The discovery that vitamin D is vital for the health of 30 or more different tissues and organs of the body has been one of the most significant medical discoveries of the last 10 years but, until very recently, only a few dozen scientists scattered round the world were interested. Most scientists and doctors thought that vitamin D was important only for the healthy bones.

But patient laboratory work has shown that vitamin D is essential for the normal development of many specialised cells and has a vital role in a process called apoptosis - the programmed death of cells that have finished their useful life.

Insufficient vitamin D is becoming recognised as the most important risk factor for cancer and other chronic diseases after smoking, obesity and alcohol.

At least 60 per cent of people in the UK obtain insufficient vitamin D - and 10 per cent are so deficient that they are at risk of severe bone disease. Food provides most people in the UK with less than a quarter of the minimum requirement of vitamin D for health. Even if a typical vitamin pill is taken as well that leaves more than half of our vitamin D requirement that can only be obtained by exposure of the skin to the sun.

For six months of the year, the sun is not strong enough in northern Europe to enable the skin to make any vitamin D. More than ever before, the pattern of modern life keeps us indoors, out of the summer sun, or in cars, while sunscreen chemicals, common in cosmetics as well as in special creams, block the ultra-violet rays which are needed for vitamin D production.

Urgent measures are needed to correct our national deficiency of vitamin D, especially in winter. Some people may take a winter holiday in the Caribbean, Canary Islands or north Africa where they can sunbathe without suncream, taking care not to burn, and obtain a useful boost to health. Others may take a strong vitamin D pill (25 microgram or 1000 IUs) which can be bought from the internet.

But only vigorous government action will improve the vitamin D levels of most people. More foods need to be fortified with vitamin D but that will probably need complicated agreements with other EU countries which will take time and political will. The greatest immediate gains in vitamin D could be obtained by a new policy recommending the public to sunbathe whenever possible, wearing as few clothes as possible while taking care not to burn. Scientific evidence now suggests that it is burning that increases the risk of skin cancer while exposure without burning seems to protect against cancer.

However Cancer Research UK have been reluctant to change their government-sponsored SunSmart policy which was developed in sunny Australia and is totally unsuited to the British climate. It recommends staying in shade in the middle of the day and wearing sunscreen which, in effect, prevents most ultra-violet light from reaching the skin.

I warned Cancer Research UK more than a year ago that their advice may be causing more cancer than it is preventing. Even Australian authorities now recommend that people spend a few minutes in the sun before covering up. It is time for the UK government to follow suit and encourage people here to sunbathe safely to reduce their cancer risk.

Oliver Gillie is the author of Sunlight Robbery: Health benefits of sunlight are denied by current public health policy in the UK www.healthresearchforum.org.uk