Jan. 3, 2022 -- If you are a regular visitor to certain popular nutritional-lifestyle websites, you might have heard some alarming news — your stomach is teeming with Candida and it's wrecking your health.

On the website Goop you can find an interview with doctor Amy Myers, who estimates that 90% of her patients, and about half of all women, have an overgrowth of this yeast. Courtesy of Dr Oz, you’ll learn that Candida overgrowth is likely causing your chronic fatigue, fibromyalgia, or spastic colon. The constellation of symptoms attributed to the fungus is so wide-ranging that mainstream news publications have labeled the diagnosis as pseudoscience.

Yet, according to other websites, the only hope are what have been variously termed "anti-Candida diets," "anti-yeast diets," or "Candida cleanses." These dietary interventions share a common goal of curbing or eliminating the sugars and carbohydrates that have been linked to Candida growth. Take aim at these components, the theory goes, and you'll starve the Candida that's at the root of your health problems. There's even a celebrity endorsement of this dietary approach via actress Rebel Wilson, who attributes it to her recent 60-pound weight loss.

Candida's increasing reputation as a gastrointestinal (GI) menace has led to a counter response from concerned experts, who say opportunistic forces are turning a largely benign and common fungus into fodder for fad diets.

One such critic is registered dietician Abby Langer, who was alarmed enough about discussions she saw about Candida overgrowth to write a critical post of it on her popular blog in 2020.

"Candida in the gut is real, but the prevalence is often overstated by people who want to sell something," Langer says. "This is a great example of how some providers or even just random people use fear to sell a product. Clearly, it's not something that a reputable professional should be doing."

Candida as Culprit: Debunking Misinformation

Those who know Candida best are happy the general public wants to know more about it; they just want its depiction to be accurate.

Among these experts is Mahmoud Ghannoum, PhD, who has spent several decades as a mycologist – someone who studies fungi -- trying to convince people of the importance of fungi in human health.

"I like people to think about fungus. But, I don't like them to think, 'Oh my God, Candida causes everything,' and to focus on the social media [aspects of the story], which are not real," says Ghannoum, director of the Center for Medical Mycology at Case Western Reserve University in Cleveland and author of Total Gut Balance: Fix Your Mycobiome Fast for Complete Digestive Wellness.

Ghannoum says there's plenty of data supporting Candida's role in various conditions, including recurring vaginal yeast infections, inflammatory bowel disease, Crohn's disease, and arthritis. However, the data is comparatively limited for some of the more opaque symptoms.

"As a cause of fatigue, brain fog, and those sorts of things, I don't think there's a lot of evidence," he said.

As researchers work to explain Candida's role in human health, it's important to remember that it largely functions as a positive force in our GI tracts, Ghannoum says.

"Having Candida in the gut at low levels can be beneficial for breaking down food, and the by-product is creating beneficial bacteria that helps symbiosis," he says.

Most humans' GI tracts get colonized with Candidaat or around birth. From an evolutionary perspective, Candida's presence may have educated our immune systems against infection from such organisms as Clostridioides difficile. Evidence from studies on mice suggests it may even have antitumor effects.

Critics argue that proponents of Candida diets and related products are having it both ways — exploiting its rare, but serious, clinical disorders, such as candidemia, to make a case that even its benign presentations are cause for concern.

"Candida in the blood is a life-threatening condition," Langer says. "If you had it, you wouldn't be walking around living your life; you'd be in the ICU."

The CDC estimates that 25,000 cases of candidemia occur every year. The most common treatment is antifungal medication, not dietary interventions.

Even rates of noninfectious Candida overgrowth are often overstated, according to Ghannoum.

Are These Diets Really a Cause for Concern?

The majority of the advice on The Candida Diet website, and in other popular Candida-focused programs, would likely find support among most clinicians.

"The Candida diet has a strong emphasis on removing processed foods, cutting added sugar, and increasing probiotic foods," Richards says. It also asks participants to abstain from alcohol and to rely heavily on fruits, vegetables, and lean proteins.

Unlike other common anti-inflammatory regimens, these diets advocate excluding certain grains like wheat. Richards cites evidence that gluten can negatively impact gut microbiome diversity as a reason for incorporating this element. However, other research suggests that the elimination of gluten has no value and can even be harmful in those without celiac disease or other known sensitivities.

If experts balk at some of the claims behind Candida overgrowth and diets meant to address it, they don't deny that studying its role in the gut is an area of promising research.

According to Ghannoum, Candida's ability to breach the gut barrier and cause a host of problems has been evident since at least the 1960s, when a German researcher ingested a test tube with this fungus and nearly died as a result.

More recently, researcher Carol Kumamoto, PhD, professor of molecular biology and microbiology at Tufts University in Boston, presented evidence that in some cases, Candida can migrate beyond the human GI tract and become an opportunistic danger elsewhere in the body.

"Studies show that the same strain of Candida can be detected in both the blood and the GI tract of patients, arguing that the infection arose from the strain that was colonizing the GI tract," Kumamoto said.

Decades spent studying Candida has taught Ghannoum to respect its destructive possibilities.

"It's an opportunistic organism, so you don't want to give it the tools to become even more so," he said. As such, he generally supports dietary interventions designed to reign it in.

"I'd like to encourage the growth of beneficial organisms and reduce the pathogenic ones. The diet that can lead to those end objectives is the way to go," he said.