Is Fungal Overgrowth Causing your Symptoms?

Are you frustrated with any of the following symptoms?

  • Gut issues such as constipation, gas, or bloating
  • Irritable bowel syndrome
  • Malabsorption
  • Recurrent yeast infections
  • Itchy ears or scalp
  • Dandruff
  • Fatigue
  • Acne or rosacea
  • Patchy skin rashes, usually itchy
  • Allergies
  • Headaches
  • Joint problems
  • Thyroiditis
  • Mood and brain symptoms

While these symptoms have multiple causes, I commonly discover fungal overgrowth in my patients with these issues. When I went through my medical training, we were taught to dismiss the idea of “Candida” being the cause. We were taught to be empathic while inwardly rolling our eyes. Then, in my own medical practice years later, after seeing so many patients with recurrent vaginal yeast infections, I hypothesized that conventional medicine could be wrong in its approach to this common diagnosis. So I decided to test myself.

At the time, I struggled with constipation, rosacea, weight loss resistance, and fatigue. I performed a stool analysis and learned that I had fungal overgrowth—moderate yeast were seen under the microscope in my stool, and Candida albicans grew out on my stool culture. I began treatment with Nystatin and Diflucan, which are common conventional therapies, but also added a yeast-free food plan, herbal remedies, and probiotics.

Within one month, my symptoms were gone.

I dropped weight, not effortlessly but it was far less difficult. I had a hunch there was something to the idea of chronic fungal overgrowth and began poring over the research. I found that more than one quarter of patients with gastrointestinal complaints were found to have small bacterial fungal overgrowth (SIFO), sometimes called fungal dysbiosis.[1]

Unfortunately, the data are limited, but lack of proof is not proof against. Armed with my own experience, I changed how I approached my patients, both in my diagnosis and treatment. Over time, I became a believer. Not in the wholesale, everything-is-caused-by-yeast strategy that I see among some practitioners in the alternative medicine world, but in having a healthy suspicion that some or many of my patients’ most nagging symptoms might be due to dysbiosis, an imbalance in the microbes of their gut flora, including overgrowth of yeast. In this blog, I will review the symptoms and mechanisms of fungal overgrowth. In future blogs, I’ll cover the diagnosis and treatment from a functional medicine perspective.

Root Causes

Normally there is a healthy balance of microbes in the gut, including a small amount of fungus. But when an insult removes good microbes (such as a course of antibiotics) or bad microbes are fed too much sugar, the gut’s ecosystem can become imbalanced.

Besides loving a body that is moist, dark, and sugary, yeast thrive under certain conditions, such as the following, which can generate too few good microbes and/or too many bad microbes. You may have one or more of these problems putting you at risk of fungal overgrowth.

  • Use of antibiotics.[2] Most commonly, my patients have taken antibiotics for chronic sinusitis, bladder infections, acne, or a benign heart condition. They are often overdiagnosed, and then overuse of antibiotics disrupts the delicate balance between healthy microbes—such as lactobacillus and bifidobacter—and unhealthy microbes, including fungi, bacteria, and parasites.
  • Not enough fiber. Fiber feeds good microbes, and you may not be getting enough of it. The optimal range is 30 to 50 grams of fiber per day, but most Americans get less than 14 grams per day (median intake 12-14 g/day), meaning that fewer than 5 percent get the right amount of fiber.[3] This problem is known as the fiber gap.[4] Eating more fiber, particularly soluble, is associated with lower blood sugar.[5] This can help prevent and treat fungal dysbiosis.
  • Too much sugar intake and/or elevated blood sugar.[6] Yeast feed on sugar. They help make beer and wine by consuming sugar and converting it into alcohol. Yeast make bread rise because they consumer sugar and produce a gas that causes the dough to rise.
  • Ketogenic diet. Yeast feed on ketones! Paul Jaminet is the one who has written the most about this problem. Jaminet, who suffered from fungal overgrowth, argues that candidahave mitochondria that can feed on both ketones and carbohydrates, so that eating a very low-carb or ketogenic food plan will fuel fungal overgrowth.
  • Estrogen, including birth control pills, hormone therapy, and pregnancy.[7] Possibly the vaginal ring that releases ethinyl estradiol, although data are mixed.[8]
  • Use of proton pump inhibitors and other acid blockers[9]
  • Immunosuppression and use of steroids like prednisone[10]
  • Excess stress can disrupt several aspects of the gut’s delicate checks and balances.[11] Stress can be physical, psychological, emotional, oxidative, and/or from toxin exposure.[12]

Common Symptoms

Keeping in mind that symptoms of fungal overgrowth are similar to other conditions, i.e., they are nonspecific, these are the most common symptoms and conditions that I see in my practice (note that some of them are associated with the broader problem of dysbiosis, which may include fungal overgrowth).

  • Brain fog
  • Sugar and alcohol cravings
  • Fatigue
  • Low sex drive
  • Thrush
  • Gastrointestinal symptoms, including gas, bloating, cramping, constipation, and/or diarrhea[13]
  • Irritable bowel syndrome[14]
  • Vaginal yeast infections
  • Rectal itching
  • Recurrent bladder infections
  • Interstitial cystitis[15]
  • Thyroid dysfunction[16]
  • Depression
  • Allergies
  • Chemical sensitivities
  • Food sensitivities
  • Poor immune function
  • Eczema
  • Psoriasis
  • Toenail fungus

If you have more than three of these symptoms, you may want to consider dysbiosis, particularly fungal dysbiosis, as a potential root cause. But this is a situation where you don’t want to guess and start a strict anti-fungal food plan and supplements. Instead, test. In my next article on fungal overgrowth, Part 2, we will discuss methods of diagnosis including blood tests (rarely if ever helpful), organic acid testing (sometimes helpful), and stool testing (the gold standard, but you need the correct test ordered to make the diagnosis). In Part 3, we’ll review the evidence-based treatments and the sequence that works best for my patients.


[1]  Erdogan, A., et al. “Small intestinal fungal overgrowth.” Current Gastroenterology Reports 17, no. 4 (2015): 16.

[2] Myers, S. P. “The causes of intestinal dysbiosis: A review.” Alternative Medicine Review 9, no. 2 (2004): 180-197; Kourbeti, I. S., et al. “Impact of prolonged treatment with high-dose ciprofloxacin on human gut flora: A case report.” Journal of Medical Case Reports 4, no. 1 (2010): 111; Blaser, M. J. Missing microbes: How the overuse of antibiotics is fueling our modern plagues. Macmillan, 2014; Holler, E., et al. “Metagenomic analysis of the stool microbiome in patients receiving allogeneic stem cell transplantation: Loss of diversity is associated with use of systemic antibiotics and more pronounced in gastrointestinal graft-versus-host disease.” Biology of Blood and Marrow Transplantation 20, no. 5 (2014): 640-645; De Lastours, V., et al. “Impact of fluoroquinolones on human microbiota. Focus on the emergence of antibiotic resistance.” Future Microbiology 10, no. 7 (2015): 1241-1255; Doan, T., et al. “Gut microbial diversity in antibiotic-naive children after systemic antibiotic exposure: A randomized controlled trial.” Clinical Infectious Diseases 64, no. 9 (2017): 1147-1153; Ferrer, M., et al. “Antibiotic use and microbiome function.” Biochemical Pharmacology 134 (2017): 114-126.

[3] Thompson, H. J., et al. “Perspective: Closing the dietary fiber gap: An ancient solution for a 21st century problem.” Advances in Nutrition 7, no. 4 (2016): 623-626.

[4] De Filippo, C., et al. “Impact of diet in shaping gut microbiota revealed by a comparative study in children from Europe and rural Africa.” Proceedings of the National Academy of Sciences 107, no. 33 (2010): 14691-14696; Han, M., et al. “Dietary fiber gap and host gut microbiota.” Protein and Peptide Letters 24, no. 5 (2017): 388-396.

[5] Al Essa, H. B., et al. “High fiber and low starch intakes are associated with circulating intermediate biomarkers of type 2 diabetes among women.” The Journal of Nutrition 146, no. 2 (2016): 306-317; Thompson, S. V., et al. “Effects of isolated soluble fiber supplementation on body weight, glycemia, and insulinemia in adults with overweight and obesity: A systematic review and meta-analysis of randomized controlled trials.” The American Journal of Clinical Nutrition 106, no. 6 (2017): 1514-1528.

[6] Crook, W. G. “Vaginal yeast infections exacerbated by sugar intake.” The Nurse Practitioner 18, no. 1 (1993): 8; Shen, J., et al. “The gut microbiota, obesity and insulin resistance.” Molecular Aspects of Medicine 34, no. 1 (2013): 39-58; Javed, F., et al. “Association between glycemic status and oral Candida carriage in patients with prediabetes.” Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology 117, no. 1 (2014): 53-58.

[7] Corsello, S., et al. “An epidemiological survey of vulvovaginal candidiasis in Italy.” European Journal of Obstetrics and Gynecology and Reproductive Biology 110, no. 1 (2003): 66-72; Zakout, Y. M., et al. “Frequency of Candida species in Papanicolaou smears taken from Sudanese oral hormonal contraceptives users.” Biotechnic & Histochemistry 87, no. 2 (2012): 95-97; Gonçalves, B., et al. “Vulvovaginal candidiasis: Epidemiology, microbiology and risk factors.” Critical Reviews in Microbiology 42, no. 6 (2016): 905-927; Man, A., et al. “New perspectives on the nutritional factors influencing growth rate of Candida albicans in diabetics. An in vitro study.” Memórias do Instituto Oswaldo Cruz 112, no. 9 (2017): 587-592.

[8] Camacho, D. P., et al. “Vaginal yeast adherence to the combined contraceptive vaginal ring (CCVR).” Contraception 76, no. 6 (2007): 439-443; Lete, I., et al. “Vaginal health in contraceptive vaginal ring users–A review.” The European Journal of Contraception & Reproductive Health Care 18, no. 4 (2013): 234-241.

[9] Jacobs, C., et al. “Dysmotility and proton pump inhibitor use are independent risk factors for small intestinal bacterial and/or fungal overgrowth.” Alimentary Pharmacology & Therapeutics 37, no. 11 (2013): 1103-1111; Freedberg, D. E., et al. “The impact of proton pump inhibitors on the human gastrointestinal microbiome.” Clinics in Laboratory Medicine34, no. 4 (2014): 771-785.

[10] Gonçalves, B., et al. “Vulvovaginal candidiasis: Epidemiology, microbiology and risk factors.” Critical Reviews in Microbiology 42, no. 6 (2016): 905-927.

[11] Myers, S. P. “The causes of intestinal dysbiosis: A review.” Alternative Medicine Review 9, no. 2 (2004): 180-197.

[12] Pellissier, S. et al. “The place of stress and emotions in the irritable bowel syndrome.” Vitamins and Hormones 103, (2016): 327-354; Weiss, G. A., et al. “Mechanisms and consequences of intestinal dysbiosis.” Cellular and Molecular Life Sciences (2017): 1-19; Wiley, N. C., et al. “The microbiota-gut-brain axis as a key regulator of neural function and the stress response: Implications for human and animal health.” Journal of Animal Science 95, no. 7 (2017): 3225-3246; Wong, T. Y. “Smog induces oxidative stress and microbiota disruption.” Journal of Food and Drug Analysis 25, no. 2 (2017): 235-244.

[13] Erdogan, A., et al. “Small intestinal fungal overgrowth.” Current Gastroenterology Reports 17, no. 4 (2015): 16.

[14] Mättö, J., et al. “Composition and temporal stability of gastrointestinal microbiota in irritable bowel syndrome— A longitudinal study in IBS and control subjects.” FEMS Immunology & Medical Microbiology 43, no. 2 (2005): 213-222; Santelmann, H., et al. “Yeast metabolic products, yeast antigens and yeasts as possible triggers for irritable bowel syndrome.” European Journal of Gastroenterology & Hepatology 17, no. 1 (2005): 21-26; Botschuijver, S. et al. “Intestinal fungal dysbiosis is associated with visceral hypersensitivity in patients with irritable bowel syndrome and rats.” Gastroenterology 153, no. 4 (2017): 1026-1039.

[15] Weinstock, L. B., et al. “Small intestinal bacterial overgrowth in patients with interstitial cystitis and gastrointestinal symptoms.” Digestive Diseases and Sciences 53, no. 5 (2008): 1246-1251.

[16] Nakatsui, T., et al. “Onycholysis and thyroid disease: Report of three cases.” Journal of Cutaneous Medicine and Surgery 3, no. 1 (1998): 40-42; Jabbour, S. A. “Cutaneous manifestations of endocrine disorders.” American Journal of Clinical Dermatology 4, no. 5 (2003): 315-331; Lauritano, E. C., et al. “Association between hypothyroidism and small intestinal bacterial overgrowth.” The Journal of Clinical Endocrinology & Metabolism 92, no. 11 (2007): 4180-4184; Virili, C., et al. “Does microbiota composition affect thyroid homeostasis?.” Endocrine 49, no. 3 (2015): 583-587; Brechmann, T., et al. “Levothyroxine therapy and impaired clearance are the strongest contributors to small intestinal bacterial overgrowth: Results of a retrospective cohort study.” World Journal of Gastroenterology 23, no. 5 (2017): 842-852; Virili, C., et al. ““With a little help from my friends”-The role of microbiota in thyroid hormone metabolism and enterohepatic recycling.” Molecular and Cellular Endocrinology 458, (2017): 39-43.