Holidays abroad may hold the key to tackling Scotland’s vitamin D deficiency, a University of Edinburgh study suggests. The study, “Farming, Foreign Holidays, and Vitamin D in Orkney,” was published in the journal PloS One.
Multiple sclerosis (MS) is a chronic, complex disease with genetic factors strongly implicated in its etiology — as are environmental and behavioral ones, including vitamin D deficiency, a marker of low UV exposure. Orkney, an archipelago off Scotland’s northeastern coast, has the world’s highest prevalence of MS, although the disease is also quite common on the mainland.
To determine vitamin D status in Orkney, researchers obtained mean vitamin D levels and deficiency prevalence from data on about 2,000 participants in the Orkney Complex Disease Study (ORCADES) and compared it with controls from the Scottish Colorectal Cancer Study (SOCCS). Vitamin D status was determined by measuring circulating 25(OH)D, a prime indicator of vitamin D levels.
Researchers were surprised to find that the average vitamin D levels were higher in Orkney than on mainland Scotland. The highest levels were among farmers (vitamin D is produced in the skin through sun exposure), and people over age 60 who regularly went on vacation to other countries.
“It was surprising to see that levels of vitamin D were not worse in Orkney, and if anything they were better than in Mainland Scotland. It would appear that poor vitamin D status, while common enough, cannot explain the excess of Multiple Sclerosis we see in Orkney,” said Dr. James Wilson, a study lead author and a senior lecturer in Population and Disease Genetics, in a news release.
“It was interesting to find that the traditional occupation of farming was associated with higher levels of blood vitamin D in Orkney. This may be because farmers are outside and utilising even the smallest window of vitamin-D strength sunshine,” said Emily Weiss, a PhD student at the university who was involved in the study. “We also found that farmers in our Orkney cohort tended to be older, suggesting that the traditional way of life is changing, leaving younger people potentially more exposed to MS risk factors such as vitamin D deficiency.”