An Integrative Medicine Approach to SIFO: Small Intestinal Fungal Overgrowth

SIFO, or small intestinal fungal overgrowth, occurs when an excess amount of fungi or yeast overgrow in the small intestine of the digestive tract. This overgrowth may cause gastrointestinal symptoms such as abdominal bloating and pain, gas, belching, diarrhea, and nausea, and over time may lead to malnutrition and weight loss if not addressed.

SIFO is a common cause of gastrointestinal distress, found in around 25% of people with previously unexplained gastrointestinal symptoms, such as those that occur with irritable bowel syndrome (IBS). The majority of SIFO cases involve an overgrowth of Candida species, which are normal in small amounts in the mouth, skin, and intestines, but cause problems when they multiply too much.

Fortunately, a functional medicine approach can help to uncover some contributing factors that allow these yeasts/fungi to proliferate. Lifestyle and dietary interventions can help to improve the balance of microbes in the gut and relieve symptoms of SIFO in many cases.

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What is Small Intestinal Fungal Overgrowth (SIFO)?

Fungal strains (like bacterial strains) are a normal part of the gut ecosystem as part of a diverse microbiome. Bacteria and fungi mostly colonize the large intestine, with far fewer microbes in the small intestine. When heavier colonization and/or an imbalance of microbes occur in the small intestine, an overgrowth can occur that leads to gastrointestinal distress.

When fungal species colonize and overgrow in the small intestine, SIFO occurs. Research suggests that 97% of the fungi associated with SIFO is a form of Candida, such as Candida albicans. Candida species are yeasts or fungi that normally live on your skin and inside your mouth, throat, gut, and vagina. When in balance, Candida yeasts help you maintain a healthy balance of microorganisms in these different areas, as well as supporting your immune system, aiding in digestion, and promoting vitamin and mineral absorption from food.

However, if fungi like Candida overgrow in the small intestine, it throws off the balance of microbes and can lead to problems like SIFO.

SIFO Symptoms

SIFO causes a variety of common digestive symptoms, many of which are similar to those that occur when bacteria overgrow in the small intestine (SIBO) and with IBS. Studies suggest that SIFO may be a common cause of gastrointestinal distress, found in around 25% of people with previously unexplained gastrointestinal symptoms, such as those that occur with IBS.

The most commonly reported symptoms of SIFO include:

• belching
• bloating
• gas
• indigestion
• fullness in the upper abdomen
• nausea
• diarrhea

Fungal overgrowth in the small intestine may have impacts that go beyond the gastrointestinal tract. Fungal overgrowth can occur in other sites of the body as well, resulting in additional signs such as:

• chronic skin yeast infections or rashes in areas where skin meets skin, like armpits or under the breasts
• vaginal yeast infections
• itching behind the ears
• toenail fungus
• thrush (a white coating on the tongue)
• urinary tract infections

If not addressed, SIFO can contribute to inflammation throughout the body as well as malnutrition and weight loss.

What Causes SIFO?

Several factors can make it more likely that fungi will overgrow in the small intestine or other body sites. To maintain a healthy balance of gut bacteria and fungi, you need proper immune function, stomach acid, and bowel motility.

Immunocompromise

Overgrowth of fungi is more common in people with weakened immune systems, including:

• very young children
• the elderly
• people taking immunosuppressant drugs like steroids after an organ transplant or for certain autoimmune diseases
• people with disorders that involve immunocompromise, like HIV/AIDS and diabetes

Low Stomach Acid

Low stomach acid also increases the risk of fungal overgrowth since stomach acid plays a key role in killing bacteria and fungi before they enter the small intestine. Low stomach acid can occur from:

• long-term use of proton-pump inhibitor (PPI) medications
• age over 65 years
• nutrient deficiencies, including protein, iron, calcium, and vitamin B12
• infection with H.pylori
• atrophic gastritis

Antibiotic use

Antibiotics can kill off healthy bacteria and other microbes in the gut, making it more likely that fungi (or certain bacteria) can overgrow and lead to SIFO.

Slow Motility

When the movement of food through the small intestine is slowed, it increases the risk of bacteria and fungi overgrowth. Some causes of slowed gastrointestinal motility include:

• diabetes
• Ehlers-Danlos syndrome
• colectomy surgery that removes part of the intestines
• sedentary behavior, which impairs blood flow to the digestive tract
• gastroparesis
• thyroid disorders, including hypothyroidism and Hashimoto's

Lifestyle Factors

Additionally, some lifestyle factors may contribute to dysbiosis and SIFO.

• eating a diet high in refined carbs or sugars
• excessive alcohol consumption
• chronic stress

Testing for The Root Cause of SIFO

Comprehensive Stool Testing

A comprehensive stool test like the GI Effects reflects the overall health and balance of the digestive tract by measuring a variety of microbes and intestinal health markers. This test can help uncover Candida albicans overgrowth and investigate possible reasons for the overgrowth, such as dysbiosis. Retesting a few months after treatment can guide an individualized approach.

SIBO Breath Test

Since SIBO and SIFO can present with very similar symptoms and often occur together, it is essential to evaluate for an overgrowth of harmful bacteria in the small intestine when SIFO is suspected. A breath test can evaluate the overgrowth of bacteria that do not normally belong in the small intestine. The 3-hour SIBO assessment is a non-invasive breath test that measures hydrogen and methane to evaluate bacterial overgrowth in the small intestine.

Small Bowel Aspirate Test

The "gold standard" for diagnosing SIFO is a small bowel aspirate. This procedure involves inserting a tubular instrument through the esophagus and stomach into a portion of the small intestines called the duodenum during an upper endoscopy. From there, fluid is collected and analyzed for the presence of abnormal fungi and/or bacteria.

Integrative Medicine Treatment for SIFO

Dietary approaches to dysbiosis, like SIFO, should be individualized. The Anti-Candida, Low FODMAP, anti-inflammatory Mediterranean diet, and elemental diets may be used in some cases.

Anti-Candida Diet

The Anti-Candida Diet includes non-starchy vegetables, some low-sugar fruits, non-gluten grains, some dairy products, and fermented foods. This low-sugar, anti-inflammatory diet is designed to help reduce the overgrowth of yeast and bring the microbiome back into balance.

Low FODMAP Diet

A low FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols) diet limits short-chain carbohydrates, which can be difficult to digest and feed yeast and bacteria in the small intestine. Eliminating foods like beans and legumes, corn, seeds and nuts, and cruciferous vegetables that can irritate the stomach or cause delayed emptying can reduce symptoms for some. Following a gluten-free or grain-free diet can also improve symptoms.

Rebalance the Gut Microbiome

A Mediterranean diet, emphasizing citrus fruits, vegetables, legumes, and complex carbohydrates with moderate fish and olive oil, helps balance inflammation and promotes gut health. Restoring equilibrium in the gut microbiota by eating a variety of real whole foods and incorporating probiotic-rich foods like kimchi and sauerkraut that contain naturally-occurring probiotics and prebiotic-rich foods like artichokes, garlic, and beans that nourish healthy bacteria is critical for helping to bring the microbiome back into balance.

Elemental Diets

An elemental diet is a liquid meal replacement formula that provides a complete nutritional profile broken down into its most "elemental" forms. Proteins, fats, and carbohydrates are broken down into amino acids, short-chain triglycerides, and short-chain maltodextrins, along with vitamins, minerals, and electrolytes in a comprehensive "predigested" formula that is easily absorbed by the digestive tract. Fiber is generally excluded as it can feed bacteria that have relocated into the small intestines. An elemental diet may be used to treat SIBO or SIFO by replacing other food for a period of two to three weeks in an attempt to starve the bacteria in the small intestine while still adequately nourishing the body.

Herbal Medicine Treatment for SIFO

The standard treatment for SIFO is several weeks of antifungal drugs such as fluconazole, itraconazole, or posaconazole which are active against candida.

Alternatively, probiotics and herbal antimicrobials like artemisinin, caprylic acid, oregano oil, garlic, and berberine are sometimes used for antifungal treatment. While many of these approaches have been studied for SIBO and not SIFO directly, these herbal antimicrobials confer both antibacterial and antifungal action to help restore balance to the microbiome. The GI Effects comprehensive stool test can help guide a personalized approach by showing which prescriptive and natural agents are effective at inhibiting the growth of the candida specific to the patient's microbiome.

To help prevent dysbiosis when taking antibiotics, a probiotic containing the beneficial yeast, Saccharomyces boulardii can help prevent SIFO.

Under medical guidance, replacing acid (betaine HCl or apple cider vinegar) and enzymes such as papain or bromelain extracts and stimulating digestion with bitters may help improve stomach acid, motility, and digestion.

• Ginger is a natural prokinetic that helps improve stomach emptying to relieve nausea.
• Other herbal prokinetic combinations such as bitter candytuft, angelica root, chamomile, and caraway, commonly found in the herbal formula Iberogast, have also improved dysmotility by helping the stomach muscles function appropriately.

Summary

An imbalance of microbes in the intestinal tract (dysbiosis) is increasingly being recognized as a major cause of gastrointestinal and systemic symptoms. Small intestinal fungal overgrowth (SIFO) occurs when this imbalance involves too many fungi growing in the small intestine.

The most common type of yeast/fungal overgrowth that causes SIFO involves Candida. This proliferation of fungi in the small intestine can cause gas, bloating, nausea, and diarrhea, along with malnutrition and weight loss if left untreated.

Intestinal dysmotility, low stomach acid, immunocompromise, long-term treatment with PPIs, and gastrointestinal dysbiosis can all increase the risk of developing SIFO. While a small bowel aspirate to collect a sample of fluid from the small intestine is the gold standard for diagnosing SIFO, functional medicine testing to look at microbes in the gastrointestinal tract and rule out SIBO can help with narrowing in on factors contributing to SIFO.

A diet focused on non-starchy vegetables, some low-sugar fruits, non-gluten grains, and fermented foods may help reduce the overgrowth of yeast and bring the microbiome back into balance. Prescription or herbal antifungals are sometimes used to help decrease the growth of fungi in the small intestine. Probiotics and natural approaches to supporting stomach acid and motility can also help reduce symptoms and prevent the recurrence of SIFO.