I have been arguing that small intestinal bacterial overgrowth, SIBO, is now epidemic in the U.S. Obviously, it’s an epidemic of a different sort than the COVID-19 pandemic. It is more like the epidemic of overweight and obesity that now affects 3 of every 4 American adults, an epidemic of lifestyle factors, not of an infectious virus. I used to believe that SIBO was uncommon until I sat down to calculate from the existing evidence just how many people have been diagnosed with SIBO.
Here is the evidence that gives us an idea of how common and widespread SIBO is, excerpted from my new Super Gut book:
If we take some of the more common health conditions that plague Americans and review the evidence that asks “How many people with condition X have SIBO?” we can discern the following:
- Obesity—SIBO has been documented in 23–88.9 percent of obese people. This alone suggests a potentially huge number of people with SIBO considering that 70 million Americans are obese, meaning somewhere between 16 and 62 million people with obesity have SIBO. This doesn’t even factor in the additional 60 million Americans who are overweight, but not obese.
- Diabetes—The likelihood of SIBO in type 1 and type 2 diabetes is in the range of 11 percent to 60 percent. With 34 million people with type 2 diabetes and 1.3 million people with type 1 diabetes, we can tally up at least several million people with diabetes who also have SIBO.
- Irritable bowel syndrome (IBS)—Estimates vary, but generally 35 percent to 84 percent of people with IBS test positive for SIBO. Thirty to 35 million Americans have been diagnosed with IBS, and an equal number are believed to have the condition without a formal diagnosis. Of the total 60 to 70 million people with IBS, this adds another 21 to 50 million Americans with SIBO to the tally.
- Inflammatory bowel disease—Around 22 percent of the 3 million people with ulcerative colitis or Crohn’s disease also have SIBO.
- Fatty liver—Nonalcoholic fatty liver disease, a condition estimated to now affect nearly half the US population, carries a 40–60 percent likelihood of SIBO. This means that around 75 million American adults with fatty liver also have SIBO.
- Autoimmune diseases—Each disease in this disparate collection of conditions, which includes systemic sclerosis, rheumatoid arthritis, psoriatic arthritis, and type 1 diabetes, has a varying association with SIBO. Preliminary studies suggest that around 40 percent of people with an autoimmune condition have SIBO.
- Skin rashes—Rosacea, psoriasis, and eczema have been associated with SIBO in about 40–50 percent of people with these conditions, meaning that another 6 million Americans have SIBO. People with rosacea, in particular, have a tenfold greater likelihood of having SIBO.
- Parkinson’s disease—Of the 1 million people in the United States with this incapacitating neurodegenerative condition, 25 percent to 67 percent have SIBO.
- Alzheimer’s dementia—The evidence is preliminary, but people with Alzheimer’s have a fivefold increased likelihood of also having SIBO.
- Restless leg syndrome—This condition prevents deep sleep with consequent substantial effects on mental, emotional, and meta- bolic health, and it is accompanied by SIBO in up to 100 percent of sufferers.
- Depression and anxiety—Emerging evidence demonstrates that many of the 60 million Americans struggling with these psychological issues have dramatically higher blood levels of LPS, along with measures of increased intestinal permeability, pointing to SIBO.
We haven’t even counted the 45-50 million Americans with some form of food intolerance—histamine intolerance, FODMAPS, nightshades, legumes, fructose, sorbitol, etc.—that are highly associated with SIBO.
It’s tough to come up with an exact figure of just how many Americans might be affected by SIBO not only because estimates vary depending on the testing method used to identify SIBO, but also because there is overlap among groups: for example, some obese people also have type 2 diabetes, fatty liver, and psoriasis. But from the figures above, I believe that you can still appreciate that SIBO is far from an uncommon condition. If you add up all the numbers, you readily exceed 100 million Americans with SIBO. I think that’s conservative. Given what I am seeing in people testing with the AIRE device, I think it may be more like 150 million people or around 1 of every 2 people.
Unlike the viral pandemic, however, this is an epidemic that you have incredible control over, even if your doctor knows nothing about it. And don’t bury your head in the sand over this issue, since uncorrected SIBO can lead to all sorts of long-term health problems, from depression, to Hashimoto’s thyroiditis, to colon cancer. And give my recipe for SIBO Yogurt a try–so far, it appears to be working for the majority of those who consume it.