By "potatoes" we mean white potatoes — sweet potatoes and yams are covered in another web page. Potatoes are a good dietary source of vitamin C and vitamin B6. Red-peeled potatoes and other special cultivars contain chemopreventive compounds such as caffeic acid, catechin, gallic acid, and chlorogenic acid, as well as the glycoalkaloids α-chaconine and α-solanine. Consuming whole cooked potatoes with the peel has been shown to improve the cholesterol profile of laboratory rats.
Potato extracts have been shown to suppress proliferation and induce apoptosis of human lymphoma, liver, stomach, cervical, colon, and prostate cancer cells. One study found that overall mortality in older Dutch women was lower for women following a "healthy" modified traditional Dutch diet: the traditional diet was made healthier by reducing alcohol and meat consumption and increasing vegetable intake without eliminating potatoes (however note that most of the potatoes were boiled or steamed, rather than fried). Potato consumption has been found to be associated with increased risks of oral and rectal cancer. Pan fried and French fried potatoes have also been found to be associated with higher risks of oral, laryngeal and esophageal cancers.
Breast cancer-related effects of eating potatoes
Potato extract has been shown to suppress proliferation of mouse mammary tumor cells. Fried potatoes were found in one study to be associated with increased risk of estrogen receptor negative (ER-) breast cancer.
Various "meat and potatoes" dietary patterns have been found to be associated with increased risks of many cancer types, including breast cancer. However, it is possible that these heightened risks may be due primarily to red meat and fried potato intake; it is possible that consumption of boiled or steamed potatoes does not carry such risks.
Potatoes typically are grown using a great deal of pesticides and significant levels of pesticides are normally present in potatoes whether purchased raw or in precooked forms such as hash browns or French fries. Studies have found increased mortality from hormone-dependent cancers in traditional potato-growing areas, presumably from potato pesticide exposure. Peeling potatoes reduces but does not eliminate pesticide exposure from the cooked food and it eliminates the vitamin D and other beneficial nutrients found primarily in the skin. Potatoes with red skins incorporate anthocyanins that are know to be provide some protection against breast cancer risk. We would suggest buying organic red-skinned potatoes and eating them (along with their skins) after steaming or boiling them.
Fried potatoes, especially potato chips and French fries, contain acrylamide, a suspected carcinogen. Acrylamide is produced by subjecting potatoes to high heat or charring them. Acrylamide intake within the range of U.S. diets has not been found to be associated with increased risk of breast cancer, nor does it appear to increase the risks of other cancer types. However, a 2012 Danish study reported that pre-diagnostic exposure to acrylamide was associated with increased mortality among breast cancer patients with ER+ breast cancer.
The toxic potato compounds alpha-chaconine and alpha-solanine both have been found to damage the liver. They are concentrated in potato sprouts, which should not be eaten. Medicinal potato extracts containing these compounds are also to be avoided.
Note that while we are continually searching for new evidence concerning this food, there is not much interest in it among cancer researchers so few recent studies are available.