Women who take multivitamin tablets along with calcium supplements seem to have a reduced risk of developing breast cancer. The authors of the study, which is to be presented Sunday at the American Association for Cancer Research annual conference, did not separate out which specific vitamins might be beneficial but suggested that the interactions of different vitamins together might account for the beneficial effect.
For this study, the authors compared vitamin and calcium intakes of 268 women with breast cancer and 457 women without breast cancer, all in Puerto Rico. They also measured the ability of the women's DNA to repair itself, a function that is critical to keeping cancer at bay. "We've known that DNA repair capacity is linked to several other types of cancer," said researchers. "DNA repair capacity is very, very linked to breast cancer risk." Here, women who were older, had low DNA repair capacity levels, a family history of breast cancer and who had not breast-fed all had a higher risk of breast cancer.
Taking a multivitamin tablet reduced the risk of tumors by about 30 percent, while calcium supplements reduced the risk by 40 percent. But when the DNA repair capacity was taken out of the equation, calcium was no longer protective, strongly suggesting that calcium's protective effect came only from its influence on DNA repair. Vitamins, on the other hand, seemed to have a beneficial effect even beyond contributions to DNA repair, the researchers said.
One drawback of the study is that the authors did not measure women's actual vitamin levels, instead relying on responses to questionnaires.
Bonnie - small study to be sure, but first I've seen to actually measure the patient's ability to repair DNA.