EXPERTS have linked Scotland’s bad weather with the rate of multiple sclerosis, which is the highest in the world.
Scientists in Aberdeen have demonstrated for the first time why people living in less sunny places are more likely to suffer with the illness.
It is the first study to show a lack of sunlight reduces the amount of vitamin D the body can produce, and how this, in turn, impacts on regulatory cells in the immune system.
The Scottish experts say this explains the increasing prevalence of autoimmune diseases in people living further from the equator, where there are lower levels of winter sun.
Auto-immune diseases, like MS and type 1 diabetes, occur when someone’s immune system mistakenly attacks the body’s own tissues.
The University of Aberdeen researchers studied patients in the north of Scotland, which has the highest incidence of MS in the UK per head of population, who were treated during winter months with artificial UV-B light therapy for issues relating to their immune systems.
Dr Anthony Ormerod, clinical reader in dermatology at the university, said: “Our study showed UV-B light, which mimics sunshine, can have a striking effect on the immune system of patients.
“We found the light boosted the production of vitamin D, and of regulatory T cells, which play an important role keeping our immune systems in check.
“This has important implications for future interventions including the recommendations for healthy lifestyle and a possible role for phototherapy and vitamin D supplementation in the prevention or treatment of autoimmune and inflammatory diseases.”
Dr Ormerod warned that overexposure to sunlight can cause cancer but said that small amounts of it, especially in winter months, can boost the immune system and could prevent illnesses like MS.
He said: “While too much exposure to sunlight is harmful and increases skin cancer risk, these results suggest subjects in our study would have some benefits from small amounts equivalent to summer exposure in the winter.”
Dr Helen Macdonald, senior lecturer in nutrition and translational musculoskeletal research, the findings did not relate to using sun beds to mimic natural sunlight to boost the immune system.
She said: “We are not advocating sunbed use since this is not the same type of radiation produced by sunbeds which already have well-documented health risks.
“The average dose of UV light the volunteers received was the equivalent to sunlight exposure in Aberdeen over spring and summer and further work is required to determine if lower doses are effective.”
The team hope the research will help in the search for new ways to prevent and treat auto-immune diseases.
MS is not directly inherited and there is no single gene that causes it. Around 12,000 people in Scotland have the illness.
The illness is virtually unheard of in Malaysia or Ecuador, but common in Britain, North America and Scandinavia, southern Australia and New Zealand.