There is evolving evidence that vitamin D insufficiency may contri
bute to food allergy,
but findings vary
between populations. Lower vitamin D–
binding protein (DBP) levels increase the
biological availa
bility of serum vitamin D. Genetic polymorphisms explain almost 80% of the variation in
binding protein levels.
bsSec_2">Objective
bspara0015">We sought to investigate whether polymorphisms that lower the DBP could compensate for adverse effects of low serum vitamin D on food allergy risk.
bsSec_3">Methods
bspara0020">From a population-based cohort study (n = 5276) we investigated the association between serum 25-hydroxyvitamin Db>3b> (25[OH]Db>3b>) levels and food allergy at age 1 year (338 challenge-proven food-allergic and 269 control participants) and age 2 years (55 participants with persistent and 50 participants with resolved food allergy). 25(OH)Db>3b> levels were measured using liquid chromatography-tandem mass spectrometry and adjusted for season of blood draw. Analyses were stratified by genotype at rs7041 as a proxy marker of DBP levels (low, the GT/TT genotype; high, the GG genotype).
bsSec_4">Results
bspara0025">Low serum 25(OH)Db>3b> level (≤50 nM/L) at age 1 years was associated with food allergy, particularly among infants with the GG genotype (odds ratio [OR], 6.0; 95% CI, 0.9-38.9) but not in those with GT/TT genotypes (OR, 0.7; 95% CI, 0.2-2.0; P interaction = .014). Maternal antenatal vitamin D supplementation was associated with less food allergy, particularly in infants with the GT/TT genotype (OR, 0.10; 95% CI, 0.03-0.41). Persistent vitamin D insufficiency increased the likelihood of persistent food allergy (OR, 12.6; 95% CI, 1.5-106.6), particularly in those with the GG genotype.
bsSec_5">Conclusions
bspara0030">Polymorphisms associated with lower DBP level attenuated the association between low serum 25(OH)Db>3b> level and food allergy, consistent with greater vitamin D bioavailability in those with a lower DBP level. This increases the biological plausibility of a role for vitamin D in the development of food allergy.