Vegetarianismo e Prevenzione Oncologica

Filippo VALORIANI Anna Rita SABBATINI Emanuela ZAGALLO Dietetica e Nutrizione Clinica

X-Files in Nutrizione Clinica e Artificiale: Oncologia e Nutrizione, dalla Prevenzione alla Terapia

Genova - 07 Giugno 2012

Vegetarianism in perspective

1. Position of the American Dietetic Association: Vegetarian Diets. J Am Diet Assoc, 2009

“A person who does not eat meat (including fowl) or seafood, or products containing these foods1”

The eating patterns of vegetarians may vary

considerably1

Considerable variation may exist in the extent to which

animal products are excluded1

Vegetarianism in perspective

1. Fraser G. Am J Clin Nutr, 2009

< 1/week

Other kinds of Vegetarianism Macrobiotic Diet

Based largely on grains, legumes, and vegetables. Fruits, nuts, and seeds are used to a lesser extent. Some people eat limited amounts of fish.

Raw Food Diet

Fruitarian Diet Based on fruits, nuts, and seeds. Avocado and tomatoes are commonly included. Other vegetables, grains, beans, and animal products are excluded.

1. Position of the American Dietetic Association: Vegetarian Diets. J Am Diet Assoc, 2009

Consisting mainly or exclusively of uncooked and unprocessed fruits, vegetables, nuts, seeds, sprouted grains and beans. In rare instances unpasteurized dairy products and even raw meat and fish.

Vegetarianism and Cancer Risk Obesity is a significant risk factor for cancer at a number of sites1

1. World Cancer Research Fund. DC: American Institute for Cancer Research; 2007 2. Winston JC. Nutr Clin Pract, 2010.

Vegetarians tend to have an overall lower cancer rate than does the general population2

The lower BMI of vegetarians may explain some of the lower cancer risk in vegetarians compared with nonvegetarians2

Vegetarianism and Cancer Risk

Vegetarianism and Cancer Risk

Vegetarianism and Cancer Risk

Vegetarianism and Cancer Risk

Vegetarianism and Cancer Risk

Vegetarianism and Cancer Risk

Vegetarianism and Cancer Risk

Vegetarianism and Cancer Risk

4 diet groups were established: - 1 MEAT EATERS (those that eat meat) - 2 FISH EATERS (those that do not eat meat but do eat fish) - 3 VEGETARIANS (those that do not eat meat or fish but do

eat dairy products or eggs or both) - 4 VEGANS (those that eat no animal products)

Vegetarianism and Cancer Risk

Vegetarianism and Cancer Risk

The incidence of all malignant neoplasms combined was lower among vegetarians and fish eaters than

among meat eaters.

The incidence of colorectal cancer was significantly higher among vegetarians than among

nonvegetarians.

Vegetarianism and Cancer Risk In this relatively health-conscious cohort the pattern of the diet (excepting meats, fruit, and vegetables) was relatively similar to the UK population in most other respects, with high consumption of tea, sauces, cakes, soft drinks (women), butter and margarine1

1. Slimani N et al. Public Health Nutr, 2002 2. Davey GK et al. Public Health Nutr, 2003 3. Fraser GE, Am J Clin Nutr, 2009

Differences in nutrient intake between British vegetarians (the few vegans excepted) are modest compared with nonvegetarians in the EPIC-Oxford study2

Consider the possibility that some other factor confounds the meat–colon cancer association in the United Kingdom and is not present in other parts of Europe or the United States3 (composition of beef)

Vegetarianism and Cancer Risk Epidemiological studies have consistently shown that regular consumption of plant foods, such as fruit and vegetables, is strongly associated with a reduced risk of cancer1-3

1. Liu RH. Am J Clin Nutr, 2003 2. Jacobs DR. Nutr Cancer, 1998 3. World Cancer Research Fund. American Institute for Cancer Research; 2007 4. Fraser GE. Am J Clin Nutr, 1999 5. Jacobs DR et al. Nutr Cancer, 1998 6. Okarter N, Crit Rev Food Sci Nutr., 2010 7. Pelucchi C et al. Nutr Cancer, 2009

Fruit and vegetables (fiber, Vit C) exhibit protective activity against cancer of the lung, mouth, esophagus, colon, and stomach and to a lesser degree some other site3

The regular use of legumes provides a measure of protection against stomach, prostate cancer3, and colon cancer4, whereas a high intake of whole grains has provided some protection against colorectal and possibly other cancers5-7

Reported a 25% reduction in risk of colorectal cancer in the highest quartile of dietary fiber intake compared to the lowest.

In populations with low average intake of dietary fibre, an approximate doubling of total fibre intake from foods could reduce the risk of colorectal cancer by 40%

Vegetarianism and Cancer Risk

More detailed food consumption and food preparation data are needed as well as data on the bioavailability of protective phytochemicals (flavonoids, indoles, sulfides, carotenoids)1

1. Winston JC. Nutr Clin Pract, 2010 2. Liu RH. J. Nutr, 2004

The phytochemicals can display additive and synergistic effects2

Vegetarianism and Cancer Risk

Vegetarianism and Cancer Risk

Jia-Yi Dong, Li-Qiang Qin. Breast Cancer Res Treat, 2011

Vegetarianism and Cancer Risk

Soy isoflavones consumption was inversely associated with risk of breast cancer incidence (RR = 0.89, 95% CI: 0.79–0.99). The protective effect of soy was only observed among studies conducted in Asian populations (RR = 0.76, 95% CI: 0.65–0.86) but not in Western populations (RR = 0.97, 95% CI: 0.87–1.06).

Vegetarianism and Cancer Risk

Key TJ. Am J Clin Nutr, 1999

Key TJ. Am J Clin Nutr, 1999

In conclusion, vegetarians had a 24% lower mortality from ischemic heart disease than nonvegetarians, but no associations of a vegetarian diet with other major causes of death were established.

Key TJ. Am J Clin Nutr, 1999

Vegetarianism and Cancer Risk

No clear differences have been shown for other major causes of death such as stroke and cancers of the colo-rectum, breast and prostate.

Vegetarianism and Cancer Risk

Vegetarianism and Cancer Risk

Human population studies have not shown large differences in cancer incidence or mortality rates between vegetarians and nonvegetarians1

1. Winston JC. Nutr Clin Pract, 2010

There is a need for additional studies of the association between the spectrum of types of vegetarian diets and risk of chronic disease1

Consumption of red meat and processed meat is consistently associated with an increase in the risk of colorectal cancer1

1. World Cancer Research Fund. American Institute for Cancer Research; 2007

Vegetarianism and Cancer Risk

Grilled, cured, and smoked meats and fish are associated with an increased risk of cancer due to the presence of polycyclic aromatic hydrocarbons and heterocyclic amines produced during their preparation10

Health Implications of Vegetarian Diets

Varied, balanced vegetarian diets tend to be lower in saturated fat and cholesterol, and have higher levels of dietary fiber, magnesium and potassium, vitamins C and E, folate, carotenoids, flavonoids and other phytochemicals1

However, vegans and some other vegetarians may have lower intakes of vitamin B12, calcium, zinc, and long-chain n-3 fatty acids1

Position of the American Dietetic Association: Vegetarian Diets . J Am Diet Assoc. 2009

Nutrition considerations for vegetarians: PROTEIN

An assortment of plant foods eaten over the course of a day can provide all essential amino acids and ensure adequate nitrogen retention and use in healthy adults; complementary proteins do not need to be consumed at the same meal 1

A meta-analysis of nitrogen balance studies found no significant difference in protein needs due to the source of dietary protein2

Ensure an adeguate intake of lysine: dietary adjustments such as the use of more beans and soy products in place of other protein sources that are lower in lysine or an increase in dietary protein from all sources3

1. Young VR. Am J Clin Nutr. 1994 2. Rand WM et al. Am J Clin Nutr, 2003 3. Position of the American Dietetic Association:

Vegetarian Diets . J Am Diet Assoc. 2009

Nutrition considerations for vegetarians: PROTEIN

Food and nutrition professionals should be aware that protein needs might be somewhat higher than the Recommended Dietary Allowance in those vegetarians whose dietary protein sources are mainly those that are less well digested, such as some cereals and legumes1

1. FAO/WHO/UNU Expert Consultation on Protein and Amino Acid Requirements in Human Nutrition. World Health Organization; 2002.

Nutrition considerations for vegetarians: n-3 FATTY ACIDS

Vegetarian diets are generally rich in n-6 fatty acids, they may be marginal in n-3 fatty acids1 Diets that do not include fish, eggs, or generous amounts of algae generally are low in EPA and DHA1

Vegetarians, and particularly vegans, tend to have lower blood levels of EPA and DHA than nonvegetarian2

1. Position of the American Dietetic Association: Vegetarian Diets . J Am Diet Assoc. 2009

2. Rosell MS. Am J Clin Nutr. 2005

Conversion rates for ALA tend to improve when dietary n-6 levels are not high or excessive1 Vegetarians should include good sources of ALA in their diet, such as flaxseed, walnuts, canola oil, and soy2

1. Williams CM. Proc Nutr Soc, 2006 2. Geppert J Lipids, 2005

Nutrition considerations for vegetarians: n-3 FATTY ACIDS

The bioconversion of α-linolenic acid (ALA) to EPA is generally less than 10% in humans; conversion of ALA to DHA is substantially less1

Incidence of iron-deficiency anemia among vegetarians is similar to that of nonvegetarians1

Although vegetarian adults have lower iron stores than nonvegetarians, their serum ferritin levels are usually within the normal1-2

1. Ball MJ Am J Clin Nutr 1999 2. Alexander D Eur J Clin Nutr, 1994 3. Institute of Medicine, Food and Nutrition Board.Washington, DC:

National Academies, 2001

Nutrition considerations for vegetarians: IRON

Because of lower bioavailability of iron from a vegetarian diet, the recommended iron intakes for vegetarians are 1.8 times those of nonvegetarians3

Inhibitors of iron absorption: phytates, calcium, and the polyphenolics in tea, coffee, herb teas, and cocoa. Fiber only slightly inhibits iron absorption1

Some food preparation techniques (soaking and sprouting beans, grains, and seeds, the leavening of bread, fermentation in miso and tempeh) can diminish phytate levels2 and thereby enhance iron absorption3,4 Vitamin C and other organic acids found in fruits and vegetables can substantially enhance iron absorption and reduce the inhibitory effects of phytate and thereby improve iron status5,6

1. Coudray C et al. Eur J Clin Nutr, 1997 2. Harland BF, Nutr Res,1995 3. Sandberg AS. Am J Clin Nutr, 1999 4. Manary MJ. Ann Trop Paediatr, 2002 5. Hallberg L. Am J Clin Nutr, 2000 6. Fleming DJ, Am J Clin Nutr, 1998

Nutrition considerations for vegetarians: IRON

Lacto-ovo-vegetarians can obtain adequate vitamin B-12 from dairy foods, eggs, or other reliable vitamin B-12 sources, for vegans, vitamin B-12 must be obtained from regular use of vitamin B-12-fortified foods1

Nutrition considerations for vegetarians: B-12

1. Position of the Am Diet Ass: Vegetarian Diets. J Am Diet Assoc. 2009 2. Herrmann W. Clin Chem, 2001

Vegetarian diets are typically rich in folacin, which may mask the hematological symptoms of vitamin B-12 deficiency, so that vitamin B-12 deficiency may go undetected until after neurological signs and symptoms may be manifest2

Calcium intakes of lacto-ovo-vegetarians are similar to, or higher than, those of nonvegetarians, whereas intakes of vegans tend to be lower than both groups and may fall below recommended intakes1

The risk of bone fracture was similar for lacto-ovo-vegetarians and meat eaters, whereas vegans had a 30% higher risk of fracture possibly due to their considerably lower mean calcium intake (EPIC-Oxford Study)2

1. FAO/WHO/UNU: Report of a Joint FAO/WHO/UNU Expert Consultation; 2002 2. Appleby P. Eur J Clin Nutr, 2007

Nutrition considerations for vegetarians: CALCIUM

The ratio of dietary calcium to protein is a better predictor of bone health than calcium intake alone. Typically, this ratio is high in lactoovo-vegetarian diets and favors bone health, whereas vegans have a ratio of calcium to protein that is similar to or lower than that of nonvegetarians1

Many vegans may find it is easier to meet their calcium needs if calcium-fortified foods or dietary supplements are utilized1

1. Weaver C. Am J Clin Nutr, 1999

Nutrition considerations for vegetarians: CALCIUM

The bioavailability of zinc from vegetarian diets is lower than from nonvegetarian diets, mainly due to the higher phytic acid content of vegetarian diets1

Zinc intakes of vegetarians vary with some research showing zinc intakes near recommendations2 and other research finding zinc intakes of vegetarians significantly below recommendations3-4 Due to the difficulty in evaluating marginal zinc status, it is not possible to determine the possible effect of lower zinc absorption from vegetarian diets2

1. Hunt JR. Am J Clin Nutr, 2003 2. Davey GK. Public Health Nutr, 2003 3. Ball MJ. Am J Clin Nutr, 1999 4. Janelle KC. J Am Diet Assoc, 1995

Nutrition considerations for vegetarians: ZINC

Take Home Messages

• The eating patterns of vegetarians may vary considerably

• Evidence: not large differences in cancer incidence or mortality rates between vegetarians and nonvegetarians

• Regular consumption of plant foods is strongly associated with a reduced risk of cancer

• Consumption of red meat, processed meat, grilled, cured, and smoked meats and fish are associated with an increased risk of cancer

• There is a need for additional studies of the association between the spectrum of types of vegetarian diets and risk of cancer

Take Home Messages

• Appropriately planned vegetarian diets are healthful and nutritionally adequate; vegans and some other vegetarians may have lower intakes of some nutrients

• Food and nutrition professionals can assist

vegetarian patients by providing current, accurate information about vegetarian nutrition, foods, and resources

Thank You

Giuseppe Arcimboldo, Estate (1572), Denver Art Museum