Vitamin D supplements for Scots should be tested “sooner rather than later” to demonstrate whether they can improve the nation's health, international experts told the Scottish government yesterday.

A conference organised by Harry Burns, the Chief Medical Officer, was told that there should be large, randomised trials as there was strong evidence that increased daily intake of vitamin D could prolong the lifespan of 7 per cent of the population.

The conference brought together leading researchers into the links between low levels of sunshine, vitamin D insufficiency and higher incidences of chronic illnesses. Delegates were told that the strongest evidence, if all the published studies were pooled, pointed to the beneficial effects of Vitamin D. But it was feared that the government may balk at the millions of pounds needed to run ten-year trials on 20,000 people.

The conference was called after The Times revealed that low levels of the vitamin may be partly responsible for Scotland's woeful health record. High latitude regions with reduced hours of sunshine such as Canada and Scandinavia suffer similar problems.

The keynote speaker, Dr Philippe Autier, of the World Health Organisation's International Agency for Research on Cancer (IARC) in Lyon, told the meeting that the epidemiological evidence that increased vitamin D levels would be beneficial was quite strong but not conclusive, and called for large-scale trials.

In a report from the IARC working group, published yesterday, Dr Autier and others said that low vitamin D status has been associated with a large number of chronic conditions such as colo-rectal cancer, high blood pressure, coronary heart disease, congestive heart failure, stroke, cognitive impairment, depressive symptoms, reduced mobility, fractures, falls, incontinence and more.

It stated that a central question was whether low vitamin D status was a causal factor or simply an indicator of impaired health status, and thus just a predictor of increased risk.

“The only way to disentangle the issue of indicator or predictor versus causal factor is to mount new randomised trials for verifying the impact of vitamin D on all causes of mortality and on the incidence and mortality from common cancers and other conditions,” it said. Dr Autier recommended that trials should test higher dosages of vitamin D and said that failure to conduct such trials before issuing new recommendations to the public on vitamin D would be an error.

The report also noted that given the well-established link between skin cancer and UV radiation on light-skinned people, the safest way to administer vitamin D would be orally.

Julian Peto, a co-author of the report, who also spoke at yesterday's meeting in Edinburgh, said: “The people responsible for funding are understandably wary of the enormous cost needed to run randomised tests on 20,000 people and follow them up ten years later. But I think a trial should begin now.

“The epidemiological evidence shows all sorts of striking correlations between vitamin D and ill health but we can't be sure if it is cause or effect.”

A Scottish government spokeswoman said: “It is important that attempts to improve health remain focused on action on the social, economic, behavioural and psychological determinants of health. If vitamin D supplements can be shown to contribute to that ... we will make the appropriate recommendations.”

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