or briefly vitamin D3. There seems to be another vitamin D /allergy abstract at the forthcoming EAACI congress from the KOALA study. The authors find

Risk for AD was highest for children in the fourth quintile of maternal 25(OH)D level [adjusted odds ratio (aOR) 2.08; 95%CI 1.07-4.03] compared to those in the third quintile; P for trend over the quintiles 0.03]. Risk of AD also increased over the childʼs 25(OH)D quintiles, P=0.01), where risk for AD was lowest in the first and second quintile (aOR 0.39; 95%CI 0.17-0.90 and aOR 0.41; 95%CI 0.19-0.91, respectively). The risk for sensitization at age 2 years increased with increasing maternal 25(OH)D levels (P-trend = 0.03) but for the child’s 25(OH)D level the risk was decreased in the lowest (a0R 0.53; 95%CI 0.29-0.96) and highest quintiles {aOR 0.52: 95%CL 0.28-0.94).

So, although very much in favor of the vitamin hypothesis, resuts are not fully clear (probably as serum levels do not always reflect oral supplements).