2 Nutrition in Cancer Prevention Because carcinogenesis occurs over years, most data linking diet and cancer is epidemiological (case control, cohort, or cross-sectional studies)It is estimated that one third of the cancer deaths each year in the US can be attributed to nutrition and other lifestyle factors (not including smoking)
3 Types of Epidemiologic Studies of Cancer Case Control StudiesThe diets of individuals with cancer are compared with those of cancer-free controls matched for age, sex, and other key factors.Cohort StudiesThe diets of different groups of subjects are determined before cancer onset, and the incidences of developing cancers in each group are compared.Cross-sectional StudiesThe diets of different groups of subjects are compared, using the same measures at a single point in time.
4 Nutrition in the Etiology of Cancer– cont’d Complex relationshipDietary carcinogens: naturally occurring and added in food preparation and preservationInhibitors of carcinogenesis: antioxidants, phytochemicalsEnhancers of carcinogenesisLatency period between initiation and promotion
5 Energy Intake, Body Weight, Obesity, and Physical Activity Energy restriction inhibits cancer and extends life span in animalsPositive associations between overweight and cancers of the breast, endometrium, kidney, colon, prostate, and othersOverweight increases risk of cancer recurrence and decreases survivalPhysical activity is inversely associated with cancer
6 Nutrition and Cancer Etiology FatProteinSoy and phytoestrogensCarbohydrates: fiber, sugars, and glycemic indexFruits and vegetablesNonnutritive sweeteners
7 Nutrition and Cancer Etiology– cont’d AlcoholCoffee and teaMethods of food preparation and preservationCancer chemopreventionCancer prevention recommendations: nutrition and physical activityNutrition and physical activity recommendations for cancer survivors
8 Color Code System of Vegetables and Fruits PhytochemicalVegetables and FruitsRedLycopeneTomatoes and tomato products, pink grapefruit, watermelonRed/purpleAnthocyanins, polyphenolsBerries, grapes, red wine, prunesOrangeα-, β-caroteneCarrots, mangoes, pumpkinOrange/yellowβ-cryptoxanthin, flavonoidsCantaloupe, peaches, oranges, papaya, nectarinesYellow/greenLutein, zeaxanthinSpinach, avocado, honeydew, collard and turnip greensGreenSulforaphanes, indolesCabbage, broccoli, Brussels sprouts, cauliflowerWhite/greenAllyl sulphidesLeeks, onion, garlic, chivesData from Heber D: Vegetables, fruits and phytoestrogens in the prevention of diseases, F Postgrad Med 50:145, 2004.
9 Guidelines for Cancer Prevention Choose a diet rich in a variety of plant-based foods.Eat plenty of vegetables and fruits.Maintain a healthy weight and be physically active.Drink alcohol only in moderation, if at all.Select foods low in fat and salt.Prepare and store food safely.And always remember Do not use tobacco in any form.From American Institute for Cancer Research: Simple steps to prevent cancer, Washington, DC, 2000, AICR.
10 Nutrition in Cancer Prevention Diets contain both inhibitors and enhancers of carcinogenesisAnimal studies also test the effect of food and nutrition on cancer and provide guidance for epidemiological studies
11 FatHigh intake of total and saturated fat is associated with increased risk of breast, colon, lung and prostate cancersHigh fat diets are associated with obesity, which is linked with cancer of the colon, rectum, esophagus, gall bladder, breast, endometrium, pancreas, and kidneyAnimal fat (from meat and dairy) was associated with increased risk of breast cancer in the Nurses Health study and othersHigher omega-3 vs omega 6 may reduce risk of breast cancerLow fat diet (<20% fat) may reduce risk of recurrence of breast cancer
12 Energy Intake and Physical Activity Total energy intake is strongly associated with breast cancer in postmenopausal womenPhysical activity may have a protective effectWomen who spent an average 3.8 hours per week in physical activities had lower risk of colon, reproductive cancers
13 Obesity is a Risk Factor for: Breast cancer (among postmenopausal women)ColonEndometriumEsophagusGallbladderPancreasKidneyIs also a risk factor for cancer recurrence
14 ProteinDifficult to isolate effects of protein, since ↑ protein diets are ↑ in fat and ↓ in fiberLow protein diets seem to reduce the risk of cancer, while risk is increased by very high protein intakesIncreased meat intake is associated with increased risk of colon cancer and advanced prostate cancer
15 FiberObservational studies and case control studies indicate that fiber-rich diets are associated with a protective effect in colon cancerHigher intakes of vegetables were inversely associated with colon cancer risk in one studyBut high fiber diets also tend to be lower in meat, fat, and refined carbohydrates
16 FiberTwo intervention trials evaluating the effect of fiber on polyp and adenoma recurrence failed to show an effect of high fiber vs low fiber dietsRecommendation is to eat high fiber foods despite lack of conclusive evidence re cancer
17 Carbohydrate and Glycemic Index High glycemic-index diet associated with increased risk of cancers including ovarian, endometrial, breast, colorectal, pancreas, and lungLimit processed foods and refined sugars and emphasize whole grains and low GI foods
18 Fruits and VegetablesFruits and vegetables found to be associated with lower risk in 128 of 156 dietary studiesIncreased consumption of fruits and vegetables is associated with lower risk of cancers of the oral cavity, esophagus, stomach, colon, rectum, and bladderEvidence less strong for hormone-related cancers such as breast and prostate cancer
19 Fruits and VegetablesPeople who develop cancer tend to have low intakes ofRaw and fresh vegetablesLeafy green vegetablesLettuce, carrots, raw and fresh fruitCruciferous (cabbage family) vegetablesFlavenoids and lignans (soy, grains, vegetables) are associated with lower risk of sex hormone-related cancers
20 Fruits and VegetablesLow in energy, good sources of fiber, vitamins, mineralsGood sources of antioxidants (vitamins C, E, selenium, phytochemicals such as carotenoids, flavonoids, plant sterols, allium compounds, indoles, phenols, terpenesDo not yet know what is the protective agent(s) so best to use food sources
21 Plant based foods may prevent cancer by Inhibiting hormone-dependent steps in tumor formation and protecting genetic material from carcinogenic agentsSuppressing free radical productionServing as bulking agents to dilute carcinogens and decrease gastrointestinal transit timeStimulators of physiologically active and anti-cancer enzymesMobley C. Nutrition and cancer prevention. In McCallum and Polisena, The Clinical Guide to Oncology Nutrition. Oncology Nutrition Dietetic Practice Group, 2000.
22 Cancer Chemoprevention Studies ß-carotene supplementation in Finnish smokers was associated with a 16% higher incidence of lung cancerHeavy alcohol intake seemed to enhance negative effectsHowever, diet studies suggest that high fruit and vegetable consumption, particularly carotenoids, tomatoes, and tomato-based products may reduce risk of lung cancer
23 Supplementation in Persons at High Risk for Esophageal-Gastric Cancer in China Study in area of China with diet low in micronutrients and very high risk of esophageal and gastric cancerß-carotene, vitamin E, and selenium at 5X the RDA was associated with significantly lower mortality from all cancers
24 Calcium and Cancer Risk Several studies suggest that foods high in calcium may reduce the risk for colorectal cancer and that calcium supplements may reduce the formation of colorectal polypsHowever, there is evidence that high calcium intake, especially supplements, is associated with increased risk of prostate cancerBottom line: get calcium through food sources
25 Lycopene and Cancer Risk Lycopene is a red-orange carotenoid found in tomatoes and tomato-based foodsSeveral studies show that consuming tomato products reduces the risk of some cancers, but unclear whether lycopene is responsibleAbsorption of lycopene is enhanced when lycopene-containing vegetables are cooked and eaten with fatNo evidence that supplements are safe and effective in cancer prevention.Source: American Cancer Society, accessed 2005
26 Preserved Meats and Cancer Risk Some studies link eating large amounts of preserved meat to increased risk of colorectal and stomach cancersMay or may not be due to nitritesNitrites can be converted in the stomach to carcinogenic nitrosamines, which may increase the risk of stomach cancerVegetables and fruit retard the conversion of nitrites to nitrosamines
27 Cooked Meat and Cancer Risk Frying, broiling, and grilling meats at high temperatures creates chemicals that might increase cancer risk (cause cancer in animals)Use techniques such as braising, steaming, poaching, stewing and microwaving
28 Soy and Cancer RiskSoy contains several phytochemicals (phytoestrogens) which have weak estrogen activity and appear to protect against hormone-dependent cancers in animal studiesNo evidence shows soy supplements reduce cancer riskHigh doses of soy may increase the risk of estrogen-responsive cancers, such as breast or endometrial cancers in certain womenBreast cancer survivors should consume only moderate amounts
29 AlcoholAlcohol associated with carcinogenesis in cancers of the mouth, pharynx, larynx, esophagus, lung, colon, rectum, liver and breast (USDHHS, 2000)Appears to act synergistically with tobaccoMalnutrition associated with alcoholism may also be implicated
30 Coffee and TeaCoffee has been investigated as a possible risk factor for a variety of cancers, but does not appear to be associated with increased cancerRegular drinking of green tea and other sources of polyphenols may reduce the risk of stomach cancerConsumption of very hot drinks may increase the risk of esophageal cancer
31 Artificial Sweeteners Cyclamate banned as food additive in US in 1969 and saccharine in 1977 after being associated with bladder cancer in miceUnder public pressure, saccharine returned to the market; it was reviewed and taken off the list of potential carcinogens in 2000Aspartame: no evidence implicating it in increased cancer risk
32 Artifical Sweeteners Five artificial sweeteners on the market: Acesulfame-KAspartameNeotameSaccharineSucralose
33 Hyperinsulinemia and Cancer Increased body mass index may promote hyperinsulinemia and metabolic syndromeInsulin resistance/hyperinsulinemia, higher estrogen levels, and insulin-like growth factor I may act synergistically to promote tumor growth, particularly mammary tumors.
34 Food Safety and CancerNaturally occurring carcinogens (aflatoxins in peanuts, safrol in plant oils, tannins in grains and grapes, benzopyrene formed by smoking meat and fish)Naturally found in plant foods like celery, parsley, figs, mustard, pepper, citrus oilsPesticides
35 Food Safety and Cancer Choose in-season, locally grown produce Rinse fruits and vegetables and remove outer leaves before eatingUse proper food storage to prevent growth of fungal carcinogensMarinate protein foods to decrease cooking timeUse cooking methods to avoid contact of foods and food drippings with flamesUse lower cooking temperatures with protein foodsMobley C. Nutrition and cancer prevention. In McCallum and Polisena, The Clinical Guide to Oncology Nutrition. Oncology Nutrition Dietetic Practice Group, 2000
36 AICR Diet and Health Guidelines for Cancer Prevention Choose a diet rich in a variety of plant-based foodsEat plenty of vegetables and fruits.Maintain a healthy weight and be physically active.Drink alcohol only in moderation, if at all.Select foods low in fat and salt.Prepare and store food safely.
37 American Cancer Society Guide to Nutrition and Activity Eat a variety of healthful foods, with an emphasis on plant sources. Eat five or more servings of a variety of vegetables and fruits each day.Include vegetables and fruits at every meal and for snacks.Eat a variety of vegetables and fruits.Limit French fries, snack chips, and other fried vegetable products.Choose 100% juice if you drink fruit or vegetable juices.
38 American Cancer Society Guide to Nutrition and Activity Choose whole grains in preference to processed (refined) grains and sugars.Choose whole grain rice, bread, pasta, and cereals.Limit consumption of refined carbohydrates, including pastries, sweetened cereals, soft drinks, and sugars.
39 American Cancer Society Guide to Nutrition and Activity Limit consumption of red meats, especially those high in fat and processed.Choose fish, poultry, or beans as an alternative to beef, pork, and lamb.When you eat meat, select lean cuts and smaller portions.Prepare meat by baking, broiling, or poaching, rather than by frying or charbroiling.
40 American Cancer Society Guide to Nutrition and Activity Choose foods that help maintain a healthful weight.When you eat away from home, choose food low in fat, calories, and sugar and avoid large portions.Eat smaller portions of high-calorie foods. Be aware that “low fat” or “fat free” does not mean “low calorie” and that low-fat cakes, cookies, and similar foods are often high in calories.Substitute vegetables, fruits, and other low-calorie foods for calorie-dense foods such as French fries, cheeseburgers, pizza, ice cream, doughnuts, and other sweets.
41 Lifestyle Changes to Reduce Breast Cancer Risk Reducing alcohol consumptionBreastfeedingAvoiding obesityBeing physically activeSource: American Cancer Society, accessed 2005
42 Lifestyle Change to Prevent Colon Cancer Increase your physical activityEat more vegetables and fruitLimit intake of red meatsAvoid obesityAvoid excess alcoholSource: American Cancer Society, accessed 2005
43 Lifestyle Changes to Prevent Oral and Esophageal Cancers The best advice to reduce the risk of oral and esophageal cancers is to:Avoid all forms of tobaccoRestrict alcohol consumptionAvoid obesity
44 Lifestyle Changes to Prevent Pancreatic Cancer Avoid tobacco useMaintain a healthful weightRemain physically activeEat five or more servings of vegetables and fruits each daySource: American Cancer Society, accessed 2005
45 Lifestyle Changes to Prevent Prostate Cancer Limit intake of animal products, especially red meat and high-fat dairy productsEat five or more servings of vegetables and fruits each day
46 Lifestyle Changes to Prevent Stomach Cancer Eat at least five servings of vegetables and fruits daily.Stomach cancer rates are falling due to reduced infection with h. pylori
47 At Present, There Are No Nutritional Risk Factors for Brain CancerLeukemiasOvarian cancerSource: American Cancer Society, accessed 2005
48 Diet Recommendations for Cancer Survivors Cancer survivor may harbor undetected primary or disseminated cancer cellsA “cured” cancer pt is at increased risk for other primary cancers in the same organ or other organsGeneral dietary guidelines are also appropriate for recovering cancer ptsDietary regimens should a) avoid stimulating growth and spread of remaining tumor cells and b) provide maximum prevention against new primary tumorsNixon DW. Nutrition during cancer recovery. In McCallum and Polisena, The Clinical Guide to Oncology Nutrition. Chicago, The American Dietetic Association, 2000.
49 Recommendations for Cancer Survivors Limit total fat intake to 15-20% of total calories. Monounsaturated fats are preferred.Aim for daily servings of a variety of whole vegetables and fruits.Consume 4-6 servings of whole grains daily. Breast cancer pts should eliminate or severely restrict alcohol intake
50 Dietary Recommendations for Cancer Survivors Consider a Vitamin E supplement of 200 IU/day to replace deficit from reduced fat intakeStandard dose multivit daily (not to exceed 100% RDA). This does not replace cancer-fighting foodsExercise moderately (30 minute daily walk, for example)Maintain desirable body weight