The sun is out and sales of sun cream are sky high, but is it really that bright to smother yourself in cream and cover up any time you venture out?

Like most things in life, the answer is about balance and it seems that we are overdosing on ‘sun sense’ at the expense of our health.

The tiny nutrient at the centre of this controversial debate is vitamin D. The bad news is that vitamin D deficiency is on the rise and has been linked to Multiple Sclerosis, Osteoporosis, Alzheimer’s and rickets.

The good news is that Oxford is home to cutting-edge research into vitamin D deficiency and how to tackle it.

So how does vitamin D actually work and how can we make sure we are getting enough?

We get vitamin D from two sources: Diet and the sun. Our dietary intake makes up about 10 per cent of the vitamin D we really need and typically comes from animal products like oily fish, meat and dairy.

This means that vegetarians and particularly vegans need to be extra careful about their vitamin D levels.

Vitamin D from diet works pretty much like other vitamins – you eat foods containing the vitamin and your gut acts like a very busy train station. Freight trains come to collect each vitamin and take them along a specific track to their ultimate destination.

The way we get vitamin D from sun is a bit like the conversion of sunlight into energy in solar panels. It is made when Ultra Violet light from sun converts a type of cholesterol in our skin into vitamin D3.

This is then taken through the body to the kidney where it is turned into the vitamin that our brains know and our bones love. But tan-aholics shouldn’t get too excited; this is not an excuse to bake yourself leathery! You really only need 10 minutes of unadulterated sun each day (a little longer on cloudy days).

We have known for a long time just how important vitamin D is for bones. This is because calcium and vitamin D work in a beautiful, but inseparable, partnership to build bone.

Rickets and osteoporosis have long been known to be linked to vitamin D deficiency but Oxford researchers are showing that the story does not end there. Professors Giulio Disanto and Sreeram Ramagopalan, from Oxford’s Wellcome Trust Centre for Human Genetics, have discovered that vitamin D deficiency is linked to a higher risk of getting Multiple Sclerosis (MS).

Their latest work shows that the vitamin is involved on a genetic level in more than 2,000 immune system activities. Prof Disanto said: “This finding demonstrated that individuals who are less able to activate vitamin D are more susceptible to the development of MS.”

It may also provide the missing puzzle piece for many other immune system diseases that have been linked to Vitamin D deficiency such as asthma and rheumatoid arthritis. There is also a link with brain health.

Professor David Smith at Oxford’s Department of Pharmacology is investigating links between Vitamin D and Alzheimer’s. He said: “We found that common mutations in the gene for the vitamin D receptor is associated with an increased risk of Alzheimer’s disease.”

Vitamin D has also been implicated in some cancers such as breast and prostate cancer. It can act like a hormone in the body and errors in the manufacture and processing of it may impact on the risk of developing these cancers. Some very large studies on this are taking place in Oxford. The EPIC-Oxford study involves more than 65,000 participants.

It will take some time for our scientists to fully understand the role of Vitamin D in disease. In the meantime you can be confident that by adding a sensible dose of sun to your daily routine you will be doing your cells a favour.