Scientists have been awarded a £225,000 grant to explore further the relationship between low levels of vitamin D in the diet and the incidence of colorectal cancer in Scotland.

They will look into the reasons behind the association between a low intake of the vitamin and bowel cancer, which is the third most common cancer in the country.

Harry Campbell, from the Centre for Population Sciences at the University of Edinburgh, said that the grant from the Chief Scientist would allow him and his team to understand more about the environmental issues surrounding the cancer.

The research is another potential strand in the growing number of links between Scotland’s poor health and a shortage of vitamin D, resulting either from lack of sunshine, diet or a combination of the two. It is also part of more widespread work exploring how genetic variants may interact with vitamin D and be implicated with various diseases. Scientists from Cambridge reported in February the discovery of what appears to be a genetic vulnerability to multiple sclerosis, apparently initiated by a lack of vitamin D, which is then passed down through families.

The World Health Organisation has recommended that vitamin D supplements for Scots should be tested “sooner rather than later”, and the Government is known to be looking at the viability of such a move.

Bowel cancer is the third most common cancer in Scotland among men and women, and a new screening programme is currently being introduced across the country. The incidence in men dropped by nearly 5 per cent from 1995 to 2005, although over a longer period, since 1980, male colorectal cancer has increased by 17 per cent, with the age standardised rate changing from 52.4 cases per 100,000 per year in 1980 to 61.3 cases in 2005.

In England and Wales recent figures showed that the number of people under 30 with colon cancer has more than doubled since 1997, although the numbers are very small. In Scotland the numbers are too small to be statistically significant.

The vitamin D research, carried out by a team led by Professor Campbell last year, found an inverse association between vitamin D through dietary intake and colorectal cancer, and supported “the interpretation of a possible preventive role for the vitamin in colorectal carcinogenesis”.

Professor Campbell said: “Our research found that there is a relationship between people with a low intake of vitamin D and colorectal cancer, yes, but the question is, what does that mean? It is not easy to interpret these studies.”

He said that the study further supported a link, but was not proof of anything causal.

The new money will allow him to return to the 5,000 case control samples and measure their vitamin D status as well as their genetic variants, using a mendelian randomisation approach.

“There is an observed relationship between vitamin D and colorectal cancer but we don’t know whether that’s a direct thing or whether it goes through confounding factors because these people are healthier or have different health behaviours,” he said.

“In our study we will use a genetic approach to investigate whether low levels of vitamin D are only associated with colorectal cancer or actually cause this disease. This could give important information that may guide the decision on whether to invest in a vitamin D supplementation trial.”

The significance of the study is that by seeking a causal link it takes things a step farther forward from other research on the subject. Previous work linking colon cancer with low vitamin D levels and a cloudy climate went no farther than a correlation.

Last year The Times revealed a five-year research project by the scientist Oliver Gillie that demonstrated remarkable parallels between Scotland’s dull weather and indices of disease. It suggested that the “Scottish effect”, the hitherto unexplained excess mortality in the country compared with other industrial countries, was in large part because of the lack of sun.

A shortage of the “sunshine vitamin” \ was established as a factor in higher rates of multiple sclerosis, diabetes, arthritis, several cancers, cardiovascular disease and other ailments, which give Scotland one of the worst health records and highest premature mortality rates in Western Europe.

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