לסקרניXXX- על תזונה וסרטן

מה לאכול מה לא לאכול ועל מה לא כדאי לבזבז את הכסף (תוספי מזון מיותרים). http://caonline.amcancersoc.org/cgi/content/full/56/5/254 Supplements Can nutritional supplements lower cancer risk? There is strong evidence that a diet rich in vegetables, fruits, AND other plant-based foods may reduce the risk of cancer, but there is no evidence at this time that supplements can reduce cancer risk, AND some evidence exists that indicates that high-dose supplements can increase cancer risk.182,183 Can I get the nutritional equivalent of vegetables AND fruits in a pill? No. Many healthful compounds are found in vegetables AND fruits, AND it is likely that these compounds work synergistically to exert their beneficial effect. There are likely to be important, but as yet unidentified, components of whole food that are not included in supplements. The small amount of dried powder in the pills that are represented as being equivalent to vegetables AND fruits frequently contains only a small fraction of the levels contained in the whole foods. Food is the best source of vitamins AND minerals. Supplements, however, may be beneficial for some people, such as pregnant women, women of childbearing age, AND people with restricted dietary intakes. If a supplement is taken, the best choice is a balanced multivitamin/mineral supplement containing no more than 100% of the "Daily Value" of most nutrients. Tea Can drinking tea reduce cancer risk? Some researchers have proposed that tea might protect against cancer because of its antioxidant content. In animal studies, some teas (including green tea) have been shown to reduce cancer risk,184,185 but epidemiologic studies have had mixed findings.186,187 Presently, tea has not been proven to reduce cancer risk in humans. Trans-saturated Fats Do trans-saturated fats increase cancer risk? Trans-saturated fats are produced during the manufacture of hydrogenated oils such as margarine OR shortening to make them solid at room temperature. Recent evidence demonstrates that trans-fats have adverse cardiovascular effects, such as raising blood cholesterol levels.13,188 Their relationship to cancer risk, however, has not been determined. Regardless, it is recommended to consume as few trans-fats as possible. Vegetables AND Fruits Will eating vegetables AND fruits lower cancer risk? Yes. Greater consumption of vegetables AND fruits has been associated in the majority of epidemiologic studies with a lower risk of lung, oral, esophageal, stomach, AND colon cancer.11 Because it is not known which of the many compounds in vegetables AND fruits are most protective, the best advice is to consume five OR more servings of a variety of colorful vegetables AND fruits each day. What are cruciferous vegetables, AND are theyimportant in cancer prevention? Cruciferous vegetables belong to the cabbage family, AND include broccoli, cauliflower, Brussels sprouts, AND kale. These vegetables contain certain chemicals thought to reduce the risk for colorectal cancer. The best evidence suggests that consumption of a wide variety of vegetables, including cruciferous AND other vegetables, reduces cancer risk.11,12 Is there a difference in the nutritional value of fresh, frozen, AND canned vegetables AND fruits? Yes, but they can all be good choices. Fresh foods are usually considered to have the most nutritional value. Often, however, frozen foods can be more nutritious than fresh foods because they are often picked ripe AND quickly frozen; nutrients can be lost in the time between harvest AND consumption for fresh foods. Canning is more likely to reduce the heat-sensitive AND water-soluble nutrients because of the high heat temperatures necessary in the canning process. Be aware that some fruits are packed in heavy syrup, AND some canned vegetables are high in sodium. Choose vegetables AND fruits in a variety of forms. Does cooking affect the nutritional value of vegetables? Boiling vegetables, especially for long periods, can leach their content of water-soluble vitamins. Microwaving AND steaming are the best ways to preserve the nutritional content in vegetables. Should I be juicing my vegetables AND fruits? Juicing can add variety to the diet, AND it can be a good way to consume vegetables AND fruits, especially for those who have difficulty chewing OR swallowing. Juicing also improves the body's absorption of some of the nutrients in vegetables AND fruits. However, juices may be less filling than whole vegetables AND fruits AND contain less fiber. Fruit juice, in particular, can contribute quite a few calories to one's diet if large amounts are consumed. Commercially juiced products should be 100% vegetable OR fruit juices AND should be pasteurized to eliminate harmful microorganisms. Vegetarian Diets Do vegetarian diets reduce cancer risk? Vegetarian diets include many health-promoting features; they tend to be low in saturated fat AND high in fiber, vitamins, AND phytochemicals.189 It is not possible to conclude at this time, however, that a vegetarian diet has any special benefits for the prevention of cancer. Diets including lean meats in small to moderate amounts can also be healthful. Strict vegetarian diets that avoid all animal products, including milk AND eggs, should be supplemented with vitamin B12, zinc, AND iron (especially for children AND premenopausal women).189 Vitamin A Does vitamin A lower cancer risk? Vitamin A (retinol) is obtained from foods in two ways: preformed from animal food sources, AND derived from beta carotene in plant-based foods. Vitamin A is needed to maintain healthy tissues. Vitamin A supplements, whether in the form of beta carotene OR retinol, have not been shown to lower cancer risk, AND high-dose supplements may, in fact, increase the risk for lung cancer in current AND former smokers.76,77 Vitamin C Does vitamin C lower cancer risk? Vitamin C is found in many vegetables AND fruits, particularly oranges, grapefruit, AND peppers. Many studies have linked consumption of vitamin C–rich foods with a reduced risk for cancer.11 The few studies in which vitamin C has been given as a supplement, however, have not shown a reduced risk for cancer. Vitamin D Does vitamin D lower cancer risk? There is a growing body of evidence from epidemiologic studies (not yet tested in RCTs) that vitamin D may have beneficial effects on some types of cancer, including cancers of the colon, prostate, AND breast.190 Vitamin D is obtained through skin exposure to ultraviolet (UV) radiation, AND through diet, particularly products fortified with vitamin D such as milk AND cereals, AND supplements. Many Americans, however, do not consume sufficient amounts of vitamin D.191 The current national recommended levels of intake of vitamin D of 200 to 600 IU164 may be inadequate to meet needs, especially among those with little sun exposure, the elderly, individuals with dark skin, AND exclusively breast-fed babies. More research is needed to define optimal blood AND intake levels for cancer risk reduction, but recommended intake is likely to fall between 200 AND 2000 IU, depending on age AND other factors that modify vitamin D status. To minimize the health risks associated with UVB radiation exposure while maximizing the potential benefits of optimum vitamin D levels, a balanced diet, supplementation, AND limiting sun exposure to small amounts are the preferred methods of obtaining vitamin D. Vitamin E Does vitamin E lower cancer risk? Alpha-tocopherol is recognized as the most active form of vitamin E in humans AND is a powerful biological antioxidant. A reduction in prostate cancer incidence was observed among men randomly assigned to receive alpha-tocopherol in the Alpha-Tocopherol Beta Carotene (ATBC) trial, a study that included only male smokers.76 However, this association was not observed in the HOPE-TOO trial,192 in postintervention follow up of the ATBC trial,193 OR in two large prospective observational studies,194,195 AND may have been a result of chance. While ongoing randomized trials196,197 will eventually provide further information, the promise of alpha-tocopherol as a cancer prevention agent appears to be dimming. http://www.cancer.org/docroot/PED/ped_3_1x_ACS_Guidelines.asp?sitearea=PED] http://cancer.about.com/od/causes/tp/topreventcancer.htm http://www.cancer.org/docroot/MBC/MBC_6.asp?sitearea=ETO

מה שווה לקרוא מה לא שווה לקרוא ועל מה לא כדאי לבזבז את הזמן (האתרים של האגודה למלחמה בסרטן האמריקקית).