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Antibiotics alone, diet alone or the combination of the two will not cure SIBO unless your specific underlying cause(s) are identified and addressed. However, a science-based diet that limits ALL fermentable carbohydrates should be used as the first line therapy over antibiotics  because:

  • The diet approach is safe and provides a durable response

  • Your underlying cause may be simply the over consumption of fermentable carbohydrates

  • Antibiotics have no proven durable response, yet carry side effects and health risks

SIBO and Its Potential Underlying Causes

SIBO stands for Small Intestinal Bacterial Overgrowth. It’s a condition where too many bacteria migrate from our large intestine and overgrow in our small intestine.  Typically, our small intestine contains few bacteria, particularly in the early part where our own critical digestion takes place. But if you are SIBO positive, too many bacteria are growing where they do not belong, and you will experience varied symptoms as a result.

Due to easy access to non-invasive breath tests, more people are being diagnosed with SIBO than ever before. And now SIBO is linked to many digestive and other health issues. The following SIBO-related conditions explain the high number of SIBO-positives in the US alone:

  • Acid Reflux and LPR: 60 million
  • Irritable Bowel Syndrome: 50 million
  • Rosacea : 32 million
  • Autoimmune diseases (all): 24 million
  • Fibromyalgia: 5 million
  • Interstitial cystitis: 3 to 8 million
  • Celiac Disease: 3 million
  • Rheumatoid arthritis: 1.3 million
  • Sjögren’s syndrome: 0.5 to 3 million
  • Crohn’s Disease: 600,000
  • Cirrhosis: 400,000
  • Chronic pancreatitis: 150,000
  • Cystic fibrosis: 30,000

Due to a variety of potential underlying causes listed here, it’s impossible to conclude that antibiotics, diet, or even a combination of the two will “CURE” SIBO across the board:

  • Altered motility
  • Ileocecal valve issues
  • Surgery, structural abnormalities, intestinal scarring
  • Inflammation, GI infections
  • Digestive enzyme deficiency
  • Loss of stomach acid
  • Immunological deficiencies
  • Alcoholism or liver problems
  • Underlying genetic conditions
  • Over consumption of fermentable carbohydrates

The greatest success will be achieved if you are able to identify and address the specific cause(s) of your own SIBO. Given this fact, let’s take a look at the effectiveness of both Antibiotics and Diet for SIBO.

Should You Take Antibiotics for SIBO?

SIBO Treatment - Antibiotics or Diet?It’s reasonable to think of SIBO as an “infection”, and therefore, something that needs to be killed. But we should keep in mind that SIBO arises primarily from our own large intestine. These bacteria are healthy commensals. They protect us from true pathogens and produce nourishing fats and vitamins from foods we don’t digest.

Keeping them contained in the right place (i.e. in the large intestine) seems like the best strategy.  Also, we don’t want to kill off indigenous small intestinal bacteria that have their own role in digestion and gut health. Many intestinal bacteria are highly resistant to antibiotics or quickly become resistant. You can already see some of the challenges in treating SIBO with antibiotics. But the biggest challenge is their lack of effectiveness and a variety of risks associated with antibiotics. And antibiotics don’t address the underlying causes.

There is scant evidence in the scientific literature that antibiotics cure SIBO or even suppress SIBO and its symptoms long term. And the result is frequent retreatment. A good example is rifaximin, approved for treating IBS in May 2016. This study showed that 68% of SIBO-related IBS–D patients who needed to be retreated with rifaximin, required a second retreatment.  And some in the group were retreated up to 5 times. Another study looking at retreatment found that the efficacy of retreatment was also questionable. It was only 33% successful vs 25% with placebo, not particularly encouraging.

The US Department of Veterans Affairs in their 2016 evaluation of rifaximin stated:  “The risk of developing bacterial resistance with long-term or repeated treatment with rifaximin remains an important concern that may outweigh the relatively small benefits provided by rifaximin therapy in IBS-D. The cost of rifaximin also weighs against the frequent use of rifaximin for IBS. Rifaximin for IBS should be restricted to patients who have the IBS-D subtype and have not responded to effective and less costly symptom-based alternative therapies” which included diets that restrict fermentable carbohydrates. In other words, they recommended diet over antibiotics as a first line therapy.

Clearly, views on new science-based diets are changing. You might be surprised to learn that according to a recent Survey of 1500 Gastroenterologists showed that “91% felt that IBS diets were as good or better than medical therapies for IBS.”

Aside from rifaximin, a variety of other antibiotics have been used for SIBO in the past including metronidazole, colistin, levofloxacin, ciprofloxacin, doxycycline, amoxicillin-clavulanate, trimethoprim-sulfamethoxazole, cephalexin and norfloxacin. Though a couple small studies on norfloxacin and amoxicillin-clavulanic and metronidazole and colistin provided some encouraging results, longer term studies are needed with more subjects. And new studies should also look at the effectiveness of retreatment for participants who revert to SIBO-positive as well as side effects, health risks and the impact on the microbiome.

How About Herbal Antibiotics?

Many herbal extracts are known to possess antimicrobial activity. But individual herbal extracts tend to be less potent than synthetic antibiotics. Therefore, they are often used in combination. While a variety of these extracts have been proposed as possible treatments for SIBO, there is not much published data on the efficacy. Recently, a small study found that a combination of herbal antibiotics were at least as effective as rifaximin, but we need more definitive studies to confirm these results. Also, keep in mind that rifaximin is only 10% better than placebo, so the bar is set fairly low.

Someone asked me recently, “Is diet enough for SIBO or do I need to take an antibiotic?” One could easily turn this question around and ask “Are antibiotics enough for SIBO or do I need to change my diet?” The answer to this question is a resounding NO for antibiotics and  YES for diet.

Are Dietary Changes Effective for SIBO?

SIBO Treatment - Antibiotics or Diet? by Dr. Norm RobillardAs with antibiotics, dietary treatment of SIBO needs to include an evaluation of underlying causes. If present, underlying causes will need to be addressed for successful treatment. But in many cases, SIBO may simply be the result of over consumption of specific fermentable carbohydrates. Think of this as one of the potential underlying causes. If this is the case, a dietary strategy to control over consumption of fermentable, hard-to-digest carbohydrates may be all that you need.

Let’s Take a Look at This Idea More Closely

In the past, many of the symptoms we now associate with SIBO (intestinal gas, bloating, distension, diarrhea, etc.) were recognized as carbohydrate intolerance.  Sound familiar?

Carbohydrate intolerance is a form of malabsorption that can lead to dysbiosis, a general imbalance of gut microbiota, which may or may not include SIBO. For instance, lactose intolerance is very common in SIBO patients and has been recognized for over a century while fructose intolerance which is also linked to SIBO was first documented in the 1970s. More recently, sugar alcohols (except erythritol) and dietary fiber intolerance have been added to the list. And I make a case in the Fast Tract Digestion books that resistant starch is related to dietary fiber and should also be limited for SIBO and other conditions involving carbohydrate intolerance.

According to the Merck Manual, the standard treatment for carbohydrate intolerance is to limit the offending species of carbohydrate. This simple conclusion is supported by the Textbook of Primary and Acute Care Medicine, which states “Dietary alterations to reduce intestinal gas (a hallmark of SIBO) require the elimination of most of the foods in Table 1”, which includes lactose, fructose, certain oligosaccharides, resistant starch, fiber and sugar alcohols. This is precisely the group of carbohydrates that the Fast Tract Diet limits.

The recommendations to reduce fermentable carbohydrates are supported by studies from leading researchers

The recommendations to reduce fermentable carbohydrates are supported by studies from leading researchers including John Hunter’s group in the UK and Mark Pimentel’s group in the US. Each group published definitive studies that intestinal gases from gut bacteria were at the center of IBS/SIBO-related symptoms. And a low fiber diet (Hunter) or an elemental diet (Pimentel) dramatically reduced both intestinal gas and symptoms. Further support for limiting fermentable carbohydrates can be found in studies of the low FODMAP and low carb diet for IBS. Keep in mind that low carb, low fiber and low FODMAP diets do not limit the full range of fermentable carbohydrates identified in the Textbook of Primary and Acute Care Medicine. The Fast Tract Diet approach limits the full range.

Unlike antibiotic treatment, limiting fermentable carbohydrates provides a durable response. A long term study which looked at the efficacy of a lactose-free diet showed symptom improvement in almost 90% of lactose malabsorbers even after five years. If you are lactose intolerant, you need to either avoid lactose or take a lactase supplement when consuming high lactose diary for the rest of your life. Simple, isn’t it?

Similar results were observed in a study that looked at both lactose and fructose plus sorbitol intolerance. Symptomatic improvement was observed in 81% of patients after one month, and in 67 % of patients after 12 months by limiting the offending carbohydrate.

In another study on fructose avoidance, symptomatic improvement differed markedly between adherent (85%) and non-adherent (36%) individuals. Since there is no supplement for fructose intolerance, limiting fructose is a long term prospect.

Dietary Recommendation for SIBO

It’s only a matter of time in my view before limiting (not eliminating) all hard-to-digest fermentable carbohydrates will be the standard first line treatment for SIBO, dysbiosis and related functional gastrointestinal disorders such as IBS and GERD. Certain carbohydrate types may be added back once tolerance to individual carbohydrates is confirmed. Similarly, overall fermentable carbohydrate limits can be eased based on improvements in tolerance levels over time.

I myself have been on this journey for the last 16 years. I had suffered severely from GERD for many years before recognizing the critical connection between my symptoms and intolerance to these fermentable carbohyrates. Now I can enjoy a variety of foods that gave me terrible symptoms in the past as long as I don’t over do it.

A three pillar approach in the Fast Tract Digestion books, SIBO Masterclasses (2 on-demand classes and Q&A sessions for the price of 1) and our Consultation Program addresses SIBO with:

  1. A diet that strictly limits all fermentable carbohydrate
  2. Pro-digestion strategies (Gut Friendly Practices) which may include supplementation
  3. A road-map to identify and address underlying causes based on the individual and his / her health history

Antibiotics should be reserved for SIBO and related conditions that either fail to respond to diet or involve the most severe symptoms such as uncontrolled weight loss, failure to thrive, steatorrhea (the body’s failure to digest fats), anemia, bleeding or bruising, night blindness, bone pain and fractures or severe autoimmune reactions. Even in these situations, diet will certainly be part of the solution.

If you liked this article, you may want to read:

SIBO Diets and Digestive Health – It’s about Fermentable Carbohydrates

Myths on SIBO Treatment