Produce May Protect Against Colon Cancer
Feb. 17, 2000 (New York) -- Spinach, broccoli, lettuce, tomatoes, oranges, and other fruits and vegetables rich in a carotenoid known as lutein may help stave off colon cancer, according to research in a recent issue of TheAmerican Journal of Clinical Nutrition.
Carotenoids are the yellow and orange pigments that give sweet potatoes, winter squash, carrots, apricots, papayas, and other fruits and vegetables their color. They are also found in broccoli and dark, leafy greens including spinach, kale, and collards. Carotenoids include alpha-carotene, beta-carotene, lycopene, lutein, zeaxanthin, and beta-cryptoxanthin.
In the study, researchers compared the diets of nearly 2,000 people with colon cancer with those of more than 2,400 colon cancer-free control subjects. Participants who reported eating the most lutein-rich foods were among the least likely to develop colon cancer, compared with those who reported eating the least lutein-rich foods. Lutein was most protective against developing colon cancer at a relatively young age (younger than 67) and developing tumors in the proximal, or central, part of the colon.
"The major dietary sources of lutein in subjects with colon cancer and in control subjects were spinach, broccoli, lettuce, tomatoes, oranges and orange juice, carrots, celery and greens, " the study's authors write. "These data suggest that incorporating these foods into the diet may help reduce the risk of developing colon cancer."
Exactly how lutein may reduce the risk of colon cancer is not fully understood, the authors point out. They speculate that this occurs because carotenoids are antioxidants, which may destroy the free radicals that are believed to accelerate aging and contribute to the formation of cancers and heart disease.
To arrive at its findings, the multicenter research team interviewed study participants about the foods that they consumed and how often they ate them during a two-year period.
The other carotenoids found in food did not protect against colon cancer, but lutein was shown to decrease the risk of developing the cancer, the research team reports.
"The benefit of all carotenoids has not been shown to consistently reduce risk of colon cancer. However, vegetables are the primary source of lutein, which has been shown to reduce risk of colon cancer," lead researcher Martha L. Slattery, PhD, MPH, of the University of Utah Medical School in Salt Lake City, tells WebMD.