Resistant Starch and Colon Cancer

Resistant Starch and Colon Cancer

August 22, 2019 100 By William Morgan


“Resistant Starch and Colon Cancer” Colorectal cancer is the third most
common cause of cancer death in the world. Thankfully, the good bacteria
in our gut take the fiber we eat and make short chain fatty acids like
butyrate that protect us from cancer. We take care of them;
they take care of us. If you do nothing to colon
cancer cells, they grow. That’s what cancer does. But if you expose colon cancer cells
to the concentration of butyrate our good bacteria make in
our gut when we eat fiber, the growth is stopped in its tracks. But if the butyrate stops, if we
just eat healthy for one day and then turn off the fiber, the
cancer can resume its growth. So ideally we have to eat
lots of fiber-rich foods, meaning whole plant foods
every single day. But what about the populations,
like in modern sub-Saharan Africa, where they don’t eat a lot of fiber,
yet still rarely get colon cancer? They used to eat a lot of fiber, but now their diet is centered
around highly refined corn meal; so, low fiber, yet still
low colon cancer rates. This was explained by the fact that while
they may be lacking protective factors like fiber, they are also lacking cancer-promoting
factors like animal protein and fat. But are they really lacking
protective factors? If you measure the pH of their stools,
the black populations in South Africa have more acidic stools—lower pH means more
acidic—despite comparable fiber intakes. As we learned before that’s a good thing:
we want alkaline pee, acidic poo. And that may account
for the lower cancer rates. But wait a second, low colon pH
is caused by short chain fatty acids, which are produced by our good
bacteria when they eat fiber, and they weren’t eating any more fiber,
suggesting there’s something else in addition to fiber in their diets
that was feeding their flora. And indeed, despite low fiber
intake, the bacteria in their colon were still churning out short
chain fatty acids like crazy. But if their bacteria weren’t eating
fiber, what were they eating? Resistant starch. The method of cooking and eating
the corn meal as a porridge resulted in an increase in
something called resistant starch, which acts in the same way as fiber
in the colon, as a prebiotic, a food for our good bacteria to produce the same
cancer preventing, short chain fatty acids. Resistant starch is any starch that resists
digestion, is not digested and absorbed in the upper digestive tract,
our small intestine, and so passes down into the large bowel,
our colon, to feed our good bacteria. See, when you boil starches and then
let them cool, some of the starch can recrystallize into a form resistant
to our digestive enzymes. So we can get resistant starch
eating cooled starches: pasta salad, potato salad,
or cold cornmeal porridge. So this may help explain the striking
differences in colon cancer rates. Thus they were feeding their
good bacteria after all, but just with lots of starch
rather than fiber. Consequently, a high carbohydrate diet
may act in the same way as a high fiber diet. Because a small fraction of the carbs
make it down into our colon, the more carbs we eat, the more
butyrate our gut bacteria can produce. And indeed countries
that eat the most starch have some of the lowest
colon cancer rates, so fiber may not be
the only protective factor. Only about 5% of starch may reach
the colon, compared to 100% of the fiber, but we eat up to 10 times
more starch than fiber, so it can potentially play
a significant role feeding our flora. So we’re talking about
even non-resistant starch. So the protection Africans enjoy
from cancer may be two-fold: a diet high in resistant starch
and low in animal products. Just eating more resistant
starch isn’t enough. See, meat contains, or contributes
to the production of, presumed carcinogens
such as N-nitroso compounds. If you split people up into three groups,
and you put one group on a low meat diet, the second group on a high meat diet,
which includes beef, pork, poultry, and the last group on the same high meat
diet but with lots of resistant starch added, the high meat groups had three times
more of these presumptive carcinogens and twice the ammonia in their
stool than the low meat group, and the addition of the resistant
starch did not seem to help. This confirms that exposure to these toxic
compounds is increased with meat intake, and 90% was created in our bowel. So it doesn’t matter if we get
nitrite-free uncured fresh meat. These nitrosamines are created from
the meat as it sits in our colon. This may help explain the higher
incidence of bowel cancer in meat-eating populations, along
with the increase in ammonia, neither of which could be helped by just
adding resistant starch on top of the meat. So the deleterious effects of animal
products on colonic metabolism override the potentially beneficial
effects of other protective nutrients, so we should do a combination of both
more whole plant foods and less meat, along with exercise, not only for
our colon but also for general health.