Bloating, cramping, gas, and indigestion are frequent symptoms of gastrointestinal and autoimmune conditions such as irritable bowel syndrome (IBS), Crohn's disease, and gut dysbiosis. But these bodily signs are also common after eating specific foods, a big meal, or even during certain times of the month.

With lots of daily fluctuation and symptom overlap, how can you determine when your digestive system is functioning properly, or when there’s something more serious going on? In this article, we’ll help you discern what exactly SIBO is, how it’s caused, and what you can do to get your gut health back on track when SIBO leads to debilitating abdominal symptoms.

What Is SIBO?

Small intestinal bacterial overgrowth, which is commonly referred to as SIBO, is a disturbance in the gut ecosystem. SIBO occurs when the mechanisms designed to keep your gut microbiome balanced through the movement of intestinal contents are not working properly, and certain bacteria are allowed to overgrow in the small intestine. When these bacteria proliferate and disrupt healthy gut flora, they can cause various symptoms and digestive system issues. (Source, Source)  

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Since the gut contains 70% of the immune system, it’s clear to see how a bacterial imbalance can impact your immunity and overall health. When bacteria or archaea — another kind of gut-inhabiting organism — grow abnormally in the small intestine, they interfere with the normal digestion process. Food is fermented in the small intestine instead of being properly digested, causing a buildup of gassy metabolic byproducts and preventing the release of nutrients into the bloodstream. The fermentation produces either hydrogen or methane, which is what causes the majority of SIBO symptoms. (Source, Source)

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What Are the Symptoms of SIBO?

Although your experience of SIBO is unique to you, there are some common symptoms associated with this condition. They include:

• bloating
• abdominal pain
• excessive flatulence
• belching
• diarrhea
• weight loss
• nutritional deficiencies, which may include malabsorption of fats, anemia from low levels of iron, and vitamin B12 deficiency
• in severe cases, steatorrhea — fatty stools that are a symptom of malabsorption

(Source, Source)

Common SIBO symptoms and IBS symptoms are similar; however, SIBO has been theorized to be an underlying cause of IBS because it exists in as much as 84% of people with IBS. So SIBO may cause IBS, but what causes SIBO? (Source)

What Causes SIBO?

SIBO can be caused by a variety of factors, but the common thread among all the causes we’ll discuss is reduced gut motility. When intestinal movement is negatively impacted and the contents of the gut are not moving efficiently through the digestive system, it creates prime conditions for bacteria to overproduce and SIBO symptoms to present themselves. (Source)

Poor intestinal motility and the resulting SIBO can occur from the following:

• low levels of stomach acid. This is also called hypochlorhydria. When the acid levels in the stomach are sub-optimal, bacteria may pass through the stomach without being neutralized and are subsequently allowed to flourish farther along in the digestive process.

There are several factors that can lower your levels of stomach acid:

• an H. Pylori bacterial infection, due to food poisoning from eating or drinking contaminated food, or by contact with body fluids that carry it
• long periods of use of antacids or proton pump inhibitors, or other medications such as antibiotics, narcotics, or gastric acid suppressants that upset the normal flora balance
• gastric bypass surgery
• dysmotility of the small intestine. When waste is retained too long in the small intestine before moving through to the large intestine, this allows small intestinal bacteria to multiply and opens up the potential for large intestinal bacteria to enter the small intestine.

Dysmotility is associated with disorders such as:

(Source, Source)

• gastroparesis, a slowing or stopping of food moving from the stomach to small intestine
• intestinal pseudo-obstruction, where the intestine cannot contract to push contents through the digestive tract
• hypothyroidism, a condition that is characterized by an under-production of hormones in the thyroid gland

(Source, Source, Source)

• small intestine structural problems. These issues can be caused by surgery complications or other gastrointestinal diseases, such as:
• scar tissue from a hysterectomy, gallbladder removal, or surgery to remove part or all of the stomach
• tissue protruding through the wall of small intestine, which is a type of diverticulosis
• medical conditions that affect the gut, including Crohn’s disease, IBS, and celiac disease

(Source, Source, Source)

It’s clear that SIBO is associated with a range of conditions, all relating back to gut health. But what puts you at risk for SIBO in the first place?

Additional SIBO Risk Factors

Gut motility slows down with age, and medical conditions that affect the motility or balance of your gut can all increase your risk for SIBO. Risk factors associated with SIBO include:

• advanced age
• chronic pancreatitis
• cirrhosis of the liver
• cystic fibrosis
• fibromyalgia
• hypothyroidism
• lupus
• diabetes
• irritable bowel syndrome (IBS)
• inflammatory bowel disease (IBD)

(Source, Source)

How Do I Know If I Have SIBO?

Getting the correct diagnosis for SIBO can be a challenge, in part because its symptoms overlap with those of IBS, and IBS is more likely to be diagnosed. But the good news is that there are specific medical tests that can help you and your health care provider determine if SIBO is in fact the cause of your gastrointestinal distress. Next, let’s discuss the testing methods that can confirm or rule out a SIBO diagnosis. (Source, Source)

Culture Sampling of Gut Bacteria

This test was once seen as the gold standard, but in more recent scientific literature its limitations have become apparent. It is an invasive process that requires an endoscopy, or threading a flexible tube through the mouth to the upper gut, to obtain a bacteria sample. The sample is then cultured in a lab, revealing which bacteria are present in the gut. But because some gut bacteria won’t grow in a lab culture, the sample may be contaminated with microbes from the mouth and throat, and the swab doesn’t account for bacteria growing in other parts of the gut, culture sampling is generally considered an ineffective way to diagnose SIBO. (Source)

Breath Testing

A more friendly approach to diagnosing SIBO is with a breath test. As we discussed earlier, SIBO causes undigested food to be fermented in the small intestine, producing excess hydrogen and methane. The breath test is able to measure these gasses and compare them to normal gas levels, potentially bringing you closer to a SIBO diagnosis. Breath testing may also measure carbon dioxide, but whichever gas is being measured the test can lack sensitivity and potentially present false positive results. (Source)

Blood, Stool, and Imaging Tests

Blood tests can reveal deficiencies that may connect to SIBO. Low iron levels and vitamin deficiencies may be revealed, both of which may be SIBO symptoms. Stool tests can show what’s not being digested, such as fats or bile acids, as a complication of SIBO. Finally, imaging tests may give you and your care provider better insight into the structure of your gut to see if there are anatomical issues preventing the smooth and timely passage of contents from organ to organ. (Source, Source)

Which Test Is Best for SIBO Screening?

A perfect test for SIBO doesn’t exist because the small intestine is a hard place to reach. But these options, used individually or in combination with each other, may get you closer to pinning down an accurate SIBO diagnosis. It’s important to discuss your options with your care team, along with presenting a detailed health history that includes any instances of food poisoning, abdominal surgeries, and medication use. Once you know for certain that you have SIBO, the next step of the journey begins: treating SIBO to regain a healthy, well-functioning gut.

How Is SIBO Managed?

SIBO can be treated in more ways than one, and combining short-term solutions with long-term prevention strategies is a holistic way to approach healing SIBO. Antibiotics, herbal remedies, and diet are 3 scientifically backed options to effectively manage SIBO.

Antibiotic Treatment

With this approach, the goal is to attack bacterial overgrowth in a very direct and swift manner. Most gastroenterologists choose antibiotics as the first step to getting SIBO under control, and for good reason: Studies show that antibiotics can be up to 91% successful in eradicating SIBO while achieving up to 94% symptom improvement. The two primary antibiotics used to treat SIBO, rifaximin and neomycin, tend to remain in the intestinal tract rather than being absorbed systemically, which helps reduce side effects. Doses vary and need to be discussed with your care team. (Source)

Herbal Antibiotics

Using herbal antibiotics that come from plant-based sources may also be effective at treating SIBO, though the research is not as extensive for this category of antibiotics. One limited study suggested that some herbal remedies may be just as safe and produce the same improvements as their pharmaceutical counterparts, but more clinical evidence is needed to prove with certainty that herbal antibiotics are a viable alternative to the pharmaceutical route. Garlic, oregano, goldenseal, neem, and cinnamon are just a few natural antibiotics that can help get rid of excess bacteria. And remember, it’s important to talk with your medical provider before starting any herbal supplements or medications. (Source, Source)

Dietary Shifts

When treating SIBO with a dietary approach, the aim is to starve the overgrowing bacteria by reducing their food source. Because bacteria primarily eat carbohydrates, SIBO diets focus on reducing carb intake. There are many variations of diets that limit carbs, but ones that are established as effective SIBO treatments are the specific carbohydrate diet (SCD), the gut and psychology syndrome (GAPS) diet, the low FODMAP diet, the Cedars-Sinai diet, and different forms of the paleo diet (such as the autoimmune protocol diet). (Source)

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Because there’s simply too much information on all of these diets to fit into one succinct article, check out WellTheory’s science-backed resources on the low FODMAP diet and the SIBO diet, along with some fun breakfast ideas to explore.

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Another dietary shift that mitigates extra bacterial growth is called the elemental diet. This approach starves the bacteria while still feeding the body. If this sounds extreme to you, you’re not wrong: The elemental diet replaces meals with pre-digested nutrients for 2 weeks so that your gut has nothing in it that feeds the bacteria and lets them multiply. The success rate for using this diet and eradicating SIBO is up to 84%, making it effective, safe, and tolerable. However, it can be expensive to procure the necessary formulas, the taste of nutrients may be unpleasant, and weight loss can occur if adequate calories are not replaced. (Source)

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Whether you’re wanting to change your diet for a couple of weeks or for the long haul, be sure to consult with your health care team to ensure you’re approaching the changes in a thoughtful way that benefits your holistic wellness and is aligned with your autoimmune care plan.

What’s the Best SIBO Treatment for Me?

Ultimately, treating SIBO effectively will depend on its root cause. Antibiotics and diets are effective in reducing bacteria growth, but if your SIBO stems from a motility disorder or a structural issue, your health care provider may recommend a different plan of action. Motility agents may be prescribed to promote peristalsis, the muscular reflex that keeps contents moving through the digestive system. Or for structural concerns, surgery may be necessary. Getting the right type of care for your SIBO is both possible and worthwhile along the path to achieving your optimal wellbeing. (Source, Source)

Why Does SIBO Keep Coming Back?

Bacteria can repopulate the small intestine within 2 weeks after finishing an antibiotic dose. SIBO relapses are common because antibiotics are effective at killing excess bacteria, but don’t necessarily address the underlying cause, which most often relates back to 2 scenarios: a structural issue in the small intestine or a deficiency in the way contents are moved through to the large intestine, which is the responsibility of the migrating motor complex (MMC). The MMC is a cyclical gut contraction that sweeps remnants out of the stomach and small intestine in between meals, an important process that’s been shown to be absent or decreased in those with SIBO. (Source, Source, Source, Source, Source)

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For these reasons, it’s crucial that after the bacteria overgrowth is managed, prevention strategies are put into place to avoid a recurrence. These strategies include:

• stimulating the MMC by using a prescription prokinetic agent to increase the cleansing motion of the gastrointestinal tract
• sticking to an ongoing SIBO diet, and introducing more carbs as they become tolerable
• increasing your antibacterial stomach acid by removing drugs such as proton pump inhibitors and antacids from your regimen, and adding herbal bitters or apple cider vinegar into your pre-meal routine
• spacing meals 4 to 5 hours apart while ingesting only water in between to allow MMC to occur
• increasing healthy bacteria populations by taking probiotics in supplement form or through fermented foods such as yogurt or kimchi

(Source, Source)

Where Can I Find More SIBO Information?

SIBO is a dense topic, and there are subject matter experts who provide additional valuable information if you’re looking to learn even more about SIBO.

• Dr. Allison Siebecker’s mission is to share SIBO news and information to empower people’s health through her easily accessible website.
• Dr. Mark Pimentel specializes in gastroenterology and has performed and published many SIBO studies.
• Lucy Mailing, Ph.D., focuses on integrative, evidence-based gut health in her blog and online course offerings.

WellTheory also has trained Nutritional Therapy Practitioners and Health Coaches who can help you if your struggling with SIBO and symptoms of autoimmunity. When you have a compassionate Care Team on your side and are empowered with pertinent information, you’ll be on a rewarding path towards successfully taking care of your gut health.

The Bottom Line on SIBO

Small intestinal bacterial overgrowth is a gastrointestinal condition caused by various factors. When the gut is not efficiently moving contents through the intestines, bacteria can multiply, creating uncomfortable symptoms and nutrient deficiencies. If you suspect you have SIBO, talk with your care provider to see what testing options are available. After being diagnosed, your SIBO management plan may consist of temporary antibiotic treatments in combination with a diet low in carbs and motility-enhancing medications. Managing SIBO and improving your gut health will allow you to live a healthier life, nurturing your body’s healing power and tending to your holistic wellbeing.