Vitamin D plays a vital, key role in your immune system. A deficiency can lead to fatigue, depression, seasonal affective disorder (SAD) and a weakened immune system. It’s the weakened immune system that exposes you to the common cold, but also to flu and other infections. On that note, vitamin D has been shown to decrease the severity of influenza, as well as your chances of catching it. Vitamin D is also know to be responsible for regulating calcium absorption and, therefore, your bone density. It’s also thought to positively affect many other diseases, including: colon and breast cancer, respiratory disease and type-1 diabetes.
So, where do we get vitamin D from?
Vitamin D is vital for human health and we get it through sunlight exposure and diet. Our main source is from the sun. In the winter, we spend more time indoors and there is less sunshine when we are outside, so our exposure level drops below what our bodies need. This decrease is linked to a weakened immune system and therefore one of the theories behind why most people get colds in the winter. Vitamin D levels also drop in pregnant and breast feeding women, young children and older people, darker-skinned people and those who wear full-body coverings.
We can supplement our decreased production of vitamin D from sunlight with our diet. Mackerel sardines and fish liver oil are good sources of natural vitamin D. You can get supplements, too. The only downside of vitamin D in our diet is that it is not as effective. When you ingest vitamin D, only 60% of it sticks to vitamin D-binding protein; but when you make vitamin D through sunlight hitting your skin, 100% of it binds to the protein. A study at Leiden University in Holland has been done on the difference of these two different methods. Three groups each received either daily supplements of vitamin D, a sunbed session three times a week or nothing. At the end of the trial, in the group that received nothing, their vitamin D levels had fallen. In the group that took supplements, their levels had significantly increased. However, the highest increase was in the group that used the sunbeds – responsibly, of course.
What is the best way to increase vitamin D levels in the winter?
In the northern hemisphere, between the months of September and March, there is insufficient sunlight to ensure optimum vitamin D synthesis. The best way to top up is to enjoy a winter holiday to the southern hemisphere. However, this isn’t a realistic solution. Therefore, it is essential to maintain a diet high in oily fish, like mackerel and sardines. This diet can be aided by supplementation as well.
On top of nutritional support, sunbeds can be used sensibly to boost your skins synthesis of vitamin D, as they’re the next best thing to natural sun exposure. For a lot of people, the idea of a sunbed conjures up the thought of increased skin cancer risk. In this regard, there is some truth. However, a sunbed used properly has health benefits that far outweigh any risks. Sunbeds produce the same UV rays as the sun, and it is these rays that produce vitamin D synthesis. Over exposure to these rays is what causes sunburn. It is when your skin is over exposed that there is an increase in the chance of a melanoma (skin cancer). The important thing to realise is the amount of time sufficient to produce vitamin D (varies depending on several factors, including skin colour) is less than the amount of time for the skin to redden and burn. Careful use of a sunbed, following recommended exposure for your skin type, and taking particular care not to burn and avoiding deliberately tanning, can actually help to maximise your natural vitamin D levels, and therefore the subsequent benefits, with minimal risk.
Professor Tim Oliver, a medical oncologist at Barts and the London Hospital, suggests a single five- to ten-minute sunbed session, once every six weeks, should be sufficient.
 F. R. de Gruijl, S. Pavel: The effects of a mid-winter 8-week course of sub-sunburn sunbed exposures on tanning, vitamin D status and colds. Photochemical Photobiological Science, 2012; 11 (1848)