Previously it was thought that the active form of vitamin D, calcitriol, which is a potent anti-cancer agent, was only made in the kidney. Scientists from the University of Birmingham and St George's Hospital, London have discovered that breast tissue also contains the enzyme that activates vitamin D, and levels of this enzyme are increased in breast tumours.
While calcitrol has until now been investigated mainly for its use in treating cancers, including breast and prostate, the new findings mean that the vitamin could play a role in the breast's natural immune response to a tumour, and therefore, in sufficient levels, act to prevent cancer.
Breast cancer is the most common cancer among women in the European Union. Each year some 60,000 women in the European Union die of it (significantly more than in the US) and 150,000 new cases are reported. Approximately one woman in 10 in Europe will develop breast cancer at some point in her life, according to the European Parliament's Directorate-General for Research.
Now the researchers believe that a contributing factor to high rates of the cancer may be low levels of vitamin D. Exposure to sunlight is the greatest source of vitamin D and population studies have previously suggested that the lower incidence of breast cancer in southern areas such as the Mediterranean may be a result of its sunny climate.
The new research provides a mechanism for this by unravelling how vitamin D is activated to calcitriol in the breast.
Dr Martin Hewison, who heads the research team, said: "Our work shows that the breast has its own local 'factory' for generating the anti-cancer form of vitamin D. Unfortunately women who live in cloudy countries like the UK may not have enough of the raw material, vitamin D, to fuel this factory."
"Exposure to sunlight is the most efficient way of generating vitamin D in our bodies, but we all know of the dangers of sunbathing. Perhaps now it's time to look at improving our dietary intake through fortification of more foods with Vitamin D," he added.
There has also been renewed attention to vitamin D deficiency in the last year, with researchers finding many UK citizens, especially elderly and Asian populations, lacking sufficient levels of the vitamin. This has led to studies on the impact of this deficiency, which have found that insufficient vitamin D could also raise the risk of numerous autoimmune diseases such as diabetes, rheumatoid arthritis and multiple sclerosis.
The new research will be presented at the joint meeting of the British Endocrine Societies with the European Federation of Endocrine Societies in Brighton, UK, today.