What Is Small Intestine Bacterial Overgrowth? – How To Conquer Your Bloating Crisis!

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So what is small intestine bacterial overgrowth anyway? The short answer is that it comes from a bacterial invasion due to your digestive tract’s malfunction. If you always feel gassy with excessive bloating, then let me help you learn what you can do about it.

In this article, I will teach you how to diagnosis this problem, steps you can take to treat it successfully, and ways to prevent it from returning.

The Essence Of The Problem

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People develop small intestine bacterial overgrowth (also called small intestinal bacterial overgrowth or SIBO) when the small intestine becomes overrun with bacteria that don’t belong there in the first place. These bacteria usually come from the large intestine (also called the colon) but may also come from the stomach.

As these bacteria continue to populate the small intestine, they can deplete the nutrients consumed during a meal before they are absorbed into your bloodstream, leading to weight loss and malnutrition.

Typical Symptoms

What Is Small Intestine Bacterial Overgrowth - A photo of someone having GI symptoms

This disorder can make your day-to-day life miserable. If you have to unbutton your pants after a normal size meal due to excessive gas with bloating, you may have small intestinal bacterial overgrowth. Everyone experiences these symptoms from time-to-time, but with SIBO, it can become a way of life.

Some people experience indigestion or a “feeling of fullness.” More serious cases can also cause nausea, pain during and after eating, and diarrhea. It’s also not unusual to have periods of constipation.

The symptoms of SIBO are by no means unique. They can also be seen in a variety of other GI ailments such as GERD (gastroesophageal reflux disease), IBS (irritable bowel syndrome), and anxiety disorders.

If your symptoms are lingering or getting worse, then make an appointment to see your health care provider for evaluation and diagnosis, especially if you have persistent abdominal (belly) pain, diarrhea, or weight loss. You will want to be sure that there isn’t a more serious underlying medical ailment causing the problem. Your situation may require a specific treatment to resolve or improve your symptoms.

Common Causes

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Many things can cause SBIO. These can range from simple ailments that resolve on their own to chronic and potentially serious diseases.

Small intestine bacterial overgrowth can occur in association with the following conditions and diseases.

  • Low stomach acidity – commonly seen in people who take potent acid-reducing medications (e.g., Prilosec or Nexium) for long periods of time
  • Infections of the GI tract – such as viral gastroenteritis or “stomach bug”
  • Disorders of the immune system – which can allow bacteria to grow in your intestine at an accelerated rate
  • Spasm of the small bowel muscle – such as with irritable bowel syndrome
  • Decreased emptying time – slow emptying of the stomach and small intestine can be caused by diabetes and scleroderma
  • Serious diseases of the GI tract – such as celiac (malabsorption) disease, Crohn’s disease, and cirrhosis of the liver
  • An underactive thyroid – also known as hypothyroidism, which can slow down the contractions of the small intestine
  • Complications of surgical procedures – such as the formation of abdominal strictures or adhesions, after gastric bypass for weight loss, and stomach resection (gastrectomy) for the treatment of ulcers or cancer
  • Abnormal areas of the small intestine – such as the formation of pouches (diverticulae), which can allow partially digested food to accumulate
  • Radiation therapy to the abdomen – which is used in the treatment of various types of cancer
  • Anxiety and depression – prolonged periods of severe anxiety or depression can slow the movement of food through your stomach and small intestine

Here is a video by The SIBO Doctor, which summarizes SIBO and some of its common causes.

Diagnosing SIBO

Many people attempt to diagnose their own SIBO by carefully tracking their symptoms and using a systematic process of elimination. They typically measure their success by the effectiveness of their chosen treatment. Sometimes this approach works well but if you have been through this process multiple times without positive results, you should consider getting professional assistance.

A common problem that can make diagnosis and treatment of your GI problem difficult is that many or all of the symptoms that point to having SIBO can be seen in other ailments. Sometimes you need to be sure you are dealing with SIBO before moving to a more aggressive treatment approach. There are two main ways that your health care provider can objectively diagnosis your symptoms as being caused by SIBO.

What Is Small Intestine Bacterial Overgrowth -  A photo of a doctor discussing a diagnosis with a patient!

Carbohydrate Breath Test

Most cases of small intestine bacterial overgrowth can be diagnosed with a breath test. This test detects hydrogen and methane gas produced in your small intestine as bacteria break down ingested food and liquids, especially those containing sugar.

During the test, you will drink a sugary substance such as lactulose and breath into a tube every 15 to 20 minutes for about two hours. An increased hydrogen gas concentration of above 20 parts per million (PPM) and /or an increased methane gas concentration above 10 PPM is generally diagnostic for SIBO.

Jejunal Aspirate Culture

A jejunal aspirate culture is the surest way (gold standard) to diagnose SBIO and may be performed when a carbohydrate breath test gives borderline results or cannot be completed.

Digested material is suctioned (aspirated) from the second part of the small intestine (jejunum) by inserting an endoscope (fiber-optic tube) down past the stomach. The material is sent for bacterial culture.

A bacterial count of greater than 1,000 bacterial colonies per milliliter (ml) is diagnostic for SIBO. The most common types of bacteria are Bacteroides Enterococcus and Lactobacillus.

Treating SIBO

The pros and cons of treatment.

When small intestinal bacterial overgrowth is left untreated, it can turn into a serious condition. The mainstay of professional treatment is antibiotics, the correction of micronutrient deficiencies, and an elemental diet. Probiotic therapy has become a popular option for the home-treatment of SIBO.

Antibiotic Therapy

The most effective way to treat SIBO, especially in severe or poorly responsive cases, is usually antibiotics. Your doctor may start antibiotic treatment without a breath test or jejunal aspirate. Such empiric treatment is usually based on a high suspicion of SIBO as the diagnosis from the description of your symptoms and examining your abdomen.

One of the most effective antibiotics is Xifaxan (rifaximin). Unfortunately, the high cost of this medication has limited its use as a first-line treatment. If a breath test or jejunal aspirate shows that you have mostly methane-producing bacteria, then Neomycin and Xifaxin is the most effective treatment. Mostly hydrogen-producing bacteria can be treated with Xifaxin alone.

Bactrim (trimethoprim-sulfamethoxazole), Cipro (ciprofloxacin), Flagyl (metronidazole), and Achromycin (tetracycline) may also be used to treat SIBO, especially in people with a Xifaxan allergy or as a lower-cost alternative. These second-line medications may have higher treatment failure rates or require multiple treatment attempts to be successful.

Correct Micronutrient Deficiencies

In severe cases of SBIO, your digestive system may not be able to efficiently absorb micronutrients like vitamins and minerals. Common vitamin deficiencies include Vitamin B1 (Thiamine), B12, Niacin, A, D, E, and K. Low iron is a frequently seen mineral deficiency. Deficiencies of Vitamin B12 and Iron can eventually lead to anemia (a decrease in red blood cell production). See Foods High In Antioxidant – Eating Smart For Better Health.

All micronutrients should be replaced and maintained during the treatment of SIBO. A multivitamin with mineral is adequate therapy in most cases. Severe micronutrient deficiencies with significant weight loss may require intravenous replacement.

Begin An Elemental Diet

An elemental diet may be useful, especially if antibiotic therapy did not correct your SIBO symptoms, but it can be expensive and poorly tolerated. It is essentially comprised of liquid nutrition that is premixed or comes in powdered form. The mixture is intended to be easily digestible and supply all the key nutrients that your body needs while not increasing the small intestine’s bacterial growth rate.

This type of diet is best done under the supervision of your health care provider.

Probiotic Therapy

Probiotic therapy is commonly used to treat the symptoms of SIBO. Probiotics work by replenishing the normal bacterial population of the gut to return the small intestine to normal. There have been limited scientific studies showing that this approach is useful, especially in severe cases of SBIO.

One study showed the probiotic lactol could help reduce abdominal pain in SBIO patients being treated simultaneously with antibiotics.

If you think you have SBIO then I recommend checking with your healthcare provider before beginning probiotic therapy.

Preventing The Recurrence Of Symptoms

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If your SIBO has an underlying cause such as diabetes, scleroderma, or Crohn’s disease, then you can keep it under control by having routine visits with your health care provider to monitor and treat these diseases.

Avoiding the long term use of certain medications has a definite role in prevention.

  • Acid reducers, especially proton pump inhibitors like Prilosec, can encourage bacterial growth by decreasing the small intestine’s acidity
  • Narcotics like Vicodin (hydrocodone) and Percocet (oxycodone) increase bacterial growth by slowing down gut motility
  • Antibiotics, especially those that have broad-spectrum activity
  • Oral contraceptives in some women that are sensitive to prolonged use

Here are some things you can try that may be effective but have an unclear role in SIBO prevention.

  • A low FODMAP diet limits the consumption of short-chain carbohydrates, which can promote bacterial overgrowth in the small intestine. This may be a good way to prevent the recurrence of gas and bloating.
  • Probiotics may help prevent the return of small intestine bacterial overgrowth by promoting the growth of good bacteria in the large bowel.
  • Statin drugs like Lipitor (atorvastatin) and Zocor (simvastatin) may inhibit the growth of methane-producing bacteria in the small intestine.

Complications of SIBO

A woman having abdominal pain from SIBO.

Small intestine bacterial overgrowth can cause a variety of complications.

Decreased absorption of vitamins, minerals, fats, carbohydrates, and proteins is commonly seen, especially in moderate to advanced cases. Vitamin and mineral deficiencies can cause anemia, weak bones leading to osteoporosis, and neurologic problems.

Diarrhea can occur from bacteria in the small intestine breaking down bile, although some people may be constipated from decreased GI motility.

Severe cases can cause malnutrition and dehydration from nausea and abdominal pain leading to decreased liquid and food consumption. Advanced cases may require hospitalization for IV fluid and nutritional replacement.

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Final Thoughts

Small intestine bacterial overgrowth is a common condition that can cause various symptoms and complications if not diagnosed and treated properly. It is often treated without testing, based on symptoms such as bloating and excessive gas production. A breath test is available to make a more definitive diagnosis, as well as an endoscopic sampling of the material in the small intestine (jejunal aspirate).

Probiotics have become a popular option for the self-treatment of SIBO. Although there is limited scientific evidence that this is an effective approach, many people have claimed to have had great results with the probiotics. You can also try a diet that is low in fibrous foods like fruits, grains, and vegetables, and sugary sweets.

If you would like to try a probiotic to treat or prevent SIBO then the number one probiotic I recommend is Probiotic 30 Billion.

Tell Us What You Think

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Please let us know what’s on your mind in the comment section, or if I can help you with anything.

  • Do you have any additional tips or suggestions?
  • Have you ever been diagnosed with SIBO?
  • What treatment worked best to treat your SIBO?

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4 thoughts on “What Is Small Intestine Bacterial Overgrowth? – How To Conquer Your Bloating Crisis!”

  1. Quite a detailed and informative article. I learned a lot about SIBO and the seriousness of this condition. My question is: are there a lot of pople who go undiagnosed with this condition? Can diet be a possible way to treat it? If you do choose the probiotic route to be your treatment, is there a particular product you recommend? I am eager to get answers to these questions.

    • Hi Elridge,

      Thank You for your comments!
      SIBO is very commonly undiagnosed or misdiagnosed. A diet low in fibrous foods (fruits, grains, and vegetables) and sugary sweets can help relieve the symptoms.
      A good probiotic to try is the one I mention in the article (Probiotic 30 Billion).


  2. I’m glad I got across this article. It is a great one. I learned so much from all the details that you outlined about the SIBO. From the essence of the problem, the symptoms, the common cause, Diagnosing, how to treat it, and how to prevent the source of the symptoms. That is a well-done job, and thank you for sharing. I’m sure you are familiar with liver cleansing. Do you think the release of those stones from the liver could also be the cause of SIBO? Big possibility, as they are toxins. This is the reason some alternative medicine doctors highly recommend doing a colon cleansing after the liver cleanse.

    • Hi Akim,

      Thank You for your comments! I’m happy to learn that you found my article useful!

      There are no published medical studies, to the best of my knowledge, on gallstones or other discharge from the gallbladder causing SIBO. Although it’s possible, I think it’s unlikely.

      There is a correlation between cirrhosis of the liver and SIBO. Cirrhosis causes decreased bile production, which decreases fat breakdown in the small intestine, which can increase bacterial overgrowth.



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