Cancer of the colon

Cancer of the Colon
May 29, 2013
 by Gabe Mirkin, MD

Although scientists are not sure what causes colon or
rectal cancers, they know that they are associated with
lack of exercise, eating too much meat, and the human
wart virus (HPV). A study from Sendai, Japan shows that
men who spend a lot of time walking are at reduced
susceptibility to developing colon cancer (1a).
An extensive review of the world’s literature shows
that colorectal cancer occurs far more frequently in
prosperous industrialized countries, and that dietary
factors may cause up to 75 percent of these cancers
(1b). You are increased risk for colon cancer if you
are overweight, and exercise reduces your risk. Rectal
cancer is not affected by obesity or exercise, and may
be associated more with infection, such as with the HPV
virus that causes genital warts. Since the vast
majority of people who are infected with HPV do not get
cancer, we have to explain why some do. The leading
theory is that of cofactors: some combination of
infectious agents, genetic susceptibility or lifestyle
factors. I think that rectal cancer requires some kind
of infection, but you do not develop the cancer unless
you also smoke, lack vitamin D, eat a lot of meat, or
some other combination of factors. Colon cancer appears
to require some combination of factors such as lack of
vitamin D, eating meat, not exercising or not eating
enough foods from plants.
David Mangelsdorf, professor of pharmacology at the
University of Texas Southwestern in Dallas, reports
that Vitamin D may help to prevent colon cancer (1).
Colon cancer is associated with eating too much red
meat and animal fat, as well as smoking and heavy
alcohol use. Your liver removes breakdown products of
metabolism from your body and concentrates them into
liquid called bile. Then bile passes through a tube
leading from the liver to the gall bladder, a balloon
that stores the bile. When you eat, the gall bladder
contracts and squeezes bile through a tube leading into
your intestines, where the bile mixes with the food
that you have eaten and breaks down the fat into
building blocks called monoglycerides, fatty acids and
glycerol that can be absorbed into you bloodstream.
Eating a high-fat diet causes your liver to make more
bile, and bile is loaded with a chemical called
lithocholic acid, a bile acid that helps digest fat.
Lithocholic acid is probably the most toxic compound
that your body makes. Lithocholic acid damages the DNA,
the genetic material in cells to cause cancer. Giving
animals high concentrations of lithocholic acid causes
colon cancer, but giving these same animals large doses
of vitamin D prevents lithocholic acid from causing
colon cancer. 

Previous research show that people who develop colon
cancer have high concentrations of lithocholic acid in
their intestines. This explains why people who have had
their gall bladders removed are at increased risk for
colon cancer. Your gall bladder is supposed to squeeze
bile into your intestines only after you eat. When you
have your gall bladder removed, bile flows continuously
from your liver into your intestines 24 hours a day.
This continuous exposure to bile acids, and lithocholic
acids in particular, can cause colon cancer.
So steps to prevent colon cancer include cutting back
on meat and fat, and making sure that you are not
vitamin D deficient. Don’t have your gall bladder
removed unless it is necessary.
Cancer of the colon as associated with eating lots of
refined carbohydrates found in bread and pastas and
meat, particularly well-cooked meat and not enough
fish, vegetables, whole grains and beans. The omega-3
fatty acids in fish appear to help prevent colon cancer
by reducing swelling in your body (2). Whole grains
appear to help prevent colon cancer by sweeping foods
and carcinogens through the colon at a faster rate. On
the other hand, refined carbohydrates in bakery
products and pastas are constipating and prolong
contact between food and the inner surface of the colon
(3). Another theory is that refined carbohydrates cause
a high rise in insulin that increases cancer risk. We
do not know how different infectious agents affect
susceptibility to colon cancer.
Researchers at Harvard show that long-term, cigarette
smoking triples your chances of developing colon cancer
(3). In the United States, 15 of 16 studies conducted
after 1970 in middle-age men and elderly men and, in
the 1990s, in women demonstrate an association.
Previous studies did not show an association because it
takes 30 to 40 years for smoking to cause colon cancer.
Cancers require new blood vessels to grow and invade
normal tissue. Smoking contains nicotine which is
potent angiogenesis factor that causes blood vessels to
grow into a tumor to nourish it and cause it to spread.
Three studies which failed to show that fiber prevents
colon cancer in North Americans have been widely
quoted, but a recent study from South Africa shows that
something else in vegetables and grains, called
resistant starches, may be the factor that prevents
colon cancer (4). Resistant starches cannot be digested
in the intestines, so they cannot be absorbed and pass
to the colon where bacteria break them down into short
chain fatty acids that help prevent cancers,
particularly colon cancer. Resistant starches are found
in whole grains, beans, nuts and other seeds. Many
people avoid the foods that contain resistant starches
because they are the most common cause of intestinal
gas, which is a byproduct of the bacterial action.
1a) European Journal of Cancer Prevention, October 2007
1b) Alimentary Pharmacology & Therapeutics, Volume 26, 2007
1) May 17, 2002, AAAS’ Journal, Science, titled:
“Vitamin D Receptor As an Intestinal Bile Acid Sensor”
David Mangelsdorf, professor of pharmacology at the
University of Texas Southwestern in Dallas
2) EAM deDeckere.Possible beneficial effect of fish and
fish n-3 polyunsaturated fatty acids in breast and
colorectal cancer.European Journal of Cancer
Prevention, 1999, Vol 8, Iss 3, pp 213-221.
3) An updated review of the epidemiological evidence
that cigarette smoking increases risk of colorectal
cancer. Cancer Epidemiology Biomarkers & Prevention,
2001, Vol 10, Iss 7, pp 725-731. E Giovannucci. E,
Brigham & Womens Hosp, Dept Med, Channing Lab, 75
Francis St, Boston,MA 02115 USA
4)R Ahmed, I Segal, H Hassan. Fermentation of dietary
starch in humans. American Journal of Gastroenterology,
2000;95(4);1017-1020. Ahmed R, Baragwanath Hosp, Div
Gastroenterol, PO Bertsham, ZA-2013 Soweto, SOUTH
AFRICA. A high-resistant starch diet and its resultant
increase in fermentation products may be partly
responsible for protecting the black population against
colorectal cancers and other large bowel diseases.
5) MC BoutronRuault, P Senesse, J Faivre, N Chatelain,
C Belghiti, S Meance. Foods as risk factors for
colorectal cancer: a case-control study in Burgundy
(France).European Journal of Cancer Prevention, 1999,
Vol 8, Iss 3, pp 229-235.
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Terada.Effects of intestinal bacteria on the
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7)R Sinha, WH Chow, M Kulldorff, J Denobile, J Butler,
M GarciaClosas, R Weil, RN Hoover, N Rothman.
8) Trans-Fatty Acids and Colon Cancer. Martha L.
Slattery, Joan Benson, Khe-Ni Ma, Donna Schaffer, and
John D. Potter. Nutrition and Cancer 39(2):170-175,