Women with low blood levels of a marker for vitamin D have an increased risk of breast cancer, German researchers say.
They studied levels of 25-hydroxyvitamin D in 1,394 breast cancer patients and an equal number of healthy postmenopausal women, finding that those with a very low blood level of 25(OH)D were much more likely to develop breast cancer, United Press International reported.
The link between low levels of 25(OH)D and increased breast cancer risk was strongest among women who didn't take hormones for relief of menopausal symptoms. The researchers did note that chemotherapy or lack of sunlight during prolonged hospital stays may have contributed to low vitamin D levels in breast cancer patients.
The body produces vitamin D in response to sunlight, and the vitamin is present in certain foods.