Bowel Wars: Hydrogen Sulfide vs. Butyrate

Michael Greger M.D. FACLM · April 27, 2015 · Volume 24

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Sulfur dioxide preservatives in dried fruit, sulfites in wine, and the putrefaction of undigested animal protein in the colon can release hydrogen sulfide, the rotten egg gas associated with inflammatory bowel disease.

Discuss

Transcript

There’s a take-off on the industry slogan, “Beef: It’s What’s For Dinner – Beef: It’s What’s Rotting in Your Colon.” I saw this on a shirt once with some friends, and I was such the party pooper—no pun intended—explaining to everyone how meat is fully digested in the small intestine, and never makes it down into the colon. It’s no fun hanging out with biology geeks—but, I was wrong!

It’s been estimated that with a typical Western diet, up to 12 grams of protein per day can escape digestion, and when it reaches the colon, it can be turned into toxic substances like ammonia. This degradation of undigested protein in the colon is called putrefaction, so a little meat can actually end up putrefying in our colon. The problem is that some of the by-products of this putrefaction can be toxic.

It’s generally accepted that carbohydrate fermentation—the fiber and resistant starches that reach our colon—results in beneficial effects for the host because of the generation of short-chain fatty acids like butyrate, whereas protein fermentation is considered detrimental for us. Protein fermentation mainly occurs in the lower end of the colon, when carbohydrates get depleted, and results in the production of potentially toxic metabolites. Perhaps that’s why we see more colorectal cancer and ulcerative colitis lower down, because that’s where the protein is putrefying. The simplest strategy to reduce the degree of potentially harmful compounds by protein fermentation is probably a reduction in dietary protein intake.

But, the accumulation of these harmful byproducts of protein metabolism may be attenuated by the fermentation of undigested plant matter. This study showed that if you give people foods containing resistant starch—starch resistant to small intestine digestion so it can feed our good bacteria down in our colon–foods such as cooked beans, peas, lentils, raw oatmeal, and cold pasta, you can block the accumulation of potentially harmful byproducts of protein metabolism. The more starch ended up in the stool, the less ammonia, for example.

But there’s protein in plants too. The difference is that animal proteins tend to have more sulfur-containing amino acids like methionine, which can be turned into hydrogen sulfide in our colon–the rotten egg gas that may play a role in the development of inflammatory bowel diseases like ulcerative colitis, as I’ve covered previously.

The toxic effects of hydrogen sulfide appear to be mediated through blocking the ability of our colon cells from utilizing butyrate, which is what our good bacteria make from the fiber we eat. So it’s like this constant battle in our colon between the bad metabolites of protein, hydrogen sulfide, and the good metabolites of carbohydrates, butyrate. Using human colon samples, they were able to show that the adverse effects of sulfide could be reversed by butyrate. So we can either cut down on meat, eat more plants, or both.

But there’s two ways hydrogen sulfide can be produced. Though it’s mainly present in our large intestine as a result of the breakdown of sulfur-containing proteins, rotten egg gas can also be generated from inorganic sulfur preservatives like sulfites and sulfur dioxide.

Sulfur dioxide is used as a preservative in dried fruit, and sulfites are added to wines. We can avoid sulfur additives by reading labels or by just choosing organic, since by law they’re forbidden from organic fruits and beverages. Cabbage family vegetables naturally have some sulfur compounds, but thankfully, after following more than 100,000 women for over 25 years, cruciferous vegetables were not associated with elevated colitis risk.

But because of the animal protein and preservative-laden processed foods, the standard American diet may have five or six times more sulfur than a diet centered around unprocessed plant foods, which may help explain the rarity of inflammatory bowel disease among those eating traditional whole food plant-based diets.

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.

Please consider volunteering to help out on the site.

Sources

Acknowledgements

Images thanks to OpenClips via Pixabay.

There’s a take-off on the industry slogan, “Beef: It’s What’s For Dinner – Beef: It’s What’s Rotting in Your Colon.” I saw this on a shirt once with some friends, and I was such the party pooper—no pun intended—explaining to everyone how meat is fully digested in the small intestine, and never makes it down into the colon. It’s no fun hanging out with biology geeks—but, I was wrong!

It’s been estimated that with a typical Western diet, up to 12 grams of protein per day can escape digestion, and when it reaches the colon, it can be turned into toxic substances like ammonia. This degradation of undigested protein in the colon is called putrefaction, so a little meat can actually end up putrefying in our colon. The problem is that some of the by-products of this putrefaction can be toxic.

It’s generally accepted that carbohydrate fermentation—the fiber and resistant starches that reach our colon—results in beneficial effects for the host because of the generation of short-chain fatty acids like butyrate, whereas protein fermentation is considered detrimental for us. Protein fermentation mainly occurs in the lower end of the colon, when carbohydrates get depleted, and results in the production of potentially toxic metabolites. Perhaps that’s why we see more colorectal cancer and ulcerative colitis lower down, because that’s where the protein is putrefying. The simplest strategy to reduce the degree of potentially harmful compounds by protein fermentation is probably a reduction in dietary protein intake.

But, the accumulation of these harmful byproducts of protein metabolism may be attenuated by the fermentation of undigested plant matter. This study showed that if you give people foods containing resistant starch—starch resistant to small intestine digestion so it can feed our good bacteria down in our colon–foods such as cooked beans, peas, lentils, raw oatmeal, and cold pasta, you can block the accumulation of potentially harmful byproducts of protein metabolism. The more starch ended up in the stool, the less ammonia, for example.

But there’s protein in plants too. The difference is that animal proteins tend to have more sulfur-containing amino acids like methionine, which can be turned into hydrogen sulfide in our colon–the rotten egg gas that may play a role in the development of inflammatory bowel diseases like ulcerative colitis, as I’ve covered previously.

The toxic effects of hydrogen sulfide appear to be mediated through blocking the ability of our colon cells from utilizing butyrate, which is what our good bacteria make from the fiber we eat. So it’s like this constant battle in our colon between the bad metabolites of protein, hydrogen sulfide, and the good metabolites of carbohydrates, butyrate. Using human colon samples, they were able to show that the adverse effects of sulfide could be reversed by butyrate. So we can either cut down on meat, eat more plants, or both.

But there’s two ways hydrogen sulfide can be produced. Though it’s mainly present in our large intestine as a result of the breakdown of sulfur-containing proteins, rotten egg gas can also be generated from inorganic sulfur preservatives like sulfites and sulfur dioxide.

Sulfur dioxide is used as a preservative in dried fruit, and sulfites are added to wines. We can avoid sulfur additives by reading labels or by just choosing organic, since by law they’re forbidden from organic fruits and beverages. Cabbage family vegetables naturally have some sulfur compounds, but thankfully, after following more than 100,000 women for over 25 years, cruciferous vegetables were not associated with elevated colitis risk.

But because of the animal protein and preservative-laden processed foods, the standard American diet may have five or six times more sulfur than a diet centered around unprocessed plant foods, which may help explain the rarity of inflammatory bowel disease among those eating traditional whole food plant-based diets.

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.

Please consider volunteering to help out on the site.

Images thanks to OpenClips via Pixabay.

Doctor's Note

More than 35 years ago, studies started implicating sulfur dioxide preservatives in the exacerbation of asthma. This so-called “sulfite-sensitivity” seems to affect only about 1 in 2,000 people, so I recommended those with asthma avoid it, but otherwise I considered the preservative harmless. I am now not so sure, and advise people to avoid it when possible. How could companies just add things to foods without adequate safety testing? See Who Determines if Food Additives are Safe? For other additives that may be a problem, see Titanium Dioxide & Inflammatory Bowel Disease and Is Carrageenan Safe?

For more on the relationship between hydrogen sulfide and inflammatory bowel disease, see my video Preventing Ulcerative Colitis with Diet. More on this epic fermentation battle in our gut in Stool pH and Colon Cancer.

Does the sulfur-containing amino acid methionine sound familiar? You may remember it from such hits as Starving Cancer with Methionine Restriction and Methionine Restriction as a Life Extension Strategy.

These short-chain fatty acids released by our good bacteria when we eat fiber and resistant starches is what may be behind the second meal effect: Beans and the Second Meal Effect.

What about Crohn’s? Glad you asked! See Preventing Crohn’s Disease With Diet and Dietary Treatment of Crohn’s Disease.

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