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8/2/2019 Cancer Prevention and Nutrition
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Nutrition in Cancer Prevention
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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 (notincluding smoking)
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Types of Epidemiologic Studies
of CancerCase Control Studies
The diets of individuals with cancer are compared with those of
cancer-free controls matched for age, sex, and other key factors.
Cohort Studies
The diets of different groups of subjects are determined beforecancer onset, and the incidences of developing cancers in each
group are compared.
Cross-sectional Studies
The diets of different groups of subjects are compared, using the
same measures at a single point in time.
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Nutrition in the Etiology of
Cancercontd Complex relationship
Dietary carcinogens: naturally occurring
and added in food preparation and
preservation
Inhibitors of carcinogenesis: antioxidants,
phytochemicals
Enhancers of carcinogenesis
Latency period between initiation and
promotion
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Energy Intake, Body Weight,
Obesity, and Physical Activity
Energy restriction inhibits cancer and
extends life span in animals
Positive associations between overweight
and cancers of the breast, endometrium,
kidney, colon, prostate, and others
Overweight increases risk of cancer
recurrence and decreases survival
Physical activity is inversely associated
with cancer
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Nutrition and Cancer Etiology
Fat
Protein
Soy and phytoestrogens Carbohydrates: fiber, sugars, and
glycemic index
Fruits and vegetables Nonnutritive sweeteners
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Nutrition and Cancer Etiology
contd Alcohol
Coffee and tea
Methods of food preparation and preservation
Cancer chemoprevention
Cancer prevention recommendations: nutritionand physical activity
Nutrition and physical activity
recommendations for cancer survivors
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Color Code System of
Vegetables and Fruits
Data from Heber D: Vegetables, fruits and phytoestrogens in the prevention of diseases, F Postgrad Med50:145, 2004.
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Guidelines for Cancer Prevention
1. Choose a diet rich in a variety of plant-based foods.
2. Eat plenty of vegetables and fruits.
3. Maintain a healthy weight and be physically active.
4. Drink alcohol only in moderation, if at all.
5. Select foods low in fat and salt.6. 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.
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Nutrition in Cancer Prevention
Diets contain both inhibitors and enhancersof carcinogenesis
Animal studies also test the effect of food
and nutrition on cancer and provideguidance for epidemiological studies
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Fat
High intake of total and saturated fat is associatedwith increased risk of breast, colon, lung andprostate cancers
High fat diets are associated with obesity, which islinked with cancer of the colon, rectum,
esophagus, gall bladder, breast, endometrium,pancreas, and kidney
Animal fat (from meat and dairy) was associatedwith increased risk of breast cancer in the Nurses
Health study and others Higher omega-3 vs omega 6 may reduce risk of
breast cancer
Low fat diet (
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Energy Intake and Physical
ActivityTotal energy intake is strongly associated
with breast cancer in postmenopausal
women
Physical activity may have a protective
effect
Women who spent an average 3.8 hours per
week in physical activities had lower risk of
colon, reproductive cancers
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Obesity is a Risk Factor for:
Breast cancer(amongpostmenopausal
women)
Colon
Endometrium
Esophagus
Gallbladder
Pancreas
Kidney
Is also a risk
factor for cancerrecurrence
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Protein
Difficult to isolate effects of protein, since
protein diets are in fat and in fiber
Low protein diets seem to reduce the risk of
cancer, while risk is increased by very high
protein intakes
Increased meat intake is associated with
increased risk of colon cancer and advanced
prostate cancer
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Fiber
Observational studies and case controlstudies indicate that fiber-rich diets areassociated with a protective effect in colon
cancerHigher intakes of vegetables were inversely
associated with colon cancer risk in onestudy
But high fiber diets also tend to be lower inmeat, fat, and refined carbohydrates
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Fiber
Two intervention trials evaluating the effect
of fiber on polyp and adenoma recurrence
failed to show an effect of high fiber vs low
fiber diets
Recommendation is to eat high fiber foods
despite lack of conclusive evidence re
cancer
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Carbohydrate and Glycemic Index
High glycemic-index diet associated with
increased risk of cancers including ovarian,
endometrial, breast, colorectal, pancreas,
and lung
Limit processed foods and refined sugars
and emphasize whole grains and low GI
foods
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Fruits and Vegetables
Fruits and vegetables found to be associated
with lower risk in 128 of 156 dietary studies
Increased consumption of fruits and
vegetables is associated with lower risk of
cancers of the oral cavity, esophagus,
stomach, colon, rectum, and bladder
Evidence less strong for hormone-related
cancers such as breast and prostate cancer
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Fruits and Vegetables
People who develop cancer tend to have low intakes
of
Raw and fresh vegetables
Leafy green vegetables
Lettuce, carrots, raw and fresh fruit
Cruciferous (cabbage family) vegetables
Flavenoids and lignans (soy, grains, vegetables)are associated with lower risk of sex hormone-
related cancers
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Fruits and Vegetables
Low in energy, good sources of fiber,
vitamins, minerals
Good sources of antioxidants (vitamins C,
E, selenium, phytochemicals such as
carotenoids, flavonoids, plant sterols, allium
compounds, indoles, phenols, terpenes
Do not yet know what is the protective
agent(s) so best to use food sources
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Cancer Chemoprevention Studies
-carotene supplementation in Finnishsmokers was associated with a 16% higherincidence of lung cancer
Heavy alcohol intake seemed to enhancenegative effects
However, diet studies suggest that high fruit
and vegetable consumption, particularlycarotenoids, tomatoes, and tomato-basedproducts may reduce risk of lung cancer
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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 cancer
-carotene, vitamin E, and selenium at 5X
the RDA was associated with significantly
lower mortality from all cancers
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Calcium and Cancer Risk
Several studies suggest that foods high incalcium may reduce the risk for colorectalcancer and that calcium supplements may
reduce the formation of colorectal polypsHowever, there is evidence that high
calcium intake, especially supplements, isassociated with increased risk of prostatecancer
Bottom line: get calcium through foodsources
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Lycopene and Cancer Risk
Lycopene is a red-orange carotenoid foundin tomatoes and tomato-based foods
Several studies show that consuming tomato
products reduces the risk of some cancers,but unclear whether lycopene is responsible
Absorption of lycopene is enhanced when
lycopene-containing vegetables are cookedand eaten with fat
No evidence that supplements are safe andeffective in cancer prevention.
Source: American Cancer Society, accessed 2005
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Preserved Meats and Cancer Risk
Some studies link eating large amounts of
preserved meat to increased risk of
colorectal and stomach cancers
May or may not be due to nitrites
Nitrites can be converted in the stomach to
carcinogenic nitrosamines, which may
increase the risk of stomach cancer
Vegetables and fruit retard the conversion
of nitrites to nitrosamines
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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
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Soy and Cancer Risk
Soy contains several phytochemicals(phytoestrogens) which have weak estrogenactivity and appear to protect against hormone-dependent cancers in animal studies
No evidence shows soy supplements reducecancer risk
High doses of soy may increase the risk of
estrogen-responsive cancers, such as breast orendometrial cancers in certain women
Breast cancer survivors should consume onlymoderate amounts
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Alcohol
Alcohol associated with carcinogenesis in
cancers of the mouth, pharynx, larynx,
esophagus, lung, colon, rectum, liver and
breast (USDHHS, 2000)
Appears to act synergistically with tobacco
Malnutrition associated with alcoholism
may also be implicated
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Coffee and Tea
Coffee has been investigated as a possiblerisk factor for a variety of cancers, but doesnot appear to be associated with increased
cancerRegular drinking of green tea and other
sources of polyphenols may reduce the riskof stomach cancer
Consumption of very hot drinks mayincrease the risk of esophageal cancer
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Artificial Sweeteners
Cyclamate banned as food additive in US in
1969 and saccharine in 1977 after being
associated with bladder cancer in mice
Under public pressure, saccharine returned
to the market; it was reviewed and taken off
the list of potential carcinogens in 2000
Aspartame: no evidence implicating it in
increased cancer risk
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Artifical Sweeteners
Five artificial sweeteners on the market:
Acesulfame-K
AspartameNeotame
Saccharine
Sucralose
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Hyperinsulinemia and Cancer
Increased body mass index may promote
hyperinsulinemia and metabolic syndrome
Insulin resistance/hyperinsulinemia, higher
estrogen levels, and insulin-like growth
factor I may act synergistically to promote
tumor growth, particularly mammary
tumors.
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Food Safety and Cancer
Naturally 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 oils
Pesticides
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Food Safety and Cancer
Choose in-season, locally grown produce
Rinse fruits and vegetables and remove outerleaves before eating
Use proper food storage to prevent growth offungal carcinogens
Marinate protein foods to decrease cooking time
Use cooking methods to avoid contact of foods
and food drippings with flames Use lower cooking temperatures with protein
foods
Mobley C. Nutrition and cancer prevention. In McCallum and Polisena, The
Clinical Guide to Oncology Nutrition. Oncology Nutrition Dietetic Practice Group,2000
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AICR Diet and Health Guidelines
for Cancer PreventionChoose 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.
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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 andfruits 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 vegetableproducts.
Choose 100% juice if you drink fruit or vegetable juices.
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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.
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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 smallerportions.
Prepare meat by baking, broiling, or poaching,rather than by frying or charbroiling.
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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 thatlow fat or fat free does not mean low calorie andthat low-fat cakes, cookies, and similar foods are oftenhigh in calories.
Substitute vegetables, fruits, and other low-calorie foodsfor calorie-dense foods such as French fries,cheeseburgers, pizza, ice cream, doughnuts, and othersweets.
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Lifestyle Changes to Reduce Breast
Cancer Risk
Reducing alcohol consumption
Breastfeeding
Avoiding obesity
Being physically active
Source: American Cancer Society, accessed2005
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Lifestyle Change to Prevent Colon
Cancer Increase your physical activity
Eat more vegetables and fruit
Limit intake of red meats
Avoid obesity
Avoid excess alcohol
Source: American Cancer Society, accessed 2005
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Lifestyle Changes to Prevent Oral
and Esophageal Cancers
The best advice to reduce the risk of oraland esophageal cancers is to:
Avoid all forms of tobacco
Restrict alcohol consumption
Avoid obesity
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Lifestyle Changes to Prevent
Pancreatic Cancer
Avoid tobacco use
Maintain a healthful weight
Remain physically active
Eat five or more servings of vegetables andfruits each day
Source: American Cancer Society, accessed 2005
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Lifestyle Changes to Prevent
Prostate Cancer
Limit intake of animal products, especially
red meat and high-fat dairy products
Eat five or more servings of vegetables and
fruits each day
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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
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At Present, There Are No Nutritional
Risk Factors for
Brain Cancer
Leukemias
Ovarian cancer
Source: American Cancer Society, accessed
2005
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Diet Recommendations for
Cancer Survivors Cancer survivor may harbor undetected primary or
disseminated cancer cells
A cured cancer pt is at increased risk for otherprimary cancers in the same organ or other organs
General dietary guidelines are also appropriate forrecovering cancer pts
Dietary regimens should a) avoid stimulating
growth and spread of remaining tumor cells and b)provide maximum prevention against new primarytumors
Nixon DW. Nutrition during cancer recovery. In McCallum and Polisena, The ClinicalGuide to Oncology Nutrition. Chicago, The American Dietetic Association, 2000.
d i f C
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Recommendations for Cancer
SurvivorsLimit total fat intake to 15-20% of total
calories. Monounsaturated fats are
preferred.
Aim for 10-12 daily servings of a variety of
whole vegetables and fruits.
Consume 4-6 servings of whole grains
daily. Breast cancer pts should eliminate orseverely restrict alcohol intake
Di R d i f
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Dietary Recommendations for
Cancer SurvivorsConsider a Vitamin E supplement of 200
IU/day to replace deficit from reduced fatintake
Standard dose multivit daily (not to exceed100% RDA). This does not replace cancer-fighting foods
Exercise moderately (30 minute daily walk,for example)
Maintain desirable body weight
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AICRs New American Plate
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New American Plate