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Role of Vitamin D in Allergy

Role of Vitamin D in Allergy. Dr. Elizabeth Kiragu Paediatric Allergy Specialist Aga Khan University Hospital, Nairobi KPA Conference 9 th April 2019. Primary role in bone homeostasis. Acceptable normal values for vitamin D. Deficiency : < 20 ng/ ml Insufficiency: 21-29 ng/ ml

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Role of Vitamin D in Allergy

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  1. Role of Vitamin D in Allergy Dr. Elizabeth Kiragu Paediatric Allergy Specialist Aga Khan University Hospital, Nairobi KPA Conference 9th April 2019

  2. Primary role in bone homeostasis

  3. Acceptable normal values for vitamin D • Deficiency : < 20 ng/ ml • Insufficiency: 21-29 ng/ ml • Sufficient : 30-50 ng/ ml

  4. Extra renal production in the immune system • Local production of Vitamin D 3 by cells that express the gene CYP27B1 • Epithelial cell,smonocytes, macrophages, APC, B & T cells express the VDR • Activation of the VDR leads to interaction with VDRE and transcription of target genes with various effects on the immune system • Immunomodulatory effect thought be an environmental factor in the pathogenesis of various immune conditions

  5. Decreases infection by microbial pathogens by increasing production of antimicrobial peptides • Strengthens the skin barrier • Promotes tolerance • Decreases lymphocyte responses • Influence on homing in of lymphocytes

  6. Adapted from Vitamin D in allergic disease: Shedding light on a complex problem. Muehleisen and Gallo, (J Allergy ClinImmunol 2013;131:324-9.)

  7. Role in asthma Mirzakhani et al, 2015

  8. Martineau et al, 2017

  9. Martineau et al, 2017

  10. Unable to do sub-analysis of doses • Wide range of doses used < 400 > 2000 IU • Bolus and daily versus daily doses • Baseline Vitamin D level • Some studies found exacerbation of COPD in patients with higher baseline vitamin D who received further doses • Severity of asthma • Excluded severe asthma

  11. Kim et al 2016

  12. Limitation • Sample size too small to make definitive conclusions • Issues noted in studies included: • Different dosses used 800 IU/ day – 4000 IU/ day • Different types of Vitamin D • Different dosing intervals • No baseline Vitamin D measured • No control for confounders

  13. Trend towards lower Vitamin D levels in CSU patients • 12 studies • 1 – no difference • 1- opposite • Vitamin D supplementation in CSU improves symptoms • Better response with higher doses

  14. 5105 participants • Pooled analysis – OR 1.35 95% CI (0.79- 2.29) p= 0.27 between Vitamin D and Food allergy • 4 studies defined Vitamin D deficiency < 20 ng/ ml: OR 1.18 95% CI ( 0.62- 2.27) p= 0.62 • 1 study – defined Vitamin D deficiency as < 30 ng/ ml: OR 2.04 95% CI( 1.02- 4.04) P = 0.04

  15. Conclusion • Vitamin D has various effects on the immune system • These effects can be utilized in the management of allergic conditions • Role in prevention require better designed long term studies • Stick to current guidelines

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