At the 2006 annual meeting of the American Association for Cancer Research, a study was presented suggesting that vitamin D exposure early in life may be important in lowering breast cancer risk later. The study compared 576 women aged 20 to 59 years of age that had been diagnosed with breast cancer against 1,135 healthy age-matched women.
The researchers found evidence for a significantly reduced risk of breast cancer in relation to vitamin D exposure. Sun exposure factors such as number of outdoor activities at ages 10 to 19 and at ages 20 to 29, as well as prolonged cod liver oil consumption (10 years or more) and consumption of nine or more glasses of milk per week were all associated with a lower risk of breast cancer.
The researchers concluded, "Evidence is growing that vitamin D might help reduce the risk of breast cancer, and what we see is consistent with the idea that what occurs during breast development in adolescence may influence future breast cancer risk."
American Association for Cancer Research Annual Meeting; Dr. Julia A. Knight, Mount Sinai Hospital, Toronto; 2006.