Foods that fight cancer
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Potraviny v prevenci nádorů
AICR document
http://www.aicr.org/
Apples
The tasty fruit we eat today likely descends from wild apples in Central
Asia. Wild apples' genetic diversity allows growers to develop thousands
of varieties. The popular “Honeycrisp,” cultivated around 1960, is a cross
of Macoun and Honeygold apples. Most apples we see in the grocery
store are best for eating raw, but some varieties are more commonly used
for cooking.
What's in Apples?
Apples are a good source of fiber and vitamin C. Most of the
antioxidant power they provide comes from phytochemicals, including:
Quercetin: a flavonoid that shows anti-inflammatory and antioxidant
properties
Other flavonoids, including epicatechin and, in red apples, anthocyanins
Triterpenoids are found especially in apple peel
Blueberries
The blueberry is one of the few fruits native to North America. Native
Americans used the berries and parts of the plant for medicine. Today,
blueberries have a rockstar reputation among fruits; one popular claim is that
blueberries help reduce age-related memory loss. It's too early to know
whether that's true, but we do know they contain powerful phytochemicals
called anthocyanins, which give these berries their blue
What's in Blueberries?
Blueberries are an excellent source of vitamins C and K, manganese and a
good source of dietary fiber. Blueberries are among the fruits highest in
antioxidant power, largely due to their many phytochemicals:
Anthocyanins, catechins, quercetin, kaempferol and other flavonoids
Ellagitannins and ellagic acid
Pterostilbene and resveratrol
Broccoli & Cruciferous
Vegetables
The four-petal flowers from these veggies resemble a cross or "crucifer," hence the name.
Broccoli is probably the best known cruciferous vegetable. Like Brussels sprouts, rapini,
cabbage (green), cauliflower and turnips (white), it forms a "head." Others - known as the
"headless crucifers" - include dark green leafy vegetables like kale and collard greens.
What's in Cruciferous Vegetables?
Nearly all are excellent or good sources of vitamin C and some are good sources of
manganese. Dark greens are high in vitamin K.
Glucosinolates are compounds found in all cruciferous vegetables; Glucosinolates form
isothiocyanates and indoles.
Other nutrients and phytochemicals vary:
Broccoli, Brussels sprouts, cauliflower and rapini are all excellent sources of folate, a B
vitamin.
Broccoli is a good source of potassium.
Broccoli and Brussels sprouts are good sources of dietary fiber and rich in magnesium.
Broccoli, Brussels sprouts and rapini contain carotenoids such as beta-carotene.
Red cabbage and radishes supply anthocyanins. Other cruciferous vegetables provide
different polyphenols, such as hydroxycinnamic acids, kaempferol and quercetin.
Cranberries
Cranberries grow in northern bogs on low-lying vines, just above
water. These bright red gems are native to North America and at one
time whalers and mariners carried cranberries on their ships to prevent
scurvy. Today you've probably heard claims that cranberry juice helps
prevent urinary tract infections; though it appears to help some women,
it is not a treatment. We do know that with their healthful nutrients and
phytochemicals along with the rich color and flavor, cranberries make
a great addition to any meal.
What's in Cranberries?
Cranberries are good sources of vitamin C and dietary fiber. They're
very high in antioxidant power, most of which comes from
phytochemicals:
Flavonoids, including anthocyanins, proanthocyanidins and flavonols
Ursolic acid
Benzoic acid and hydroxycinnamic acid
Dark Green Leafy Vegetables
Spinach, kale, romaine lettuce, leaf lettuce, mustard greens, collard greens,
chicory and Swiss chard are excellent sources of fiber, folate and a wide
range of carotenoids such as lutein and zeaxanthin, along with saponins and
flavonoids.
According to AICR's second expert report, Food, Nutrition, Physical Activity,
and the Prevention of Cancer: A Global Perspective, foods containing
carotenoids probably protect against cancers of the mouth, pharynx and
larynx.
Researchers believe that carotenoids seem to prevent cancer by acting as
antioxidants – that is, scouring potentially dangerous “free radicals” from the
body before they can do harm. Some laboratory research has found that the
carotenoids in dark green leafy vegetables can inhibit the growth of certain
types of breast cancer cells, skin cancer cells, lung cancer and stomach cancer.
The Second Expert Report also noted probable evidence that foods containing
folate decrease risk of pancreatic cancer and that foods containing dietary
fiber probably reduce one’s chances of developing colorectal cancer.
Legumes (Dry Beans, Split Peas
& Lentils)
Kidney and black beans, yellow split peas and red lentils are among the thousands of
colorful legumes. Legumes use nitrogen from the atmosphere to make protein and are
an important protein source worldwide. So valuable in ancient Rome, prominent
families derived their names from legumes; for example, Cicero is from the Latin
word for chickpea.
What's in Beans and Peas?
Dry beans and peas are rich in fiber (20% of Daily Value) and a good source of
protein (10% of Daily Value). They are also an excellent source of folate, a B
vitamin. Foods containing folate help reduce the risk of pancreatic cancer probably
because of folate's role in healthy cell division and repair of damaged cells.Legumes
contain other health-promoting substances that may also protect against cancer:
Lignans and saponins
Resistant starch, starch not digested in the small intestine, is used by healthful
bacteria in the colon to produce short-chain fatty acids, which seem to protect colon
cells.
Antioxidants from a variety of phytochemicals, including triterpenoids, flavonoids,
inositol, protease inhibitors ans sterols.
Flaxseed
Flaxseed, flaxseed oil and linen are all products of flax, one of the first crops to be
domesticated. Flaxseed has long been used for nutritional and medicinal purposes.
Today, it is being touted for many health benefits and researchers are studying flaxseed
and its oil to sort through the many claims.
What's in Flaxseed?
Flaxseed is an excellent source of magnesium, manganese and thiamin, and fiber; a
good source of selenium; and provides protein and copper, too.
Lignans: flaxseed is a particularly rich source of these plant estrogens
Dietary fiber: One serving, about 4 tablespoons of ground flaxseed, contains more than
7 grams of fiber.
Alpha-linolenic acid (ALA): about half of the fat in flaxseed is this plant form of
omega-3 fat.
Gamma-tocopherol: a form of vitamin E
Flaxseed oil provides alpha-linolenic acid and both alpha- and gamma-tocopherol, two
forms of vitamin E. It is not a source of fiber, selenium or the other nutrients noted
above. It does not naturally contain lignans, though some brands contain added
lignans.
Grapes and Grape Juice
Both grapes and grape juice are rich sources of resveratrol, a type of natural phytochemical that
belongs to a much larger group of phytochemicals called polyphenols. The skin of the grape
contains the most resveratrol, and red and purple grapes contain significantly more resveratrol
than green grapes. Grape jam and raisins contain much smaller amounts of this phytochemical.
Red wine also contains resveratrol. However, with AICR’s second expert report noting convincing
evidence that alcohol is associated with increased risk for cancers of the mouth, pharynx and
larynx, esophagus, breast (pre- and postmenopausal) and colon and rectum (in men), wine is not a
recommended source of resveratrol.
Studies suggest that polyphenols in general and resveratrol, in particular, possess potent
antioxidant and anti-inflammatory properties. In laboratory studies, resveratrol prevented the kind
of damage known to trigger the cancer process in cell, tissue and animal models.
Other laboratory research points to resveratrol’s ability to slow the growth of cancer cells and
inhibit the formation of tumors in lymph, liver, stomach and breast cells. Resveratrol has also
triggered the death of leukemic and colon cancer tumors.
In one series of studies, resveratrol blocked the development of skin, breast and leukemia cancers
at all three stages of the disease (initiation, promotion and progression).
Green Tea
Since ancient times, tea has been used as both beverage and medicine. Both black and green
teas contain numerous active ingredients, including polyphenols and flavonoids, which are
potent antioxidants.
One class of flavonoids called catechins has recently become the focus of widespread study
for their anti-cancer potential. Tea is the best source of catechins in the human diet, and green
tea contains about three times the quantity of catechins found in black tea.
In laboratory studies, green tea has been shown to slow or completely prevent cancer
developent in colon, liver, breast and prostate cells. Other studies involving green tea have
shown similar protective effects in tissues of the lung, skin and digestive tract.
Studies that track the diets of human subjects over several years (particularly studies
conducted in Asia, where green tea consumption is common) have also associated regular
usage of green tea with lower risk for bladder, colon, stomach, pancreatic and esophageal
cancers.
AICR’s second expert report, Food, Nutrition, Physical Activity, and the Prevention of Cancer:
A Global Perspective, was unable to make a recommendation regarding the relationship
between tea consumption and cancer risk due to insufficient evidence.
Note: Very high amounts of green tea components (usually associated with overdosage of
green tea supplements) have been shown to interact with drugs that affect blood clotting such
as aspirin and change the way the body metabolizes certain medications.
Soy
Soybeans are a type of legume, or bean. Foods made from soybeans include tofu, soymilk,
soybeans, soynuts, miso (soy paste), tempeh, soy burgers and soynut butter.
Scientists believe that several active ingredients in soy may have anti-cancer effects. These
include: isoflavones (which have been studied most), saponins, phenolic acids, phytic acid,
phytosterols, and protein kinase inhibitors.
Soy appears to contain some components that resemble very weak forms of the body’s natural
hormones. As a result, soy foods can mimic the actions of hormones under certain conditions and
counteract these hormonal actions at other times. Because of such complexities, most of the
studies that have investigated soy’s role in cancer development have dealt with hormone-related
cancers such as those of the breast and prostate.
Soy has been shown to inhibit the growth of prostate cancer cells in a variety of laboratory
conditions. Soy has also been associated with the inhibition of breast cancer cells in some, but not
all, laboratory experiments. Diets rich soy have been shown to alter the metabolism of breast
tissue in animal subjects in ways that may translate into added anti-cancer protection.
Several human and laboratory studies suggest that consuming soy early in life (such as
adolescence) may help protect against breast cancer later in life. Results are less encouraging
when soy is consumed later in life.
As a general rule of thumb, soy seems to be a good food to include in your diet (along with other
beans) as a source of protein and nutrients. But, there's limited evidence in U.S. populations
supporting hopes that soy food might offer special protection against breast cancer.
Current research shows that it is safe to eat moderate amounts of soy foods (e.g., soymilk, tofu),
up to two to three servings per day.As a precaution, women receiving anti-estrogen treatments
such as tamoxifen, should minimize soy foods and avoid isoflavone supplements.
Squash (Winter)
True American natives, winter squash have hard skins unlike the soft-skinned summer
squash. They also come in a wonderful variety of colors, textures and flavors. Names
like buttercup, banana, turban and delicata may sound delightful and pique your
interest, but if you’re like many Americans, their irregular shapes and textures have
kept you from venturing beyond the convenient canned pumpkin. The most common
varieties you’ll see in supermarkets are acorn, butternut, spaghetti and hubbard.
What's in Winter Squash?
Winter squash are excellent sources of vitamin A, good sources of vitamin C and
dietary fiber. They are also a good way to get potassium.
Winter squash, including pumpkins, are rich in carotenoids, including:
beta-carotene and alpha-carotene: these carotenoids can act as antioxidants. Also, our
bodies convert these to vitamin A, a nutrient important for immune function and
maintaining healthy cells among other roles.
lutein and zeaxanthin: these yellow pigmented carotenoids help protect eye health by
filtering high-energy ultraviolet rays that can damage our eyes’ lens and retina. They
act as antioxidants here and possibly elsewhere in our bodies.
Tomatoes
The tomato’s red hue comes chiefly from a phytochemical called lycopene. Tomatoes have
attracted particular attention from prostate cancer researchers because lycopene and its related
compounds tend to concentrate in tissues of the prostate.
AICR's second expert report, Nutrition, Physical Activity, and the Prevention of Cancer: A
Global Perspective, found substantial and convincing evidence that foods containing lycopene
probably protect against prostate cancer.
In animal models, consumption of tomato compounds has been linked to large decreases in
prostate cancer risk. Moreover, there is evidence that this cancer-fighting potential is increased if
tomatoes are consumed in a processed form that allows these natural compounds to be released
and more easily absorbed, such as tomato sauce, tomato paste or tomato juice.
Lycopene, a powerful antioxidant, together with a group of related compounds collectively
called the “red family,” has displayed anti-cancer potential in a variety of laboratory studies. In
the laboratory, tomato components have stopped the proliferation of several other cancer cells
types, including breast, lung, and endometrial.
Although the evidence suggests it is likely that foods containing lycopene, including tomatoes,
offer cancer protection, AICR stresses the importance of eating a variety of plant foods to ensure
the most protection against cancer development. No food in isolation can effectively lower
cancer risk.
Whole Grains
The term “whole grain” means that all three parts of the grain kernel (germ, bran and
endosperm) are included. Refined grains usually have the bran and germ removed,
leaving only the starchy endosperm. Brown rice is a whole grain, white rice is not. Other
whole-grain foods include wheat breads, rolls, pasta and cereals; whole grain oat cereals
such as oatmeal, popcorn, wild rice, tortilla and tortilla chips, corn, kasha (roasted
buckwheat) and tabouleh (bulghur wheat).
Whole grains are rich in fiber, vitamins, minerals and hundreds of natural plant
compounds, called phytochemicals, which protect cells from the types of damage that
may lead to cancer. In addition research points to specific substances in whole grains
that have been linked to lower cancer risk, including antioxidants, phenols, lignans
(which is a kind of phytoestrogen) and saponins.
AICR's second expert report, Nutrition, Physical Activity, and the Prevention of Cancer:
A Global Perspective, found probable evidence that foods containing dietary fiber, like
whole grains, can decrease one’s risk of developing colorectal cancer.
Moreover, limiting energy dense foods and eating a predominantly plant-based diet rich
in vegetables, fruits, whole grains and beans can help with weight maintenance and, in
turn, may decrease your risk of developing cancer.
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Získané vlastnosti nádoru
Většina nádorů získává během
vývoje stejný soubor funkčních
vlastností, i když různými
mechanismy.
•Samostatnost s ohledem na
růstové signály
•Necitlivost k růstově inhibičním
signálům
•Neomezený proliferační potenciál
•Poruchy apoptózy
•Zachování angiogeneze
•Tkáňová invaze a tvorba metastáz
Hanahan D. and Weinberg R:A., Cell 100:57, 2000
Paralelní dráhy vzniku a rozvoje nádorového
onemocnění Obecně všechny nádory
získávají stejných
6 charakteristických znaků.
Různé typy nádorových typů a
subtypů se však liší způsobem
jak je získávají i chronologickým
pořadím.
U některých nádorů může
genetická porucha vybudit
několik těchto znaků současně.
Např. ztráta funkce p53 usnadňuje
jak angiogenezi tak rezistenci
k apoptóze a vyvolává genomovou
nestabilitu (5 krokový model).
U jiného nádoru dochází k souhře
2 a více různých genetických
změn, čímž se zvyšuje počet kroků
vedoucích k dokončení nádorové
progrese (8 krokový model).
Hanahan D. and Weinberg R:A., Cell 100:57, 2000 16
Nádorové mikroprostředí - podpora nádorového
stromatu
Li H et al, J Cell Biochem 101:805, 2007
Nádorové stroma přispívá
ke genetické nestabilitě
nádorových buněk.
Hypoxie, nedostatečná výživa,
snížené pH a tvorba volných
radikálů ve stromatu jako
důsledek nedostatečného
přísunu krve a faktory
uvolňované zánětlivými
buňkami a aktivovanými
fibroblasty podporují mutace
DNA a tlumí reparační
mechanismy.
Mutátorový fenotyp nádorových
buněk dovoluje tvorbu a selekci
agresivních klonů s velkým
metastatickým potenciálem.
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Nádory jako komplexní tkáně
V nádorech mutované nádorové buňky přeměňují normální buněčné
typy tak, aby s nimi spolupracovaly v dalším rozvoji onemocnění.
Objasnění interakce mezi nádorovými geneticky změněnými a
normálními buňkami je zásadní pro porozumění rozvoje nádorů a
pro vývoj nových efektivních terapeutických přístupů.
18Hanahan D. and Weinberg R:A., Cell 100:57, 2000
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