Sunday, 1 March 2015

Vitamin D status affecting autoimmune disease risk?

I want to bring the paper from Tea Skaaby and colleagues [1] to your attention for today's brief blog post and their observation that there may be: "a possible protective role of a higher vitamin D status on autoimmune disease". Autoimmune disease by the way, reflects a breakdown in communication and tolerance of 'self' whereby the body attacks healthy tissue.

Their findings, based on an analysis of "a total of 12,555 individuals from three population-based studies with measurements of vitamin D status (25-hydroxy vitamin D)" hinted that "for a 10 nmol/l higher vitamin D" the hazard ratios for quite a few autoimmune conditions seemed to be reduced albeit with some quite wide confidence intervals (CIs). Overall however, the authors found a reduced HR "for any autoimmune disease (HR = 0.94 % CI 0.90, 0.98)" with that increasing levels of vitamin D.

It's not necessarily new news that vitamin D seems to have some important biological effects when it comes to immune function [2] outside of the more classical physiological connections made to the stuff. Indeed, the paper by Tamblyn and colleagues [3] talking about an immunological role for vitamin D at the 'maternal-fetal interface' (where immune tolerance is required to "prevent fetal rejection") represents an area requiring far greater inspection particularly in light of guidance recommending vitamin D supplementation to pregnant women among other groups (see here).

Without hopefully cherry-picking from the growing research literature looking at vitamin D and autoimmunity, I would also like to bring in the paper by Dong Yeob Shin and colleagues [4] (open-access) and the suggestion that low vitamin D status might be "associated with anti-thyroid peroxidase antibody in autoimmune thyroiditis." Anti-thyroid peroxidase antibody (TPOAb) and autoimmune thyroiditis have been of particular interest to this blog in light of some initial data suggesting a connection with certain cases of depression (see here). That also depression has been looked at through the vitamin D lens specifically from the deficiency point of view is an interesting correlation (see here) perhaps connecting psychiatry, autoimmunity and vitamin D. I say all this acknowledging that correlation is not the same as causation and that not everyone with depression will present with autoimmune thyroiditis or other autoimmune conditions.

Certainly however, I'd wager that there is perhaps more to see when it comes to how the sunshine vitamin/hormone might link up with immune function (and dysfunction) and perhaps beyond taking into account some interesting work with autism in mind too. I'd be minded to also bring in the idea that permeability of a particular membrane might also be a spot requiring a little more study in light of other research suggestions [5] and some preliminary tie up with vitamin D (see here) combined with more recent data [6]. Just sayin'.

Bloodbuzz Ohio by The National to close, and what a baritone...

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[1] Skaaby T. et al. Prospective population-based study of the association between vitamin D status and incidence of autoimmune disease. Endocrine. 2015 Feb 11.

[2] Antico A. et al. Can supplementation with vitamin D reduce the risk or modify the course of autoimmune diseases? A systematic review of the literature. Autoimmun Rev. 2012 Dec;12(2):127-36.

[3] Tamblyn JA. et al. Immunological role of vitamin D at the maternal-fetal interface. J Endocrinol. 2015 Mar;224(3):R107-R121.

[4] Shin DY. et al. Low serum vitamin D is associated with anti-thyroid peroxidase antibody in autoimmune thyroiditis. Yonsei Med J. 2014 Mar;55(2):476-81.

[5] Fasano A. et al. Intestinal permeability and its regulation by zonulin: diagnostic and therapeutic implications. Clin Gastroenterol Hepatol. 2012 Oct;10(10):1096-100.

[6] Assa A. et al. Vitamin D deficiency promotes epithelial barrier dysfunction and intestinal inflammation. J Infect Dis. 2014 Oct 15;210(8):1296-305.

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ResearchBlogging.org Skaaby T, Husemoen LL, Thuesen BH, & Linneberg A (2015). Prospective population-based study of the association between vitamin D status and incidence of autoimmune disease. Endocrine PMID: 25666936