Vitamin D Status in Cow’s Milk Protein Allergy

Introduction: Cow’s milk protein allergy (CMPA) affects 1.9 - 4.9% of children worldwide and can be IgE-mediated or non-IgE mediated. Studies have highlighted the increased risk of inadequate vitamin D intake in children with CMPA on elimination diets, with potential effects on bone health, respiratory health and immune function. This study aims to investigate whether children with CMPA are at a higher risk of vitamin D insufficiency than their healthy counterparts. Methods: This was an observational, cross-sectional study carried out at the specialist Paediatric Allergy Clinic, Bon Secours Hospital Cork and the Department of Paediatrics, Bon Secours Hospital Cork. 52 children with CMPA and 26 healthy controls, aged 6 to 24 months, were included. Exclusion criteria included known bone metabolism disorders, chronic renal and gastrointestinal disorders, and chronic infectious diseases. A retrospective chart review of children with CMPA was conducted to collect data on patient demographics, clinical presentation, and management. Serum 25(OH)D levels of children with CMPA (n=18) and healthy controls (n=26) were quantified and compared. Caregivers of children with CMPA were administered an online questionnaire to assess compliance to vitamin D supplementation.  Results: The serum 25(OH)D levels of children with CMPA were significantly lower than that of healthy controls (47.5 vs 62.5 nmol/L, p = 0.030). Among children with CMPA, children with IgE-mediated CMPA (p=0.041) and children with multiple concomitant IgE-mediated food allergies (p=0.011) had significantly lower serum 25(OH)D levels than their healthy counterparts. Among children with CMPA, breastfeeding status, reported vitamin D supplement use, age and gender were not significantly associated with serum 25(OH)D levels. The questionnaire revealed only 44.4% of caregivers to be fully adherent to vitamin D supplementation guidelines. Conclusion: Children with CMPA are at higher risk of serum 25(OH)D insufficiency than healthy controls. Closer monitoring is required to ensure that vitamin D supplements are administered from birth to 12 months, at the recommended frequency.