Sweet yellow corn (Zea mays var. saccharata) ("corn") is a good source of zeaxanthin, melatonin, thiamine (vitamin B1) and pantothenic acid (vitamin B5). It also contains other B-vitamins such as niacin (vitamin B3), pyridoxine (vitamin B6), riboflavin (vitamin B2) and folate. Corn also contains meaningful amounts of alpha-carotene, beta-carotene, beta-cryptoxanthin, ferulic acid, lutein, and insoluble fiber.
One study attributed the documented increase in the incidence of esophageal cancer in the U.S. to increasing carbohydrate consumption, including corn. Relatively high liver cancer rates in U.S. Latinx populations have been ascribed in part to aflatoxin exposure from corn consumption. On the other hand, cornmeal appears to be protective against colon cancer, possibly due to its fiber content. Generally speaking, white corn contains significantly less of beneficial nutrients than yellow corn. Corn oil is covered in a separate webpage.

Breast cancer-related effects of eating corn

Corn and corn products

There is little available information concerning the relationship between the consumption of fresh corn, cornmeal, cornstarch or grits and breast cancer risk.
Corn and foods made from corn have a high glycemic index. 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.

Beneficial sweet corn compounds

Sweet corn contains some melatonin. Melatonin protects against ER+ breast cancer by reducing aromatase activity within the breast, thereby decreasing estrogen production. Melatonin has also been found to reduce triple negative (ER-/PR-/HER2-) breast cancer growth, proliferation and migration in cell and animal studies. In addition, melatonin has been shown to reduce the cardiotoxicity associated with Adriamycin (doxorubicin) chemotherapy. Sweet corn and field corn (used to make corn tortillas and corn chips) both contain zeaxanthin and lutein, which have been shown to have chemopreventive properties.

Purple and blue corn

Purple and blue corn are abundant sources of anthocyanins (primarily cyanidin-3-glucoside). The darker the corn, the higher the level of anthocyanins. Such corn anthocyanins have been shown to have potent antioxidant, anti-inflammatory, antimutagenic, anticarcinogenic, and anti-angiogenic properties. Blue corn and blue corn tortilla extracts have been shown to have antiproliferative effects against hormone receptor positive (ER+/PR+) and triple negative breast cancer cells.
High fructose corn syrup is a sweetener derived from corn starch which has been associated with chronic inflammation, a breast cancer risk factor. High fructose corn syrup diets have been linked to increased risk of triple negative breast cancer. Breast cancer cell metabolism is characterized by enhanced uptake and use of glucose. It has been demonstrated that when glucose is not available (i.e., the cells are in glucose-deficiency), fructose can be used instead by breast cancer cells. This suggests that a high-fructose diet could accelerate the progress of breast cancer.

Additional comments

Functional fiber products

Fiber is added to some processed foods in order to qualify the foods as “high fiber” or to improve texture. This isolated or functional fiber is extracted or synthesized from plant sources. Examples include soluble corn fiber (from corn), inulin (chicory root or sugar beets), cellulose (wood pulp), maltodextrin (corn, rice, or potato starch) and polydextrose (corn starch). Such fiber-fortified foods typically lack the flavonoids and other biologically active components of the foods from which they are derived and may lack nutritional value, however there is no evidence that functional fiber is harmful.

Fungi and corn products

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 levels are regulated by the Food and Drug Administration in corn meant for human consumption and in animal feed. However, one study of fresh corn and corn products sold in small family-owned markets in San Diego, California, detected zearalenone (a breast carcinogen which is produced by several species of fusarium fungi) in more than 70% of the samples tested.