Transcript Nutrition in Cancer Prevention

Nutrition in Cancer Prevention
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)
Types of Epidemiologic Studies
of Cancer
Case 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 before
cancer 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.
Nutrition in the Etiology of
Cancer– cont’d
 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
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
Nutrition and Cancer Etiology
 Fat
 Protein
 Soy and phytoestrogens
 Carbohydrates: fiber, sugars, and
glycemic index
 Fruits and vegetables
 Nonnutritive sweeteners
Nutrition and Cancer Etiology–
cont’d
 Alcohol
 Coffee and tea
 Methods of food preparation and preservation
 Cancer chemoprevention
 Cancer prevention recommendations: nutrition
and physical activity
 Nutrition and physical activity
recommendations for cancer survivors
Color Code System of
Vegetables and Fruits
Color
Phytochemical
Vegetables and Fruits
Red
Lycopene
Red/purple
Anthocyanins,
polyphenols
Tomatoes and tomato
products, pink grapefruit,
watermelon
Berries, grapes, red wine,
prunes
Orange
α-, β-carotene
Carrots, mangoes,
pumpkin
Orange/yellow
β-cryptoxanthin,
flavonoids
Yellow/green
Lutein, zeaxanthin
Green
Sulforaphanes, indoles
White/green
Allyl sulphides
Cantaloupe, peaches,
oranges, papaya,
nectarines
Spinach, avocado,
honeydew, collard and
turnip greens
Cabbage, broccoli,
Brussels sprouts,
cauliflower
Leeks, onion, garlic,
chives
Data from Heber D: Vegetables, fruits and phytoestrogens in the prevention of diseases, F Postgrad Med 50:145, 2004.
Guidelines for Cancer Prevention
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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.
Nutrition in Cancer Prevention
 Diets contain both inhibitors and enhancers
of carcinogenesis
 Animal studies also test the effect of food
and nutrition on cancer and provide
guidance for epidemiological studies
Fat
 High intake of total and saturated fat is associated
with increased risk of breast, colon, lung and
prostate cancers
 High fat diets are associated with obesity, which is
linked with cancer of the colon, rectum,
esophagus, gall bladder, breast, endometrium,
pancreas, and kidney
 Animal fat (from meat and dairy) was associated
with 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 (<20% fat) may reduce risk of
recurrence of breast cancer
Energy Intake and Physical
Activity
 Total 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
Obesity is a Risk Factor for:
 Breast cancer
(among
postmenopausal
women)
 Colon
 Endometrium
 Esophagus
 Gallbladder
 Pancreas
 Kidney
 Is also a risk
factor for cancer
recurrence
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
Fiber
 Observational studies and case control
studies indicate that fiber-rich diets are
associated with a protective effect in colon
cancer
 Higher intakes of vegetables were inversely
associated with colon cancer risk in one
study
 But high fiber diets also tend to be lower in
meat, fat, and refined carbohydrates
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
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
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
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 hormonerelated cancers
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
Plant based foods may prevent
cancer by
 Inhibiting hormone-dependent steps in
tumor formation and protecting genetic
material from carcinogenic agents
 Suppressing free radical production
 Serving as bulking agents to dilute
carcinogens and decrease gastrointestinal
transit time
 Stimulators of physiologically active and
anti-cancer enzymes
Mobley C. Nutrition and cancer prevention. In McCallum and Polisena, The Clinical
Guide to Oncology Nutrition. Oncology Nutrition Dietetic Practice Group, 2000.
Cancer Chemoprevention Studies
 ß-carotene supplementation in Finnish
smokers was associated with a 16% higher
incidence of lung cancer
 Heavy alcohol intake seemed to enhance
negative effects
 However, diet studies suggest that high fruit
and vegetable consumption, particularly
carotenoids, tomatoes, and tomato-based
products may reduce risk of lung cancer
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
 ß-carotene, vitamin E, and selenium at 5X
the RDA was associated with significantly
lower mortality from all cancers
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 polyps
 However, there is evidence that high
calcium intake, especially supplements, is
associated with increased risk of prostate
cancer
 Bottom line: get calcium through food
sources
Lycopene and Cancer Risk
 Lycopene is a red-orange carotenoid found
in 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 cooked
and eaten with fat
 No evidence that supplements are safe and
effective in cancer prevention.
Source: American Cancer Society, accessed 2005
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
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
Soy and Cancer Risk
 Soy contains several phytochemicals
(phytoestrogens) which have weak estrogen
activity and appear to protect against hormonedependent cancers in animal studies
 No evidence shows soy supplements reduce
cancer risk
 High doses of soy may increase the risk of
estrogen-responsive cancers, such as breast or
endometrial cancers in certain women
 Breast cancer survivors should consume only
moderate amounts
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
Coffee and Tea
 Coffee has been investigated as a possible
risk factor for a variety of cancers, but does
not appear to be associated with increased
cancer
 Regular drinking of green tea and other
sources of polyphenols may reduce the risk
of stomach cancer
 Consumption of very hot drinks may
increase the risk of esophageal cancer
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
Artifical Sweeteners
Five artificial sweeteners on the market:
 Acesulfame-K
 Aspartame
 Neotame
 Saccharine
 Sucralose
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.
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
Food Safety and Cancer
 Choose in-season, locally grown produce
 Rinse fruits and vegetables and remove outer
leaves before eating
 Use proper food storage to prevent growth of
fungal 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
AICR Diet and Health 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.
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.
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.
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.
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.
Lifestyle Changes to Reduce Breast
Cancer Risk
 Reducing alcohol consumption
 Breastfeeding
 Avoiding obesity
 Being physically active
Source: American Cancer Society, accessed
2005
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
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 tobacco
 Restrict alcohol consumption
 Avoid obesity
Lifestyle Changes to Prevent
Pancreatic Cancer
 Avoid tobacco use
 Maintain a healthful weight
 Remain physically active
 Eat five or more servings of vegetables and
fruits each day
Source: American Cancer Society, accessed 2005
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
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
At Present, There Are No Nutritional
Risk Factors for
 Brain Cancer
 Leukemias
 Ovarian cancer
Source: American Cancer Society, accessed
2005
Diet Recommendations for
Cancer Survivors
 Cancer survivor may harbor undetected primary or
disseminated cancer cells
 A “cured” cancer pt is at increased risk for other
primary cancers in the same organ or other organs
 General dietary guidelines are also appropriate for
recovering cancer pts
 Dietary regimens should a) avoid stimulating
growth and spread of remaining tumor cells and b)
provide maximum prevention against new primary
tumors
Nixon DW. Nutrition during cancer recovery. In McCallum and Polisena, The Clinical
Guide to Oncology Nutrition. Chicago, The American Dietetic Association, 2000.
Recommendations for Cancer
Survivors
 Limit 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 or
severely restrict alcohol intake
Dietary Recommendations for
Cancer Survivors
 Consider a Vitamin E supplement of 200
IU/day to replace deficit from reduced fat
intake
 Standard dose multivit daily (not to exceed
100% RDA). This does not replace cancerfighting foods
 Exercise moderately (30 minute daily walk,
for example)
 Maintain desirable body weight
AICR’s New American Plate
New American Plate