How to Tell If You Have SIFO or SIBO

by JJ Virgin on February 2, 2024

Your gut is a busy place, inhabited by many tiny organisms, like bacteria and fungi. They help with digestion and keep you healthy. 

But sometimes, things can go wrong. Bad foods, toxins, medicines, sugar, and stress can upset the microbial balance in your gut, allowing harmful bacteria to take over. Over time, gut imbalances can lead to problems like small intestinal bacterial overgrowth (SIBO) and small intestinal fungal overgrowth (SIFO). 

Understanding SIBO 

Small intestinal bacterial overgrowth (SIBO) is a condition characterized by an excessive amount of bacteria in the small intestine. Unlike the large intestine, which houses a diverse and dense bacterial population, the small intestine typically contains fewer bacteria. However, in SIBO, this delicate balance is disrupted, leading to an overgrowth in an area where it shouldn’t occur. 

In a healthy digestive system, the small intestine is involved in the digestion and absorption of nutrients, with minimal bacterial interference. But with SIBO, the excessive bacteria in the small intestine prematurely ferment carbohydrates. This premature fermentation, typically a function of the large intestine, leads to the production of gases like hydrogen and methane. This abnormal process can disrupt normal digestion and absorption.1

The symptoms of SIBO include bloating, abdominal pain, and excessive gas. SIBO can also cause diarrhea, constipation, and unintended weight loss. These symptoms arise because the excess bacteria disrupts the normal absorption of nutrients, leading to deficiencies and malabsorption.2

Testing for SIBO 

Accurate diagnosis of SIBO is essential for effective treatment. Healthcare practitioners commonly use two primary tests to diagnose this condition: 

  • Breath Tests (Hydrogen Breath Test and Methane Breath Test): These non-invasive tests are the first line of diagnosis for SIBO. They involve drinking a sugar solution and then measuring the levels of hydrogen and methane in your breath at regular intervals. Elevated levels of these gases can suggest SIBO, as they indicate abnormal fermentation in the small intestine.3 
  • Small Intestine Aspirate and Culture: When breath tests are inconclusive or a more precise diagnosis is required, your doctor may opt for this more invasive test. It involves the use of an endoscope, a flexible tube with a camera, to access the small intestine and collect a fluid sample. This sample is then cultured to identify any bacterial overgrowth, providing a definitive diagnosis.4

Genova’s SIBO Profiles are non-invasive breath tests that capture exhaled gases after you ingest a lactulose solution. This test is ideal for determining bacterial overgrowth in your small intestine. Learn more and order your test here. 

Managing SIBO 

To manage SIBO, many experts suggest a low-FODMAP diet.5 FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, which are certain types of carbohydrates that are not easily absorbed and can be fermented by gut bacteria. By limiting these foods, you can reduce the food source for the overgrown bacteria, thereby easing symptoms like bloating and discomfort. 

Consulting with a healthcare professional, such as a gastroenterologist or a functional medicine doctor, is crucial in developing a complete management plan for SIBO. They are equipped to provide an accurate diagnosis, create a treatment plan tailored to your unique needs, and monitor your progress throughout the treatment. Each element of the treatment is customized to effectively target the root cause of SIBO and promote long-term gut health. 

Your treatment might include probiotics, natural supplements, and changes to your lifestyle. These will be tailored to your needs to take care of SIBO and improve your gut and overall health. 

Understanding SIFO  

SIFO is a gastrointestinal condition characterized by an excessive growth of fungi, particularly Candida species, in the small intestine. While Candida naturally exists in the human gut, its overgrowth can lead to SIFO and an array of gastrointestinal symptoms and discomfort.6

Testing for SIFO 

Diagnostic tests for SIFO are similar to those used for SIBO.  

  • Breath Tests: These are the same tests used for diagnosing SIBO. However, their effectiveness in diagnosing SIFO is less established due to the different metabolic processes of fungi. 
  • Stool Analysis: A complete stool analysis is another way to diagnose SIFO. This test helps identify fungi, their metabolic byproducts, and other signs of fungal overgrowth in the stool, providing insights into the fungal activity within the gut. 
  • Endoscopy: In more complex cases, a gastroenterologist might perform an upper endoscopy. This procedure involves using an endoscope to examine the small intestine’s lining and take biopsies. These tissue samples are crucial for confirming the presence of fungal overgrowth and establishing a SIFO diagnosis.7

Managing SIFO 

To manage SIFO, you can change your diet to reduce or eliminate foods that promote fungal growth too much and focus on foods that support a healthy gut environment.8 Here are some things you can do: 

  • Reduce sugar in your diet. Fungi, particularly Candida, thrive on sugar. Limiting your intake of sugary foods can help limit their growth. 
  • Eat gut-healing foods. Focus on foods that promote gut health and support the healing of your intestinal lining. 
  • Avoid high-FODMAP foods. These can provide fungi with more fuel and worsen gut problems. 
  • Add in probiotics. Use a probiotic supplement and eat fermented foods to support a balanced gut. 
  • Incorporate anti-fungal foods: Some foods and supplements can fight fungi naturally. My favorites include: 
    • Garlic: Contains a natural antifungal called allicin that can inhibit the growth of fungi, including Candida. 
    • Extra-virgin coconut oil: Rich in caprylic and lauric acids, known for their antifungal effects. 
    • Oregano oil: Has nutrients like thymol that fight fungi. You can take it as a supplement or use it in cooking. 
    • Ginger: Offers antifungal and anti-inflammatory benefits that can help with fungal problems. You can eat ginger fresh, use dried as a seasoning for your food, or drink ginger tea. 
    • Turmeric: Contains curcumin, known for its antimicrobial properties and potential to control fungal overgrowth. You can add turmeric to your food or take it as a supplement. 
  • Prebiotic foods: Foods like asparagus, garlic, onions, and leeks are rich in prebiotics, which are essential for gut health. 
  • Water: Drink plenty of water to keep your gut healthy overall. 

I highly recommend working with a functional medicine doctor, who can tailor these recommendations based on your specific symptoms, medical history, and dietary preferences. 

Not Sure If You Have SIBO or SIFO? Take This Quiz 

The most obvious signs of SIBO and SIFO are gut discomfort and digestive issues. However, other symptoms can help you determine whether you’re at risk. 

Answer the following questions with a yes or no. 

  • Do you often suffer from digestive symptoms like gas, bloating, diarrhea, constipation, or cramping? 
  • Have you gained or lost weight even though your diet and exercise habits haven’t changed? 
  • Are you frequently tired, even when you get good sleep? 
  • Have you been diagnosed with an autoimmune condition like Hashimoto’s, lupus, fibromyalgia, or multiple sclerosis? 
  • Do you have trouble focusing or often feel mentally foggy? 
  • Do you have skin issues like acne, psoriasis, eczema, or hives? 
  • Have you struggled with mood swings, anxiety, depression, or a panic disorder? 
  • Do you get frequent infections, especially UTIs, vaginal infections, skin infections, or ear infections? 
  • Do you have strong sugar and carb cravings? 
  • Do you have seasonal allergies? 
  • Do you have food intolerances? 
  • Do you have a B12 deficiency?

Scoring Your Results: 

If you answered yes to 0-1 question: Your risk of SIBO or SIFO is low. To maintain your gut health, follow these steps: 

If you answered yes to 2-3 questions: Your gut needs some TLC! In addition to the gut-healthy habits mentioned above, consider: 

  • Starting The Virgin Diet, which includes a 21-day plan for eliminating the seven most inflammatory foods that can wreak havoc on your gut. You’ll then test to find out which foods can safely be added back to your diet and which ones should stay out for good. 
  • 5 Gut-Healing Strategies for Lasting Energy & Weight Loss is my free guide to help you identify potential problems and provides my five most trusted strategies to heal your gut. 

If you answered yes to 4 or more questions: SIBO/SIFO can lead to more severe conditions such as autoimmune disorders, nutrient deficiencies, IBS, and fibromyalgia. Work with a functional health practitioner on a diagnosis and treatment plan. 

Going Low-Sugar-Impact to Manage SIBO and SIFO 

Sugar is a significant factor in SIBO and SIFO.9 High sugar intake can disrupt the delicate balance of gut microbes, promoting the overgrowth of harmful bacteria and fungi. 

But quitting sugar all at once isn’t always the most effective approach. When you go cold turkey, you might have mood swings, intense cravings, and other withdrawal-like symptoms, making the process challenging. 

I’ve found a better way to beat sugar addiction. My Sugar Impact Diet book is the perfect place to begin when you want to eliminate sneaky sugars from your diet without feeling deprived or struggling with withdrawal. 

Learn more and order your copy of the Sugar Impact Diet here


  1. Dukowicz AC, Lacy BE, Levine GM. Small intestinal bacterial overgrowth: a comprehensive review. Gastroenterol Hepatol (N Y). 2007 Feb;3(2):112-22. PMID: 21960820; PMCID: PMC3099351.
  2. Mayo Clinic: Small intestinal bacterial overgrowth (SIBO)
  3. Cleveland Clinic: Hydrogen Breath Test: What Is It, How To Prep & Results
  4. Franco DL, Disbrow MB, Kahn A, Koepke LM, Harris LA, Harrison ME, Crowell MD, Ramirez FC. Duodenal Aspirates for Small Intestine Bacterial Overgrowth: Yield, PPIs, and Outcomes after Treatment at a Tertiary Academic Medical Center. Gastroenterol Res Pract. 2015;2015:971582. doi: 10.1155/2015/971582. Epub 2015 Jan 28. PMID: 25694782; PMCID: PMC4324922.
  5. Health: SIBO Diet: Best Food and Drinks
  6. Healthline: What Is SIFO and How Can It Affect Your Gut Health?
  7. Healthline: What Is SIFO and How Can It Affect Your Gut Health?
  8. Banaszak M, Górna I, Woźniak D, Przysławski J, Drzymała-Czyż S. Association between Gut Dysbiosis and the Occurrence of SIBO, LIBO, SIFO and IMO. Microorganisms. 2023 Feb 24;11(3):573. doi: 10.3390/microorganisms11030573. PMID: 36985147; PMCID: PMC10052891.
  9. Scientific Wellness: Sugar linked to gut bacteria overgrowth

The views in this blog by JJ Virgin should never be used as a substitute for professional medical advice. Please work with a healthcare practitioner concerning any medical problem or concern. The information here is not intended to diagnose, treat, or prevent any disease or condition. Statements contained here have not been evaluated by the Food and Drug Administration.