Too little sunlight can be a dangerous thing

While our weather may be the subject of worldwide jokes our gloomy skies do have medical implications. Daily light levels throughout July have been dismal; not one day reached the expected average for this time of year, and seven days produced levels that were so low they could have come from a particularly bad day in midwinter. It's not just sufferers of SAD (seasonal affective disorder) that will be affected — it's the lack of sunlight on our skin that may lead to problems.

Despite preaching hellfire and damnation to teenagers addicted to sunbeds and cheap beach holidays I am a strong believer in "a bit of what you fancy does you good" therapy, and sunlight is no exception. Sunlight is actually good for health (here I insert all the usual caveats about midday sun, too much, too long etc).

Research shows that not being exposed to adequate amounts of sunlight causes many of us to develop vitamin D deficiency, especially as our diets can be low in it — it's found in only a small number of foods such as oily fish and eggs, which many people don't eat much of.

Sunlight exposure of the skin is known to be the most important source of vitamin D, and veiled Muslim women, despite living in countries with very high sunlight levels, are frequently deficient in vitamin D. Their health often suffers as a result.

Lack of sun has also been proposed as an important risk factor for cancer in western Europe, something that directly contradicts official advice about sunlight. The lower the sunlight levels, the higher the cancer rates. The cancers that seem to be most influenced by sunlight are breast, colon and ovarian cancer.

This doesn't mean that sun exposure has no effect on skin cancer — it most certainly does — but it suggests that perhaps our advice should be relaxed a little and not dictate that everyone must be smothered in sunblock all the time. My fear is that people aren't very good at judging how much is enough. To many it will seem we now have yet another risk assessment to make: bathe in the sun and increase our risk of skin cancer, or avoid it and increase our risk of other, far more common and deadlier cancers.

I would say that even with the potential increase in skin cancers most are relatively benign when compared with breast, colon and prostate and that sunshine can be enjoyed sensibly and safely.

Moderation in all things, my grandfather used to say — and as with most grandfathers, he was right.