Seventh Food & Health Group Meeting – Vitamin D

By contrived coincidence our vitamin D talk was held on the Summer Solstice June 21st.

In the first set of slides, above, we look at the role of vitamin D in the body, vitamin D status – as indicated by the levels of 25-hydroxyvitamin D in your blood – and what level is now considered insufficient, sufficient, optimal or excessive. We see how many people in Northern latitudes are deficient or insufficient for much of the year, especially if they avoid the sun or have dark skin. A remarkable set of graphs show the link between vitamin D status and a wide range of diseases, including cancers, heart disease and autoimmune diseases – leaving us in no doubt that our vitamin D status is important. In the section “Vitamin D metabolism” the basic physiology of vitamin-D and calcium metabolism is considered, before turning to the much more recently discovered critical role of vitamin-D in cellular DNA switching. This last section was a complete eye-opener to me and to many of the doctors and laymen in the audience.

The second section of slides covers a series of independent studies of Vit D and various medical conditions; some amazing information about how Vit D is crucial for maintaining tight junctions – the ‘stitching’ between cells that not only holds them together, but also permits adjacent cells to communicate with each other. It is shown how a lack of Vit D means cells can get out of sync with each other, and so may start to behave independently leading to excessive growth and cancer (this is a relatively recent theory by the brilliant Frank Garland of University of California and explains why Vit D deficiency is so strongly correlated with cancer). The subject of which supplementation may be better is then covered, with caveats followed by the all important food sources of Vit D and why it may be that so many people are currently found to be in the deficient category.

The third section of slides covers sunlight’s varoius wavelengths and how they affect the skin and the cells within the skin including the melanocytes (that give you a tan). We look at Richard Weller’s work, which shows that sunlight itself – not just the UVB part that produces Vit D – lowers blood pressure and is a significant factor in heart and blood vessel health. Skin cancer, especially melanoma, is considered along with the relative effects due to UVA and UVB. The effect of sun creams is considered showing that their preferential absorption of UVB may tend to increase skin cancer risk. Unbelievably, no sun-block has ever been tested for skin cancer protection! In the next section we see how world-wide disease incidence correlates to latitude suggesting a central protective role for sun exposure, and particulalrly UVB. We then a look at the sun-lamps for vitamin D, leading to the conclusion that a UVB Narrowband lamp (311 nm types) are the best choice for maximising vitamin D production whilst minimising skin damage and aging. We briefly look at the skin anti-aging effect of red light therapy through stimulating collagen production. Finally, a common observation among low-carb dieters is that they burn less in the sun. We present some little known evidence for the skin protective effects of meat and animal products and contrast this with the detrimental effects of vegetable oils (n6-PUFAs) which can increase skin damage.

We hope you enjoy reading these slides as much as we enjoyed putting the talk together. A big subject, but then, it all starts with a big star – the sun!

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