Blastocystis: What came first, anxiety or the parasite?

Being labelled as having IBS-A or IBS-M, you may believe that your anxiety is affecting your digestion… your anxious mind causes your muscles to tense and therefore affects gut motility. But dig a little deeper and you may find that your anxious mind is not to blame… the racing thoughts and middle of the night wakings could very well be a result of a blastocystis hominis infection.

Blastocystis hominis

Blastocystis species also referred to as “blasto” is endemic across Australia, but is also associated with recent overseas travel. For years it was considered to be a harmless yeast, however today it is considered a persistent parasite or protozoa (a microscopic single-cell non-bacterial organism).

Many types of protozoans are found within your gastrointestinal tract with some demonstrated to be beneficial. Unfortunately this is not the case for all, with some shown to cause disease.

Blastocystis is controversial amongst the medical community as the symptoms are varied – it is very possible to test positive to Blastocystis yet be considered asymptomatic. In which case it would it may be more harmful to treat them than it is to do nothing, as standard first line approach is triple-antibiotic therapy which not only doesn’t work in the majority of cases, but also comes with a long list of detrimental side-effects including nausea and vomiting.

From a Naturopath perspective, I would like to challenge the word asymptomatic and suggest that the client isn’t aware of what the symptoms are. Perhaps for them going to the toilet every few days then having diarrhoea may be normal as they’ve been like this for as long as they remember.  They wouldn’t mention it to their medical practitioner and would therefore be labelled as asymptomatic.

Ultimately Blastocystis hominis is a weak bully – they do their worst when your immune system is compromised and other harmful parasites, bacteria or fungus are active. When they have no buddies to back them up, they tend to back down and lay low. That’s why symptoms flare up and down during times of stress.

Symptoms vary and can be very unpredictable. If you’re unsure, always seek medical advice:

  • anxiety
  • mild persistent diarrhoea
  • allergic responses
  • skin issues
  • immune flare-ups
  • nausea
  • abdominal cramps
  • bloating
  • excessive gas (flatulence)
  • hives
  • loss of appetite
  • fatigue

Can you think back to a time when you had “travellers diarrhoea” and have never quite been the same again? Perhaps it’s time to get tested.


Experts believe the protozoa is transferred through oral-fecal contact. This can occur when a person doesn’t wash his or her hands thoroughly after using the toilet and before preparing food. The prevalence of blastocystis increases in places with inadequate sanitation and poor personal hygiene.


A Multiplex PCR stool test can be requested by a GP or Naturopath and will determine whether you have an active pathogenic parasite and bacterial infection. This is a simple home kit that gets sent to a lab for processing. The report will tell you whether you have any of the following:

  • Giardia intestinalis
  • Cryptosporidium species
  • Dientamoeba fragilis
  • Entamoeba histolytica
  • Blastocystis species
  • Campylobacter species
  • Salmonella species
  • Shigella species
  • Yersinia enterocolitica
  • Aeromonas species
  • Plesiomonas species


Standard medical treatment for immune compromised individuals triple-antibiotic therapy. How ever in the cases where the client is asymptomatic or only has mild symptoms, they are often recommended to do nothing. This is where coming to see a Naturopath is helpful…

There has been growing evidence and research into specific probiotic strains including Saccharomyces boularrdii and other natural food compounds on  eradication of the parasite including fat-digesting enzymes and high-strength antimicrobial herbs such as oregano, black walnut and garlic.

Additionally, Blastocystis is seen to be a “grain loving” parasite, therefore avoiding sugars and grains alongside a nutrient dense diet rich in pre-biotic fiber and pro-biotic cultures can help.

If you’re interested in discussing your case with Naturopath Sarah Claiden please don’t hesitate to reach out. Choose to meet either in clinic (or online thanks to FaceTime or Zoom) – click here to request an appointment.

Roberts, T., Bush, S., Ellis, J., Harkness, J., & Stark, D.

Sekar, U., & Shanthi, M. (2013). Blastocystis: Consensus of treatment and controversiesTropical Parasitology3(1), 35–39.

MayoClinic (2018). Blastocystis hominis infection.

Parasite Info (2010) Blastocystis hominis.


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