From The August 1999 Issue of Nutrition Science News
by Jill E. Stansbury, N.D.
The potential of protective phytochemicals
Many people's lives have been touched in some way by cancer.
Maybe they've lost a relative, a friend or an acquaintance; maybe
they had a scare as a result of an annual physical. Regardless of
what drives your customers to ask about cancer prevention, it is
a perfect opportunity to discuss diet and supplements.
Cancer is a prominent killer of Americans -- second only to heart
disease -- and responsible for more than a half million deaths
yearly. The good news is that scientific validation for the
protective power of food is accumulating. And empowering people
to preserve their health through daily choices puts
responsibility in patients' hands.
So where do you start? A dizzying amount of information exists on
cancer-preventive food and supplements. The easiest step people
can take is to modify their diets. By eating a rainbow of food
colors or by emphasizing certain food groups, people will
incorporate a variety of protective phytochemicals into their
We are exposed to oxidizing- and cancer-producing substances
daily, but compounds found in vegetables help limit the free
radical initiation and DNA damage caused by these carcinogens and
therefore appear to lower the incidence of various types of
cancer. [1,2 ]
A Rainbow of Protection
Pigmented plant compounds appear to be important
anti-inflammatories and antioxidants, and people who eat more of
them have a decreased risk of cancer. Plant pigments are mostly
polyphenolic, meaning they are multiphenol-containing molecules,
and include chlorophyll, carotenoids and bioflavonoids.
Green plants contain particularly large amounts of chlorophyll,
which is a detoxifier and possibly an anticancer
agent.  Foods rich in chlorophyll include chlorella
and other blue-green algae, beet greens, bok choy, collards,
dandelion greens, kale, mustard greens and nettles. These
greens--among the most nutritious of all plants or plant
parts--also contain other diverse nutrients and healthy
constituents.  The blue-green algae family has a high
chlorophyll content and has been credited with immune-enhancing
effects including stimulation of phagocytosis and enhanced
response to tumors and microbes. Chlorella powder, specifically,
may reduce side effects of chemotherapy for some patients and may
possess direct anticancer activities. 
Orange, yellow and red-orange foods are rich in carotenoids such
as beta-carotene, lutein and lycopene. These constituents are
antioxidants and anticancer agents due to several different
More than 600 carotenoids occur naturally, but carotenes are the
most widely known. Carotenes seem to offer protection against
lung, colorectal, breast, uterine and prostate cancers. [8
]Carotenes, which destroy oxygen free radicals in lipids,
enhance immune response and protect cells against UV
radiation. [9 ]Foods rich in these flavonoids include
apricots, carrots, citrus fruits, squash and tomatoes in addition
to many green foods.
The anthocyanidins are a type of complex flavonoid that produce
blue, purple or red colors. Foods rich in these phytochemicals
include beets, blackberries, blueberries, cherries, purple and
red grapes, and purple cabbage. Anthocyanidins support connective
tissue regeneration and are anti-inflammatory; they promote blood
flow and reduce cholesterol, in addition to being
antioxidants.  Anthocyanidins seem to stabilize and
protect capillaries from oxidative damage  and have
been shown to stabilize connective tissue, promote collagen
formation, improve microcirculation and help protect blood
vessels from oxidative damage. [12,13] Thus, by eating
these antioxidant pigments, some believe cancer risk can be
reduced because the antioxidants protect against damage and help
repair connective and vascular tissues.
Procyanidins are the precursors to anthocyanidins, and are
comprised of smaller units including catechins and epicatechins.
Catechins are simple flavonoids that are abundant in green tea.
Several Japanese studies show that tea consumption is protective
against breast and other types of cancer. [14,15]
Detoxifying, stimulating and spicy sulfur compounds are present
in a variety of colorful foods including broccoli, garlic and
pineapple. Sulfur-containing compounds in plants are believed
active, or at least protective, against cancer because many
pathogens are deterred by sulfur.
The crucifer family--which includes broccoli, brussel sprouts,
cabbage, cauliflower, mustard greens, radishes and turnips--has
many sulfur-containing compounds as well as indoles, a subclass
of phytonutrients that binds chemical carcinogens and activates
detoxification enzymes, mostly in the gastrointestinal
tract. [16 ]Indoles and related compounds may promote
metabolism of carcinogens  as well as improve
estrogen balance, which could reduce the risk of estrogen-related
cancers such as breast cancer. 
The lily family includes garlic (Allium sativum) and onions (A.
cepa), both of which also contain sulfur compounds. Studies have
shown the sulfur compounds diallyl disulphide and diallyl
trisulfide--two of the active agents in garlic oil--and S-allyl
cysteine--found in crushed garlic--to inhibit tumor metabolism
and enhance immune response. [19-21 ]Allyl sulfides also
enhance glutathione S-transferase enzyme systems, which are
biochemical pathways involved in the liver's detoxification of
carcinogenic substances. Allium species also have
immune-enhancing actions that include promotion of lymphocyte
synthesis, cytokine release, phagocytosis and natural killer-cell
activity. [22 ]
Several animal studies have shown that garlic and onions prevent
cancer and inhibit the progression of existing cancers,
especially stomach and gastrointestinal cancers. 
Garlic appears particularly effective in reducing the risk of
N-nitroso-induced cancers.  N-nitroso compounds, also
known as nitrosamines, are potent carcinogens formed within the
intestines as a result of bacterial degradation of nitrates and
nitrites, two common food chemicals used in the processing of
ham, sausages and other meat products.
All forms of garlic have been shown to have some medicinal
activity. Which one is best or most effective remains to be
proven. Different forms may be better suited for some people.
Pineapples contain bromelain, a sulfur-rich proteolytic enzyme
that has been investigated for antitumor effects. U.S. and French
research shows oral bromelain can reduce cancer in animals. Some
documented cases show cancerous tumors regressing as a result of
bromelain therapy. Bromelain may also have antimetastatic
effects. It has been examined in vitro to both oppose leukemia by
promoting the normalization of blood cells and to reduce
metastasis in lung-cancer cells. [25,26]
Prescription for Cancer Prevention
Bromelain: 100 mg/day of 500-1,000 MCU/100 mg potency
Carotenoids: 25,000-50,000 IU/day full spectrum carotenoid
Curcumin: tincture: 2 tsp/day; capsules: 1,500-3,000 mg/day
Flax Meal: 1/4 cup or more/day
Flax Oil: 1 tbsp/day
Garlic: 4,000 mcg allicin or 10,000 mcg alliin or 3,000 mcg
s-allylcystein or 4 g fresh garlic
Genistein: 50-75 mg/day
Glutathione: 2,000-3,000 mg/day reduced glutathione or 300 mg
Quercitin: 1,500-3,000 mg/day
Reishi: tincture: 2 tsp/day; capsules: 1,500-3,000 mg/day
Shiitake: tincture: 2 tsp/day; capsules: 1,500-3,000 mg/day
Vitamin C: 2-3 g/day
Other protective phytochemicals include the caffeic, ferulic and
ellagic acids, which have been shown to degrade carcinogenic
substances.  Among other things, caffeic acid helps
degrade carcinogens, and ferulic acid helps prevent nitrates in
the digestive tract from being converted into the carcinogenic
nitrosamines. Caffeic and ferulic acids are found in green tea.
Ellagic acid, which is particularly plentiful in pomegranates,
also prevents carcinogen oxidation of cellular membranes. Ellagic
acid is also found in blueberries, grapes, raspberries and
Limonene is a bioflavonoid substance found in citrus rinds that
stimulates both the glutathione transferase and the cytochrome
p-450 detoxification systems.  These enzymatic liver
reactions break down carcinogenic substances in the body and help
prevent them from damaging cellular DNA. Another bioflavonoid,
quercitin, is ubiquitous in higher plants and has been widely
studied for its antioxidant and concommitant anticancer
Whole-grain foods, rather than those derived from processed
grains, are also worth emphasizing. Whole grains contain
essential fatty acids (EFAs), which serve as precursors to
prostaglandins and are important components of cell membranes.
Lignans, prominent in the woody parts of plants, are found
primarily in rye and flax. They are believed to be converted by
intestinal bacteria into enterolactone and enterodiol, which are
absorbed across the intestinal walls where they travel to tissues
and blood, binding with hormonal receptors. Like soy isoflavones,
these weak estrogens may reduce excessive hormonal stimulation in
tissues and reduce estrogen-related cancers. [31 ]Fiber
is also thought to reduce cancer risk by binding carcinogens in
the intestines and making a favorable environment for beneficial
bacterial flora. Fiber is acted upon by intestinal enzymes and
microbes, yielding short chain fatty acids (SCFAs), which are
noted to have anticancer effects. 
Legumes--especially soybeans--are another source of anticancer
fiber, phytoestrogens, lignans and saponins. [33 ]Whether
soy is a unique superfood or is simply the best-studied legume
remains to be seen. Soy also contains the isoflavones genistein
and daidzein, which have been found to protect against
estrogen-related cancers in numerous animal and epidemiological
studies. [34 ]Soy contains protease inhibitors that may
inhibit the proliferation of cancer cells.  Genistein
in soy and in red clover diminishes the growth of new blood
vessels in cancerous tissues. 
Antitumor and anticancer properties also have been studied in
mushrooms. Shiitake (Lentinus edodes) and reishi (Ganoderma
ludidum) have been found to have general anticancer and
immune-stimulating activity.  Lentinan in shiitake
mushrooms has been shown to be a potent immune
potentiator.  Maitake (Grifolia frondosa) also
contains immune-stimulating polysaccharides. In a study by
Hiroaki Namba, Ph.D., of Japan, mice were fed either a control
diet, a diet that included 20 percent maitake powder or a control
diet plus injections of maitake D-fraction extract at a rate of 1
mg/kg of body weight. Results showed that maitake inhibited
metastasis by 81.3 percent in the maitake-fed group and by 91.3
percent in the D-fraction injection group. 
Food Choice in a Nutshell
Incorporating more of these foods may help reduce cancer risk:
Avoiding these foods is also a protective measure:
- Cabbage-family vegetables
- Essential fatty acids
- Fish and fish oils
- Fruits and vegetables rich in plant fibers, pigments and
- Soybeans and other legumes
- Vegetables, especially orange and yellow and leafy greens
- Animal products: meat, fat, dairy
- Anything artificial: colors, pesticides, preservatives,
- synthetic chemicals
- Saturated fat
Kelp and seaweed are also anticancer agents, rich in the
mucilagenous alginates, which, like most fibers, gums and
mucilages, swell in the intestines and absorb liquid as well as
toxins and heavy metals. [39 ]Alginates also may
stimulate T cell production and function since numerous other
mucopolysaccharides have been shown to do this. Japanese studies
show regular consumption of kelp reduces breast cancer
risk.  Kelp extracts have been highly successful in
inhibiting laboratory cancer strains. [41 ]
Another place your customers may not expect to find cancer
protection is on their spice rack. Cayenne pepper,
ginger,  rosemary,  sage, thyme,
turmeric  and many others have anti-inflammatory,
anticancer, immune-stimulating and antioxidant properties.
Research suggests that curcumin, the bright yellow flavonoid
present in turmeric (Curcuma longa) roots, selectively inhibits
thromboxane production while sparing prostacyclin. [45,46
]Thromboxane is a potent inflammatory compound produced by
the body in response to injury or irritation. It causes blood
vessels to constrict and the blood to clot, while prostacyclin is
an inflammatory mediator that can respond to tissue injury
without leading to further inflammation. Inhibiting thromboxane
prevents excessive inflammatory response and reduces damage to
vascular endothelia. Curcumin has also been shown to inhibit
tobacco smoke mutagenicity,  suggesting it may help
protect the vascular endothelia from damage caused by smoking.
Anticancer agents can be found in the supplements section as well
as at the local produce stand. By emphasizing fresh fruits and
vegetables of all colors, customers can reduce their risk of
cancer and many other diseases.
Jill E. Stansbury, N.D., maintains a private practice in
Battleground, Wash., where she specializes in botanical and
natural therapies. She heads the botanical medicine department at
the National College of Naturopathic Medicine in Portland,
Catechins are powerful antioxidants found in green tea. They
differ slightly in chemical structure from other flavonoids but
share their protective properties.
Ellagic acid is a polyphenol that aids in scavenging and
detoxifying carcinogenic substances. Ellagic acid is found is
Rubus species including raspberries and blackberries, and also
apples, grapes and strawberries.
Glutathione is a sulfur-containing antioxidant nutrient with
strong anticancer activity. Glutathione is involved with the
detoxification of harmful substances. Rich sources of glutathione
include asparagus, avocados, broccoli and watermelon.
Isoflavones, particularly genistein and daidzein, have been shown
to inhibit tumor growth by inhibiting vascularization of the
tumor. Isoflavones also cause tumor cells to become less
aggressive. Isoflavones are present in Trifolium species
(clover),soybeans and many other legumes. Isoflavones can
interfere with the mitotic process of cancer cells. 
Lignans, present in berries, flaxseeds and whole grains, are
thought to protect against hormonal cancers due to their
Sulfur-containing compounds such as allyl sulfides and other
isothiocyantes promote the glutathione S-transferase system of
detoxification, which helps the liver break down carcinogenic
substances. Glucosinolates in crucifers, such as cabbage,
broccoli and especially their sprouts, promote immune response by
enhancing cytokine release and inhibiting enzymes involved with
Terpenes include the carotenoids and limonoids, which have
demonstrated potential anticancer effects. They function as
antioxidants, protecting lipids, blood and other body fluids from
assault by free radicals.
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