The debate about whether European consumers should be advised to take vitamin D supplements has gathered momentum after researchers found that four times as many women in the north of the UK are deprived of the nutrient compared with their southern counterparts.
In a study published in the Nov. 18 issue of Osteoporosis International, scientists based at the Universities of Aberdeen in northeast Scotland and Surrey in southeast England recruited 518 local female volunteers aged between 55 and 70 to wear a badge with a film that detected the amount of UVB rays they were exposed to daily.
They also measured vitamin D levels in the subjects' blood. Since vitamin D is predominantly obtained from exposure to sunlight, the researchers were hoping to see a correlation between the results of the two tests.
What they discovered was that 40 percent of the women living in Aberdeen had less than the UK government's minimum recommended amount of the vitamin in their bodies during the winter months. But only 10% of those in the southeast of England were below this level. At the same, the badges showed that women in Scotland received half as much sun as their southern counterparts.
The researchers determined that the minimal amount was 25nmol/l (10ng/ml). By contrast, the Institute of Medicine in the US, which released new guidelines last month for North America, determined the sufficiency level for most people should be set at 50nmol/l (20ng/mL). It is notable that even though the North American level is set at twice that of the UK, vitamin D researchers advocate levels that are at minimum 50 percent higher than the revised North American official recommendations. The scientists said their findings highlighted the need for better public advice on ways to boost vitamin D levels in the winter months.
Study leader Helen Macdonald, from the University of Aberdeen's Institute of Medical Sciences, said: "Vitamin D is only found naturally in a small number of foods – namely egg yolks and oily fish. In the UK we obtain the majority of our vitamin D intake from sunlight. We need to look at appropriate guidelines regarding safe sunlight exposure, to strike the balance between ensuring adequate protection from the sun and obtaining vitamin D from UVB rays.
"We also need to consider the advice which should be given to the public on taking supplements or eating foods which are fortified with vitamin D."
In the UK, the government says almost no vitamin D is required in the diet to supplement that obtained from sunlight – though this advice is currently under review by the country's Scientific Advisory Committee on Nutrition.
Just days after the Aberdeen/Surrey research was published, the US government panel in charge of setting recommended daily intake levels for vitamins announced a large increase of vitamin D for all populations in North America. The Institute of Medicine report advocated a doubling of vitamin D intake for infants, a tripling of vitamin D intake for those between ages 1 and 50, a 50 percent hike in those ages 51 to 70, and a 33% increase for those older than 71 years old.
The European Union, meanwhile, is due to begin a review of recommended intakes of essential nutrients in 2011, with some experts calling for a rise in the levels of vitamin D consumers are advised to take through the diet. National recommendations currently vary from state to state across the EU.