Does Candida Overgrowth Exist?

It’s not uncommon in my clinic for someone to walk in describing a cluster of symptoms: fatigue, bloating, sugar cravings, and acne. Many of these individuals have either been told or come to believe that they’re dealing with fungal overgrowth, often referred to as Candida overgrowth.

When I was in dietetics school, we never talked about Candida. But in my post-graduate training in functional medicine, it became a recurring theme. I learned how an overgrowth of fungal species like Candida albicans in the gut could, in theory, lead to a wide range of systemic symptoms.

But what does the science actually say? Does Candida overgrowth in the intestines really exist, and can it cause things like brain fog, skin rashes, and intense sugar cravings?

In this blog post, I’ll unpack both the clinical perspective and the research to explore where truth may live in this often oversimplified narrative.

The Candida Conundrum

It’s easy to understand why the idea of Candida overgrowth has caught on. Here’s how the story usually goes:

Someone is experiencing a mix of symptoms such as bloating, fatigue, sugar cravings, and maybe some brain fog or skin issues. They bring these concerns to their primary care provider, but their labs are normal and no clear diagnosis is offered. They are told it is stress, or that nothing is wrong.

Eventually, they find a functional medicine practitioner who listens closely, takes their symptoms seriously, and runs more comprehensive testing. A stool test comes back showing elevated levels of Candida albicans. Finally, something to point to. Something that explains what they have been feeling all along.

The diagnosis of “Candida overgrowth” provides more than just a label. It offers a clear narrative, a target to treat, and often, a protocol to follow. This usually includes a sugar-free diet, antifungal herbs, and gut repair supplements. And for many, these protocols help. They feel clearer, less bloated, more energized.

But this is where things get complicated. Did Candida cause these symptoms in the first place? Or was it simply taking advantage of an already imbalanced gut environment? Was it the reduction in fungal load that helped, or the removal of sugar and processed foods?

This is the conundrum. Candida becomes a convenient villain, but the real story may be more nuanced.

My Clinical Lens: curious, cautious, and committed to the science

To be perfectly clear, Candida overgrowth is not a medically recognized diagnosis, and there are no standardized criteria for identifying it. There is no specific level of Candida on a stool or urine test that has been proven to cause symptoms in otherwise healthy individuals.

A stool test only tells us that Candida is present; It doesn’t confirm overgrowth, colonization, or harm. We’ll explore those limitations later, but for now, it’s important to say that presence alone isn’t proof of pathology.

In functional medicine, we view health on a spectrum. I see Candida not as a disease, but as a possible sign of microbiome imbalance, especially after antibiotics, stress, or dietary disruption.

This is why I’ve remained open to working with patients who suspect they’re dealing with fungal overgrowth. And in many cases, they improve. Sometimes it’s with targeted antifungal protocols. Other times, it’s just from addressing diet, gut health, and microbial diversity more broadly.

But that brings us to the core question: Are we actually treating Candida? Are we restoring the environment that allowed it to thrive? Or is Candida just a red herring, a convenient scapegoat for a deeper imbalance?

What Is Candida, Really?

Candida albicans and the Gut Mycobiome

Candida albicans is a yeast that lives both inside and outside the human body. Under normal circumstances, Candida is a normal part of the human ecosystem. It happily exists in the gut, on the skin, and inside the vagina without causing any problems.

Within the gut, candida lives alongside bacteria, viruses, and other fungi. These microorganisms typically keep each other in check and prevent one from becoming overgrown. Within this balance and in low abundance, Candida is not harmful.

A Normal Commensal with Opportunistic Tendencies

Under the right conditions, Candida can shift from a harmless commensal to a pathogenic organism. In other words, it has the potential to cause disease when the environment allows it to thrive unchecked. 

This is well-documented in people with compromised immunity, such as individuals with HIV, those undergoing chemotherapy, people with diabetes, long-term antibiotic users, and organ transplant recipients.(1)

In these severe cases, Candida can enter the bloodstream, a disease known as invasive candidiasis (2). This involves translocation from the gut or other mucosal sites into the body’s circulation. 

Invasive candidiasis is a serious medical condition, but it’s not what this blog post is about. Here, we’re exploring whether Candida can cause symptoms in people who are not acutely ill.

What the Research Actually Says

For the purposes of this article, I scanned all recent research on the topic of Candida infection and overgrowth. Here is what I found:

Where Candida plays a confirmed role

Candida overgrowth has been observed in several specific disease states. In most cases, the connection is associative, meaning we know Candida is present more often in these conditions, but we haven’t proven whether it plays a causal role or is simply a consequence of the disease environment.

Inflammatory Bowel Disease (IBD)

IBD is a chronic inflammatory condition of the gastrointestinal tract, including Crohn’s disease and ulcerative colitis. Studies have found elevated levels of Candida albicans in the gut of patients with IBD, particularly Crohn’s disease (3). 

The hypothesis is that Candida worsens mucosal inflammation by triggering immune responses and forming biofilms with pathogenic bacteria. This may not apply to individuals without IBD, but it suggests a role for Candida in chronic gut inflammation. Read more on biofilms here.

Chronic Liver Disease (NAFLD, ALD)

Chronic liver diseases like NAFLD and ALD involve long-term inflammation and fat accumulation in the liver. Patients with these conditions often show increased fungal burden, including higher levels of Candida in the gut. 

One theory is that fungal toxins translocate to the liver through a leaky gut, promoting immune activation. This supports a gut-liver connection for Candida overgrowth but hasn’t been studied in people without liver disease.

Obesity/Metabolic Syndrome

Metabolic syndrome includes insulin resistance, inflammation, and abdominal obesity. Some research has found changes in the fungal community, including more Candida, in people with obesity. 

It’s hypothesized that fungal imbalance may contribute to low-grade inflammation or interfere with metabolic signaling. Whether Candida plays a causal role or is simply responding to the environment remains unclear.

Immunodeficiency (HIV, transplant, chemotherapy)

Immunosuppressed individuals, such as those with HIV or undergoing chemotherapy, are at high risk for Candida overgrowth and systemic infection. In these cases, Candida can translocate into the bloodstream, leading to serious disease. This clearly demonstrates its pathogenic potential, though it’s specific to individuals with compromised immunity.

Where the data falls short

Despite growing interest in Candida, there is very little evidence linking it to symptoms in otherwise healthy individuals. Most of the research focuses on people with diagnosed disease, not those with vague or functional complaints.

The presence of Candida in a stool test does not confirm overgrowth or harm. It does not tell us if Candida is colonizing the gut lining, forming biofilms, or producing toxins. It only tells us that it was present in the sample.

Even studies using antifungal medications show mixed results. Some people improve, while others do not. It is difficult to know whether the benefits come from reducing Candida or from improving the gut environment overall.

Diagnostic tests like stool cultures, urine arabinitol, or yeast antibodies are not specific or well-validated. They may be helpful as part of a bigger picture, but they cannot confirm Candida as the cause of symptoms.

Why “Presence” Doesn’t Equal “Pathology”

Candida is found in more than 60 percent of healthy individuals. In many cases, it is simply a normal part of the microbiome that does not cause problems.

Whether or not Candida becomes problematic depends on the context. Immune health, microbial diversity, gut integrity, and recent antibiotic use all influence how Candida behaves.

In a healthy gut, Candida may be present without causing any issues. In a stressed or imbalanced gut, it may take advantage of the environment and contribute to symptoms.

But What Do We Mean by “Healthy”?

Most of the research that dismisses Candida as harmless is focused on two groups: people with severe illness and people who are completely symptom-free. But there is a large population that falls somewhere in between.

These are the people who are tired, bloated, breaking out, or reacting to foods, but whose labs are normal. They do not meet the criteria for any diagnosis, but they also do not feel well.

In my practice, this in-between group is often where I see Candida show up. Not as the cause of disease, but as part of a bigger pattern that points to imbalance in the gut.

Why Dysbiosis isn’t Benign

Even without a diagnosed disease, gut imbalance can affect energy, digestion, and immune health. It may not cause dramatic symptoms, but it often shows up as fatigue, food sensitivities, or feeling generally off.

In this type of environment, Candida is not always the cause of the problem. More often, it is responding to a lack of balance in the gut. When the usual checks and balances are missing, Candida can take the opportunity to grow.

The issue is not that Candida is inherently aggressive. It is that the terrain has shifted in a way that allows it to take up more space than it should (4).

What Are the Symptoms of Candida Overgrowth?

This is where things tend to get confusing. In functional medicine, many of us are trained to associate certain symptoms, like fatigue, bloating, brain fog, and sugar cravings, with possible Candida overgrowth. These associations are based on known mechanisms, patterns observed in practice, and our understanding of microbial behavior in the gut.

But it is important to be clear about what the research does and does not show. A proposed mechanism is not the same as proven causation. And the absence of data is not the same as negative data. Sometimes, the research just has not caught up to what we are observing clinically.

In the section below, I will walk through some of the most commonly reported symptoms and break each one into two parts. First, I will explain the theory, or what functional medicine suggests might be happening. Then, I will look at the current evidence and where the science stands today.

These are hypotheses, not established facts. Whether or not they resonate with your experience is something only you and your clinician can determine.

1. Sugar and Carb Cravings

Theory
Candida feeds on sugar, so it has been suggested that an overgrowth might cause the host to crave sugar in order to support its growth. In functional medicine, sudden or intense sugar cravings are often considered a hallmark sign of fungal imbalance.

Evidence
There is no direct evidence that Candida causes sugar cravings. While the microbiome can influence appetite based on available nutrients, and Candida can sense sugar levels, no studies have shown that its presence leads to increased sugar-seeking behavior in humans (5,6).

2. Bloating and Digestive Discomfort

Theory
Candida ferments carbohydrates into gases and compounds like acetaldehyde and ethanol, which can contribute to bloating and discomfort. It may also form biofilms that impair digestion and disrupt microbial balance.

Evidence
Candida overgrowth has been observed in patients after antibiotic use, particularly when microbial diversity is low. One study found that people with confirmed Candida overgrowth experienced symptoms like flatulence and bloating, but these findings were not in otherwise healthy individuals (7,8).

3. Fatigue and Brain Fog

Theory
Candida produces acetaldehyde, a byproduct of sugar fermentation that is also created during alcohol metabolism. Acetaldehyde is considered neurotoxic and may impair mitochondrial function, which could contribute to fatigue, brain fog, and poor concentration.

Evidence
While Candida can produce acetaldehyde, it is not the only organism that does. Many gut bacteria generate this compound as well, especially in dysbiotic environments. 

If brain fog is connected to Candida, it is likely part of a broader picture that includes microbial imbalance, increased gut permeability, and systemic inflammation. So far, this remains a theory without direct human evidence.

4. Skin Rashes and Itching

Theory
It has been proposed that antigens from Candida may leak through the gut wall in cases of increased permeability and activate the immune system. This could contribute to skin symptoms like rashes, itching, or eczema.

Evidence
Candida has been associated with inflammatory skin conditions like psoriasis and seborrheic dermatitis. A 2018 meta-analysis found that individuals with psoriasis were more likely to carry Candida, particularly in the oral mucosa (9)​. However, the theory that gut Candida causes skin symptoms remains unproven and largely speculative.

5. Histamine or Chemical Sensitivities

Theory
Candida is thought to activate mast cells and stimulate immune responses that may contribute to histamine release. In people with low histamine tolerance, this could show up as food reactions, skin flushing, congestion, or chemical sensitivities.

Evidence
So far, there are no clinical studies directly linking gut Candida to histamine intolerance. However, in vitro research has shown that Candida albicans can activate inflammasomes and immune cells involved in histamine signaling, including mast cells​ (10) . 

These findings are theoretical and suggest Candida could contribute to symptoms in a dysregulated immune environment, but human data is lacking.

What About Testing for Candida?

There are several lab markers that claim to measure Candida, but none of them offer a clear or reliable diagnosis—especially in people who are not acutely ill. These tests may raise suspicion, but they should be interpreted cautiously and always in context.

Anti-Saccharomyces cerevisiae Antibodies (ASCA)

ASCA measures immune reactivity to Saccharomyces cerevisiae, a common yeast found in food and the microbiome. While it is sometimes used to infer fungal overgrowth, it does not measure Candida albicans specifically.

ASCA is primarily associated with Crohn’s disease and other autoimmune conditions. A positive result may indicate heightened immune sensitivity to yeast, but it is not diagnostic of Candida overgrowth in the gut.

D-Arabinitol and the D/L Ratio

D-arabinitol is a sugar alcohol produced by some Candida species during metabolism. It can be measured in the urine, and elevated levels may indicate systemic or invasive candidiasis.

However, this marker is not considered reliable for detecting gut-only overgrowth in healthy or mildly symptomatic individuals. It is best used in hospital settings for immunocompromised patients.

Stool Testing: Culture vs. PCR

Stool culture is often included on functional lab panels and looks for fungal growth under lab conditions. While it can detect Candida, it does not reflect what is happening along the gut lining or how active the organism is in vivo.

PCR testing detects fungal DNA and may be more sensitive, but it still cannot confirm whether Candida is overgrowing, causing symptoms, or simply present as part of a normal microbial ecosystem. Neither test can diagnose Candida overgrowth in isolation.

Functional Advice

If you are looking to address suspected Candida overgrowth clinically, the best approach combines both symptom patterns and positive findings on a stool or urine test. Neither is diagnostic on its own, but together they may strengthen the case for intervention. At the end of the day, it is still a working hypothesis, not a proven diagnosis.

Candida as a Clue, Not the Culprit

In my experience, Candida is rarely the root cause. More often, it is a sign that the gut environment is off—low in diversity, high in inflammation, or recovering from antibiotic use. When the ecosystem breaks down, opportunistic organisms tend to fill the space.

In this sense, Candida may be more of a symptom than a cause. It can amplify existing imbalances, but that does not mean it created them.

This is why I often take a “treat the terrain” approach rather than focusing solely on antifungals or restrictive cleanses. Trying to kill Candida without addressing the gut environment can backfire or lead to short-term results at best.

Long-term improvement comes from restoring microbial diversity, supporting the gut lining, and improving immune regulation. When the terrain is healthy, Candida has less opportunity to become a problem.

Addressing Candida Through a Systems Lens

When to consider Candida as a therapeutic target

While Candida is not always the cause, there are certain cases where it makes sense to consider it as part of the treatment plan. This is especially true after a recent course of antibiotics or illness that may have disrupted the gut microbiome.

I also pay closer attention when there is a personal history of fungal issues—recurrent thrush, vaginal yeast infections, athlete’s foot, or other fungal rashes. These can signal a pattern of susceptibility that might show up internally as well.

In many cases, symptoms like bloating, brain fog, fatigue, or sugar cravings overlap with general dysbiosis or immune dysfunction. If there is clinical suspicion and some evidence from testing, it may be reasonable to include antifungal support as part of a broader protocol.

Interventions that work by restoring balance

When Candida becomes part of the picture, the goal is not just to suppress it, but to change the environment that allowed it to overgrow in the first place. This means supporting the gut as a whole, not just targeting the yeast.

Diet

I do not recommend extreme carbohydrate restriction. While cutting out added sugars and refined carbs may reduce symptoms short term, this is not the same as treating the root cause.

Candida can survive in low-sugar environments and may even form protective biofilms under stress. A better long-term approach includes fiber, polyphenols, and a diverse range of whole foods that support microbial balance.

Probiotics

Certain strains like Saccharomyces boulardii and Lactobacillus rhamnosus have shown potential in crowding out Candida and supporting immune function. These can be helpful when part of a broader protocol that includes gut repair.

Immune and Antioxidant Support

Herbs and compounds like curcumin, quercetin, resveratrol, and catechins have all been studied for their antifungal, anti-inflammatory, and immune-modulating effects (11). Supporting the immune system is critical because fungal balance in the gut is largely maintained through immune surveillance. 

Antioxidants may also help reduce oxidative stress triggered by fungal metabolites like acetaldehyde, which can contribute to fatigue, inflammation, and brain fog.

Gut integrity and Detox

Supporting the gut lining and liver are essential, especially during protocols that mobilize microbial toxins. This may include nutrients for barrier repair, gentle liver support, and the use of binders if die-off symptoms occur.

Final Thoughts

We’re still in the hypothesis phase—but that doesn’t mean we stop listening

We are still in the hypothesis phase when it comes to Candida overgrowth, but that does not mean we stop paying attention. Just because something has not been fully proven does not mean it is irrelevant. A lack of evidence is not the same as evidence of absence.

Candida may not be the root cause of everyone’s symptoms, but in the right context, it can still be part of the story. Especially when symptoms point to deeper gut or immune imbalance, it is worth considering as one piece of the puzzle.

Why nuanced clinical reasoning matters more than ever

What matters most is nuance. In functional medicine, we have to be careful not to fearmonger, but also not to dismiss something just because it hasn’t been studied enough. We listen to the research, but we also listen to the patient in front of us. That is where good clinical care lives, in the space between evidence and lived experience.

If you are struggling with symptoms and wondering whether Candida might be part of the picture, I invite you to book a free consultation. This is what I do. I help patients uncover what is driving their symptoms, using both science and common sense to guide the way forward.