What is SIBO?

What is Small Intestinal Bacterial Overgrowth (SIBO)? 

The small intestine is responsible for absorbing nutrients from the food that we eat, and it also helps to maintain a healthy balance of bacteria in our gut. When this balance is disturbed by an overgrowth of bacteria in the small intestines, this condition is known as SIBO or small intestinal bacterial overgrowth. This article will discuss what SIBO is, what negative side effects are associated with SIBO, and how you can alleviate the negative symptoms of SIBO by making changes to your diet. 

Small Intestinal Bacterial Overgrowth 

When the small intestine contains an overabundance of bacteria, SIBO develops. A healthy individual has a balance between good and bad bacteria in their gut. This helps to maintain overall health as well as regulate digestion. When there are too many harmful or pathogenic bacteria that begin to take over the small intestine, an imbalance occurs.  

Small intestinal bacterial overgrowth, also known as small bowel bacterial overgrowth, can lead to a disruption of normal nutrient absorption which is why it's important for this condition to be treated as soon as possible. If you suspect bacterial overgrowth in the small intestine, you should speak with your doctor to confirm this diagnosis, and if confirmed discuss treatment options like an antibiotics prescription. 

Small Intestinal Bacterial Overgrowth

Symptoms of Small Intestinal Bacterial Overgrowth (SIBO) 

It's important to be aware of the symptoms that are associated with small intestinal bacterial overgrowth, as they can help you detect SIBO early. Some common symptoms of small bowel bacterial overgrowth include: 

  • Gas and bloating after eating food 
  • Belching or excessive burping 
  • Stomach pain or cramping  
  • Diarrhea  
  • Constipation 
  • Nutritional deficiencies  

SIBO side effects

Similar Digestive Conditions 

SIBO has very similar symptoms as other digestive conditions such as Crohn's Disease, Irritable Bowel Syndrome, Celiac Disease, Inflammatory Bowel Disease, and Small Bowel Diverticulosis. It's important to be diagnosed by a gastrointestinal doctor to know exactly which digestive condition you may suffer from. 

Irritable Bowel Syndrome 

Irritable Bowel Syndrome (IBS) is a condition that is characterized by abdominal pain, bloating, constipation, and/or diarrhea. Irritable Bowel Syndrome is the most common digestive disorder in the United States. 

Inflammatory Bowel Disease 

Inflammatory Bowel Disease (IBD) is a condition that causes inflammation in the digestive tract. Some common symptoms of IBD include: abdominal pain, cramping, diarrhea, weight loss, and anemia. 

Crohn's Disease 

Crohn's Disease is a type of inflammatory bowel disease that affects any part of the digestive tract, like the small intestine and/or large intestine. Crohn's Disease can cause severe abdominal pain, diarrhea, weight loss, and anemia. 

Small Bowel Diverticulosis 

Small Bowel Diverticulosis is a condition that causes small, bulging pouches to grow on the walls of your intestines. This can cause pain and cramping in your abdomen as well as constipation or diarrhea. 

Celiac Disease 

Celiac Disease is an autoimmune disorder that affects the small intestine. When a person with celiac disease consumes gluten, their immune system responds by damaging the lining of the small intestine. Celiac disease can cause abdominal pain, diarrhea, constipation, weight loss, and anemia. 

Digestive discomfort

Causes of SIBO 

You may be wondering, "What causes SIBO?" There are various factors that play into developing SIBO, including bacterial infections that cause an overgrowth of small intestine bacteria, along with conditions or diseases that decrease intestinal motility.

One of the most common causes of small intestinal bacterial growth is an infection with gram-negative bacteria. This type of bacteria is most commonly found in water, soil, and food sources, so it's easy to become infected with these types of bacteria. When gram-negative bacteria infect the small intestine, they begin to take over and form SIBO. 

Diagnosis of SIBO 

Diagnosing a digestive condition typically requires blood tests or other diagnostic procedures. A gastrointestinal doctor may order a breath test to help diagnose SIBO. 

Sometimes the breath test can be inconclusive, which may lead to an aspiration test or a medication trial to pinpoint whether or not small bowel bacterial overgrowth is present.

Gastroenterologist Doctor

Lactulose Breath Test 

If you are experiencing some of the symptoms mentioned above, your doctor may order a lactulose breath test to determine if you have SIBO. The lactulose breath test is used to measure hydrogen and methane gas levels in your breath after drinking a sugar solution. If there is an overgrowth of bacteria in your small intestine, these gases will be produced as the bacteria ferments the sugar into energy. 

Other Testing Options 

Other ways to test SIBO is with jejunal aspiration test or a medicine trial. A jejunal aspiration test is often considered the most accurate, but also the most intrusive way of diagnosing SIBO as it requires an upper endoscopy procedure. 

medicine trial is the easiest way because a doctor could prescribe medication and if there's immediate symptom relief then it means SIBO was most likely present. 

How to Treat SIBO 

There are two main ways that small intestinal bacterial overgrowth can be treated! A doctor can prescribe an antibiotic regiment and/or they could suggest a diet change. The main goal is to eliminate high FODMAP carbohydrate foods that can ferment in the gut and feed bacterial overgrowth. 

Both treatments work, but a Low FODMAP diet change can support long term changes, while an antibiotic regimen will give temporary relief of uncomfortable symptoms and help stop the small intestinal bacterial overgrowth. 

Antibiotics Prescription 

A doctor will typically treat small intestinal bacterial overgrowth by prescribing antibiotics to control the overgrowth of bacteria. Here are antibiotics that are often prescribed to a SIBO patient: 

  • ciprofloxacin 
  • metronidazole 
  • rifaximin
  • neomycin

The antibiotics will not treat the underlying condition that caused the small intestinal bacterial overgrowth so that will have to be addressed by a medical professional as well. 

Diet Changes 

To address small intestinal bacterial overgrowth, a doctor will also suggest the patient undergoes a major change to their nutritional intake. This diet change will be an elimination diet protocol that focuses on certain types of food that will promote small intestinal bacterial overgrowth. 

The best diet for eliminating small intestinal bacterial overgrowth is the Low FODMAP diet. The Low FODMAP diet was created by Monash University and focuses on removing short chain carbohydrates that digest poorly in the small intestine. 

SIBO Complications 

There are many complications that can occur if small intestinal bacterial overgrowth (SIBO) goes untreated for an extended period of time. 

Small intestinal bacterial overgrowth can cause both malnutrition and dehydration due to the intestinal bacteria overgrowth stealing nutrition from the body. This can lead to major vitamin and mineral deficiencies, unintentional weight loss, and other negative persistent symptoms.  

Understanding the relationship between SIBO and Your Nutritional Intake 

There is a huge correlation between small intestinal bacterial overgrowth (SIBO) and your nutritional intake. The small intestinal bacterial overgrowth is commonly caused by a multitude of conditions such as IBS, Crohn's, Celiac Disease, stomach bug, and other conditions, but it worsens when the bacteria in the small intestine feeds on certain carbohydrates. 

It can be very important for people suffering with SIBO to avoid specific carbohydrates to stop further bacteria overgrowth in the small intestine. The best way to avoid these carbohydrates is to follow an elimination diet called a Low FODMAP diet.


What is a Low FODMAP Diet? 

A Low FODMAP Diet is an elimination diet that focuses on avoiding many types of carbohydrates in order to reduce symptoms from digestive issues like IBS or small intestinal bacterial overgrowth (SIBO). 

Carbohydrates are sugars, starches, and fibers. Certain carbohydrates are known as FODMAPS, and they digest poorly in the small intestine and feed bacteria which can ferment into gas when digested. This can cause some people to experience symptoms such as bloating, abdominal pain, diarrhea, and constipation. 

The Low FODMAP diet removes many high-FODMAP foods from your diet and replaces them with low-FODMAP alternatives. The goal is to eat more vegetables, fruits, proteins, and healthy fats while avoiding foods that cause symptoms for people with small intestinal bacterial overgrowth. 

Implementing a Low FODMAP Diet 

Implementing a Low FODMAP diet can seem like a daunting task since it requires research, grocery shopping, and meal prepping to ensure High-FODMAP foods are avoided. It can also be a difficult diet to follow as there are FODMAPs hidden in certain types of foods that you may eat on a regular basis. 

The easiest way to ensure you can follow a Low FODMAP diet consistently is by using a Low FODMAP meal delivery service like ModifyHealth. If you are interested in learning more about fully prepared Low FODMAP meals delivered to your home then click here. 

Foods You Should Eat On A Low FODMAP Diet 

Here are some Low FODMAP foods that you can eat on a Low FODMAP diet to help fight off small intestinal bacterial overgrowth (SIBO): 

  • meat 
  • fish 
  • chicken
  • eggs 
  • *oatmeal (1/2 cup)
  • spaghetti squash and summer squashes 
  • *broccoli (heads only, less than 3/4 cup) 
  • leafy greens 
  • carrots 
  • rice or gluten-free rice noodles 
  • olives 
  • *peanuts
  • potatoes  
  • quinoa 
  • seeds 
  • *fruits (blueberries, grapes, oranges, and strawberries) 

Any food that has a star next to is only Low FODMAP up to a certain amount.

Foods You Should Not Eat During The Elimination Phase Of The Low FODMAP Diet 

Here are some foods that are high-FODMAP which you should avoid eating to avoid symptoms of small intestinal bacterial overgrowth (SIBO): 

  • high-fructose corn syrup 
  • agave nectar 
  • honey 
  • soda and soft drinks 
  • garlic 
  • onions 
  • asparagus 
  • cauliflower 
  • artichokes 
  • beans (black beans, navy beans, kidney beans, pinto beans) 
  • apples 
  • dried fruits 
  • avacado
  • dairy
  • regular yogurt 
  • ice cream 
  • sweetened cereals 
  • gluten-containing grains (wheat, rye, barley)

Low FODMAP Meals For SIBO 

As you can see, there are a lot of different foods that you can and cannot eat while on a Low FODMAP diet. This can make it difficult to make Low FODMAP meals as you will have to change the way you shop for groceries and how you cook your food. The easiest and best way to ensure you are following a Low FODMAP SIBO Diet is by ordering fully prepared Low FODMAP meals and working with a certified dietitian who has been trained to help people who suffer from SIBO. 

Low FODMAP Meal Delivery by ModifyHealth 

ModifyHealth's mission is to use food as medicine to fight chronic conditions like SIBO. Our Low FODMAP meals are perfect for fighting SIBO as it helps you eliminate the FODMAPS that can contribute to bacterial overgrowth in your small intestine. 

Our fully prepared Low FODMAP meals are delicious, made with fresh organic ingredients, and delivered right to your front door with FREE shipping nationwide. We make treating SIBO and other digestive issues easier for people who suffer from them. 


Bacterial overgrowth in the small intestine, known as SIBO, is a condition where excess bacteria grows in the small intestine and causes serious negative symptoms over time such as vitamin deficiencies, malnutrition, and dehydration. It also causes uncomfortable daily symptoms such as bloating, gas, diarrhea, stomach pain, and constipation.  

The best ways to attack bacterial overgrowth in the small intestine is by being diagnosed by your doctor first, then if advised by your doctor, getting an antibiotic prescription, and adopting a Low FODMAP diet for SIBO to eliminate the bad gut bacteria. ModifyHealth makes adopting a Low FODMAP diet easy with our fully prepared, home delivered Low FODMAP meals. 

If you suffer from SIBO, IBS, IBD, or Crohn's Disease then we would love to help you get your life back. Click here to check out our life changing Low FODMAP meal plan. 


Written by:

Christine Lothen-Kline, MCHES, RD, LD

Dietitian Director, ModifyHealth