Symptoms of SIBO: How to Recognize Small Intestinal Bacterial Overgrowth

Symptoms of SIBO: When Gut Bacteria Go Rogue

If you’ve been struggling with unexplained bloating, fatigue, or food sensitivities, the root cause might be something few people have heard of: SIBO—small intestinal bacterial overgrowth. This condition happens when bacteria (or sometimes fungi, called SIFO) set up camp in the wrong place: your small intestine.

Normally, most of your microbes live peacefully in the large intestine, where they help digest fiber and produce beneficial compounds. But when they migrate upward, they can wreak havoc, leading to symptoms that often overlap with IBS (irritable bowel syndrome) or even Candida overgrowth (read our Candida blog here).

Why SIBO Develops

One of the key regulators of gut health is the migrating motor complex (MMC)—your digestive system’s “housekeeping wave” that sweeps food, bacteria, and toxins through the small intestine when your stomach is empty. If the MMC slows down due to stress, nerve issues, or eating too close to bedtime, bacteria linger and multiply.

Other factors that can trigger SIBO include:

• Low stomach acid (from medications or aging)
• Weak gut valves that allow bacteria to backwash from the colon
• Enzyme deficiencies that leave food undigested
• High-carbohydrate diets that fuel fermentation

Symptoms of SIBO

SIBO symptoms vary, but most fall into three categories:

1. Digestive Discomfort

• Gas and bloating (often higher up, under the rib cage)
• Abdominal pain or cramping
• Constipation, diarrhea, or both
• Food sensitivities due to fermentation and leaky gut

2. Whole-Body Effects

• Fatigue and brain fog from nutrient competition and toxins
• Nutrient deficiencies (especially B12, iron, and vitamin D)
• Unexplained weight changes or stubborn belly fat

3. Long-Term Risks

Left unchecked, SIBO can set the stage for non-alcoholic fatty liver disease (NAFLD) as the liver becomes overwhelmed by bacterial toxins. Research also links SIBO to IBS and autoimmune conditions (Takakura & Pimentel, 2020).

How SIBO is Different from Candida

Like SIBO, Candida overgrowth can cause bloating, fatigue, and food reactions. But Candida is fungal, while SIBO involves bacteria or archaea. Many people experience symptoms of both—which is why the two are sometimes confused. Take my Candida questionnaire here: Brenda Watson_Candida Questionnaire.indd

Testing for SIBO

If these symptoms sound familiar, you don’t have to guess. A breath test, typically ordered through a doctor, gastroenterologist, or functional medicine practitioner, measures hydrogen and methane gases—the byproducts of bacterial fermentation in the small intestine (Lim et al., 2023).

What to Do If You Suspect SIBO

Healing usually involves a two-step approach:

1. Reduce Overgrowth
   
   • Short-term low-FODMAP or low-fermentation diet
   • Antimicrobial herbs like oregano or thyme. Brenda formulated a 2-part program that combines powerful herbs and nutraceuticals to help address SIBO.
   • Avoid eating right before bed to support the MMC
     
2. Rebuild Gut Health
   
   • Repair the gut lining
   • Reintroduce beneficial bacteria once symptoms improve
   • Support long-term balance with fiber and whole foods

For a deeper dive into how SIBO develops and how to address it naturally, watch Brenda Watson’s YouTube video on SIBO.

Download Brenda’s free SIBO Relief guide: https://brendawatson.com/wp-content/uploads/Brenda-Watson_SIBO-Relief-Guide.pdf

Takeaway

The symptoms of SIBO can look like IBS, Candida, or even simple indigestion or heartburn—but when bacteria live where they don’t belong, the ripple effects are widespread. If you’ve been living with persistent bloating, fatigue, or food reactions, it’s worth considering SIBO as an underlying cause. With the right testing and a thoughtful healing plan, balance can be restored.