Boosting levels of vitamin D could cut the incidence of breast cancer by a quarter, bowel cancer by a third and it should be offered to the population as part of a public health drive, scientists say.
The finding is based on a review of 2,750 research studies involving vitamin D, sometimes called "bottled sunshine", which show that taking daily supplements of the vitamin could do more for cancer prevention than a library full of lifestyle advice.
Vitamin D is made by the action of sunlight on the skin but the gloomy weather and long winter in countries north of 30 degrees latitude, such as the UK, means that a large part of the earth's population is deficient between October and March.
Vitamin D has attracted increasing attention in recent years as its role in preventing cancer and other conditions including heart disease, diabetes and multiple sclerosis, has been revealed. The weight of evidence has grown so dramatically that governments around the world are reviewing their recommendations. The US and Canadian governments have set up a taskforce on vitamin D, and the Scottish government is taking expert advice. The pressure is now on the Department of Health in England to respond.
Scotland's chief medical officer, Harry Burns, attended a conference last November convened by the Scottish government at which international experts recommended randomised trials be established in the wake of strong evidence that increased intake could improve health.
High rates of heart disease, cancer and multiple sclerosis in Scotland have been blamed on the weak sunlight and short summers. Some experts believe the benefits of the Mediterranean diet have as much to do with the sun as with the regional food. However, too much sun exposure leading to sunburn is damaging to the skin and a cause of malignant melanoma, one of the most rapidly growing – and deadly – cancers. Figures published this month show cases of melanoma have topped 10,000 annually for the first time.
Now scientists at the University of Edinburgh have been awarded a £225,000 grant to investigate the link between low levels of vitamin D in Scotland and bowel cancer.
The US and Canadian government taskforce is examining whether the current recommendation for people to achieve a blood level of vitamin D equivalent to taking 200-600 international units (IU) a day, depending on their age, should be increased. The recommended level was set in 1997 and is based on what was necessary for bone health, not cancer prevention.