Claims of a need to bolster our vitamin D levels were further endorsed in the last week with the publication of new research, which adds a whole new dimension to the body of evidence supporting its essentiality for our health. In a rather small (n=8) but neat intervention trial researchers investigated the effects of vitamin D on gene expression - using white blood cells from supplemented individuals for analysis [1].
The researchers found that there was an extensive need for vitamin D in the body with it significantly effecting the expression of 291 genes - primarily involved in inflammation, autoimmune responses, cardiovascular functioning and cellular growth. This is in line with previous analyses which estimated that 0.5-5% of the total human genome is influenced by the actions of vitamin D. With such far-reaching effects it is important that we don't make the mistake of perceiving vitamin D as a straightforward nutrient, but instead it being a pro-hormone. It is these hormonal actions which make it a master regulator of our physiological workings, and that it exerts such a wide breadth of effect. It is also why, just like in the case of any hormonal deficiency, achievement of sufficient levels is imperative in the pursuit of great health. And while the overt effects of correcting hormonal deficiencies can be more obvious in say the likes of the thyroid or sex hormones, we should not discount the subtler, but still essential, intricate workings of vitamin D.
Indeed in the aforementioned genomic analysis a comparison of vitamin D deficiency (16.2ng/ml - a typical level for this time of year in the UK) with those who were sufficient (27.5ng/ml - the level that sensible supplementation achieves) found that was a big difference in the expression of 66 genes. An analysis of these 66 genes revealed their role in immune functioning, and cellular response to stresses and DNA damage. Put simply; those who don't rectify the UK norm of having low vitamin D levels have unnecessarily put themselves at increased risk of cancer and immune disease, even if they follow an otherwise healthy diet and lifestyle.
It is because of this I want to address the current best scientific recommendations, as published in The Health Delusion, that individuals in the UK and countries of similar latitude should supplement 1,100 - 1,200 IU of vitamin D a day (to attain levels in the upper end of the 20-32ng/ml range) but only from October to March. Whilst the research continues to support this dosing recommendation, it is the time period I would like to address. The reasoning for supplementing throughout the winter months is that we can't make any vitamin D. Even on a sunny day the UVB is not of the correct wavelength (290-320nm) for vitamin D production.
But, from the start of April onwards we once again become capable of synthesising vitamin D from safe sun exposure. But, that's the snag; the requirement for the sun to be out. For who are we kidding; the calendar may say summer is coming, but clearly someone forgot to remind Mother Nature. Right now as I write this it's a boreal one degree and the ground is covered in a flurry of white. So as long as the weather continues with its perennial winter I will continue to take my vitamin D supplements. And it is only when the rain departs and the sun shows some face time, allowing me to at least be in t-shirt for a few consecutive days that I will stop supplementing. And I strongly suggest you do the same. As more and more research is published we become further convinced on just how important vitamin D is for our health, and why it is necessary to ensure we stay replete.
[1] Hossein-nezhad A, Spira A, Holick MF (2013) Influence of Vitamin D Status and Vitamin D3 Supplementation on Genome Wide Expression of White Blood Cells: A Randomized Double-Blind Clinical Trial. PLoS ONE 8(3): e58725. doi:10.1371/journal.pone.0058725