Transcript: Putrefying Protein & “Toxifying” Enzymes
Colon cancer is a leading cancer killer, yet, there’s this paradox in Africa where they rarely get the disease—even in modern times, when they are no longer eating their traditional whole food diet. So, they’re no longer eating lots of fiber and fresh fruits and vegetables. It is likely, therefore, that their continued low prevalence of colon cancer—50 times lower than ours—is related to their low intake of animal protein and fat, as I explored previously. But why would animal protein and fat increase cancer risk? Well, as I noted in Bowel Wars, if you eat egg whites, for example, between 5% and 35% of the protein isn’t digested, isn’t absorbed, and ends up in the colon, where it undergoes a process called putrefaction.
When animal protein putrefies in the gut, it can lead to the production of the rotten egg gas, hydrogen sulfide, which, over and above its objectionable odor, can produce changes that increase cancer risk. Putrefying protein also produces ammonia.
Over a lifetime on a standard Western diet, the bacteria in our colon may release the amount of ammonia found in a thousand gallons of Windex. At concentrations found day-to-day inside the colon on usual Western diets, ammonia destroys cells, alters DNA synthesis, increases cellular proliferation, may increase virus infections, favors the growth of cancerous cells, and evidently increases virus infections for a second time. It’s the products of protein and fat digestion that are to blame, such that you can double ammonia concentration in the colon by eating a lot of meat.
But put people on a plant-based diet and within just one week, the enzyme activity that creates the ammonia in the colon drops like a rock.
Other bacterial enzymes are affected as well. Remember how broccoli-family vegetables can boost detoxifying enzymes in the liver? These so-called phase 2 enzymes, UDP-glucuronosyltransferases, detoxify drugs and chemicals by applying a chemical straightjacket, here shown in red, deactivating the date rape drug GHB, or taking the carcinogens in meat, like benzopyrene, and rendering them harmless before dumping them back into the intestine for disposal. But if our liver detoxifies it, why is benzopyrene in meat still associated with rectal cancer? Well, certain bacteria in our gut contain the opposite enzyme, a “toxifying” enzyme that removes the straightjacket and frees the carcinogen to wreak a last bit of havoc before it leaves the body.
But, within one week of eating plant-based, we can drop that enzyme activity in our colon by about 30%. But, this was with a raw, “extreme” vegan diet. What about a regular vegetarian diet? Compared to a pound-of-meat-a-day diet, those placed on a meat-free diet for a month experienced a 70% drop in “toxifying” activity. This, in turn, may raise the amount of substances, such as carcinogens, within the colon. And long-time vegetarians exhibit just a fraction of carcinogen-releasing activity compared to those on a standard American diet.
So, might this all help the increased risk in the United States? Researchers put it to the test by taking biopsies from the lining of the colons of Americans versus Africans, to measure proliferation rates—how fast the cells are dividing, a marker for increased cancer risk—and decreased cancer survival. This is what they found: the black dots denote proliferating cells, which we can see throughout the colons of Caucasian-Americans and African-Americans, but only a few were seen in the African biopsies. They had dramatically lower proliferation rates.
Overall higher colorectal cancer risk was associated with “higher dietary intakes of animal products and higher colonic populations of potentially toxic hydrogen and secondary bile-salt-producing bacteria.”
And, while they were in there to get the biopsies, they looked around a little bit, and out of all the African colons they looked at, they detected only four issues out of 18 colons. But out of the 17 African-American or Caucasian-American colons, they found 21 problems each: polyps, diverticulosis, and lots of hemorrhoids. The remarkably pristine condition of the colons in our African volunteers further supports our impression that African colons were, in general, far healthier than American colons.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.
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