2014届最新高考英语一轮单元复习 精品阅读理解提升文章精选一百篇（49）

　　2014届最新高考英语一轮单元复习 精品阅读理解提升文章精选一百篇（49）

　　Unit 52 Dietary Changes That Will Lower Your Cancer Risk Some foods actually contribute to the development of cancer; other foods lessen the risk. The following anti-cancer diet greatly lowers your risk of colorectal cancer and nearly all other types of cancers. For people with a genetic tendency toward colorectal cancer, it is not just an option, it's a lifesaving necessity. here are some anti-cancer dietary changes. Keep your diet low in total fat and very low in saturated fats. There are at least two ways in which dietary fat contributes to cancer. First, tumor cells need low density lipoproteins (LDL) to grow. There fore, a diet that helps to lower LDL levels could keep potentially cancerous cells from growing. Eating fat also stimulates the production of bile, which is needed to digest fat. If a lot of bile is allowed to stagnate in the large intestine for a long period of time, it's converted into apcholic acid, a proven carcinogen. Too much body fat is one of the leading risk factors for cancer, especially colorectal cancer. Obesity is also a risk factor for breast cancer. Vegetarian women who typically consume low-fat, high-fiber diet tend to have lower blood levels of estrogen, excrete more estrogen, and therefore are less prone to breast cancer. Obese men have a higher rate of prostate cancer. Increase your fiber intake. In all the research between food and cancer, the evidence for a relationship between a high fiber diet and lower chances of colorectal cancer is the most conclusive. It follows common sense as well. Fiber moves potential carcinogens through the intestines faster, decreasing the contact time between carcinogens and the intestinal wall. The less exposure to carcinogens, the less chance of colon cancer. Besides pushing them through faster, fiber binds carcinogens, keeping them away from the intestinal wall. Fiber also absorb bile acids, keeping them from acting on bacteria to produce fecapentanes, the cancerous substances that are formed by decaying foods within the colon. There are about twenty of these compounds that can mutate colon cells into cancerous cells. Fiber also promotes the growth of healthy bacteria in the intestines, which crowd out the undesirable bacteria that produce fecapentanes. Switch from red meat to seafood. Populations who eat the most red meat and fat in their diet have the highest incidence of colon cancer. Eat more soy products. Soy is a more healthful source of protein than meat. The primary anti-cancer value of soy seems to come from phytonutrients which inhibit the growth of new blood vessels necessary for tumor survival. Soy also protects against colon cancer by blocking the carcinogenic effects of bile acids. Eat a diet high antioxidants, calcium, beta-carotene and vitamin E. Calcium binds cancer-producing bile acids and keeps them from irritating the colon wall. Beta-carotene fights against cancer by both boosting the immune system and releasing a specific chemical blocking the growth of potentially cancerous cells.