You have this gut feeling (no pun intended) that something's wrong but haven't been able to put your finger on exactly what it is. Luckily, there might be a very plausible explanation. Across two studies and 244 participants with unexplained gastrointestinal symptoms, 25% were found to have SIFO.
What Exactly Is SIFO?
Small intestinal fungal overgrowth (aka SIFO for short) is a gut-related condition that involves an overgrowth of fungus in your small intestine. This overgrowth can result in gastrointestinal symptoms like bloating, gas, and abdominal pain or discomfort. SIFO is not to be confused with SIBO, which has to do with bacterial overgrowth in the small intestine.
SIFO vs. SIBO:
- SIFO — Fungal overgrowth in the small intestine.
- SIBO — Bacterial overgrowth in the small intestine.
An eye-popping 97 percent of SIFO fungi comes from Candida. Considering it falls under the fungal umbrella taxonomically, you can think of Candida as the most common type of SIFO.
Candida is a yeast that's perfectly normal to have in your gut. You'll also find it in your throat, mouth, and vaginal canal for women. As long as Candida stays at low levels, you're fine. But when it starts to multiply and spread, your body can run into issues that lead to a wide range of infections, such as yeast infections or oral thrush (an infection of the mouth).
It's also been linked to a wide variety of gastrointestinal conditions, such as IBS, Crohn's disease, and ulcerative colitis .
The honest answer depends on your own gut. You can have your gut sequenced to find out.
What Are the Symptoms of SIFO?
As are typical with a lot of gut-related conditions, common symptoms of SIFO include:
- Bloating
- Gas
- Abdominal pain
- Nausea
- Diarrhea
- Belching
- Indigestion
What Causes SIFO?
Many different things can increase the likelihood of developing SIFO:
- Using proton pump inhibitors too much — Medications are useful for providing relief from conditions like GERD by reducing the amount of acid in your stomach. But depleted levels of stomach acid can increase your chances of contracting bacterial or fungal infections in your GI tract.
- The muscles of your intestines become impaired — Also known as intestinal dysmotility, this can be brought on by conditions like diabetes, lupus, and Ehlers-Danlos syndrome.
- Frequent use of antibiotics — Antibiotics can't differentiate between which bacteria are bad and which are good. So, while they do destroy bad microbes sitting in your gut, they also take out healthy bacteria that help your gut thrive. This can give bad microbes the opportunity they need to spread and cause problems like SIFO.
- Taking drugs that stifle your immune system — Some medicines have the unintended consequence of suppressing your immune system, which makes it harder for your body to fight off fungal or bacterial infections.
- Colectomy — Research shows there is a high correlation between colectomy and the development of SIFO.
How to Test for SIFO
The world of gut health tests is always expanding. There are numerous ways to test for a variety of GI-related conditions, such as stool tests, breath tests, and blood tests.
For SIFO specifically, the best way to identify it comes from a small bowel aspirate. This SIFO test happens during an upper endoscopy and looks for infection in the small intestine. To perform the test, a gastroenterologist will insert a tube-like device starting in the esophagus and reaching a part of your small intestine known as the duodenum. A sample gets collected and is examined for fungi that could indicate the existence of SIFO.
SIFO treatment: how doctors approach it
1. Antifungal medication
Once SIFO is confirmed, antifungal medicines such as fluconazole or nystatin are the usual first step, prescribed by your doctor.
Probiotics come up often in SIFO conversations. Research suggests some Lactobacillus strains, including L. acidophilus, compete with Candida in the gut, but no trials show probiotics clear SIFO. Think of them as part of supporting your gut, not a replacement for your doctor’s plan.
2. The Candida diet
Some clinicians suggest a lower-sugar, Candida-style diet alongside medicine. Candida thrives on glucose, so it's best to avoid refined carbs and foods high in sugar (including fruits like bananas and mangos). The Candida diet also calls for the elimination of grains and anything made with yeast (i.e. alcohol, kombucha, soy sauce, etc).
3. Get active and space out your meals
Poor gastrointestinal motility (the process where food moves through your GI tract) may be what's causing your SIFO. Here are two ways to improve motility:
- Physical activity to get your heart rate up and blood pumping.
- Spacing out your meals by at least three hours. Always having food just sitting in your stomach bogs down your migrating motor complex, which is important for digestion. It's a system of recurring movement that advances food through your bowels. You can't get the full benefit of this process on a full stomach.
4. Combatting low stomach acid
Stomach acid is one of your body’s natural checks on microbes reaching the small intestine, which is why long-term acid-reducing medicine is a risk factor. Some practitioners suggest a betaine HCl supplement. Ask your doctor before trying one, especially if you take acid reducers or have ulcers or reflux.
The Bottom Line
If you feel like something's been going on with your gut but just haven't been able to put your finger on what, it could be SIFO or small intestinal fungal overgrowth
Candida, a yeast that is classified under fungi taxonomically, is responsible for roughly 97% of the fungi in SIFO. Research has also linked it to IBS, Crohn's disease and ulcerative colitis.
The primary SIFO test is a small bowel aspirate, which is performed during an upper endoscopy and detects the presence of SIFO-related fungi.
If you think it is SIFO, the path is: confirm it with your doctor, clear what is confirmed with prescribed medicine, and support the rest of your gut with diet, movement and time between meals. Once you are through it, a personalized probiotic built from your own gut data is one way to support the community that is left.
Interested in probiotics tailored to your unique gut profile?
SIFO: FAQ
What is SIFO?
SIFO stands for small intestinal fungal overgrowth: too much fungus, most often Candida, in the small intestine. It can cause bloating, gas, belly pain, nausea and diarrhea.
What is the difference between SIFO and SIBO?
SIFO is an overgrowth of fungus in the small intestine. SIBO is an overgrowth of bacteria there. The symptoms overlap, and some people have both, which is why testing matters.
How is SIFO tested?
The main test is a small bowel aspirate: during an upper endoscopy, a gastroenterologist collects fluid from the small intestine and a lab checks it for fungi.
How do doctors approach SIFO treatment?
Once SIFO is confirmed, doctors typically prescribe an antifungal and look at risk factors such as long-term acid-reducing medicine or slow gut motility. Diet, movement and spacing out meals are common supporting steps.
This article is for general education and is not medical advice. It is not intended to diagnose, treat, cure, or prevent any disease. If you have symptoms that worry you, talk to a licensed health care provider.
Not sure where to start with your gut?
Ask the Flore Microbiome Concierge — a guided, personalized walkthrough of testing, your results, and a formula matched to your goals.
Talk to the Concierge →SIFO and Candida overgrowth are easy to confuse. If you're unsure which you're dealing with, start with the four Candida tests.