Psssst…Got some acid?


This is the third part of my blog series on small intestinal bacterial overgrowth (SIBO). In part one, I covered what it is and in part two I discussed what diseases are associated with it. This and the next two posts covers the causes of SIBO.

As I wrote in my opening article in this series, there are two main routes of infection. The first involves compromised gastric or stomach barrier function. The second involves dysfunction in intestinal movement or motility. This post will cover gastric barrier dysfunction.

In order for any pathogen (or pill) to enter your small intestine via the stomach it has to survive stomach acid. Stomach or hydrochloric acid is there to not only begin the digestion of protein, but to kill any pathogens ingested with food or present in saliva before they take up residence in your gut and cause dysbiosis. At a pH of 4, most bacteria are killed within 30 minutes, but the pH of a normal human stomach is an even more acidic 2. That means that 99% of bacteria are killed within 5 minutes of entering the stomach. This is why relying on yogurt or kefir to quickly repopulate your gut with beneficial bacteria isn’t going to happen. If it did, you would have much bigger problems.

Therefore, it follows that anything that compromises this very important gastric barrier is going to predispose you to SIBO. So, dear reader, what would that be?

Well, the biggest elephant in the room are the antacids and proton-pump inhibitors (Prilosec®, Prevacid®, Nexium®) many are popping to treat their acid reflux and heartburn like so much candy at a kid’s birthday party. You know who you are. You go to sleep at night and wake up shortly afterwards with that awful vomit taste in your mouth. Or perhaps you experience pretty bad heartburn. I have a friend who’s always pounding his chest shortly after he eats as if he’s Tarzan calling out to Jane. So I understand why these purple little pills are popular.

But (you knew that “but” was coming didn’t you?) you’re playing with fire doing this. It’s like kicking open the door to your house in a crime-ridden neighborhood. In this case, the criminals are the harmful bacteria not being killed off in your stomach, and the house is your small intestine where they take up residence and deprive you, not of your TV or computer, but something far more precious, your health. Hence it explains these findings.

But Ray, I can’t live without these things. I’d be up all night or burping up that yummy pizza and beer I had for dinner. I’ll give you some pointers on what to do about GERD in my upcoming post on dietary causes of SIBO so stay tuned!

There’s another elephant in this dysbiosis ballroom but this one is pink, not purple.

Small quantities of alcohol actually increases stomach emptying and intestinal movement, aka motility. Increased intestinal motility always helps prevent attachment of pathogens to the gut wall.

It also improves gastric barrier function by lowering stomach pH although this does stimulate appetite. That waiter or waitress asking you if you would like to have a cocktail before dinner is doing so not only in the hope of earning a bigger tip, but because every restaurant owner under the sun trains their staff to do so. They know that a “bit of bending at the elbow” stimulates both drink and food sales leading to higher restaurant checks and more money in their pocket. So assuming weight gain or alcohol isn’t a problem for you, enjoy your occasional cocktail or glass of wine.

The trouble, however, begins when you enter binge drinking territory, a land I have stumbled through on more than one occasion and not always with pleasant results. Binge drinking is usually defined as drinking more than 2 to 3 drinks in a two-hour period if you’re a man and more than 1 to 2 drinks in the same time period if you’re a woman. To be clear, a drink is defined as a cocktail, a glass of wine or a beer. That’s an estimate, and some may be able to get away with more while others less or none at all. Your mileage may vary.

Once you enter binge drinking la la land, what was true for small quantities of alcohol turns into its dialectical opposite. Intestinal and stomach motility slows down and pH becomes less acidic. Put those two together often enough and you’ll probably end up with a SIBO hangover that long outlasts your real one. It should therefore not come as a shock that alcoholics suffer from high rates of SIBO and endotoxemia induced liver and heart disease.

Other causes of impaired gastric barrier function include H. pylori infection, malnutrition and various autoimmune diseases like pernicious anemia. Gastric surgeries like gastrectomy (partial or full removal of the stomach) and truncal vagotomy (resection of the vagus nerve) can also cause SIBO by either raising stomach pH, preventing its production or impairing motility

Finally, just getting older is a cause as we all begin to produce less hydrochloric acid as we get on in years.

So you can imagine my utter dismay when I witness a senior whose natural production of stomach acid is already on the decline popping proton-pump inhibitors and washing them all down with their fifth glass of Pinot noir. No wonder the study I mentioned in the previous post found up to 90% of seniors studied had SIBO.

Ok, that’s it for now. I’ll cover impaired intestinal movement in the next post.



Bujanda, L. M.D. (2000). The Effects of Alcohol Consumption Upon the Gastrointestinal Tract. The American Journal of Gastroenterology, 95(12): 3374-82.

Bures J., Cyrany J., Kohoutova D., et al. (2010) Small intestinal bacterial overgrowth syndrome. World Journal of Gastroenterology, 16(24): 2978-90.

Parodi A., Lauritano E.C., Nardone G., Fontana L., Savarino V., Gasbarrini A. (2009). Small intestinal bacterial overgrowth. Digestive and Liver Disease, (3), 44-49.

Purohit V., Bode J.C., Bode C., et al. (2008) Alcohol, Intestinal Bacterial Growth, Intestinal Permeability to Endotoxin, and Medical Consequences: Summary of a Symposium. Alcohol, 42(5): 349-61.

Quigley E. M. M., Quera R. (2006). Small Intestinal Bacterial Overgrowth: Roles of Antibiotics, Prebiotics and Probiotics. Gastroenterology, 130: S78-S90.


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