And in a recent Harved Medical School study it was found that lung cancer patients operated on in the summer months doubled their chances of five-year survival compared to those operated on in winter.

A meeting of the American Association for Cancer Research heard that the study - involving 456 early-stage patients - was structured to exclude distorting factors such as diet and surgical techniques.

The researchers therefore concluded that the happier outcome for summer patients was due to sunlight boosting vitamin D levels.

It is not however recommended that cancer sufferers wait till summer for treatment.

British cancer specialists have given a cautious welcome to the researchers' conclusions. "There is evidence to suggest that the vitamin plays a role in keeping cells healthy," said Sara Hiom, the head of health information at Cancer Research UK. "But further research is needed to understand what role vitamin D may play in preventing cancer in humans."

In Australia Cancer Council called for "balance" to sun exposure after years of stressing the need for cover-up and sun-block. The policy switch was made in light of research showing that vitamin D deficiency in one of the world's sunniest countries was far greater than supposed.

Of course vitamin D is implicated in a variety of health problems including multiple sclerosis, hypertension, diabetes, rheumatoid arthritis and schizophrenia.

Sunlight exposure is natural for us and it very healthy to get some exposure the key is to make sure it is moderate and controlled don't allow yourself to be burned as this a the major risk factor for skin cancers. For those that would prefer not to get sun exposure then you could consider dietary supplements including cod liver oil.