Author Oliver Gillie, a freelance medical writer, is the latest to raise the alarm about vitamin D deficiency among northern populations. In the last year, a number of reports and studies published in medical journals have warned of a resurgence of the bone disease rickets, while others have linked lack of the vitamin to a range of diseases.
The new report, called 'Sunlight Robbery', attacks UK government policy on sunbathing, which it claims is based on outdated information, mistaken interpretation of evidence and guesswork, and argues that advice to avoid strong sunlight should be cancelled.
Gillie claims the policy ignores evidence showing that insufficient vitamin D is closely associated with, and even a cause of, dozens of chronic diseases including 16 different types of cancers, several nervous system diseases such as schizophrenia and multiple sclerosis, diabetes, raised blood pressure, polycystic ovary disease, menstrual problems, infertility, infections and dental decay.
Cancer Research UK however vehemently denies that their SunSmart campaign can cause vitamin D deficiency, claiming that there is evidence that small amounts of sun before 1100 and after 1500 can provide optimal levels.
Furthermore, studies show that the campaign is not even having much effect on changing sunbathing habits in the UK, Sara Hoim, the campaign coordinator, told NutraIngredients.com.
But while skin cancer campaigners and scientists fail to see eye to eye, there seems to be consensus that vitamin D supplements and fortified foods are an effective way of potentially improving health without putting skin at risk.
"With the big debate about sunlight and cancer, you need to look to the diet. Fortification, if done sensibly, is the only way to achieve optimum vitamin D levels," said Sue Fairweather-Tait, head of nutrition at the UK's Institue of Food Research.
"The best source of vitamin D at the moment is fortified cereals," she added.
Vitamin D is found in small amounts in some foods such as oily fish but about 90 per cent is made by the body from sunlight. However the vitamin cannot be stored in the body for much longer than six weeks, so in areas with little winter sun, such as the UK, people can become deficient during the winter months.
"Previously we decided that there was no requirement for dietary intake as the hormone is made by the body. But we didn't take into account the available sunlight," said Fairweather-Tait.
Gillie argues that for six months of the year, the sunlight reaching the British Isles is not strong enough to make any vitamin D in the skin, and supplements or fortified foods need to be recommended.
Elderly people are generally advised to take vitamin D supplements as they tend to spend less time outdoors. There is also increasing evidence of vitamin D's role in bone health and for protection against osteoporosis-related fractures.
However although fortified milk is available in France, a scare about the effects of D-fortified milk on babies in the 1950s ended all fortification in the UK.
But there is enough evidence of the vitamin's association with other diseases to carry out further studies investigating optimal levels for our health, said Fairweather-Tait.
Recent studies have found vitamin D intake to be inversely associated with rheumatoid arthritis and multiple sclerosis. It has also been found to reduce colon cancer risk and been linked to heart disease.
Hoim said there is also a need to investigate how much sunlight is needed to make the required amounts of vitamin D.
"There is a balance between how much sunlight you need and the amount that will damage your skin. We need more robust, much larger studies to look into this."
Gillie is calling for "all kinds of research involving vitamin D from epidemiology through cell biology to trials of prevention and treatment of disease".
He also wants an international conference of doctors, scientists and policy makers to review "what is known about the effects of vitamin D insufficiency and deficiency, the risks and benefits of sunlight, and best policy on supplementation with vitamin D and fortification of foods with vitamin D".
Meanwhile there are signs that consumers could start buying more vitamin D supplements. In the US, where awareness of D deficiency arose before Europe, BASF has increased its production of the vitamin by 50 per cent, albeit from a small base, Barry Kaufman, senior product manager of human nutrition, told NutraIngredients.com recently.
"This can definitely be attributed to the news. Five or six articles in a row has a positive effect on demand," he said.