Most dietary nutrients do not affect ovarian cancer risk, although intake of phytochemical isoflavones may be associated with a reduction in risk, researchers report in the April 1 issue of the 

Ellen T. Chang, ScD, from Northern California Cancer Center in Fremont, Calif., and colleagues examined nutrient consumption and the risk of invasive or borderline ovarian cancer in 97,275 women who completed a baseline dietary assessment in 1995–1996. 

The researchers observed 280 cases of ovarian cancer by the end of 2003. Consumption of phytochemical isoflavones reduced the risk of ovarian cancer, with a relative risk of 0.56 for more than 3 mg/day compared with less than 1 mg/day. There was no association between ovarian cancer risk and consumption of isothiocyanates, macronutrients, antioxidant vitamins, or other micronutrients. 

Chang ET, Canchda AJ, Lee VS, et al. Diet and risk of ovarian cancer in the California teachers study cohort. 