GERD and SIBO - Are They Connected?

man with heartburn
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At first glance, it does not seem to make any sense that there would be a connection between heartburn and gut bacteria. How could something downstream (the intestines) have anything to do with anything upstream (heartburn)? However, there is an intriguing theory that connects the two. Let's take a look...

The Theory

In his book, Fast Tract Digestion, Norman Robillard, Ph.D. makes a case that small intestine bacterial overgrowth (SIBO) may be the real cause of gastroesophageal reflux disease (GERD).

SIBO is a health condition in which there are too many bacteria in the upper part of the small intestine - a place where these micro-organisms really shouldn't be. GERD, as you may know, is a disease in which stomach acid burns the lining of the esophagus (acid reflux), causing the symptom of heartburn.

How might these two be connected? Dr. Robillard's theory is that the gas produced by the bacteria residing in the small intestine puts enough pressure on the small intestine and stomach that it can push the acid from the stomach into the esophagus.

In addition to identifying a new way to look at the cause of GERD, Dr. Robillard also offers a new look at treatment. He does not endorse the use of acid-reducing medications, particularly the use of proton pump inhibitors (PPIs), which is currently the standard treatment for GERD. His theory is that the reduced stomach acid resulting from PPIs contributes to the bacterial overgrowth in the small intestine in the first place, as stomach acid serves a preventative role in terms of keeping bacteria from populating the small intestine.

What Dr. Robillard recommends is that GERD patients follow a diet that is low in what he calls "difficult to digest" carbohydrates. It is his belief that a diet high in these carbohydrates contributes to both the overgrowth of these bacteria and the increased gas output that is directly causing reflux.

Interestingly, his list of carbohydrates to avoid is very similar to those of the low-FODMAP diet for IBS. A crucial difference is those foods that are high in resistant starch, such as unripe bananas and corn, which are encouraged on the low-FODMAP diet, but discouraged by Dr. Robillard in terms of treating GERD.

The Science

Although the theory is compelling, there is not yet a lot of research to support it.

One small study involved having GERD patients swallow a solution of either fructooligosaccharide (FOS) or placebo after meals for one week each. FOS are non-digestible and therefore are available to be fermented on by intestinal bacteria. Interestingly, FOS are a type of FODMAP, found in foods like onions, garlic, and asparagus. The researchers found that the FOS increased the times of relaxation of the esophageal sphincter muscles, as well as increased the amount of acid reflux and GERD symptoms. In this study, there was no mention of SIBO, but the researchers did conclude that it was fermentation within the colon that caused the increase in GERD symptoms.

Another very small study found that a low-carbohydrate diet significantly improved GERD symptoms in a small group of obese GERD patients.

The Bottom Line

For now, it seems that all we can conclude is that this is an interesting theory. Hopefully, further research will be conducted to find out if a low-carbohydrate diet does indeed resolve SIBO and ease the symptoms of GERD. Unfortunately, funding for dietary treatments for medical problems tends to be scarce. Personally, I would love to see some research as to whether or not the low-FODMAP diet has an effect on heartburn symptoms - something that I have heard from clients who are on the diet.

Persistent GERD is a condition best managed by your doctor. However, if this theory resonates for you, talk to your doctor about it. If you decide that you want to try the low-carbohydrate diet recommended by Dr. Robillard and then assess its effects on your symptoms, you should consult with a qualified dietary professional to ensure that all of your nutritional needs are being met.

Sources:

Austin, G., et.al. "A Very Low-Carbohydrate Diet Improves Gastroesophageal Reflux and Its Symptoms" Digestive Diseases and Sciences

Piche, T., et.al. "Colonic fermentation influences lower esophageal sphincter function in gastroesophageal reflux disease" Gastroenterology 2003 124:894-902.

Robillard, N. (2012) Fast Tract Digestion: Heartburn. Watertown, MA:Self Health Publishing.

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