Investigating the Relationship Between Vitamin D, Food-Related Allergies, and Anaphylaxis: A Systematic Review

Context Food-related allergies are a growing public health concern, with increasing prevalence and severity in recent decades. The Vitamin D hypothesis suggests a potential link between Vitamin D levels and food allergies, yet scientific understanding remains limited. This review is particularly relevant for family medicine and primary care as it explores preventive strategies and therapeutic approaches for food-related allergies. Objective To investigate the relationship between serum 25(OH)D levels, food-related allergies, and anaphylaxis in children and adults. Design This systematic literature review was conducted per PRISMA guidelines. Patients or Other Participants Eligible studies included peer-reviewed cohort studies, randomized controlled trials, or cross-sectional studies investigating the outcome of interest in children and/or adults. Participants included 10,220 individuals across 14 studies (mean age of children: 4 years; adults: 20 years). Racial, ethnic, and socioeconomic backgrounds varied significantly. Most participants had Fitzpatrick Type II-III skin. Egg allergy was most frequently reported, followed by cow’s milk protein allergy. Intervention/Instrument Measurement of serum 25(OH)D levels in participants with a history of food-related allergies or anaphylaxis. Main and Secondary Outcome Measures Serum Vitamin D levels in participants with food allergies compared to participants without food allergies. Results In children, the average Vitamin D level was 26 nmol/L in the food allergy group compared to 28 nmol/L in the control group, with a higher prevalence of Vitamin D deficiency or insufficiency observed in the allergy group compared to the control (1069 vs. 607 participants). There was insufficient data pooled for adult study participants. Conclusions Data generally supports an inverse correlation between Vitamin D levels and food-related allergies in children. However, limited data and methodological inconsistencies hinder definitive conclusions. Future research should focus on standardized Vitamin D reporting and methodological consistency to clarify Vitamin D’s role in food-mediated allergies and anaphylaxis.