Many studies suggest that Vitamin D insufficiency contribute to allergen sensitization and allergic diseases, but those findings vary between populations. The aims of this study were to evaluate vitamin D levels in pregnant women and infant at birth and 1 year, and to assess association of vitamin D levels with allergic diseases and allergen sensitization in early life.
CHIBA study is a longitudinal birth cohort study of 256 infants with family history of atopy in Chiba city (urban area), Japan. Serum Vitamin D levels in mothers during pregnancy, cord blood, and children at 1 year of age were measured using liquid chromatography tandem mass spectrometry. Associations between vitamin D levels with allergic diseases and allergen sensitization at 1 year of age were analyzed.
Prevalence of atopic dermatitis, food allergy, and bronchial asthma at 1 year of age were 15.6%, 8.3%, and 2.0%, respectively. Sensitization rate to house dust mite and egg white were 7.1% and 33.3%. Median vitamin D levels (ng/ml) in mothers, cord blood, and children were 12.1 (interquartile range: 9.1-16.0), 6.0 (4.6-8.2) and 21.0 (13.7-25.7), respectively. Prevalence of vitamin D deficiency (Vitamin D<20 ng/ml) in mother and 1-year-old children were about 90% and 50%. There was no correlation between vitamin D levels in maternal and cord blood and allergic diseases /allergen sensitization at 1 year of age. Vitamin D levels in 1-year-old children were correlated with egg sensitization.
In Japanese urban area, almost all pregnant women and a half of 1-year-old children have vitamin D deficiency.