The Flaws of Parasite Testing—and What To Do About It

Welcome to Healthy Gut Healthy Thyroid!

This is your weekly roundup of the BEST actionable steps for those people with thyroid and autoimmune thyroid conditions who want to restore their health…by healing their gut. Whether you have hyperthyroidism or Hashimoto’s you will benefit from the content in this newsletter.

In today's issue:

• Main Topic: The Flaws of Parasite Testing—and What To Do About It

• Podcast Review: What This New Graves’ Disease Study Reveals

• Ask Dr. Eric: Should You Heal Your Gut Before Supporting Detoxification?

The Flaws of Parasite Testing — and What To Do About It

There’s no shortage of controversy when it comes to parasites these days.

On the Save My Thyroid podcast, I’ve interviewed several experts—many with completely opposing views—on testing for and treating parasites. Some recommend aggressive treatment without testing, while others prefer a more cautious, data-driven approach.

Let’s take a closer look at the flaws of parasite testing, and what you can do about it if you suspect parasites may be affecting your gut health, thyroid function, or immune system.

Two Opposing Viewpoints: Test vs. Treat Everyone

I’ve had the pleasure of interviewing both Dr. Jason Hawrelak, a leading gut microbiome researcher, and Elizabeth Yarnell, an expert in autoimmune conditions. Their opinions on parasites couldn’t be more different:

Dr. Jason Hawrelak does not recommend treating everyone for parasites—and in some cases, even when a parasite shows up on testing, he may decide not to treat if it appears to be a non-pathogenic strain or if the overall clinical picture doesn’t warrant intervention.

Elizabeth Yarnell, on the other hand, takes a more aggressive stance: she treats every client for parasites regardless of testing, citing two key reasons:

Reason #1: False negatives are extremely common on stool tests.

Reason #2: Parasites may reside in tissues outside the gut, such as the liver, brain, and lymphatic system—making them difficult to detect via stool alone.

The Limitations of Stool Testing for Parasites

There’s no question that false negatives are possible with conventional and even functional stool tests. In fact, if comprehensive stool panels like the GI-MAP only tested for parasites, I likely wouldn’t recommend them.

That said, these tests offer a broad snapshot of gut health, including:

✅ Microbial diversity

✅ Opportunistic bacteria

✅ H. pylori

✅ Candida

✅ Digestive markers (e.g. elastase, secretory IgA)

✅ Inflammatory markers (e.g. calprotectin)

So while they aren’t perfect for parasite detection, they still offer tremendous value in clinical decision-making.

Do Parasites Live Outside the Gut?

Yes—there’s truth to the idea that some parasites can exist in extraintestinal locations. This includes organs like the liver, brain, and even the thyroid itself (although this is rare). However, this doesn’t mean that everyone should automatically undergo a parasite cleanse.

Remember, just because parasites can be elusive doesn’t mean aggressive cleansing is the best first step. Treatment should always be tailored to the individual.

3 Smart Options If You Suspect Parasites

If you’re concerned about parasites, here are three approaches to consider:

Option 1: Do Stool Testing—With a Twist. Even though parasite detection is imperfect, a comprehensive stool test can still be a great starting point—especially if you take steps to reduce false negatives.

🔬 Pro Tip: Consider taking a biofilm disruptor for 7–10 days before collecting your sample. According to biofilm expert Dr. Paul Anderson, disrupting the protective matrix surrounding pathogens can increase detection rates.

Examples of biofilm disruptors:

✔️ NAC (N-acetylcysteine) – also supports detoxification

✔️ Proteolytic enzymes (taken on an empty stomach)

✔️ Bismuth

This approach can make parasite testing more accurate without immediately jumping to aggressive treatment.

Option 2: Use a Parasite-Specific Lab. Although I commonly recommend a GI-MAP to my patients, if you want to focus solely on parasite detection, consider a lab that specializes in it.

🧪 Example: ParaWellness Research

Led by Dr. Raphael D’Angelo (a retired holistic MD with over 45 years of experience in medical microbiology and parasitology), ParaWellness uses:

✔️ Microscopic stool analysis with special stains

✔️ Urine testing

✔️ A broader approach than PCR-only labs

This can sometimes reveal infections that conventional or DNA-based tests might miss.

Option 3: Treat Without Testing. Some practitioners prefer to treat empirically, assuming that parasites are affecting everyone. This is the approach taken by Elizabeth Yarnell and others who believe that the risks of undiagnosed parasites outweigh the risks of treatment.

I don’t usually recommend this approach out of the gate, but I’m also not completely opposed to it—especially in persistent cases where symptoms aren’t improving despite dietary and lifestyle changes.

How I Approach Parasite Concerns

I usually start with Option #1 (comprehensive stool testing), especially if we’re still exploring possible root causes. If the test shows no parasites and symptoms persist, I’ll consider retesting or refer to ParaWellness.

In more stubborn cases, I may suggest a gentle antiparasitic protocol—even without a positive test—if the clinical picture strongly suggests a hidden infection.

It all comes down to clinical context, symptom severity, and the individual's history.

Conclusion

Parasite testing isn’t perfect. But there are still smart, evidence-based ways to investigate and address potential infections without going overboard.

Whether you choose to test, treat empirically, or work with a specialist lab, the key is to take a strategic and personalized approach that supports the gut, immune system, and thyroid—not just a one-size-fits-all cleanse

Find Your Hashimoto’s Triggers

If you have Hashimoto’s thyroiditis, visiting an endocrinologist is likely to result in a prescription for thyroid hormone replacement. And while there is a time and place for thyroid hormone, the problem is that it doesn’t do anything for the autoimmune component of Hashimoto’s.

And so what happens is that many people will take thyroid hormone without doing anything to improve the health of their immune system, which means that over time further damage to their thyroid gland will take place.

The good news is that you can do things to reverse the autoimmune component of Hashimoto’s. And the best way to accomplish this is by finding and removing your triggers.

My book “Hashimoto’s Triggers” will show you how to do this. By reading this book you will discover the following:

• More than one dozen triggers of Hashimoto’s thyroiditis

• The different diet options, and how to detect your specific food triggers

• Everything you need to know to heal your gut

• How to reduce fatigue, brain fog, hair loss, lose weight, and address other common symptoms

• Strategies to lower thyroid antibodies when nothing else has worked

• Nutritional supplements and herbs for Hashimoto’s

• A comprehensive list of the blood tests you should get, along with other specific tests that can help detect your triggers

• What you need to do to achieve optimal adrenal health

• Natural treatment options for viruses, pathogenic bacteria, parasites, Candida, and SIBO

Click Here to order the book “Hashimoto’s Triggers”

Save My Thyroid Podcast Review

I have a podcast called "Save My Thyroid", where I discuss how people with hyperthyroidism and Hashimoto's can save their thyroid and regain their health. And during each edition of this newsletter I'll briefly discuss a recent podcast episode.

In a recent podcast episode I discussed a new study related to Graves’ disease.

A 2025 research study looked at the combination of L-carnitine and selenium alongside methimazole, and the results were more encouraging than I expected.

In this episode I discuss how this combination may help lower thyroid antibodies, improve symptom control, and even reduce the total dosage of methimazole. I also share my clinical perspective when these nutrients might help, the specific dosages used for the study, and why we still need to look beyond supplements to address deeper triggers like stress, gut health, and environmental toxins.

Tune in to learn what this new research could mean for your own healing path.

Ask Dr. Eric

During every issue I'll answer a question or two that I think can benefit most people with a thyroid or autoimmune thyroid condition. If you'd like for me to consider your question for a future edition of this newsletter email your question to [email protected].

QUESTION: SHOULD YOU HEAL YOUR GUT BEFORE SUPPORTING DETOXIFICATION?

Dr. Eric, I was watching a YouTube video on gut healing and the speaker mentioned that you should heal your gut before supporting detoxification. Is this true?

Thanks for your question! Having a healthy gut is essential for optimal detoxification—but this doesn’t mean your gut must be fully healed before you begin supporting detox pathways.

In today’s world, we are constantly exposed to toxins and toxicants through our food, water, air, and environment, many of which negatively impact the gut microbiome. Realistically, no one has a perfectly functioning microbiome, and so it's important to understand the balance between gut repair and detoxification.

That said, if your gut is significantly compromised, it’s wise to proceed with caution. Aggressively detoxifying without first supporting gut function may backfire.

Why Your Gut Impacts Detoxification

The liver plays a central role in detoxification, converting toxins into water-soluble compounds that are excreted into bile. Bile then drains into the intestines, and toxins are eliminated through the feces.

If you’re not having at least one bowel movement per day, your detoxification system can’t function efficiently. Chronic constipation means toxins may be reabsorbed, rather than eliminated—potentially doing more harm than good.

Additionally, optimal nutrient absorption is essential for proper detoxification. If your digestion is impaired and you're not breaking down or absorbing key nutrients—like B vitamins, magnesium, and glutathione precursors—your detox pathways may be sluggish.

Gut Imbalances and Detox Burden

Research shows that gut dysbiosis (an imbalance of gut bacteria) increases circulating endotoxins and depletes glutathione, the body’s master antioxidant and detoxifier. Restoring gut balance improves liver function, bile flow, and the ability to eliminate xenobiotics (foreign chemical substances).

A helpful marker on comprehensive stool tests is beta-glucuronidase. Elevated levels can indicate that toxins and hormones are being recirculated instead of excreted—especially concerning if estrogen dominance or chemical overload is present.

If beta-glucuronidase is high, this doesn’t mean you can’t do anything to support detoxification. But it does suggest that aggressive detox programs should be paused until the gut has been sufficiently supported.

Additional Thyroid-Related Resources

Click Here for What This New Graves’ Disease Study Reveals (episode 221)

Click Here for Prebiotics, Probiotics and the Gut Microbiome with Dr. Jason Hawrelak (episode 95)

Click Here for Parasites and Thyroid Autoimmunity with Elizabeth Yarnell (episode 30)

Click Here to access hundreds of thyroid-related articles and blog posts

Click Here to join the Graves’ disease and Hashimoto’s community

Click Here to join the Healing Graves’ Naturally Skool group

Click Here to purchase one of Dr. Eric’s thyroid-related books

Click Here to work with Dr. Eric and his team

That’s a wrap