Does drinking alcohol increase the risk of cancer? Yes, alcohol consumption increases the risk of cancers of the mouth, pharynx, larynx, esophagus, liver, breast, colon and rectum. Drinkers should limit their alcohol intake to no more than 2 alcohol units per day for men and no more than 1 alcohol unit per day for women. 1 alcohol unit is equivalent to 360 ml (1 U.S. fluid ounce ≈ 30 ml), 150 ml of wine, or 45 ml of 40 proof spirits. For some cancers, the increased risk of cancer from drinking alcohol and smoking together is much higher than the risk from drinking only alcohol or smoking only. Regular alcohol consumption, even in small amounts per week, can increase a woman’s risk of developing breast cancer. The group of women with high risk of breast cancer may consider quitting alcohol. Jiang Zhaoding, Department of Traditional Chinese Medicine and Oncology, Qinzhou City Hospital of Traditional Chinese Medicine What are antioxidants (substances)? What is the relationship between them and cancer? Antioxidants (substances) can be certain compounds in food or synthesized by the body itself. The body uses antioxidants (substances) to protect its tissues from ongoing damage caused by normal metabolism (oxidation). Because this damage can increase the risk of cancer, certain antioxidants may help prevent cancer. Antioxidants (substances) include vitamin C, vitamin E, carotenoids (such as beta-carotene and vitamin A), and other phytochemicals. Studies have shown that consuming more vegetables and fruits rich in antioxidants (substances) may reduce people’s risk of developing certain cancers. However, this result is not necessarily a function of antioxidants (substances), as these foods contain many other substances as well. Several studies have found that supplementation with antioxidants (substances) does not reduce the risk of cancer. In fact, one study found that people who took supplements (substances) had a higher risk of cancer. (See the following entries: beta carotene, lycopene, vitamin E, supplements). For reducing the risk of cancer, the best current recommendation is to get antioxidants through food rather than supplements. Can beta-carotene reduce the risk of cancer? Beta carotene belongs to the carotenoids, a group of antioxidants that give certain parts of plants (including vegetables and fruits) a deep orange color. In the body, beta carotene is converted to vitamin A, which is thought to help prevent cancer. Because consumption of vegetables and fruits reduces the risk of cancer, the idea that cancer risk can be reduced by taking high doses of beta carotene supplements seems plausible. However, the results of several large studies suggest that this is not the case. Two of these studies, in which subjects who smoked were given high doses of beta carotene supplements to prevent lung and other cancers, showed that taking these supplements increased their risk of developing lung cancer. Another study found no benefit or harm from taking beta carotene supplements. While eating vegetables and fruits containing beta carotene may help prevent cancer, people should avoid taking supplements that contain high amounts of beta carotene, especially smokers. Is calcium associated with cancer? Many studies have shown that foods high in calcium may help reduce the risk of colorectal cancer and that calcium supplements can appropriately reduce the recurrence of colorectal polyps. However, consuming too much calcium (from calcium supplements or from food sources) can increase one’s risk of developing prostate cancer. Therefore, men should consume the recommended dose of calcium primarily through food rather than in excess. Women do not develop prostate cancer, but are susceptible to osteoporosis, so they should also get the recommended dose of calcium through food. The recommended intake of calcium is 1,000 mg per day for those aged 19-50 years and 1,200 mg per day for those aged 50 years and older. Dairy products and certain green leafy vegetables are good sources of calcium. People who get their calcium primarily from dairy products should use low-fat or nonfat dairy products to reduce their intake of saturated fat. Does drinking coffee cause cancer? No, it does not. Is there a link between coffee and pancreatic cancer? This question has received a lot of attention, but recent studies have not confirmed a link between the two. There is no evidence that coffee or caffeine increases the risk of cancer. Can dietary supplements reduce the risk of cancer? No. The answer, at least based on current knowledge, is no. While a diet rich in vegetables, fruits and other plant-based foods may reduce cancer risk, the conclusion that dietary supplements can reduce cancer risk has not been confirmed. The exception may be calcium supplements, which may reduce the risk of colorectal cancer (see the above description of calcium). In fact, some high doses of supplements can increase cancer risk. Moderate amounts of dietary supplements can be beneficial for people with specific conditions, such as pregnant women, women of childbearing age, and people who need to restrict their dietary intake. If people choose to take dietary supplements, they are best served with a multivitamin/mineral balance and most of these nutrients should not exceed the body’s daily requirement. Is it possible to get the same nutritional value from supplements as from vegetables and fruits? No. Vegetables and fruits contain many healthful compounds that most likely need to be consumed together to have beneficial effects. In addition, there may be important compounds in natural foods that are not currently known and that are not present in dietary supplements. Some dietary supplements are described as having the same nutritional value as vegetables and fruits, but their nutritional content or variety is only a small fraction of that found in natural foods. Therefore, food is the best source of vitamins and minerals. Does eating less fat reduce cancer risk? Some studies have found that nationals of countries with diets high in fatty foods have a higher risk of breast, prostate, colon and other cancers. However, more in-depth studies have not concluded that fat intake increases cancer risk, or that reducing fat intake decreases cancer risk. There is insufficient evidence that the total amount of fat consumed by an individual affects the risk of cancer. What is dietary fiber? Can dietary fiber reduce the risk of cancer? Dietary fiber refers to a variety of plant-based carbohydrates that the body cannot digest. Dry legumes, vegetables, whole grains and fruits are good sources of dietary fiber. Dietary fiber can be further classified as “soluble” (such as oat bran, peas, beans and psyllium fiber) and “insoluble” (such as wheat bran, fruit peels, nuts, seeds and cellulose). Recent research suggests that dietary fiber may reduce the risk of certain cancers, particularly colorectal cancer. But it is not clear whether this effect is produced by dietary fiber or other components of high-fiber foods. Therefore, the ACS recommends that people consume high-fiber foods such as whole grains, vegetables and fruits to help reduce cancer risk, but does not explicitly recommend taking dietary fiber supplements. Can eating fish prevent cancer? Fish is rich in omega-3 fatty acids. Some animal studies have found that omega-3 fatty acids can prevent cancer formation or slow down the growth of cancer cells, but it is not clear whether these fatty acids reduce cancer risk in humans. Consumption of fish rich in omega-3 fatty acids may reduce the risk of heart disease, but some fish (e.g., swordfish, tuna, squareheads, shark and mackerel) may contain high levels of mercury, polychlorinated biphenyls (PCBs), dioxins and other harmful substances. Some studies have also found that fish farmed in captivity contain more harmful substances than wild fish. Pregnant women, women planning to become pregnant or breastfeeding, and young children should not consume these fish and should not consume more than 170 g of albacore tuna per week or 340 g of canned light tuna per week. people should consume different types of fish to reduce the likelihood of ingesting toxins. What is folic acid? Can folic acid reduce cancer risk? Folic acid is a naturally occurring B vitamin that is found in many vegetables, legumes, fruits, whole grains and fortified breakfast cereals. studies conducted in the 1990s suggested that a deficiency of folic acid may increase people’s risk of colorectal and breast cancer, especially in people who drink alcohol. However, since 1998, artificial folic acid has been added to fortified cereal products in the United States, so most people are getting enough folic acid in their diet. Some studies have shown that folic acid supplements increase people’s risk of prostate cancer, high-grade colorectal polyps, and breast cancer, and that most people are getting enough folic acid in their diet. With this in mind, the best way to consume folic acid is to eat vegetables, fruits and fortified grain products or whole grain products. Does garlic reduce the risk of cancer? The health benefits of allium compounds contained in garlic and other onion plants are widely known. Research is ongoing to determine whether garlic can reduce cancer risk, and some studies have shown that garlic can reduce the risk of colorectal cancer. Garlic and other onion plants may be included in the list of recommended vegetables that can reduce cancer risk. There is insufficient evidence that supplements of onion plant compounds can reduce cancer risk. What are genetically modified foods? Are they safe? Genetically modified or bioengineered foods are made from genetically modified crops, which are genetically modified by adding genes from other plants or organisms before they are planted, with the goal of enhancing the crop’s resistance to pests, slowing spoilage, improving taste, increasing nutrient content, or obtaining other characteristics. In recent years, genetic engineering has been increasingly used to produce certain foods. For example, most of the soybeans and corn grown in the United States use genetic modification technology, which allows these crops to be resistant to herbicides, in addition to genetically modified corn that produces a natural pesticide. Concerns have been raised about the safety of genetic modification technology. Theoretically, the added genes could produce substances that cause allergies and could increase the levels of health-damaging compounds. GM technology, on the other hand, can be used to improve public health. For example, genetic modification has been used to increase the folic acid content of various crops. There is no evidence that commercially available GM foods are harmful to human health, nor is there evidence that these added genes increase or decrease cancer risk. However, the lack of evidence does not prove their safety. Since people have been using GM foods for a fairly short period of time, the possible health effects of long-term consumption of GM foods are not yet known. It is important to continually assess the safety of GM foods to ensure their true safety and to increase confidence in their use. Genetically modified foods approved for sale in the United States include a variety of carrots, corn, tomatoes, and soybeans. The U.S. National Environmental Protection Agency (EPA), the U.S. Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA) jointly oversee genetically modified foods. Can irradiated foods cause cancer? There is no evidence that irradiated foods can cause cancer or harm human health. Irradiation is increasingly being used to kill harmful bacteria in foods to extend their shelf life. Radiation does not remain in the food after irradiation treatment, and consumption of irradiated foods does not seem to increase the risk of cancer. Should I avoid processed meats? 14. Can irradiated foods cause cancer? Some studies have found that high consumption of processed meats can increase people’s risk of colorectal and stomach cancers, possibly in part because of nitrites. Nitrites are added to many luncheon meats, hams and hot dogs to maintain color and prevent bacterial growth. Consumption of processed meats and smoked or salted meats can increase people’s intake of potentially carcinogenic agents, so people should reduce their consumption of these meats as much as possible. How does cooking meat affect cancer risk? Adequate cooking kills harmful bacteria in meat, but some studies suggest that chemicals (polycyclic aromatic hydrocarbons or heterocyclic aromatic amines) produced by frying, grilling and deep-frying meat at high temperatures may increase the risk of cancer. These chemicals can damage DNA and cause cancer in animals. Some studies have also found that people who eat a lot of meat have a higher risk of colorectal cancer, but it is still unclear how much of a role the chemicals produced by cooking at high temperatures (compared to other substances in meat) play in this. Cooking methods such as simmering, steaming, cooking at low temperatures and microwaving meat produce fewer of these chemicals. Do non-nutritive sweeteners or sugar substitutes cause cancer? There is no evidence that sweeteners at the human diet level cause cancer. the few non-nutritive sweeteners approved for use by the FDA include aspartame, saccharin and sucralose. Available studies have also failed to confirm a link between these compounds and cancer risk. Some animal studies suggest that use of these sweeteners may be associated with a higher risk of bladder cancer and brain tumors, and possibly with a higher risk of leukemia and lymphoma, but population studies have shown that use of these sweeteners does not increase people’s risk of cancer. It is important to note that people with phenylketonuria, a genetic disorder, should avoid aspartame in their diets. New sugar substitutes include sweeteners such as sugar alcohols (sorbitol, xylitol and mannitol) and sweeteners derived from natural plants (stevia and agave syrup). All of these sweeteners appear to be safe in moderation, but certain populations may experience bloating and stomach discomfort if they use sugar alcohols in large amounts. Does obesity increase the risk of cancer? Yes. Being overweight or obese is associated with a higher risk of breast cancer (in postmenopausal women), colorectal cancer, endometrial cancer, esophageal cancer, kidney cancer, pancreatic cancer, and gallbladder cancer (possibly). Obesity may also be associated with a higher risk of liver, cervical, and ovarian cancers, as well as non-Hodgkin’s lymphoma, multiple myeloma, and aggressive prostate cancer. Although there is limited research on whether weight loss reduces cancer risk, some studies suggest that weight loss reduces the risk of breast and other cancers in postmenopausal women. Other health benefits of weight loss have been demonstrated, so people who are overweight are encouraged to lose weight and maintain a healthy weight. It is also important for adults to avoid excessive weight gain, as this may not only reduce the risk of cancer, but also their risk of other chronic diseases. Does olive oil affect cancer risk? Consumption of olive oil is associated with a lower risk of heart disease in people, but in terms of its effect on cancer risk, the most likely scenario is not good or bad. Although olive oil is rich in monounsaturated fats and can be a healthy alternative to butter and margarine, it is still a great source of calories and can greatly increase the amount of calories people get in their diet. Are foods labeled “organic” more effective at reducing cancer risk? The term “organic” is widely used to describe plant foods that have no artificial chemicals added and animal foods that have not been raised with hormones and antibiotics. In the case of plant-based organic foods, the raw materials are grown without the use of conventional pesticides or herbicides, without the use of chemical fertilizers or sewage sludge as fertilizer, and without food irradiation. Genetically modified foods cannot be called organic. The purpose of producing organic food is actually to promote sustainable agricultural production, but it is widely believed that organic food may be beneficial to health. At the same time, there is debate as to whether the nutritional levels of organic produce are higher than those of conventionally grown produce. However, there is no evidence that organic foods are more effective at reducing cancer risk or provide health benefits not found in similar foods grown by other farming methods. Do pesticides and herbicides in food cause cancer? Pesticides and herbicides are toxic if they are used improperly in industry, agriculture or other workplaces. Although vegetables and fruits sometimes contain small amounts of pesticides and herbicides, the overwhelming scientific evidence suggests that, overall, eating vegetables and fruits is good for health and prevents cancer. There is no evidence that low doses of residual pesticides and herbicides in foods increase cancer risk. However, fruits and vegetables should be washed thoroughly before consumption to reduce people’s intake of these compounds and to reduce the health risks caused by bacteria. Will increased physical activity reduce the risk of cancer? Yes. The risk of certain cancers such as breast, colon, endometrial and advanced prostate cancers is lower for people who engage in moderate or high levels of physical activity. Exercise itself reduces the risk of certain cancers, whether or not it affects weight. Currently, data on the direct effect of physical activity on the risk of other cancers is more limited, but even so, physical activity is a key factor in people achieving and maintaining a healthy weight, and being overweight or obese is associated with many cancers. Physical activity also helps reduce people’s risk of heart disease, diabetes and other diseases. What are phytochemicals? Can they reduce the risk of cancer? The term “phytochemicals” refers to a variety of compounds produced by plants. Some of these compounds protect plants from insect damage or have other important functions. Others have antioxidant or hormone-like effects, both on the plants themselves and on the people who consume them. Because consumption of vegetables and fruits is associated with a reduced risk of cancer, researchers are looking for specific compounds that produce beneficial effects. However, there is no evidence yet that the intake of phytochemicals in supplement form has similar effects on long-term human health as vegetables, fruits, legumes and grains. Phytochemicals include flavonoids (found in soy, chickpeas and tea), carotenoids (found in winter squash, melon and carrots), anthocyanins (found in eggplant and red cabbage) and sulfides (found in garlic and onions). Does a high salt diet increase cancer risk? There is ample evidence that consumption of high amounts of pickled foods can increase the risk of stomach, nasopharyngeal and throat cancers. Pickled foods are not usually a staple of most people’s diets in the United States, but reducing the amount of pickled foods consumed may help reduce people’s risk of developing certain cancers. There is little evidence that the amount of salt used in cooking or the amount of salt used to flavor foods or the amount of salt added during food processing has an effect on cancer risk in the United States. However, it is well known that a high-salt diet increases the risk of high blood pressure and heart disease, so both the 2010 U.S. Dietary Guidelines and the American Heart Association’s Dietary Guidelines recommend that people limit their salt intake. What is selenium? Can selenium reduce the risk of cancer? Selenium is a mineral that contributes to the body’s antioxidant defense mechanisms. Animal studies have shown that selenium may prevent cancer. One study suggests that selenium supplements may reduce the risk of lung, colon and prostate cancers in people. However, a large clinical trial did not find that selenium supplements reduced the risk of prostate cancer, so overall, there is not enough evidence that selenium supplements reduce cancer risk. Therefore, it is not recommended that people take selenium supplements, and they should also avoid taking high doses of selenium supplements because the difference between a safe dose and a toxic dose of selenium supplements is very small. The maximum dose of selenium supplements should not exceed 200 micrograms per day. Do soy products reduce cancer risk? Like other legumes, soybeans and soy products are a high-quality source of protein as well as a beneficial alternative to meat. Soy contains a variety of phytochemicals, including isoflavones. The phytochemicals in soy have weak estrogen-like activity and may help prevent hormone-dependent cancers. There is growing evidence that consumption of traditional soy products such as tofu may reduce the risk of breast, prostate or endometrial cancer in people. There is also some evidence that consumption of traditional soy products may also reduce people’s risk of certain other cancers. It is not clear whether this conclusion applies to foods containing soy isolate or organized soy protein. There is little data to confirm that taking isolated soy phytochemical supplements reduces the risk of cancer. Does sugar increase the risk of cancer? Sugar does not provide any nutrients that reduce cancer risk while increasing caloric intake. High sugar intake may indirectly increase cancer risk by promoting obesity. White sugar (refined sugar) does not differ from brown sugar (crude sugar) and honey in its effect on body weight or insulin levels. Limiting the consumption of cakes, candy and sugar-sweetened cereals and limiting the consumption of sugary drinks such as soda and sports drinks can help people reduce their caloric intake. Can drinking tea (black or green tea) reduce cancer risk? Tea is a beverage that can be brewed from the leaves, shoots or fine twigs of the tea tree. Black tea, green tea, white tea, pu-erh tea and various other types of tea all come from the same tea tree, but they reflect different ways of processing. Some researchers have suggested that tea prevents cancer because it contains antioxidants, polyphenols and flavonoids. Animal studies have demonstrated that some teas (including green tea) reduce cancer risk, but human studies have found mixed results. Although laboratory studies have been satisfactory and tea drinking is part of many cuisines, the current evidence does not yet prove that tea drinking is a major cause of cancer risk reduction. Do trans fats increase cancer risk? Trans fats come from vegetable oils that have been hydrogenated to make margarine or ghee, which are solid at room temperature. Trans fats can raise blood cholesterol levels and increase the risk of heart disease. However, no link between trans fats and cancer risk has been established. Nevertheless, given the impact of trans fats on heart disease risk, the 2010 U.S. Dietary Guidelines and the American Heart Association’s Dietary Guidelines recommend that people limit or avoid trans fats. Do turmeric and other spices reduce cancer risk? Researchers are currently studying whether turmeric affects tumor growth, and they are also investigating the possible anti-cancer effects of other spices such as capsaicin (red pepper), cumin and curry. However, there is a lack of research examining the long-term effects of spices on diseases such as cancer. Does eating vegetables and fruits reduce the risk of cancer? Yes. Recently, the evidence that eating vegetables and fruits reduces cancer risk has weakened as more and more studies have found no or weak effects, but the totality of evidence available suggests that eating vegetables and fruits may reduce the risk of cancers, including lung, oral cavity, larynx, larynx, esophagus, stomach, colon and rectum, to some extent. The risk of lung, mouth, larynx, larynx, esophagus, stomach, colon and rectum cancers is reduced to some extent. The types of vegetables and fruits that may reduce the risk of a specific cancer may vary. It is not known which compounds contained in vegetables and fruits are most likely to prevent cancer, and the different phytochemicals that reduce the risk of cancer may be derived from different vegetables and fruits. Recent studies suggest that eating more vegetables and fruits may also help reduce people’s risk of obesity, so eating more vegetables and fruits may indirectly affect cancer risk. The best advice is to eat a variety of vegetables and fruits, at least 600 ml per day. Is there a difference in the nutritional value of fresh, frozen and canned vegetables and fruits? Yes, but they are all good choices. Fresh foods are often considered to have the highest nutritional value (and often the best flavor). However, frozen foods are actually more nutritious than fresh foods because frozen foods are usually picked when ripe and frozen quickly, whereas fresh foods may lose some nutrients due to the time lapse between harvest and consumption. Because high temperatures must be used to process canned foods, canned foods are more likely to have reduced heat-sensitive nutrients and water-soluble nutrients. Please note that some canned fruits come with thick syrup and some canned vegetables are high in sodium (salt), so choose a variety of forms of vegetables and fruits. Does cooking affect the nutritional value of vegetables? Cooking vegetables, especially for long periods of time, can eliminate the water-soluble vitamins in vegetables. Since some of the potentially beneficial phytochemicals contained in vegetables are fat-soluble, sautéing vegetables in oil may increase the availability of these phytochemicals. Cooking may often break down plant cell walls, making the nutrients and other phytochemicals they contain more easily absorbed. Cooking vegetables in the microwave and steam is the best way to preserve their nutrient content. Eating raw vegetables such as salads will also retain the nutrients of the vegetables. So, in addition to recommending that people eat a wide variety of vegetables, using different methods of cooking vegetables will improve the availability of many nutrients and phytochemicals. Should I juice vegetables and fruits? Juicing not only adds variety to the diet, it is also a great way to get people to consume vegetables and fruits, especially for those who have difficulty chewing or swallowing. Juicing also helps the body absorb the nutrients found in vegetables and fruits. However, fruit and vegetable juices contain less fiber and are less likely to fill the stomach when compared to whole vegetables and fruits. However, juices are more specific, and if a person drinks a lot of juice, they can get just as many calories. Commercially speaking, juicing products should be 100% fruit and vegetable juice and should also be pasteurized to kill harmful bacteria in them. Can a vegetarian diet reduce the risk of cancer? A vegetarian diet can include many healthful features. Vegetarian diets tend to be low in saturated fat and high in fiber, vitamins and phytochemicals, while also not including the consumption of red and processed meats. Therefore, the hypothesis that a vegetarian diet may help reduce cancer risk is reasonable. It is unclear whether a completely vegetarian diet would be more beneficial for cancer prevention than a diet structure formed by reducing the amount of animal foods in the traditional Western diet. A strict vegetarian diet should avoid all animal products, including milk and eggs, and this vegetarian diet, also known as a vegan diet, may be beneficial for people taking vitamin B12, zinc and iron supplements, especially for children and premenopausal women. A vegan diet should also include adequate calcium, as it has been shown that vegans who adhere to a very low calcium content have a higher risk of fractures than those who adhere to a vegetarian or meat-containing diet. Does vitamin A reduce cancer risk? There are two ways to obtain vitamin A from food: first, vitamin A can be obtained from animal food sources, and second, vitamin A can be produced in the body from beta carotene or other carotenoids derived from plant foods. People need vitamin A to maintain healthy body tissues. Vitamin A supplements have not been shown to reduce cancer risk, and taking high doses of vitamin A supplements may actually increase the risk of lung cancer in smokers and ex-smokers. Does vitamin C reduce cancer risk? Vitamin C is commonly found in many vegetables and fruits, especially oranges, grapefruits and peppers. Many studies have linked the intake of vitamin C-rich foods to a lower risk of cancer. However, the few studies that have been conducted on the use of vitamin C supplements have not shown that taking vitamin C supplements reduces the risk of cancer. Does vitamin D reduce cancer risk? A growing body of evidence from large-scale studies suggests that vitamin D may help prevent colorectal cancer, but the evidence obtained so far does not support a link between vitamin D and other cancers. A large number of studies are underway, but the results will be difficult to obtain for several years. Recently, the Institute of Medicine made updated recommendations for daily vitamin D intake based on the level of vitamin D needed for bone health, increasing the daily vitamin D intake from 400 to 600 international units for most adults and to 800 international units for people 70 years and older. The safe upper limit of daily vitamin D intake was increased from 2,000 to 4,000 international units. Vitamin D is obtained in three ways, first through skin exposure to ultraviolet (UV) radiation, second through diet, especially vitamin D-rich foods such as milk and cereals, and third through taking vitamin D supplements. However, many Americans do not get enough vitamin D and are at risk for vitamin D deficiency, with dark-skinned people, people with little exposure to sunlight, older adults and exclusively breastfed infants being particularly vulnerable to vitamin D deficiency. Does vitamin E reduce cancer risk? Alpha-tocopherol is the most active form of vitamin E present in the body and is also a powerful antioxidant. In one study, male smokers who took alpha-tocopherol had a lower risk of prostate cancer than male smokers who took a placebo. This finding prompted researchers to initiate a large research project (called “SELECT”) to study the effects of selenium and vitamin E supplements on prostate cancer risk. However, the study found that selenium and vitamin E supplements did not reduce the risk of prostate cancer. Even on the contrary, the group of men taking vitamin E supplements may also have a higher risk of prostate cancer. In another large study (called “HOPE”), researchers compared the risk of cancer and heart disease with vitamin E supplements and a placebo. There was no difference in the incidence of cancer or heart disease between the vitamin E supplement group and the placebo group. Subjects who took vitamin E supplements actually had a higher incidence of heart failure. Although foods containing vitamin E such as nuts and certain unsaturated oils may be healthy and they have been shown to reduce the risk of heart disease, it is not currently recommended that people take vitamin E supplements to reduce their risk of cancer or chronic disease.