by Dr. Evan McCarvill, ND, Upper Beach Health & Wellness, Melfort, Canada

A fairly common but often underrecognized condition I encounter as a naturopathic doctor is “chronic yeast infection”; something you may have heard of. It is also sometimes called Candida overgrowth syndrome (COS). This condition can manifest through a variety of mild, systemic, nonspecific symptoms, which may go unexplained and untreated for months or even years at a time for many patients.

The Microbiome (and MYCObiome)

While it can be a problem for many people, COS is not the result of an “infection” per se. The human body normally plays host to a baffling variety of microorganisms. In fact, there are 100 trillion microbial cells in the typical human body, outnumbering human cells by ten to one. The mutual community that these bugs create in our bodies is called our “microbiome.” These microbes often have symbiotic relationships with us, meaning their presence actually helps our bodies in terms of immune modulation and digestive function. However, they may also have “commensal” relationships with us, which is a term that means the microbes just live here and don’t necessarily help us in exchange for us providing them real estate.

The vast majority (99.9%) of the microbes that live in and on our bodies consists of only a relative few species of bacteria. The tiny remaining minority (0.01%), which includes fungal species, is much more diverse. This is called the “rare biosphere,” and while it is unclear whether this minority of microbes plays a significant role in our health, it is clear that they can be a reservoir of certain species which can be harmful to the body, if they were to “bloom”; that is, under certain conditions, they can overgrow and unbalance the otherwise healthy microbe community.[1]

Candida Overgrowth Syndrome (COS):

So what, if anything, is Candida overgrowth syndrome? This relates specifically to one particular genus of fungi, called Candida, of which there are over 160 known species, mostly adapted to live in mammalian hosts.[2] However, the most common species is Candida albicans. This fungal microbe normally is present in small amounts on the mucosal lining of the gastrointestinal tract, including intestines and mouth, as well as in the vagina and on the skin. Under most circumstances, Candida is kept in check due to microbial resistance (i.e. competition) from bacterial microbes, as well as by the body’s competent immune system. However, if fungal growth in the body becomes unbalanced, it can create problems.

There are a couple of ways that an overgrowth of Candida can manifest itself quite obviously; one being vaginal candidiasis, also known as a “yeast infection,” the other being oral candidiasis, also known as “oral thrush.” Vaginal candidiasis results in vaginal itching and a whitish discharge, and is a common complication of antibiotic use, especially if there is repeated use for recurrent bacterial infections.[3] Oral candidiasis is more often seen as a complication of steroid inhaler use for asthma, or in individuals with compromised immune systems.[3]

Both of the above manifestations of Candida are associated with Candida overgrowth syndrome and may indeed be indicators of underlying COS, but this is not necessarily the case.

It should be noted that COS is considered controversial. Some physicians accept it, while others consider it a “fad” diagnosis. Nutritional or functional-medicine–oriented doctors—and naturopathic doctors—will usually acknowledge that COS is a real and specific condition that can result in long-term impacts on quality of life.

It is also important to distinguish that COS is different from the potentially fatal Candida fungal infection of the bloodstream (candidemia), which is a form of sepsis. This much more serious condition usually only happens in weakened and debilitated patients with severely compromised immune systems, and requires aggressive treatment in a hospital setting.[5]

Candida overgrowth syndrome, rather, is the result of an overabundance of Candida organisms, which are nonetheless limited to certain regions and cavities of the body. An overgrowth in the intestines is characterized by symptoms such as excessive gas, bloating, and changes in bowel-movement patterns. While the Candida remains restricted to these regions of the body, thus not actually resulting in sepsis, the body nevertheless absorbs residual particles from dead Candida cells as well as the wastes and metabolic products produced by live cells. The absorption of such substances and their subsequent spread throughout the body result in systemic symptoms such as chronic fatigue, muscle aches, and trouble concentrating (i.e. “brain fog”).

In some more severe cases of Candida overgrowth, the proliferating hyphae structures of the organism can spread into the delicate mucosal lining of the intestinal tract, disrupting its function as a semipermeable membrane, and creating a condition known as hyperpermeability or “leaky gut.” When this happens, minute amounts of inappropriate particles such as not-fully-digested food proteins and waste products can “leak” through the gut wall into the blood, which the body then reacts to as though it were dealing with an infection. Thus, people can develop new food sensitivities and intolerances to foods that were harmless before. Some of the more common food sensitivities include wheat (gluten), dairy, eggs, and corn. This is not to say that all such food sensitivities are the result of Candida overgrowth, but it can contribute to the development of such food sensitivities. In fact, it has been shown that when mice have their GI tracts experimentally colonized with Candida, it can actually drive allergic sensitization to food antigens by disrupting the mucosal barrier.[4]

Symptoms to watch for, which may be indicative of COS:

- Bloating and gas;

- Diarrhea/constipation/changes in bowel habits;

- New sensitivities to previously harmless foods;

- Chronic fatigue;

- Headaches;

- Depression/irritability; and

- Dizziness and/or trouble concentrating (“brain fog”).

Common Causes

Probably the most common cause of COS is the overuse of broad-spectrum antibiotics. Unfortunately, these drugs tend to be overprescribed, often for mild colds and flus which are usually viral and thus would not be helped by antibiotics anyway. But what they will often do is kill off a good many of the beneficial bacteria that live in our intestines, perturbing the balance of the microbiome, and freeing up Candida from its competition.[1] Candida, being a fungus, is unaffected by antibiotics.

Additionally, other medications that can promote COS include birth-control pills and oral corticosteroids such as prednisone. Such steroid anti-inflammatories are often given for chronic inflammatory and autoimmune conditions, such as lupus, because of their depressive effect on the immune response. Any factor that depresses immune function, such as stress, high levels of sugar and refined carbohydrates in the diet, hormonal changes in pregnancy, as well as diabetes, will all leave the body more vulnerable to COS.


Most naturopathic, holistic, and nutrition-based practitioners don’t rely on any single test to support a diagnosis of COS. Rather, the whole patient is evaluated, most notably for any significant history of frequent antibiotic use and/or recurrent vaginal yeast infections in women, as well as any other symptoms strongly suggestive of COS.

Treatment and Prevention

Most cases of COS are mild and can be treated with a combination of natural supplements and sensible lifestyle changes. These should be implemented first in most cases, rather than going directly for pharmaceutical antifungals. Antifungal medications can be expensive if not covered by your insurance plan, and they can also result in a massive die-off of Candida happening all at once, with the resulting release of dead organisms and toxins causing unpleasant flu-like symptoms. Gentler natural therapies can reduce the Candida presence more gradually and painlessly.

In terms of natural strategies, the first thing to do is to address any dietary factors that would contribute to Candida growth. There should be an abundance of healthy protein and high-fibre vegetables in the diet. High-carb foods—including whole-grain breads as well as fruit and starchy vegetables such as white potatoes, beets, oranges, and bananas—should be restricted.

Sugar in general should be restricted in the diet, for not only do high amounts of sugar depress immune function and open the door for Candida overgrowth, but also because Candida thrives on sugar as a fuel source.

To reduce the risks of developing or redeveloping COS, it is a good idea to avoid unnecessary antibiotic use, as this is the most common cause of COS. Most self-limited colds and flus are viral in origin, not bacterial, and so are unaffected by antibiotics. Therefore, it is often best to let such mild infections run their course and/or opt for nonantibiotic options for antimicrobial support and immune support.

There are, of course, some cases where antibiotics are needed. In such cases, ask your doctor to prescribe, if at all possible, a narrow-spectrum antibiotic, specific to your particular infection, rather than a broad-spectrum drug that will kill too many of the good bacteria along with the bad.

In the wake of any course of antibiotics, it is a good idea to take a round of probiotics, to replace any good bacteria that may have been affected, for at least three weeks to a month after the antibiotic treatment is completed.

If you have a medical condition that requires steroid anti-inflammatory use, you should try to aim for the lowest effective dose possible. Work with your medical doctor to achieve this, as it will minimize the impact on the ability of your immune system to keep Candida overgrowth in check. If you use a steroid inhaler, rinse your mouth thoroughly after each use.

Supplement Recommendations

For those who may have a serious medical condition, it is a good idea to check with your health-care provider before starting any significant supplement regimen, especially if you are already taking prescription drugs with potential for interactions.

Supplements and natural medicines, in the treatment of COS, will usually fall into one of three therapeutic categories, namely antimicrobial/antifungals to directly kill yeast, immune-supporting substances, as well as probiotics to restore healthy gut bacteria.

Echinacea (Echinacea angustifolia)—Echinacea is an herb frequently used to boost the immune system, to lessen susceptibility to colds and flus. It can also be used to enhance the immune system against excessive Candida growth. Other herbs such as astragalus and goldenseal are also known to support immune function, and can be taken in alternating cycles with echinacea for maximum effect.

Goldenseal (Hydrastis canadensis)—Because of its berberine content, goldenseal has considerable antimicrobial effect, especially when it comes to infections that affect the mucosal lining of the respiratory and digestive tracts. Because Candida loves to colonize the mucosa of the intestine, this herb can be another method to counteract Candida growth. It may be especially helpful in cases of diarrhea related to COS.

Caprylic Acid—Caprylic acid is a fatty acid known to have antifungal properties, inhibiting Candida’s ability to grow and replicate. In my experience, it is one of the most effective and accessible anti Candida nutrients. Larger amounts can be derived from the diet from palm oil and coconut oil. Taking a tablespoon of coconut oil added to your morning smoothie, for instance, is a useful strategy. Of course, caprylic acid can be more potent still if taken in supplement form. Supplementation may be more advisable in the case of clearing an active overgrowth of Candida, and dietary sources, such as coconut oil, can be used regularly afterward to help keep Candida in check.

Probiotics—Supplemental probiotic bacteria, in particular species of the Lactobacillus genus (e.g. Lactobacillus acidophilus) and Bifidobacteria, help by producing lactic acid, which helps to restore healthy pH levels in the intestine, which is less conducive to Candida growth and contributes to its decline. They themselves reseed the gut and help to restore conditions for healthy symbiotic bacterial biodiversity. A good probiotic will have several billion colony-forming units (CFU) per capsule, will feature several species of bacteria belonging to the Lactobacillus and often Bifidobacterium genera, and will have a guaranteed potency at time of expiry listed on the label. Often such quality probiotics require refrigeration after opening.

When to Call a Doctor

You may want to seek more aggressive treatment, perhaps with stronger pharmaceutical antifungals, if your self-treatment or natural treatment strategies are not helping.

Call your doctor, if:

- Your COS symptoms persist for three months or more, with no sign of improvement; 

- Your symptoms are severe enough to affect your day-to-day activities;

- You have a vaginal discharge that has a strong, unpleasant odour, or is tinged with blood; or

- You have a vaginal yeast infection that returns within two months.

References: 1. Huffnagle, G.B., and M.C. Noverr. “The emerging world of the fungal microbiome.” Trends in Microbiology, Vol. 21, No. 7 (2013): 334–341.     2. Blaschke-Hellmessen, R. “[Habitats for Candida in medical and hygienic respects]” [article in German]. Mycoses, Vol. 42, Suppl. 1 (1999): 22–29.     3. Yano, J., et al. “Cytokines in the host response to Candida vaginitis: Identifying a role for non-classical immune mediators, S100 alarmins.” Cytokine, Vol. 58, No. 1 (2012): 118–128.     4. Yamaguchi, N., et al. “Gastrointestinal Candida colonisation promotes sensitisation against food antigens by affecting the mucosal barrier in mice.” Gut, Vol. 55, No. 7 (2006): 954–960.     5. Garey, K.W., et al. “Time to initiation of fluconazole therapy impacts mortality in patients with candidemia: A multi-institutional study.” Clinical Infectious Diseases, Vol. 43, No. 1 (2006): 25–31.