Small Intestine Fungal Overgrowth (SIFO)

Understanding Small Intestine Fungal Overgrowth (SIFO): A Comprehensive Guide

Small Intestine Fungal Overgrowth (SIFO) is an emerging health concern that often goes undiagnosed due to its overlap with other gastrointestinal disorders. This blog will delve into what SIFO is, its risk factors, causes, symptoms, diagnostic methods, and effective treatment strategies, including the role of probiotics, prebiotics, antimicrobial herbs, and anti-fungal medications.

What Is Small Intestine Fungal Overgrowth (SIFO)?

SIFO is a condition characterised by an excessive growth of fungal organisms, primarily Candida species, in the small intestine. Unlike the large intestine, which harbours a diverse microbial community, the small intestine is typically home to fewer fungi and bacteria. When fungal organisms proliferate uncontrollably, they can disrupt digestion, nutrient absorption, and immune function, leading to a range of gastrointestinal symptoms (source).

SIFO is often confused with Small Intestine Bacterial Overgrowth (SIBO) because of overlapping symptoms, but while SIBO involves bacterial overgrowth, SIFO is specifically related to fungi.

Risk Factors for SIFO

Several factors can predispose individuals to SIFO (source, source, source), including:

1. Antibiotic Use: Broad-spectrum antibiotics disrupt the gut microbiota, reducing bacterial populations and allowing fungi to thrive unchecked.
2. Immunosuppression: Conditions like HIV/AIDS, cancer, or the use of immunosuppressive drugs weaken the body’s defence mechanisms.
3. Diabetes Mellitus: High blood sugar levels create an environment conducive to fungal growth.
4. Proton Pump Inhibitors (PPIs): These reduce stomach acid, diminishing a natural barrier against fungal proliferation.
5. Gut Motility Disorders: Conditions like irritable bowel syndrome (IBS) can slow intestinal movement, promoting fungal colonisation.
6. Dietary Factors: Diets high in refined sugars and carbohydrates can fuel fungal overgrowth.
7. Frequent Use of Corticosteroids: These medications suppress the immune system and can alter gut flora.
8. Colectomy. Patients with colectomy demonstrate significantly higher prevalence of SIBO/SIFO and greater severity of gastrointestinal symptoms.

Causes Of SIFO

Any damage to the mucosal barrier or disruption of gut microbiome with chemotherapy or antibiotic use, inflammatory processes, activation of immune molecules and disruption of epithelial repair may all cause small intestine fungal overgrowth. (source) This could include:

• Compromised small intestine motility.
• Use of proton pump inhibitors.
• Colectomy.
• Ileocecal valve dysfunction.
• High BMI.
• Underlying medical conditions.
• Diabetes mellitus.
• Steroids.
• Immunosuppressant drugs.
• Steroids.
• Antibiotics.
• Patients undergoing transplantation.
• Suboptimal digestion (e.g pancreatic enzyme deficiency)
• The oral contraceptive pill.

Common Symptoms of SIFO

SIFO symptoms are non-specific and often mimic other gastrointestinal disorders, making diagnosis challenging. Common symptoms include (source):

• Bloating, Belching and Gas: Resulting from fermentation by fungi.
• Abdominal Pain or Discomfort: Often crampy and associated with meals.
• Diarrhoea or Constipation: Alternating bowel habits may occur.
• Nausea: Sometimes accompanied by vomiting.
• Fatigue: Due to malabsorption and systemic inflammation.
• Brain Fog, Migraines, and Depression: Cognitive disturbances linked to gut-brain axis disruption.
• Indigestion.

These symptoms are chronic and can significantly impair the quality of life if left untreated.

How to Test for SIFO

Diagnosing SIFO requires a combination of clinical assessment and laboratory testing:

1. Upper Endoscopy with Small Intestinal Aspirate: This is the gold standard. A fluid sample from the small intestine is cultured to detect fungal overgrowth. However, it’s invasive and not widely available.
2. Fungal Culture or PCR Testing: Stool or aspirate samples can be tested for fungal DNA or grown in culture to identify fungal species.
3. Indirect Diagnostic Clues: Since definitive tests are not always accessible, clinicians may rely on symptom patterns, response to anti-fungal therapy, and exclusion of other conditions like SIBO.

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It’s important to rule out other causes of gastrointestinal distress before concluding a diagnosis of SIFO.

Can You Have SIBO and SIFO At The Same Time?

Yes you can, and the research demonstrates it is actually quite common.

In one study, 150 subjects experiencing unexplained gut issues were evaluated for small intestine fungal overgrowth and SIBO. The results were quite alarming: 

• 63% had either SIBO or SIFO
• 40% had SIBO
• 26% had small intestine fungal overgrowth 
• 34% had mixed SIBO/SIFO. 

SIBO was predominately due to Streptococcus, Enterococcus, Klebsiella and E. coli.

Small intestine fungal overgrowth was due to Candida albicans. 

Treatment Strategies for Small Intestine Fungal Overgrowth (SIFO)

Effective management of SIFO involves addressing the fungal overgrowth, restoring gut health, and correcting underlying risk factors.

1. Anti-fungal Medications

Prescription anti-fungal drugs are often necessary to reduce fungal load (source):

• Fluconazole: A commonly prescribed azole anti-fungal with good intestinal absorption.
• Nystatin: An anti-fungal that stays within the gut, targeting fungi directly without systemic absorption.
• Itraconazole: Used for resistant cases, though it requires monitoring for side effects.

2. Essential Oils

These include things like oregano oil. Research has clearly shown that these are as effective as antibiotics in treating SIBO, and research has found them as effective as anti-fungals in eradicating small intestine fungal overgrowth. I have excellent results with the product ADP – an oregano oil extract.

Here’s the findings of one study: “Mint, basil, lavender, tea tree oil, winter savory and oregano essential oils inhibited both the growth and the activity of C. albicans more efficiently than clotrimazole. Damages induced by essential oils at the cellular level were stronger than those caused by clotrimazole“.

A very effective product is A.D.P which contains emulsified oregano oil.

While herbal therapies are promising, they should be used under professional guidance to avoid interactions with medications.

3. Probiotics For Small Intestine Fungal Overgrowth (SIFO)

Probiotics help restore microbial balance in the gut by:

• Competing with Fungi: Beneficial bacteria like Lactobacillus and Bifidobacterium can inhibit fungal growth through the production of lactic acid and other metabolites.
• Modulating Immunity: Probiotics support the gut-associated lymphoid tissue (GALT), enhancing immune responses to fungal invaders.

Recommended Strains:

• Lactobacillus rhamnosus GG: One of the most researched probiotics in the world with multiple benefits to the gut and gut microbiome (source).
• Saccharomyces boulardii (a beneficial yeast that competes with pathogenic fungi). In fact research has demonstrated that S. boulardii supplementation is as effective as nystatin in reducing fungal colonisation and invasive fungal infection (source).

4. Prebiotics

Prebiotics are non-digestible fibers that feed beneficial gut bacteria, promoting a healthy microbiome:

• PHGG: Supports butyrate producing bacteria. I add this to my morning coffee for a gut friendly start to the day (coffee is good for your gut microbiome too!).
• Fructooligosaccharides or/and inulin.

Caution: In cases of active SIFO, prebiotics may initially worsen symptoms due to fermentation. They should be introduced gradually, preferably after reducing the fungal load.

Additional Considerations:

• NAC: Although there is no direct research on NAC for small intestine fungal overgrowth, NAC has been shown to have biofilm busting properties on candida albicans, and as already mentioned this is the most common candida to cause small intestine fungal overgrowth.
• Bile support: We can support bile with bitters and phosphatidylcholine. These help bile production and flow. Bile has anti-fungal properties and therefore it is important to have a healthy biliary system (liver and gall bladder).
• Consider stomach pH: We know that adequate stomach acid is required to help maintain a healthy small intestine. Low stomach acid is a known risk factor for small intestine bacterial overgrowth, and as we have seen above, small intestine fungal overgrowth too. When low we can consider using things like apple cider vinegar, or Betaine Hydrochloride as a way to re-acidify the stomach.
• Support motility: If small intestine motility has been compromised then this needs to be addressed too. Two key considerations are the use of a prokinetic, such as Bio.Revive Kinetic, and avoiding snacks. A prokinetic is a something which supports motility (the movement of food through the small intestine) and motility is most active away from eating. So aim to eat 3 times per day and allow plenty of time between meals.
• Monolaurin: Monolaurin has a potential anti-fungal activity against C. albicans and can modulate the pro-inflammatory response of the host. (source)

Dietary and Lifestyle Modifications

• Low-Sugar, Low-Refined Carbohydrate Diet: Fungi thrive on sugars, so minimising their intake helps starve the overgrowth.
• Anti-Inflammatory Diet: Emphasise whole foods, lean proteins, healthy fats, and fiber.
• Stress Management: Chronic stress can impair gut motility and immune function, exacerbating fungal issues.
• Address Underlying Conditions: Managing diabetes, reducing unnecessary antibiotic use, and correcting motility disorders are crucial for long-term success.

One review published in 2023 concluded that “a diversified diet containing vegetable fiber, omega-3 polyunsaturated fatty acids, vitamins D and E, as well as micronutrients associated with probiotic or prebiotic supplements can improve the biodiversity of the microbiota, lead to short-chain fatty acid production, and reduce the abundance of fungal species in the gut.”

A different paper found that eating between meals has also been correlated with candida overgrowth.

There have been some other interesting findings such as candida abundance being reported with recent consumption of carbohydrates, and that candida abundance negatively correlates with a diet high in amino acids, fatty acids and proteins.

This means that we may want to move towards more of a higher fat/protein, lower carb framework.

When to Seek Medical Advice

Persistent gastrointestinal symptoms warrant medical attention, especially if accompanied by:

• Unintentional weight loss
• Severe or worsening abdominal pain
• Bloody stools
• Signs of systemic infection (fever, chills)

Early diagnosis and treatment can prevent complications and improve quality of life.

Final Thoughts On Small Intestine Fungal Overgrowth (SIFO)

Small Intestine Fungal Overgrowth is a complex condition that requires a multifaceted approach for effective management. If you suspect you may have SIFO, consult a healthcare provider experienced in gastrointestinal disorders. A combination of anti-fungal therapies, natural remedies, and lifestyle changes can significantly improve symptoms and restore gut health.