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Issue 2, Volume 1 • Summer 2007 Nutrition education after a cancer diagnosis Green Tea: What is the cancer connection? In this issue: • Green Tea:What is the cancer connection? • Selenium and Cancer: What is we recommended? • Soy:What you need to know • Organic Fruits and Vegetables: Are they better? There are four major forms of tea – green tea, black tea, oolong tea and white tea. All of these forms differ in how they are produced and in their chemical make-up. All tea contains polyphenols which are found in the tea leaves. The polyphenol group that is of most interest to researchers at this time is the catechins which includes four types - epicatechin (EC), epicatechin-3-gallate (ECG), epigallocatechin (EGC) and epigallocatechin-3-gallate (EGCG). More catechins are available in green tea than in black tea. Catechins are of interest in cancer research because they act as antioxidants which prevent damage to DNA and other molecules caused by free radicals. Laboratory studies support the anti-cancer properties of adequate and consistent intakes of green tea. Green tea may be more beneficial to some individuals than others. A study conducted with individuals who were at risk for lung cancer development found that those who were “genetically deficient” in GSTM1, an enzyme that quickly eliminates carcinogens from the body, received the greatest reduction in lung cancer risk from drinking green tea. This means the chemopreventive effects of green tea may be restricted to individuals who are particularly susceptible to oxidative stress and oxidative DNA damage. Experimental studies using cell cultures and animals have supported green tea as a chemopreventive agent for breast, prostate and colorectal cancer, meaning that it has some type of protective effect against cancer cell development. In laboratory experiments green tea has been shown to induce breast cancer cell apoptosis (cell death) in estrogen-receptor negative cells and also found to increase the effects of tamoxifen on estrogenreceptor positive breast cancer cells. Cell apoptosis has also been observed in lung cancer cells with exposure to green tea. Clinical trials will help determine if green tea extracts are as effective as drinking green tea. A recent study conducted in individuals who have prostate neoplasia, a precursor of prostate cancer, found that those who received green tea polyphenols in capsule form had a lower incidence of prostate cancer diagnosis after one year. There is also more attention being given to the amount and type of fat in the diet and its role in absorption of the catechins from green tea. In animal models those with colon carcinogenesis that received a high corn oil diet did not see the same cancer preventive effects as did the mice that received a low fat diet meaning that the amount To maintain the greatest catechin content use small, loose leaf green tea. If you do use a teabag dunk the bag continuously in the water to increase the extraction of catechins. Use boiling water and steep for two to five minutes. and type of fat in the diet may influence the preventive properties of catechins. This type of information is important to consider when evaluating the health benefits of certain foods and nutrients. At this time it appears that drinking about 3 to 6 cups of green tea or decaffeinated green tea each day may provide health benefits such as cancer prevention and delayed progression after cancer diagnosis, for most individuals. Selenium And Cancer: What is recommended? Selenium is an essential mineral, responsible for antioxidant function, energy metabolism, and protection against DNA damage. However, it is considered highly toxic, with the difference between the Recommended Dietary Allowance (55 micrograms/day for adults) and the upper limit of safe intake (400 micrograms/day) relatively narrow, compared to most nutrients. In some parts of the world, the soil content of selenium is very low. Some areas in Europe and China, for example, have a long history of selenium deficiency because the foods that grow in these soils pick up very little selenium. In contrast, the soil in the U.S. is relatively rich in selenium. Foods grown here, and the animals that consume those foods, are relatively good sources of selenium. Estimates of selenium intakes from a large representative sample of people in the U.S. is estimated to be about 100 micrograms per day. Selenium has come under attention recently because of its association with cancer. Many studies show that an adequate selenium intake – one that is neither too low nor too high – may protect against certain cancers, including prostate, colorectal, and lung. A large, 12-year study currently in progress is studying the effects of selenium supplementation (200 micrograms/day) and vitamin E supplementation (400 IU/day) on the development of prostate cancer in men. Confirmation of these studies – many of which have been observational vs. randomized, controlled clinical trials – is a high priority in cancer research today. The status of the research thus far suggests the following: • Selenium deficiency, as measured by low selenium intakes or low blood selenium concentrations, should be corrected with a combination of diet and supplementation. • Selenium should be obtained, as much as possible, from foods rather than supplements in order to obtain the type of selenium that appears to be most easily absorbed (i.e., organic selenomethionine). • Selenium from supplements, which is inorganic, may not be absorbed as well as that from foods; studies are mixed. There is no evidence that supplementation with selenium above 200 micrograms per day is protective against cancer. Good food sources of selenium are wheat and meat. Brazil nuts are very high in selenium, with two nuts providing about 200 micrograms. Fish is relatively high in selenium, but some reports suggest that selenium from fish may not be absorbed in our bodies as well as selenium found in other foods. There are many forms of selenium found in foods. Some forms are being studied for their protection against cancer growth. Research suggests that it is best to eat a variety of foods to obtain the health benefits of different forms of selenium. Selected Food Sources of Selenium Serving size Micrograms/ serving Percent DV* Brazil nuts, dried 1 ounce (~ 6 nuts) 544 780 Tuna, light, canned in oil, drained 3 ounces 63 95 Beef, cooked 3 1/2 ounces 35 50 Spaghetti with meat sauce, frozen entrée 1 serving 34 50 Cod, cooked 3 ounces 32 45 Turkey, light meat, roasted 3 1/2 ounces 32 45 Chicken breast, meat only, roasted 3 1/2 ounces 20 30 Noodles, enriched, boiled 1/2 cup 17 25 Egg, whole 1 medium 14 20 Brazil nuts are very high in selenium. Two nuts per day provides about 200 micrograms. References: 1.) Finley JW. Bioavailability of selenium from foods. Nutr Rev 64: 146-151, 2006. 2.) Daniels LA. Selenium: does selenium status have health outcomes beyond overt deficiency? MJA 180: 373-374, 2004. 3.) Dietary Supplement Fact Sheet. National Institutes of Health, Office of Dietary Supplements. Available at http://dietary-supplements.info.nih.gov/ factsheets/selenium.asp. Accessed 3/13/07. Adapted from: National Institutes of Health. Office of Dietary Supplements. http://dietary-supplements.info.nih.gov/ factsheets/selenium.asp. Accessed June 1, 2007. *DV = Daily Value. DVs are reference numbers developed by the Food and Drug Administration (FDA) to help consumers determine if a food contains a lot or a little of a specific nutrient. The DV for selenium is 70 micrograms. Most food labels do not list a food’s selenium content. The percent DV (%DV) listed on the table indicates the percentage of the DV provided in one serving. A food providing 5% of the DV or less is a low source while a food that provides 20% of more of the DV is high in that nutrient. It is important to remember that foods that provide lower percentages of the DV also contribute to a healthful diet. For foods not listed in this table, please refer to the U.S. Department of Agriculture’s Nutrient Database Web site: http://www.nal.usda.gov/fnic/ cgi-bin/nut_search.pl. Soy: What you need to know The facts surrounding soy foods and certain types of cancers have been presented in ways that are misleading for many health professionals and consumers. This has produced some anxiety in individuals who have been diagnosed with hormone dependent cancers such as breast cancer and prostate cancer. Soy foods contain “phytoestrogens” or soy isoflavones. The bioactive food compounds found in soybeans that have gained recent attention are – genistein, daidzein and glycitein. Most likely soy foods are most protective when consumed in small amounts throughout a lifetime. Several studies in individuals who consumed soy in small amounts over their lifetime show reduced incidence of breast cancer and prostate cancer development later in life. A recent study found that individuals with the highest intakes of phytoestrogens from soy foods had a significant reduction in colorectal cancer and lung cancer risk. Cell culture research has confirmed that soy isoflavones inhibit growth of breast cancer cells, prostate cancer cells and colorectal cancer cells. Genistein induces apoptosis (cancer cell death) in lung cancer cell cultures. This association exists in humans is not known at this time, although adding soy foods to your daily diet may have some cancer preventive properties, as well as other health benefits, such as reducing the risk of heart disease. Why do I hear conflicting information about soy? Because soy contains “phytoestrogens” many people became concerned that soy foods contained estrogen. This is not true. Some of the phytochemicals in soy foods do have weak estrogen-like activity but this doesn’t mean they act the same way as human estrogen does in your body. In animal studies soy foods appear to actually protect against estrogen activity in hormone dependent cancers. Soy foods also contain dozens of other compounds that appear to have many important functions in our bodies. The phytoestrogens in soy foods protect cells from damage, assist with cell apoptosis (cancer cell death) and help control normal cell growth. Soy supplements have not been shown to have the same health benefits as soy foods. Even if you have an estrogen-receptor positive breast cancer there has not been any research to show that eating a modest amount of soy promotes cancer growth. In fact, recent studies have shown that diets with adequate amounts of soy may make the cancer cells more responsive to chemotherapy and radiotherapy. One to two servings of soy foods per day is beneficial as part of a healthy diet. What about a soy supplement? At this time soy supplements have not been shown to be effective in reducing cancer risk or delaying progression of disease after diagnosis. The best evidence for health benefits has been when a moderate amount of soy foods have been added as part of a healthy diet. References: 1.) Setchell KD. Soy isoflavones Benefits and risks from nature's selective estrogen receptor modulators (SERMs). J Am Coll Nutr. 20:354S-362S. 2001. 2.) Trock BJ, Hilakivi-Clarke L, Clarke R. Meta-analysis of soy intake and breast cancer risk. JNCI. 2006;98:459-471. What foods contain soy and how much do I need? One to two servings of soy foods per day are beneficial as part of a healthy diet. Dietary sources and serving sizes of soy foods are: tofu (4 oz); soy milk (8 fl. oz.); tempeh (1/2 cup); soy beans or edamame (1/2 cup); soy nuts (1/4 cup). 3.) National Library of Medicine. Agency for Healthcare Research and Quality. Available at: http://www.ahrq.gov/clinic/epcsums/ soysum.htm. Accessed June 3, 2007. Type of Soy Food Serving size Protein content (g) Total isoflavone (mg) Genistein* (mg) Soy beans, green (Edamame) 1/2 cup 17 12 6 Tofu 3 oz 13 20 12 Tofu yogurt 1/2 cup 5 21 12 Soy flour, defatted 1/4 cup 13 22 13 Soy milk 1 cup 10 30 17 Soy nuts 1/4 cup 15 37 19 Tempeh 3 oz 10 37 21 Adapted from: U.S. Department of Agriculture’s Nutrient Database Web site: http://nal.usda.gov/fnic/cgi-bin/nut_search.pl Note: Nutrient content can vary by brand name. * Genistein is a specific isoflavone that may have a role in reducing risk of heart disease and some types of cancer. Nutrition Connections is a pilot project funded by a grant from UW Health. Organic Fruits and Vegetables: Are they better? The primary focus of this project is to provide up-to-date nutrition education for individuals after a cancer diagnosis. Consuming adequate nutrients in your diet may help reduce your risk of cancer recurrence as well as other diseases. All fruits and vegetables contain a wide array of carotenes, polyphenols and other phytochemicals that are important for optimal health and protection against cancer and cardiovascular disease. Fruits and vegetables also provide many vitamins and minerals that are essential for good health. Thousands of studies, involving hundreds of thousands of people all over the world, prove that a high intake of fruits and vegetables is associated with improved health. Nearly all of these studies were conducted using non-organic fruits and vegetables. To meet with a Clinical Nutritionist at the UW Paul P. Carbone Comprehensive Cancer Center, please contact Cancer Connect at (800) 622.8922 or (608) 262.5223. The increase in organic farming has raised interest in the health benefits of organic fruits and vegetables, If you have moved, do not wish to receive this publication in the future, or have feedback for future publications, please return this form to: UW Paul P. Carbone Comprehensive Cancer Center Megan Waltz-Hill, MS, RD Clinical Nutrition, Oncology 600 Highland Ave., F4/120 Madison, WI 53792-1510 (608) 263.8245 [email protected] Kristina Penniston, PhD, RD Clinical Nutrition, Urology 600 Highland Ave., F4/120 Madison, WI 53792-1510 (608) 265.9797 [email protected] I am moving. Here is my new address: Please remove me from the mailing list. I am receiving more than one copy and I’m returning these labels to be removed from the mailing list. 600 Highland Ave., K4/658 Madison, WI 53792-6164 particularly with respect to nutrient content and pesticide exposure. Some studies show that organic vegetables do have higher levels of vitamins C and E, iron, magnesium, and some phytochemicals than those grown with conventional methods. Other studies show no difference. Studies do show that people who eat organic fruits and vegetables have lower levels of pesticides in their bodies than those who eat non-organic fruits and vegetables. Bottom line: Eating 8 or more servings of fruits and vegetables every day – whether organic or not – protects against cancer and promotes overall health. If you have access to organic fruits and vegetables, you may Eating eight or more servings of fruits and vegetables everyday may protect against some cancers. reduce your pesticide exposure but it is uncertain how necessary this is in reducing risk of certain types of cancers. The Environmental Working Group (http://www.ewg.org/) has published information on the pesticide content of commonly-consumed fruits and vegetables. 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