How Many Americans May Have SIBO in 2026 — What the Numbers Suggest
Small Intestinal Bacterial Overgrowth (SIBO) isn’t a household term, but it’s a digestive condition that may be much more common than most people realize
SIBO happens when too many bacteria grow in the small intestine, where they can interfere with digestion and cause symptoms like bloating, gas, abdominal discomfort, diarrhea or constipation.
Unlike well-defined diseases like celiac or Crohn’s, there aren’t exact nationwide figures for how many people in the U.S. have SIBO, partly because it’s under-recognized in conventional medicine and diagnostic tests are imperfect. However, we can estimate its potential prevalence by looking at research and patterns seen both in the U.S. and globally.
What We Know From Research
1. SIBO Is Common in People With Digestive Symptoms
Studies show that among people who undergo breath testing because of persistent gastrointestinal complaints, SIBO is present in about one-third of cases. This suggests a high rate among symptomatic individuals.
Because many people with bloating and irregular bowel habits never get tested, the true number of people affected could be higher than reported.
2. Estimates Vary Widely
In Spain and other countries where SIBO prevalence has been studied, experts estimate that 6–15% of the general population may have SIBO, with some studies suggesting up to 25% depending on diagnostic methods used.
Although we don’t have exact U.S. numbers, digestive dysfunction rates and symptoms are similar across Western industrialized countries, including the United States. Functional digestive disorders (like irritable bowel syndrome, IBS) — which often overlap with SIBO — affect roughly 1 in 5 Americans. Many researchers estimate that a substantial portion of those patients may also have SIBO, given the strong association between IBS and bacterial overgrowth.
Putting This Into American Context
Estimated Prevalence in the U.S.
Here’s how we can think about SIBO prevalence in the United States in 2026:
General population: If even the lower end of estimates applies (6–15%), that would translate to roughly 20 to 50 million Americans with possible SIBO symptoms (given the U.S. population of ~330 million).
Among people with chronic digestive complaints: Among those actively seeking care for chronic gas, bloating, discomfort, or bowel irregularity, the prevalence could be much higher — possibly 30% or more.
These figures are estimates, not formal epidemiological data — because SIBO is still under-diagnosed and not routinely screened in mainstream clinical practice.
Why SIBO Might Be Underestimated
Several factors make SIBO hard to quantify:
Symptoms overlap with other common conditions like IBS, food intolerances, and functional dyspepsia.
Diagnostic tests are imperfect. Breath tests, the most commonly used tools in clinical practice, vary widely in sensitivity and specificity.
Awareness among healthcare providers varies, so many people with SIBO symptoms are never tested or are told other diagnoses instead.
Why These Numbers Matter
Understanding how many Americans may have SIBO is more than a statistic — it highlights the scale of digestive health struggles in the U.S. and the need for better recognition and care:
Many people live with chronic discomfort that could be related to bacterial overgrowth.
Earlier recognition could lead to better symptom management through dietary, lifestyle, and medical strategies.
Public awareness and clinical research are gradually increasing, which may improve diagnosis and treatment over time.
Key Takeaway
There isn’t a precise, nationwide count of how many Americans have SIBO in 2026, but research and international estimates suggest it could affect millions of people, especially those with chronic gastrointestinal symptoms. Looking at data from other countries and studies of symptomatic patients, SIBO is likely more common than most people think — albeit under-recognized and under-diagnosed in mainstream American healthcare.