Women who had a vitamin D deficiency when they were diagnosed with breast cancer were 94% more likely to have their cancer metastasize and 73% more likely to die within 10 years, Canadian researchers reported Thursday. The team also found that only 24% of the women in its study had what are normally considered adequate levels of vitamin D at the time of the diagnosis.
"There is some evidence that some of the drugs we use to treat breast cancer, such as aromatase inhibitors, need vitamin D to be activated and metabolized." Some women who take the drugs get joint aches, Mortimer said, and when they are put on vitamin D, "they get better."
Earlier studies have suggested that vitamin D may prevent prostate and colon cancer. In laboratory dishes and animals, the chemical blocks the formation of new blood vessels feeding tumors and interferes with the growth of abnormal cells.