To D or not to D?

Most of us living in the more northern latitudes know how vital vitamin D supplementation is during the winter months, but are our levels compromised in the summer months too by sunscreen and covering up?

Vitamin D is formed by the action of sun on the skin. The specific wavelength of light needed to do this is the UVB wavelength - the same rays that sunscreens are designed to block in order to prevent damage to the skin. Of course nobody wants to run a higher risk of skin cancer, and parents are encouraged to keep children out of the sun or covered up with sunscreen, clothing and headgear, but is this a double edged sword?

Research

Some research suggests adhering strictly to this advice can lead to vitamin D deficiency. Other studies conclude that vitamin D levels are not compromised, but ironically this is largely thought to be due to inadequate application of sunscreen (i.e. not enough). With campaigns geared up to encourage better application, deficiency could prove to be a growing problem.

It's not just children that might be at risk of vitamin D deficiency. As we age, our capacity to make our own vitamin D diminishes, whilst genetic variations and magnesium deficiency are also known to leave some of us more prone to lower levels. Those with darker complexions are more at risk as vitamin D synthesis is less than in those with fairer coloured skin. Interestingly, those with a BMI of over 30 are also at increased risk as the body tends to store vitamin D in the fat cells making it less available for use.

It has been estimated that spending 15 minutes uncovered and unprotected at midday during the summer months at around 40 degrees North, fair skinned people are able to produce around 1000iu of vitamin D a day. With a latitude of just over 55 degrees north this time would increase in the UK and much of Northern Europe. But why do we even need vitamin D?

Research shows ever increasing roles for vitamin D in the body. Bone health, immune function, prevention of autoimmune conditions (Lupus, MS and Rheumatoid arthritis in particular), blood pressure regulation and cancer protection are amongst the most well researched areas. Newer research is also starting to build up a better picture of its role in cognition, Alzheimer’s disease and blood sugar control.

So where does that leave us?

Well the jury might still be out on the sunscreen debate, but our northerly latitude certainly seems to earn vitamin D supplementation a deserved place in the summer months as well as the winter ones. Don’t leave yourself or your loved ones deficient - do the D!