Why natural sun exposure is better than supplementation for increasing vitman D levels.

What if I told you we actually NEED sun exposure to survive? And not just looking at it through the window – I mean getting out there, into the sun, no hat, no sunscreen and lots of skin on display!

Why do we need the sun?

Apart from the fact that sunshine makes most of us feel happier, we need the sun to stimulate synthesis of vitamin D.

Now, we all know the risks of excessive  exposure – and by excessive I mean laying out on the beach until you could pass for a lobster. No, this is not the way to go. I mean sensible, monitored & safe sun exposure.

The World Health Organisation (WHO) released a report in 2006 which examined the burden of disease caused by exposure to ultraviolet radiation. Other than malignant melanoma, the actual resulting disease from UV radiation that disrupted quality of life was far lower than expected, and represented a very small portion of the global burden associated with reduction in life expectancy, or disability caused by disease (0.1%).[1]

This same report also showed that the burden caused by vitamin D deficiency due to LACK of sun exposure was significantly higher – 3.3 billion disability adjusted life years or DALY’s.  DALYs measure how much a person’s expectancy of healthy life is reduced by death or disability. [2]

In addition, the other benefits of healthy sun exposure include release of nitric oxide to lower blood pressure and endorphin production which helps to elevate mood. Sunshine helps to regulate the sleep-wake cycle, as melatonin production is partly dependent on exposure to natural light.

Why vitamin D deficiency contributes to ill health.

Low levels of vitamin D are associated with many of the more serious illnesses, including many cancers, autoimmune conditions (like lupus, rheumatoid arthritis & Coeliac disease), chronic fatigue & fibromyalgia and structural disease like osteoporosis & Rickets. Why is this? Because vitamin D is required by over 3000 different genes in the body, and virtually every tissue requires it in one way or another.

Why vitamin D supplementation is not ideal.

There is a difference between our own endogenously manufactured vitamin D & the one we get from a bottle.  For instance, just a half hour in the sun with maximum skin exposure (i.e. bathers or swimsuit) & no sunscreen applied, will result in vitamin D production of up to 50,000IU. This amount is reduced if the person is tanned or dark-skinned. This level of vitamin D is very difficult to obtain through supplementation – a standard capsule usually contains a mere 1000IU.

UVR induced immunosuppression

An interesting reaction occurs in the skin in response to ultraviolet radiation. T cell responses are suppressed, but the innate immune system response is upregulated.

T cell activation contributes to epithelial inflammation, so this reduction in response may not necessarily be a bad thing. Increased risk of infection is not an issue, because the innate side of the immune system takes care of any invading pathogens by producing antimicrobial peptides. Thus, suppression of the adaptive and induction of the innate immune system by UVR may be components of a physiological protection process.[3]

So the motto of this story is  – respect the sunshine! Understand that, as with many things, moderation is the key. A little bit of sun is good, too much is bad.


[1] Mead, N.M. (2008). Benefits of Sunlight: A Bright Spot for Human Health. Environmental Health Perspective. 116(4): A160–A167.

[2] Mead, N.M. (2008). Benefits of Sunlight: A Bright Spot for Human Health. Environmental Health Perspective. 116(4): A160–A167.

[3] Schwarz, T. (2010). The dark and sunny sunsides of UVR-induced immunosuppression: photoimmunology revisited. Journal of Investigative Terminology.130(1):49-54.


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