Corn oil is not recommended for breast cancer
Corn oil has a high omega-6 fatty acid content, in the form of linoleic acid. Increasing consumption of corn oil has been shown in animals studies to be associated with higher risks of cancer of the colon, stomach, prostate, pancreas, liver and lung. However, note that cornmeal appears to be protective against colon cancer, possibly due to its fiber content. Exposure to cooking oil fumes, including corn oil fumes, has been shown to increase the risk of lung cancer.
One study published in 2008 attributed the documented increase in the incidence of esophageal cancer in the U.S. to increasing carbohydrate consumption, including corn. Various studies of non-U.S. populations have found that consumption of corn contaminated with fusarium fungi accounts for high levels of esophageal cancer in parts of Iran, Brazil, South Africa, and China. Fusarium fungi produce fumonisins that reduce to compounds that synthesize carcinogenic nitrosamines. Fumonisins have been found to survive most types of baking and frying. Both fumonisin and aflatoxin (also found in corn) levels are regulated by the Food and Drug Administration in corn meant for human consumption and animal feed.
Breast cancer-related effects of consuming corn oil
Numerous studies have shown that a diet high in corn oil stimulates the formation of breast tumors in laboratory rats. Several experiments also have shown that offspring of rat mothers fed high corn oil diets are more likely to develop mammary tumors than offspring of mothers fed canola oil diets. The explanations given for these findings are related to corn oil's relatively high level of omega-6 fatty acids. Several studies have found that lower omega-3/omega-6 polyunsaturated fatty acid ratios are associated with increased risk of breast cancer.
Additional comments
There is little available information concerning the relationship between the consumption of fresh corn, cornmeal, cornstarch and grits and breast cancer risk. Sweet corn contains some melatonin. Melatonin protects against breast cancer in several ways, including by reducing aromatase activity within the breast, thereby reducing estrogen production. Sweet corn and yellow cornmeal contain the carotenoids lutein and zeaxanthin, which may have chemopreventive properties. Cornmeal, cornstarch and grits do not appear to promote breast cancer directly. However, one study found a link between increased starch intake after a diagnosis of early-stage breast cancer and a greater risk of recurrence.