On Wednesday morning I had a nice chat over coffee with Oliver Gillie, a writer and researcher with a particular interest in vitamin D. We spent much of our time talking about the role vitamin D may have in a wide range of conditions including role in a range of conditions including cancer, diabetes, multiple sclerosis and schizophrenia. We also talked about the role of vitamin D in the functioning of the immune system. We talked, for instance, about the ability of vitamin D to stimulate the production of anti-microbial compounds.

Back in June I devoted a post to some research which links vitamin D with protection from infection, including ‘upper respiratory tract infections’ (URTIs) such as coughs and colds. This may have particular significance in winter, when vitamin D levels tend to fall. In 2007 I wrote a post which played with the idea that peaks in rates of cold and flu in the wintertime might be related to relative vitamin D deficiency and the immune compromise this may induce.

Some of you may know that over the last year or so I have been on a personal mission to optimise my vitamin D levels. I wrote about this most recently in December. One of the commenters on this piece (Nigeepoo) raised the issue of vitamin D’s influence on resistance to infection, and expressed interest in how I would go before catching something. I remembered this during my conversation with Oliver earlier this week.

It suddenly occurred to me that I have not had a single infection for at least a year. As Nigeepoo pointed out, I might be at somewhat enhanced risk of contracting an infection because I see patients. There may be some truth in this. On top of this, I do a fair amount of air travel, and as many of us know, aircraft cabins can be incubating chambers for cold, flu and other infective organisms. I spent a fair amount of time over Christmas a New Year in a house inhabited by people who went down with something viral at one time of another. The bottom line is I’ve had plenty of opportunity to contract a viral infection.

And through all of this, I have not had so much as a hint of infection. No runny nose, cough, sore throat, fevered brow – nothing.

Going a whole year without any infection at all is, I think, rare if not unheard of for me. For example, I remember going down with a cold/flu-like illness the previous Christmas (2008) that lasted a few days.

Now, it’s impossible for me to say whether vitamin D has anything to do with this. However, my personal experience is that optimising my vitamin D levels has coincided with a degree of immune resilience (Nigeepoo had a similar experience). Should I eventually succumb to something, I’ll fess up in the form of a post.