The American Cancer Society predicted in 2011 that nearly 1.6 million new cases of cancer would be diagnosed in the United States by the end of the year. Americans seeking ways to both prevent and treat cancer often turn to various foods and supplements in hopes of improving their odds. Sweet potatoes, consumed for more than 10,000 years, have several health benefits and nutritional compounds that may make them a beneficial addition to a cancer-preventive diet. If you have already been diagnosed with cancer, check with your health-care practitioner about the diet that's right for you.
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The sweet potato, or Ipomoea batatas, is an important food crop around the world. There are more than 8,000 varieties of sweet potato in a range of colors, including white, yellow, orange and purple, according to the International Potato Center. In addition to the flesh and skin, many parts of the plant, including the leaves, roots and vines, are edible. Sweet potatoes are good sources of carbohydrates, fiber, micronutrients, vitamins A and C and riboflavin. Sweet potatoes also contain the polyphenol anti-oxidants caffeic acid and di- and tri-caffeoylquinic acids, which are the substances that may have cancer-fighting properties.
Researchers in Japan tested sweet-potato extracts on rats with breast cancer. The results, published in 2005 in “Bioscience, Biotechnology and Biochemistry,” showed that amounts equivalent to 5 percent of total-feed weight reduced the number of tumors relative to a control group and inhibited the growth of new tumors.
A study involving 64 cases of gallbladder cancer and 101 cases of gallstones gathered evidence to determine any links between specific foods and cancer risk. Those with gallstones are believed to be at a higher risk of developing gallbladder cancer. The scientists published their results in 2002 in the “European Journal of Cancer Prevention.” They concluded that those who ate vegetables, including sweet potatoes, had a decreased risk of developing cancer.
A Japanese review, published in June 2005 in the “Journal of Epidemiology,” didn’t find any links between specific vegetables and the development of renal-cell cancer. However, the researchers did find that those who consumed three to four starchy roots -- including sweet potatoes, regular potatoes and taro -- had a lower mortality risk. They advised that more research is needed, because their study was small.
One study investigated sweet potato extracts on promyelocytic leukemia cells. The Taiwanese researchers published their findings in the April 2007 issue of the “Journal of Agricultural and Food Chemistry." They found that the potato extracts were able to inhibit growth of the leukemia cells. Although the results haven't been tested yet on animal or humans with leukemia, the researchers concluded that sweet potatoes may be useful as a cancer-preventive substance.
Laboratory mice with liver cancer were treated with the anti-oxidant anthocyanin extracted from sweet potatoes. The scientists reported in the Chinese journal “Wei Sheng Yan Jiu” in 2008 that 150 mg of anthocyanin caused a 33.33 percent reduction in the growth of liver cancer tumors.
A study in Taiwan of 301 lung cancer cases, 602 hospital controls and 602 neighborhood controls investigated the link between the consumption of local foods rich in vitamin A, such as sweet potato leaves, and the risk of lung cancer. The researchers concluded in their review, published in 2007 in the “Asia Pacific Journal of Clinical Nutrition,” that those who ate the most sweet potato leaves had a 43 to 65 percent reduced risk of developing lung cancer.