Blastocystis Hominis, H. Pylori, and Yeast Over Growth

Update: Not sure how I missed this, but a 2015 case study has just been submitted to a medical journal connecting Blastocystis hominis to Hashimoto’s! See reference #9 below for a link to the study to print and take to your doctor!

When I first set out to figure out the root cause of my Hashimoto’s, I took an inventory of all of my symptoms, in an effort to find an underlying connection. (I highly suggest that you make your own health timeline to help guide you as well).

Here’s a brief overview of my health history:

  • My health troubles started during my freshman year in undergrad, after catching “mono”, a common viral infection that is caused by the Epstein-Barr virus. Prior to this infection, I was a really bright eyed, bushy-tailed and energetic young woman.
  • The summer before I started college, I would wake up at 5:30am or 6am each morning so that I could go to the gym, before starting work at 8 or 9am in the pharmacy. I loved my job as a pharmacy technician, learning about the body and medications, and couldn’t wait to start my studies to become a pharmacist! I worked full time in the pharmacy, and spent each evening studying for the pharmacy technician certification. I was proud to be the youngest person in Illinois to become a certified pharmacy technician, even before starting college. I loved learning and being out in the world!
  • But all of that changed during my second semester in college. I became chronically exhausted. I often slept through my morning classes, and sometimes even slept through lunch and dinner. I once even slept through a mid-term exam. I found myself with a strange brain fog that made studying and even socializing a huge effort.
  • Needless to say, I didn’t do too well in college that semester. I came home the following summer feeling defeated. My parents were also really concerned as I was a shell of my former self. I slept until 2pm each day, was moody, and lost so much weight, people suspected that I had an eating disorder.
  • After much rest, I got somewhat better at the end of the summer, and went back to college. I focused all of my limited energy on my studies, and was eventually able to improve my GPA to be accepted into a competitive doctor of pharmacy program. While I never returned to my previous levels of energy, I learned to be more efficient, compensate and made sacrifices which allowed me to succeed in all of my classes.
  • A few years later, while in my first year of pharmacy school, I developed irritable bowel syndrome. A few years after that, anxiety attacks, acid reflux, allergies and hives. A year or so after, I began to experience acid brain fog, hair loss and joint pain. The fatigue persisted. A year later, I was diagnosed with Hashimoto’s.

Once I had the diagnosis, I began to spend a lot of time on research, as well as self-reflection and self-experimentation in an effort to overcome Hashimoto’s.

My symptoms and research kept leading me back to the gut…

I learned about the gut and autoimmune thyroid connection after reading the work of Dr. Alessio Fasano (my article on his work Gluten and Hashimoto’s). He has found that in order for autoimmune disease to develop, in addition to genes, a trigger and a leaky gut barrier must be present. Healing the leaky gut can put the autoimmune condition into remission. I eventually uncovered my personal leaky gut root causes and set out to educate people with thyroid disease about how to uncover theirs, in my Hashimoto’s patient guide.

I learned that I not only had food sensitivities and a lack of beneficial bacteria, but I also had gut infections: small bowel bacterial overgrowth, H Pylori, yeast overgrowth and Blastocystis hominis, a protozoan parasite.

I addressed these root causes, one by one, and saw an improvement in symptoms and reduction in antibodies with each intervention.

In working with clients over the past few years, I’ve noticed some similar patterns, that I’d like to share with you. Please note, these patterns are based on my own research and observations and may not be accepted by conventional physicians.

Hashimoto’s, Hives, IBS and Blastocystis Connection

  • People with Hashimoto’s are more likely to develop the skin condition chronic spontaneous urticaria, also known as chronic hives which is manifested by widespread, itchy and swollen skin rashes. These hives can be very distressful and they can seem to come up randomly. 42 scientific studies have linked Hashimoto’s with chronic hives!
  • People with Hashimoto’s are also more likely to develop irritable bowel syndrome. This condition can manifest as either diarrhea or constipation, and often shows up before the Hashimoto’s diagnosis.
  • Whenever I work with people with Hashimoto’s, I always recommend gut function testing. By far the most common parasite I’ve found in people with Hashimoto’s is Blastocystis hominis, or “Blasto”.

Many conventional physicians have regarded this parasite as a commensal organism (up to 20% of “healthy controls” may have Blasto without any symptoms), and will say that there is no need to treat it, however, multiple studies have implicated in irritable bowel syndrome (IBS) and chronic urticaria (hives), two conditions that are very commonly associated with Hashimoto’s.

Although I have not seen any research studies documenting this, I have found this parasite in a large subset of my clients with Hashimoto’s, especially in those who develop Epstein Barr Virus (EBV) in adulthood, then are “never quite the same”. This could be because EBV and other herpes viruses feed on the amino acid arginine, and thus can cause a depletion of this amino acid which normally suppresses Blastocystis hominis.

Blastocystis and Hives Connection

Blastocystis hominis is a common human intestinal parasite, and it may be present in up to 50% of people in developing countries. A study of 54 people in Egypt with chronic urticaria (hives) revealed that that Blastocystis hominis was found in 61% of them, while only 8% of the healthy controls had the parasite.

This parasite has been found in some asymptomatic carriers and researchers hypothesize that other factors can influence the pathogenicity of this parasite, such as the immune status of the host, parasite load, presence of gut imbalance or other factors that can influence the behavior of parasite.

Researchers have suggested that the amoeboid form of Blastocystis hominis is more infective that the protozoa form and that it can adhere better to gut cells, and interestingly, the Egyptian study found this form in 60.6% of the Blastocystis infected people with hives, while none of the Blastocystis infected controls had this form.

In a letter to the editors of the British Journal of Dermatology, Dr. Tilo Biedermann from the Ludwig-Maximillians University in Munich, Germany reported that urticaria and reactions to NSAIDs subsided after treating 10 subjects infected with Blastocystis with paromomycin 25 mg/kg for 10 days.

Another drug, called Alinia (nitazoxanide), is an FDA approved antiprotozoal for treating other parasites, has been helpful for eradicating Blastocystis hominis. The parasite has been shown to be highly resistant to Flagyl (metronidazole), the usual drug of choice.

A 2014 study found that almost 25% of people with chronic urticaria had Hashimoto’s, and thyroid suppression by levothyroxine can result in clinical remission of hives, however, I wonder if the medication is just masking the symptoms of the parasite.

Blastocystis and IBS Research Connection

Various studies, using many different methods for parasite identification, have found the prevalence rate of Blastocystis hominis to be between 13 to 73% of people with irritable bowel syndrome. As parasite detection methods are not 100% reliable (with many false negatives), these rates could be even higher. I recommend the GI Pathogen Screen with H. pylori Antigen-BioHealth KIT.

Blasto has been shown to cause dysbiosis and cause leaky gut, which predispose us to autoimmunity!

Much controversy is out about this protozoan. Some studies, namely from Thailand and Mexico suggest that this is a commensal (harmless) organism, thus doctors may be told that there is no need to treat it. However, studies from Europe, Australia and the mid-east have connected this pathogen to irritable bowel syndrome and chronic urticaria (hives), both of which are very common manifestations in the early stages of Hashimoto’s!

Studies have found that Blastocystis species of protozoa do not invade the colonic mucosa, but they do lead to disturbances of the barrier function and increased intestinal permeability, thus Blastocystis has been shown to cause leaky gut.  Blastocystis breaks down secretory IgA, the protective barrier and the immune system of its infected host.

Research has found that eradicating Blastocystis in urticaria and IBS often leads to the remission of both conditions. I’ve found that eradicating a Blastocystis infection in a person with Hashimoto’s often leads to a remission of Hashimoto’s, with an improvement in symptoms, a reduction in food sensitivities and a reduction in thyroid antibodies- I’ve discussed this connection in many of the interviews I’ve done in the last couple of years, including the Fall 2014 Hashimoto’s Institute summit. I was super excited to learn that a new paper has been published in a medical journal, detailing the case of a person who saw areduction in TSH and thyroid antibodies after the eradication of Blastocystis hominis.

Eradicating this infection has also helped many of my clients reduce their joint pain, eliminate or reduce their IBS symptoms, reduce their food sensitivities, reduce fatigue and reduce thyroid antibodies.


According to the Blastocystis Research Foundation, “Some patients are able to manage symptoms with an extensive exclusion diet, which may include exclusion of refined sugar, wheat, dairy products, rice, corn, carbonated drinks, tea, coffee, alcohol, and fruit.” Blastocystis can also cause carbohydrate intolerance. Sound familiar?

While diet can help to manage symptoms, it will not eradicate the pathogen. This parasite needs to be treated with antiprotozoal medications and/or herbs

I have seen the following protocols for eradicating Blastocystis hominis to work effectively:


1) Triple therapy used in Australia:  diloxanide furoate, trimethoprim/sulfamethoxazole and secnidazole*


2) Alinia for three days on, then off for two weeks, repeated twice*


Natural Treatment Options

3) The beneficial yeast Saccharomyces boulardii, taken twice per day for at least 30 days

4) The use of antiparasitic/anti-yeast herbs such as oil of oregano and berberine.


The key is to use these treatments long enough, or in a pulsed fashion to fully eradicate Blasto. Blasto can take on four different forms during its lifecycle, and some of the forms are resistant to treatment.

* Keep in mind that antiprotozoal medications can lead to a yeast overgrowth, and a treatment with anti-yeast herbs or a medication like Nystatin may be necessary to rebalance the gut.

Removing sensitizing foods and getting probiotics on board will also be very helpful for recovering from Blasto.


Often, Blastocystis co-occurs with H Pylori, another potential root cause/trigger of Hashimoto’s, some professionals will go as far as to treat a person for both infections when one or the other Is found.

What else causes leaky gut?

I always talk about how switching my diet was the best thing I ever did.  It was my first step into the root cause approach to health. I went gluten and dairy free, and this lifestyle change completely eliminated my acid reflux, bloating and irritable bowel syndrome. Within 3 months I no longer had symptoms of carpal tunnel, and saw a reduction in my thyroid antibodies as well. You can read about my articles aboutHashimoto’s and acid reflux and Hashimoto’s and dairy.

Some people with Hashimoto’s are able to completely reverse their condition just by going gluten and dairy free, and some see no improvement at all. Gluten and dairy are common leaky gut triggers, but there are many others.

I meet Steve Wright and Jordan Reasoner, two engineers, at a health conference in Florida last year. Both of them have had their fair share of gut problems. Steve struggled with IBS, while Jordan battled with many symptoms of celiac disease despite being on a gluten-free diet.

We discussed the importance of the gut in Hashimoto’s and I asked them if there was a way to share their knowledge with the thyroid community. They suggested that we do a joint webinar “How to Solve A Leaky Gut”, to share their insight into fixing the gut, as well as how they turned their own gut health struggles into helping people with their gut struggles.

We’re going to cover:

  • Why your digestion is often the root cause behind problems like brain fog, bad skin, hormone problems, food sensitivities, autoimmunity, and more
  • Your top digestive risk factor – what it means and how to fix it
  • The 19 triggers that ruin your digestion
  • The 3 step pleiotropic process to rebuild your gut
  • Specific anti-inflammatory foods to eat (and not eat) to stop suffering
  • 2 game changing supplements that can fix your digestive complaints tomorrow


Hope this information helps you on your journey!!

Your Thyroid Pharmacist,


By Dr. Izabella Wentz, Pharm D.