Anticarcinogenic
compounds in food
Non-nutritive ingredients:
phytochemicals
Objectives
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What are phytochemicals?
Where are they found?
What are the health benefits?
Are there any risks?
What are functional foods and how are they
regulated?
What do we tell consumers?
Definition of Phytochemicals
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Biologically active chemical compounds found
in plants
Not nutrients like vitamins or minerals
Believed to have health benefits especially
related to heart disease and cancer
How Scientists View
Phytochemicals in Foods
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Some phytochemicals have profound effects on the
body through actions such as
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Acting as antioxidants
Mimicking hormones
Altering blood constituents in ways that may protect
against some diseases
Mechanisms of Chemoprevention
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Antioxidants: defense against radicals
Phase 1 enzyme inducers
Phase 2 enzyme inducers
Anti-proliferative agents
Anti-hormonal compounds
Disruption of mutational gain or loss of
function
Is More Better?
Choose Food First
Avoid Overdosing
Avoid Self Prescribing
Berries
(sources of vitamin C, E, carotinoids, flavonoids, phytoestrogenes
and other phytochemicals)
cloudberry
cranberries
blackberry
blackthorn
raspberry
gooseberry
dogberry
huckleberry
loganberry
blueberry
strawberry
redcurrant
blackcurrant
Spices and cancer (data based on human epidemiologic
studies and animal experiences)
Italy: chilli, cinnamon, clove, pepper, nutmeg
=> ↓ gastric cancer
ánizs
France and other mediterranian countries:
anise, curry, ginger, mustard, paprika, pepper, allspice =>
↑ bladder cancer
Garam masala (mixture of pepper,
clove, cinnemon, nutmeg, ginger,
cardamom, caraway, laurel) => ↓ cancer
incidence after DMBA treatment
szegfűbors
babér
kömény
Walnuts and oleaginous seeds (high amount of vitamin E,
selenium, ellagic acid, phytic acid, phytoestrogenes =>
protective effect)
walnut
pistachio
poppy-seed
hazelnut
sunflower seed
almond
pine seeds
sesame seed
pumpkin seed
Whole Foods, Wine, and Tea
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Epidemiological evidence spanning many
countries indicates that deaths from cancer, heart
disease, and heart attacks are less common where
these foods are plentiful in the diet, where tea is a
beverage, or where red wine is consumed in
moderation
Phytochemicals
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Whole Foods, Wine, and Tea
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Historically, diets containing whole grains, fruits,
vegetables, herbs, spices, teas, and red wines have
been reputed to possess health-promoting qualities
These foods and beverages all have something in
common
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Phytochemicals of the flavonoid family
Flavonoids
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Many flavonoids act as antioxidants
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May protect against cancers and heart disease by
this mechanism
More evidence is needed before any claims can be
made for flavonoids themselves as the protective
factor in foods
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Particularly when they are extracted from foods or herbs
and sold as supplements
Why are antoxidants important?
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free radicals are molecules missing electrons:
unstable
formation of 1 free radical causes a chain
reaction with many free radicals formed
antioxidants prevent formation of free radicals
or break the chain reaction by becoming
oxidized
Antioxidants
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Because flavonoids often impart a bitter taste
to food, food producers may refine away
natural flavonoids to please consumers who
generally prefer milder flavors
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To produce white grape juice or white wine,
makers remove the red, flavonoid-rich grape skins
to lighten the flavor and color of the product
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While greatly reducing its flavonoid content
Antioxidants
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Whether or not research confirms the cancerfighting and heart-defending nature of
flavonoids, consumers should seek out a
variety of whole fruits, vegetables, and other
plant-derived foods with their flavonoids intact
in place of their more refined counterparts
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Such diets are consistently associated with low
rates of disease
Antioxidants
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Flavonoid supplements have not been proved
effective or safe
As for red wine, the potential health benefits may not
be worth alcohol’s immediate and substantial risk
Other sources:
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Blueberries
Tea
Grapes
Vegetables
Tea
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Black- most often sold, fermented and more
processed
Oolong- semi-fermented, heated and dried
more than green tea but less than black, served
in Chinese restaurants
Green- unfermented, very little processing
White- unfermented, very little processing,
harvested before leaves are fully open
Tea
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Calorie Free
87% of dietary
flavonoids consumed
Antioxident
polyphenols including
flavonoids
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Catechin
EGCG
Proanthocyanidins
Cancer
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Protects against free radical damage
Decrease growth of abnormal cells
Associated with decreased risk of rectal, colon
and skin cancer
Other Benefits
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Memory
Immune function
Oral health
Decreased risk of kidney stones
Obesity
Mostly epidemiological research and research on tea
consumption, concentrated tea extracts may not be
safe
Antioxidants
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Chocolate
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Research subjects were instructed to eat three
ounces of dark (bittersweet) chocolate chips
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Flavonoid antioxidants from chocolate accumulate in
the blood
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The level of certain harmful oxidizing compounds dropped
40%
The antioxidant effects of dark chocolate may turn out
to be as powerful as those of tea or red wine
Chocolate
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In theory, chocolate may also “thin the blood”
by reducing the tendency of blood to clot
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Blood clots are a major cause of heart attacks and
strokes
No evidence exists to indicate that people who eat
chocolate suffer fewer heart attacks or strokes than
people who do not
Chocolate
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Chocolate consumption promotes weight gain
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Three ounces of sweetened chocolate candy
contain over 400 calories
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A significant portion of most people’s daily calorie
allowance
Chocolate contributes few nutrients save fat and
sugar
Antioxidants
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For most people,
antioxidant
phytochemicals are best
obtained from nutrientdense low-calorie fruits
and vegetables and
calorie -free green or
black tea
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With chocolate enjoyed
as an occasional treat
Soybeans
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Compared with people living in the West, Asians
living in Asia suffer less frequently from:
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osteoporosis
cancers, especially of the breast, colon, and prostate
heart disease
Asian women also suffer less from symptoms related to
menopause
Soybeans
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When Asians migrate to the U.S. and adopt
Western diets and habits they experience these
disease and problems at the same rates as
native Westerners
Among many differences between the diets of
the two regions
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Asians consume far more soybeans and soy
products such as miso, soy drink, and tofu than do
Westerners
Soybeans
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Soybeans contain phytochemicals known as
phytoestrogens
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Researchers suspect that the phytoestrogens of soy
foods, their protein content, or a combination of
these factors may be responsible for the health
effect in soy-eating peoples
Research, though ongoing, is limited and
inconsistent
Soybeans
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We know with certainty that phytoestrogens
are plant-derived chemical relatives of the
human hormone estrogen
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They weakly mimic or modulate the hormone’s
effects on some body tissues
They act as antioxidants
Soybeans
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We know that breast cancer, colon cancer, and
prostate cancer are estrogen-sensitive
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They grow when exposed to estrogen
It is unknown if actions of phytoestrogens may
alter the course of estrogen-sensitive cancers
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Results from recent breast cancer studies do not support
the idea unless soy is consumed beginning in childhood
Soybeans: genistein
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Symptoms of menopause
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Phytoestrogens may reduce risk of adult bone loss
and the sensation of elevated body temperature
known as “hot flashes”
A diet high in soy may offer bone protection
rivaling that of hormone replacement therapy
(HRT)
May not reverse bone loss but may prevent it
Soybeans
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Because HRT involves some serious health risks,
supplements of soy are often sold to menopausal
women as a “natural” alternative
Research does not support taking phytoestrogen
supplements for bone mineral retention or hot
flashes
Soybeans
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Phytoestrogen supplement use may involve
some risk
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While studying one soy phytoestrogen, genistein,
researchers found that instead of suppressing
cancer growth, high doses appeared to speed
division of breast cancer cells in laboratory
cultures and in mice
Soybeans
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Findings on the health effects of phytoestrogens
should raise a red warning flag against taking
supplements
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Especially in women whose close relatives have developed
breast cancer
Until more is known, a safer route to obtaining soy
phytoestrogens is to include moderate amounts of
soy-based foods in the diet
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As generations of Asian people have safely done through
the ages
Flaxseed
Historically, people have used flaxseed for
relieving constipation or digestive distress
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Currently, flaxseed and its oil are under study for
potential health benefits
Contains lignans, compounds converted into
biologically active phytoestrogens by bacteria that
normally reside in the human intestine
Flaxseed
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Studies of populations suggest that women who
excrete more phytoestrogens in the urine (an
indicator of phytoestrogen intake from flaxseed
and other sources) have lower rates of breast
cancer
Animal studies show a decrease in tumors of the
breast and lung when fed flaxseed
Flaxseed
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Studies of the direct effects of giving flaxseed
to people are lacking
Some risks are possible with its use
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Flaxseed contains compounds that may interfere
with vitamin or mineral absorption
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Thus high daily doses could cause nutrient deficiency
diseases
Large quantities can cause digestive distress
Flaxseed
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Although no clear role has been established for
flaxseed in the prevention of human cancer
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Including a spoonful or two of flaxseed in the diet
may not be a bad idea
Flaxseed richly supplies linolenic acid
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A needed nutrient often lacking in the U.S. diet
Choose most fats from sources of
monounsaturated and polyunsaturated
fatty acids
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Keep the amount within calorie needs
Choose more fish, nuts and vegetable oils
Use lean meats and low fat dairy products
Limit saturated and trans fats
To provide essential fatty acids and vitamin E
while keeping calories controlled and
cholesterol and saturated fat low
Tomatoes
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People around the world
who eat the most
tomatoes, about 5
tomato-containing meals
per week, are less likely
to suffer from cancers of
the esophagus, prostate,
or stomach than those
who avoid tomatoes
Tomatoes
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Among the phytochemical candidates for
promoting this effect is lycopene
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A red pigment with antioxidant activity
Found in guava, papaya, pink grapefruit, tomatoes
(especially cooked tomatoes and tomato products),
and watermelon
Tomatoes
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Lycopene may inhibit the reproduction of
cancer cells
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Some research suggests that low blood levels of
lycopene and related compounds correlate with
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increased risk of breast cancer
elevated incidence of heart disease, heart attack, and
stroke
May also protect against the damaging sun rays
that cause skin cancer
Tomatoes
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In one study, women who consumed a diet rich in
fruits and vegetables had high lycopene
concentrations and a greatly reduced concentration of
an indicator of cervical cancer
Do scientists conclude that lycopene prevents cervical
cancer? No.
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The suggestion is that a diet rich in fruits and vegetables
with their host of nutrients and phytochemicals reduces
women’s risk of cervical cancer and many other diseases
Tomatoes
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A lesson about supplements can be learned
from experience with lycopene’s chemical
cousin
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The normally beneficial vitamin A relative betacarotene
Diets high in fruits and vegetables that contain
beta-carotene often correlate with low rates of
lung cancer
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When beta-carotene supplements were given to
smokers lung cancer rates increased
Garlic
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Descriptions of its uses for headaches, heart disease,
and tumors are recorded in early Egyptian medical
writings
In modern medical research, over 3,000 publications
have investigated the potential health benefits of garlic
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Many have reported positive findings
Garlic
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Among garlic’s active compounds are
organosulfur compounds
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Reported to inhibit cancer development in
laboratory animals
suppress the formation of certain harmful
oxidizing compounds that damage DNA and
trigger cancerous changes
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This evidence hints that eating garlic may be beneficial
against some forms of cancer in human beings
Garlic
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More potential roles for garlic
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allergies
heart disease
bacterial cause of ulcers
fungal infections
reduce the clotting of the blood
improve levels of blood cholesterol in people
whose cholesterol is too high for heart health
Garlic
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Volatile sulfur compounds are not present as such in
intact cells.
The reaction between
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The enzyme allinase and
The volatile precursors
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S-alk(en)yl cysteine sulfoxide and
Sulfonic acid
takes place when cells are ruptured
Results in the formation of
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Different thiosulfonates and
Related sulfonic acid derivatives
Garlic
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Studies of garlic supplements, such as powders
and oils, have been disappointing
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Positive results seem to be associated with an aged
preparation of garlic that lack garlic’s
characteristic odor
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But is rich in antioxidants and other compounds
From the scientist’s point of view, no evidence that
large doses of concentrated chemicals from garlic
may improve a person’s health or injure it
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People who eat the recommended amounts of a
variety of fruits and vegetables may cut their risk of
many diseases by as much as half
Replacing some meat with soy foods or other
legumes may lower heart disease and cancer risks
In the context of a healthy diet, foods are time-tested
for safety, posing virtually no risk of toxic levels of
nutrients or phytochemicals
What do we tell consumers?
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Eat more fruit
Increase vegetable portions
Use herbs and spices
Replace some meat
Add grated vegetables
Try new foods
MECHANISM OF ACTION
ON NUTRITIONAL ANTICARCINOGENESIS I.
I. Inhibition the binding to DNA
brocoli, cabbage, brussels sprout,
savoy cabbage (brassicans)
- phenylisotiacyanats
- ellagil acid
greens, fruits,
seeds, hazel nut
- ellagil acid
- flavonoids
II. Inhibition of promotion
green yellow vegetables,
fruits (melon, squash,
carrot, brussels, etc.)
- retinoids
- beta carotin
hazel nut, seeds
- vitamin E
paprika, tomato, lemon, chili
orange
- vitamin C
garlic, onion
- organic sulphur chemicals
curry
- curcumin
chili pepper
- capsaicin
MECHANISM OF ACTION
ON NUTRITIONAL ANTICARCINOGENESIS II.
III. Modulation of biotransformation
brokkoli, cukkini, káposzta,
kel, kínai kel, spenót, cékla,
karalábé, karfiol
- indol-3-carbinol
garlic, grains, seal oil, olive
sea-fish oils
- selenium
IV. Induction of physical features, changing of absorption
greens, fruits,
nut, hazel nut, cereals, grains
- fiber
greens, nut, hazel nut,
cereals, fungus
- riboflavin - chlorophyl
Other
soyabean, olive, maize, sesame, coconut oil, butter, fish coice, poultries,
bran, rye
Scientific publications:
Questions
S-ALLYLCYSTEINE INHIBITS CIRCULATORY LIPID PEROXIDATION AND
PROMOTES ANTIOXIDANTS IN N-NITROSODIETHYLAMINE-INDUCED
CARCINOGENESIS.
ALTERED CYTOKERATIN EXPRESSION DURING CHEMOPREVENTION
OF HAMSTER BUCCAL POUCH CARCINOGENESIS BY S-ALLYLCYSTEINE.
DIETARY SOY AND INCREASED RISK OF BLADDER CANCER:
THE SINGAPORE CHINESE HEALTH STUDY
EFFECTS OF TEA ON PRENEOPLASTIC LESIONS
AND CELL CYCLE REGULATORS IN RAT LIVER
CHEMOPREVENTIVE EFFECT OF FARNESOL AND LANOSTEROL
ON COLON CARCINOGENESIS I.
FIG. 1. STRUCTURES OF FARNESOL AND LANOSTEROL
FARNESOL
LANOSTEROL
APOPTOSIS INDUCTION BY S-ALLYLCYSTEINE, A GARLIC CONSTITUENT,
DURING 7,12-DIMETHYLBENZ[A]ANTHRACENE-INDUCED HAMSTER BUCCAL
POUCH CARCINOGENESIS.
INDOLE-3-CARBINOL HAS POSSIBLE ANTICARCINOGENIC ACTIVITY
TOMATO AND GARLIC CAN MODULATE AZOXYMETHANE-INDUCED
COLON CARCINOGENESIS IN RATS
IDENTIFICATION OF POTENTIAL ARYL HYDROCARBON RECEPTOR
ANTAGONISTS IN GREEN TEA
Phytochemicals
Foodstuffs (fruits, vegetables)
Ditions (isothiocyanate, benzylisothiocyanate, phenyl-ethylisothiocyanate, sulforaphan)
Brassicas, peas
Terpenoids (D-limonene, geraniol,
menthol, carvone)
Citruses
Flavonoids
- kvercetin
- kemferol, tangeretin, nobiletin, rutin
Generally all vegetables and fruits
- berries, tomato, broccoli, onion
- savoy cabbage, endivia, citruses,
horse-radish
Phenols (ellagic acid)
Tea, fresh harvested fruits and
vegetables, walnuts, berries
Glucosinolates, indoles
Brassicas
Sterols (beta-sitosterol, campesterol,
stigmasterol)
Vegetables
Coumarine compounds
Manioc, citruses
One of sources of the lecture:
Fruits and Vegetables – The Real Thing Matters!
Being Fit with Phytochemicals
Mollie Smith, MS, RD
California State University, Fresno
Department of Food Science and Nutrition