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: ng/ ml
Sufficient : 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,s monocytes, 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 Clin Immunol 2013;131:324-9.)

7. Role in asthma Mirzakhani et al, 2015
Vitamin D increases glucocorticoid effect – stimulation on MPK1 ( mitogen activated protein kinase phosphatase → anti infl, Also increases IL 10 - immunosuppressive
Mirzakhani et al, 2015

9. Reduction from 0. 44 – 0. 28 per person per year
Reduction from 0.44 – 0.28 per person per year. No effect on day to day asthma control, lung functions
Martineau et al, 2017

10. This analysis had a larger presentation of adults vs children 4% vs 19%
Martineau et al, 2017

11. 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

13. Kim et al 2016

14. 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

16. 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

17. 5105 participants
Pooled analysis – OR % CI ( ) p= between Vitamin D and Food allergy
4 studies defined Vitamin D deficiency < 20 ng/ ml: OR % CI ( ) p= 0.62
1 study – defined Vitamin D deficiency as < 30 ng/ ml: OR % CI( ) P = 0.04
Hampered by definition of Vitamin D deficiency

20. 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