Cancer Prevention and Nutrition

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Nutrition in Cancer Prevention


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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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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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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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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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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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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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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



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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



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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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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

Cancer Prevention and Nutrition

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