Final answer:
Free radicals contribute to the occurrence of cancer by damaging DNA. Substances like flavonoids, fiber, and antioxidants, such as Vitamins A, C, E, and selenium, are associated with lowering cancer risk. Dietary guidelines recommend eating more fruits, vegetables, and whole grains to reduce the risk of cancer.
Step-by-step explanation:
Among the choices given, which can contribute to the occurrence of cancer is B) free radicals. Free radicals are highly reactive molecules with unpaired electrons, resulting usually from metabolic reactions or environmental factors such as radiation and pollution. They can damage DNA and initiate the cancer process. In contrast, substances like flavonoids, fiber, and antioxidants are associated with a reduction in cancer risk. Fiber, for example, is known to decrease the risk of colon cancer by hastening bile acid excretion and speeding up the passage of materials through the colon, thereby reducing exposure to potential carcinogens.
Antioxidants such as Vitamins A, C, E, and selenium play protective roles against cancer. They help prevent DNA damage by neutralising free radicals, with some antioxidants working on a more local scale like Vitamin E in the colon, and others more globally like Vitamin C. For instance, Vitamin A helps by maintaining cellular differentiation which slows down growth rates of potentially cancerous cells.
Eating diets rich in fruits, vegetables, and whole grains is recommended to decrease cancer risk, thanks to their high content of antioxidants, phytochemicals, and fiber. Cruciferous vegetables, being rich in nutrients, fiber, and compounds such as indoles and isothiocyanates, are particularly noted for their cancer-preventing properties in animal studies. However, results in human studies have been mixed. Following dietary recommendations by reputable institutions such as the American Institute for Cancer Research involves eating more of these food types and reducing intake of processed and red meats and alcohol.