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Co-Infections as Signals of Heavy Metal Toxicity

Co-Infections as Signals of Heavy Metal Toxicity

Zack West

Candida albicans is an example of a microorganism common to the human microbiome. This opportunistic yeast stays in check among those with healthy lifestyles and healthy immune systems—a group whose numbers seem to be dwindling. Candida overgrowth can be a sign of many things but I’m here to make the case of it being a potential signal for heavy metal toxicity.

Candida, as well as many other microorganisms, absorb certain metals as part of their natural defensive systems to protect against things like anti-biotics, immune cells, and toxins like heavy metals. The overabundance of a single microorganism isn’t likely a functional endpoint for predicting heavy metal toxicity. However, several such bacteria with an affinity for particular metals might offer a collective endpoint for predicting heavy metal poisoning.


  • Microorganisms create biofilms to protect themselves
  • Biofilms often contain metallic minerals as structural components
  • In cases of toxic levels of metals, biofilms absorb those metals in higher percentages as part of their innate defensive strategy
  • Bioremediation is a process by which microorganisms tendency to bind to toxins is leveraged commercially to clean up environmental waste
  • The Gulf Oil Spill (thanks BP) of 2010 used bioremediation as part of the cleanup effort
  • The presence of multiple microorganisms with a known affinity for specific metals may collectively help signal heavy metal poisoning

Bioremediation & Heavy Metals

Bioremediation refers to the use of living organisms to remove toxins from an environment. A common application is the deliberate introduction of outside organisms into ocean waters following a chemical spill.

Maybe you remember the Deepwater Horizon oil spill of 2010 in the Gulf of Mexico? An estimated 210 million gallons of oil leaked into the Gulf of Mexico having dramatic effects on local ecosystems. Bioremediation ultimately became a pivotal strategy for helping clean that up.

Imagine your body like the Gulf of Mexico— with a hypothetical mercury poisoning as the oil spill. Candida is known to readily bind to environmental toxins to such a degree that they’re used as commercial bioremediation compounds (R)(R). Companies don’t use things that don’t work—at least not the companies that care to stay in business!

Biofilms & Defensive Strategies of Microorganisms

Most microorganisms form protective structures known as biofilms. These are like tiny bomb shelters in which many bacteria huddle together to protect themselves from things like antibiotics or immune cells. Acute doses of heavy metals are toxic to Candida, much like they’re toxic to us. Candida, as well as other microorganisms, can take action to prevent such toxicity by using the toxins in biofilm structures.

Candida has been observed as gradually absorbing certain heavy metals into biofilms in a protective manner (R). This type of protective absorption helps protect the candida from future exposure to heavy metals. Out in the world, this is observed in many tropical and oceanic regions where heavy metal contamination is common. Think volcanic eruptions, mining, and concentrated oceanic currents bring nasty things to the shores of paradise. Good for the study of environmental science—bad for vacationers.

In such cases, many Candida species are observed as becoming the predominant microbial species in these environments. Candida leverages biofilms to protect itself against the toxins to a higher degree than many other microbial species. This makes Candida albicans a more powerful competitor in the local environment, thus becoming a more prevalent member.

Heavy Metal Toxicity & Co-Infections

Defining certain microorganisms as “good” or “bad” is a complex task—Candida albicans is a prime example. It typically resides as part of a natural microbiome among those of us with healthy immune systems, balanced diets, and without underlying medical conditions. So—maybe not many of us after all!

Candida infections are more common among those with diets high in refined carbohydrates and sugars (R), having excessive antibiotic use (R), and especially those with medical implants (R). In such cases, Candida can out-compete more favorable bacteria for the market share of your body. My interpretation of most Candida-related literature led me to believe candidiasis resulted solely from Candida scarfing up more sugar than other bacteria.

Turns out, that’s not the case at all.

A recent study, developed following the toxic lead levels in the Flint, MI water, found that not only did lead alter the gut microbiome, but also affected many other vital metabolic pathways (R). Collectively, these could have prolific consequences on long term health. The trouble is when the symptoms are spotted before the underlying cause. What if doctors in Flint Michigan didn’t know a patient was at higher risk for lead poisoning?

Bioremediation highlights cases where populations of microorganisms grow at disproportionate rates relative to other bacteria, due to a failure of other bacteria to compete in toxic conditions. While hardly predictive in isolation, multiple pathogenic bacteria all possessing known affinity for specific metals may signal underlying toxicity.

In other words, a stool sample showing high levels of Klebsiella (R), Enterobacter (R), or Citrobacter (R) might be indicative of underlying manganese toxicity. Throw on IgG high levels for Candida albicans and you’ve got a diagnostic red flag.

Final Thoughts

It’s curious that many microbial species tend to appear as co-infections alongside chronic heavy metal toxicity. At least, I always thought it was curious. The ability of candida to develop defensive measures against such toxicity help explain why such species gain a larger prevalence compared to other bacteria.

In practice, I’d argue that anytime one tests positive for multiple pathogenic bacteria overgrowth that researching those species’ affinity for certain metallic compounds can help discover deeper issues. If your stool test came back positive for 6 pathogenic species and 4 are known bioremediative agents for mercury—it’s probably time to get tested for mercury poisoning!

Open Questions

  1. Could a systemic Candida albicans infection (Candidiasis) characterized by metal-absorbing biofilms cause a heavy-metals blood test to result positive? If so, would this be a false positive—or some kind of asterisk positive?
  2. Animal research suggests that Candida albicans is able to cross the blood-brain barrier (R). Could such affinity towards potentially-toxic metals contribute to a higher risk of neurotoxicity?