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Did You Know That Most Cancers Can Be Linked To Nutrition Deficiency?
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Nutrition
and Colon Cancer Prevention
John J. Walker, M.D.
There has been a great deal of press lately
on colon cancer. Several high profile celebrities have been
afflicted with this disease and have brought it to national
attention. And justifiably so. Colon cancer is the number
2 killer of both sexes in the US and poses a staggering
health care and personal cost. How can we, or can we, prevent
colon cancer? It is clear that colon cancer screening works
to decrease the occurrence and death rates from colon cancer
in both high risk and average risk populations.
The use of sigmoidoscopy and colonoscopy is now gaining
widespread acceptance among physicians, patients and even
insurance companies. While these techniques are beneficial
and important, I’d like to focus on whether nutrition may
play a role in colon cancer prevention. Our goal as health
care providers should be to intervene at the earliest possible
step, by giving each person the best chance of preventing
this disease.
It is important to briefly discuss some
theories about colon cancer formation. It seems that many
people with colon cancer have one, or a series, of genetic
abnormalities that may predispose to the development of
colon cancer. These genetic malfunctions may be inherited,
as is the case of people with family histories of colon
cancer, or induced by damage to the DNA of the colon cells.
The cause of the latter may be primarily due to oxidative
stress from the environment or diet, with a complex relationship
being the body’s response to what we eat. What we do know
is that most colon cancer start as polyps, small growths
of precancerous tissue, that if left in place will go on
to develop cancer. Colon cancer screening with colonoscopy
is used to remove polyps before they become cancers, thus
preventing it.
But is there a way to prevent the change
to cancer, or even the formation of polyps? Intuitively,
we can surmise that this would need occur at the level of
DNA, before any mutation. We know that DNA is damaged by
oxidation, so this is certainly one possibility.
Additionally, many of the body’s enzyme reactions that help
repair DNA are dependent upon certain nutrients, including
vitamins and minerals. Thus, if deficiencies or a relative
lack occurs, one may be more susceptible to the various
factors, which lead to the development of cancer. So it
may very well be that what we put into our intestinal tracts
holds the key to prevention of this dreaded disease.
With this background in mind, let’s now
look at the available evidence:
1. Fiber. It was long thought that a high
fiber diet diminished one’s risk of colon cancer. Most evidence
was epidemiological, from population studies. The interaction
with dietary fat was also thought to be important- a reduction
in dietary fat with increased fiber.
The issue of whether colon cancer incidence
can be decreased by dietary fiber is still being debated,
with some recent literature shedding doubt on the subject.
Still, the majority of the evidence favors a high fiber
diet. Since fiber has so many other beneficial effects (bowel
regularity, decreasing serum cholesterol etc) my recommendation
is to use get plenty of dietary fiber, and if you are not
close to 25 or 30 grams/day, use a psyllium based supplement.
Why psyllium? It has beneficial properties that help promote
stool bulk, absorption of bile salts (which may be a promoter
in colon cancer formation) and possibly elimination of other
toxins. Additional benefits include a feeling of fullness,
which may promote weight loss, and a well-documented reduction
in serum cholesterol.
2. Dietary fat intake. The evidence is
pretty clear that increased colon cancer rates occur in
populations with increased dietary fat intakes. This would
be most strongly associated with saturated fat, and several
studies have specifically pointed to red meat. However,
the mechanism may actually be increased bile acid production
(see above), so the exact mechanism is not known. While
eating some red meat is likely safe, one should probably
not consume a diet high in saturated fat or red meat, for
this and other health reasons.
3. Calcium. Increased levels of dietary
and supplemental calcium have been shown to decrease polyp
formation in susceptible populations, and decrease the experimental
markers of polyp formation. Since calcium intake is vital
for the prevention of osteoporosis (in both men and women),
one should make sure they have a daily total calcium intake
of 1200 mg for men and 1500 mg for women. This includes
both dietary and supplemental forms.
The form of calcium is also important, and the most well
studied and effective supplemental form is calcium citrate
malate. Your supplement should contain this form, or you
may not be getting what you are paying for. Vitamin D supplements
will enhance absorption, and it is essential for osteoporosis
prevention. In addition, there may be some additional effect
of Vitamin D on colon cancer prevention, but this is not
at all clear at the present time.
4. Folic Acid. This vital nutrient has
come to light recently in a number of areas. Maternal deficiency
leads to neural tube defects in infants, and supplementation
prevents this complication. Folic acid also can decrease
homocysteine levels and reduce the risk of coronary artery
disease. Pertinent to our discussion is the recent report
from the nurse’s health study that indicated that supplemental
vitamins could decrease risk of colon cancer. Specifically,
those women with folic acid consumption > 400 mcgm/day
had the lowest incidence of colon cancer.
Numerous scientific studies have shown that folic acid is
a key part of the bodies enzymatic defense system to help
prevent or repair damage to DNA. It is widely believed that
damage to DNA in colon cells arises on both a genetic basis
and through environmental triggers. It is believed that
folic acid may stabilize the DNA, making it less susceptible
to damage. The bottom line: for the prevention of heart
disease and probable decrease in the risk of colon cancer,
supplement your dietary intake of folic acid to the level
of 800 mcgm/day.
5. Antioxidant vitamins. I’m going to
lump together a broad category of vitamins that we call
antioxidants. These include A, C and E. It is important
to understand that this is a complex area, because there
are a variety of different forms and preparations of each
vitamin, and studies that have been done are really inconclusive.
Additionally, my criticism of the currently available studies
is that they may have tried to pull apart this whole group
to find out which particular one is active, when in fact
there are documented synergies between the antioxidant group
that simply cannot be ignored. In my opinion, none of the
studies available show a clearly detrimental effect, many
are positive, and some are neutral. Again, taking this health
concern into consideration with all others, a diet rich
in antioxidant vitamins is beneficial, and I believe supplementation
will enhance any possible benefits.
6. Green Tea. Although not a vitamin,
this agent has been getting a lot of press also, and some
of the studies are most compelling.
There are several epidemiological studies indicating that
one of the reasons for a lower colon cancer incidence in
certain countries may be related to consumption of green
tea.
Additionally, experimental models using human colon cancer
cell lines have indicated a reduction in growth and an inhibition
of colon cancer cells in some cases. The active ingredient
in green tea appears to be epigallocatechin. While this
topic clearly needs more study, the body of literature that
is developing around the benefits of green tea is growing,
and is very compelling.
7. Exercise. Exercise promotes bowel regularity,
generally makes one more vigilant about what they are eating,
and may have some direct effects on the incidence of colon
cancer. It is so intertwined with other parts of a healthy
lifestyle, that it may be difficult to determine if it has
beneficial effects on it’s own. Nonetheless, it’s an important
part of maintaining vigorous health.
8. Aspirin and NSAIDS. Aspirin has been
shown in some studies to decrease the risk of developing
colon cancer. It is not clear if this was a direct effect,
or if it is related to the earlier detection because aspirin
caused tumors or polyps to bleed, which allowed detection.
Some theoretical effects on aspirin’s effect on the cyclooxygenase
system may also contribute, but nothing has been clearly
established. Clinical trials are going on with the use of
celebrex, a Cyclooxygenase-2 (COX-2) inhibitor to prevent
colon adenomas in at risk populations.
9. Omega 3 fatty acids. These dietary
constituents are most commonly found in fish oils, and have
been widely studied in a variety of diseases. Some epidemiologic
data have shown reduced colorectal cancer rates in those
individuals with high consumption of fish oils. Additionally,
there is some experimental data showing decreased proliferation
of colonic cells (i.e. slower growth), which may have a
beneficial effect. No prospective studies are yet available.
10. Curcumin (Turmeric) is a traditional
spice which contains a phenolic compound called curcumin.
Curcumin has been shown to have significant potential as
a chemopreventive agent for cancer, especially colon. It
has been shown to prevent colon adenoma formation in mice
by modulating lymphocyte-mediated immune functions. In one
study, rats fed a diet containing curcumin showed a dose-dependent
decrease in colon cancer.
Studies using human colon cancer cell lines have also demonstrated
an inhibition in the progression of the colon cancer sequence,
via inhibition of cyclo-oxygenase as well as cyclo-oxygenase
independent mechanisms.Studies on basal cell cancer as well
as metastatic melanoma have also yielded promising results.
11. Selenium. I’ve actually saved the
best for last. Selenium is a necessary cofactor for an enzymatic
reaction in the body that is vital for proper immune system
function. There are many areas of the US that have soil
that is selenium deficient; hence the crops grown there
are also deficient. Numerous studies have documented that
people with low selenium levels have a higher incidence
of cancer. Additionally, one large study of 1300 patients
found that supplementing the diet with 200 mcgm/day in the
form of selenomethionine decreased the risk of not only
colon cancer, but lung and prostate cancer, by upwards of
40%! This was a well-done study published in the Journal
of the American Medical Association (JAMA) in 1997. I believe
there is ample evidence to recommend selenium as a dietary
supplement.
In summary, there is a growing body of
literature supporting the fact that nutrition plays a major
role in colon cancer formation, and that supplementation
of the diet with certain nutrients may diminish this risk.
While all the evidence is not clear-cut, what I’ve presented
above is at the very least compelling. Additionally, dietary
supplementation as I will outline below may have additional
benefits in general health, specifically for coronary artery
disease and other vascular disease. Our food supply has
changed, so please don’t think that eating a healthy diet
alone will provide you with the OPTIMAL level of nutrients.
Also, there is a difference between the Recommended Daily
Allowance (RDA) and the optimal dosage. The RDA is the level
necessary to prevent deficiency, and makes no effort to
determine the level of nutrients needed to maintain optimal
health (a perfect example is folic acid).
What I have presented is the optimal dosages and forms that
have been used in scientific studies. I hope that one day
we will be able to present absolute data on this topic,
but until then we have to use the weight of the evidence.
And don’t forget to ask your doctor about appropriate colon
cancer screening.
Dietary supplement recommendations
1. Psyllium based fiber supplement and high fiber diet
2. Low fat diet
3. Calcium 1200 to 1500 mg/day (calcium citrate malate is
best form)
4. General antioxidants Vitamin A as beta carotene 12,000
units/day, Vitamin C (as Ester-C) 1000 mg/day, Vitamin E
(as natural mixed tocopherols) 500 units/day.
5. Folic Acid 800 mcgm/day
6. Selenium (as selenomethionine) 200 mcgm/day
7. Curcumin 400 to 600 mg two to three times each day.
Optional, may also be beneficial:
8.Green Tea: 5 cups day or supplemental extract standardized
for epigallocatechin
Where to find great prices on
vitamins
Based on my Internet shopping, I’ve identified a few websites
where you can get some of the products you may need:
vitacost.com : absolutely the lowest prices
on the Internet, and many top quality brands are available.
Selection is somewhat limited, but growing. They have the
best line of nutriceuticals available for specific diseases
(ex. Arthripower for arthritis, Occupower for macular degeneration
and Cardiolift for heart disease) from a company called
Nutraceutical Sciences Institute (NSI). NSI also has the
best all around antioxidant supplement (Synergy 2000) and
one designed just for women (Synergy 3000). Great encyclopedia
of medical problems
vitaminshoppe.com : large selection, just
about every brand and product, mediocre prices. They occasionally
run specials from a particular company, so you can check
monthly for the best price, but still rarely lower cost
than vitacost.
http://www.syracusegastro.com/
nutrition.html
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