Breast tumours in mice deficient in vitamin D grow faster and are more likely to metastasize than tumours in mice with adequate levels of vitamin D, a study at the Stanford University School of Medicine has found.
The research highlights a direct link between circulating vitamin D levels and the expression of a gene called ID1, known to be associated with tumour growth and breast cancer metastasis.
Former studies have suggested that low levels of vitamin D not only increase a person’s risk of developing breast cancer, but are also correlated with more aggressive tumours and worse prognoses.
Vitamin D has long been known to be essential for calcium absorption and overall bone health.
More recently, however, researchers have begun to suspect that vitamin D may affect many other important biological processes, including tumour progression. However, it’s not clear exactly which step in cancer development the vitamin may affect.
In the study, mouse breast cancer cells were implanted into the mammary fat pad of laboratory mice.
“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,” Dr Feldman said.
Although the new research was conducted primarily in mice and on mouse cells, the researchers found in a study of 34 breast cancer patients that vitamin D is directly linked with the expression of the ID1 gene in a human breast cancer cell line.
The study’s senior author Dr Brian Feldman said those of us at risk of the disease should be monitoring our vitamin levels.
“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,” Dr Feldman said.
The researchers emphasize that their findings don’t imply that more vitamin D is always better. Correcting a deficiency is very different from taking more than the recommended dosage.
Excess levels of Vitamin D have been linked to kidney and cardiovascular damage.
The exact amount of Vitamin D a person should consume is not uniform across medical organisations, with the root of the confusion being blamed in large part on the fact the vitamin can be ingested via food and supplements, but it is also produced by our bodies when we’re exposed to the sun’s ultraviolet rays.