The Nutrigenetics and Pharmacogenetics of Vitamin D Pathways

In this manuscript, we review the literature on the nutrigenetics and pharmacogenetics of vitamin D pathways, with a focus on genes involved in the pharmacokinetic and pharmacodynamic pathways of vitamin D as they have been major research targets. These include: VDR, CYP2R1, CYP27B1, DHCR7/NADSYN1, GC and CYP24A1. So far only 2 genome wide associations studies evaluated the potential role of genetic polymorphisms in the variability in 25 hydroxy vitamin D (25(OH)D) levels. Most of the evidence is based on the candidate gene approach with some conflicting results when it comes to effect size and associating disease outcome with 25(OH)D levels and genetic polymorphisms. Moreover, very little has been done to look at the effect of significant polymorphisms on the response to vitamin D supplementation. Further research is needed on larger population samples of different ethnicities to resolve some of the controversies. In addition, emerging technologies such as next generation sequencing may be a better genotyping alternative in order to detect rare but potentially important genetic variants. Functional studies are also needed to better understand the association results. This includes coupling genotyping data with gene expression studies as well as epigenetic evaluations.