Serum levels of micronutrients, antioxidants and total antioxidant status predict risk of breast cancer in a case control study.

We performed a case control study to assess the association between serum micronutrient and antioxidant levels and the risk of breast cancer. Newly diagnosed breast cancer cases were recruited before any treatment and matched with controls randomly selected from the electoral roll. Blood samples were collected from 153 breast cancer cases and 151 controls. Serum samples were analyzed for retinol, alpha-tocopherol, lycopene, alpha- and beta-carotene by HPLC, and total antioxidant status by the Trolox-equivalent antioxidant assay. Serum albumin, bilirubin and uric acid levels were also determined. After adjustment for age at menarche, parity, dietary fat and alcohol intake, we observed the following reductions in odds ratios for breast cancer risk comparing the highest with the lowest quartiles: 0.47 [95% confidence interval (CI) 0.24, 0.91] for beta-carotene; 0.53 (CI 0.28, 1.01) for retinol; 0.50 (CI 0.26, 0.97) for bilirubin and 0.47 (CI 0.24, 0.94) for total antioxidant status. We conclude that increased serum levels of beta-carotene, retinol, bilirubin and total antioxidant status are associated with reductions in breast cancer risk.