Vitamin D is found in oily fish, eggs and breakfast cereal and is produced naturally by the body when skin is exposed to sunlight. However levels of the ‘sunshine vitamin’ are often very low in Yorkshire people and other north European residents during winter months.
Research by Stanford University has discovered a direct link between vitamin D levels and the expression of a gene called ID1, known to be associated with tumour growth and breast cancer.
It adds to previous findings that a Vitamin D deficiency not only increase a person’s risk of developing breast cancer, but are also correlated with more aggressive tumours and worse prognoses.
The research was carried out in mice but researchers found in a study of 34 breast cancer patients that women with lower levels of vitamin D had more ID1 in their tumour tissues than did women with higher levels of vitamin D.
Assistant professor of paediatrics Dr Brian Feldman said: “Our study shows that a deficiency in vitamin D levels, or an inability of tumour cells to respond appropriately to the presence of vitamin D, is sufficient to trigger non-metastatic cancer cells to become metastatic.
“It’s enough to significantly accelerate tumour progression in our mouse model.
“Although much more research needs to be done, research from our lab and others suggests that people at risk for breast cancer should know their vitamin D levels and take steps to correct any deficiencies.”
The NHS recommends pregnant women, those over 65 and those housebound should take a daily supplement containing 10 micrograms (0.01mg) of vitamin D.
Too much vitamin D has been linked to damage to the kidneys, cardiovascular system and other organs.
Although vitamin D occurs naturally, health experts advise against over-exposure to sunlight due to the dangers of developing melanoma. Skin cancer levels in Yorkshire have doubled in the last 20 years, prompted by people taking more foreign holidays and use of sunbeds.
Vitamin D supplements are widely available from chemists and there is growing evidence that most people in the UK would benefit from them.
As well as the link with breast cancer, low vitamin D levels have also been associated with poor musculoskeletal health, heart disease, diabetes and multiple sclerosis.