnicity to account for the variation in prevalence of vitamin D binding protein polymorphisms. Future trials to determine whether supplementation in individuals with low vitamin D decreases the risk of food allergy or increases tolerance development in allergic infants are warranted, and stratification by ethnicity or genotype is likely to be important in these trials.
The Journal of Allergy and Clinical Immunology (JACI) is an official scientific journal of the AAAAI, and is the most-cited journal in the field of allergy and clinical immunology.