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 StudiesThe 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 StudiesThe 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 FruitsColor Phytochemical Vegetables and Fruits

Red Lycopene Tomatoes and tomato products, pink grapefruit, watermelon

Red/purple Anthocyanins, polyphenols

Berries, grapes, red wine, prunes

Orange α-, β-carotene Carrots, mangoes, pumpkin

Orange/yellow β-cryptoxanthin, flavonoids

Cantaloupe, peaches, oranges, papaya, nectarines

Yellow/green Lutein, zeaxanthin Spinach, avocado, honeydew, collard and turnip greens

Green Sulforaphanes, indoles Cabbage, broccoli, Brussels sprouts, cauliflower

White/green Allyl sulphides Leeks, onion, garlic, chives

Data from Heber D: Vegetables, fruits and phytoestrogens in the prevention of diseases, Data from Heber D: Vegetables, fruits and phytoestrogens in the prevention of diseases, F Postgrad MedF Postgrad Med 50:145, 2004. 50:145, 2004.

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: From American Institute for Cancer Research: Simple steps to prevent cancer,Simple steps to prevent cancer, Washington, DC, 2000, AICR. 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


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


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 hormone-dependent 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

foodsMobley 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


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


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


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


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 cancer-fighting foods

Exercise moderately (30 minute daily walk, for example)

Maintain desirable body weight

AICR’s New American Plate

New American Plate

nutrition in cancer prevention

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