Introduction

Izabella Wentz is a pharmacist and the founder of Thyroid Pharmacist, best known for her work helping people get Hashimoto's into remission. In this episode, she joins me to talk about her newest book, IBS: Finding and Treating the Root Cause of Irritable Bowel Syndrome — and the deep, often overlooked connection between gut health, IBS, and autoimmune disease.

Episode Highlights

From IBS Diagnosis to Hashimoto's — and Why She Didn't Take It Seriously at First

Izabella shares how she was diagnosed with IBS during pharmacy school and told it was just stress — so she largely ignored it. Years later, a cascade of new symptoms led to a Hashimoto's diagnosis, which finally pushed her to dig deeper into what was really going on.

• She was diagnosed with IBS in pharmacy school, experiencing urgent diarrhea and even carrying a change of clothes and Imodium to get through her day
• Her doctor attributed it to the stress of graduate school and offered no real solutions
• Over time she developed anxiety, panic attacks, hair loss, carpal tunnel, acid reflux, chronic fatigue, and more
• About six years after the IBS diagnosis, she received a Hashimoto's thyroiditis diagnosis — which became the turning point that made her take her health seriously
• Getting her IBS under control turned out to be one of the first steps in healing her Hashimoto's

The Gut-Autoimmunity Connection Most Doctors Miss

IBS isn't just a digestive inconvenience — it can be an early warning sign that the gut barrier is breaking down, which is one of the three required conditions for an autoimmune disease to develop.

• Three things must be present for autoimmunity to develop: genetic predisposition, a triggering event, and intestinal permeability (leaky gut)
• We can't change our genes, and we can't always remove triggers — but we can always work on gut health
• Research suggests the gut barrier begins breaking down 5–15 years before an autoimmune condition manifests
• Treating the gut can improve not just digestive symptoms, but also anxiety, depression, fibromyalgia, and various autoimmune conditions
• Many people with one autoimmune condition go on to develop others — addressing gut permeability may help break that cycle

Why Functional Gut Testing Changes Everything

Conventional medicine often writes off IBS as untestable, but functional medicine has changed that. A 2011 report found that 98% of IBS-diarrhea cases had identifiable and treatable causes — when someone actually looked for them.

• IBS is considered a "diagnosis of exclusion" in conventional medicine, and most standard scopes won't find anything if the issue is functional rather than structural
• A colonoscopy is still important to rule out inflammatory bowel disease (IBD), which is sometimes misdiagnosed as IBS
• Dr. Habba's 2011 report found identifiable, treatable causes in 98% of IBS-diarrhea patients — versus less than 25% improvement with standard conventional treatment
• Izabella's preferred stool tests: Gut Zoomer and GI-MAP for a broad look at pathogens and markers; Parawellness Research for a more specialized focus on parasites
• Functional tests can also identify inflammation markers like calprotectin and pathogens linked to higher rates of colorectal cancer, such as H. pylori, Giardia, and Blastocystis hominis

Pharmaceuticals vs. Herbs — Why Matching Treatment to the Infection Matters More Than Choosing "Natural"

In functional medicine circles, herbs are often assumed to be the safer or better option. But Izabella makes the case that matching your treatment to your specific infection matters far more than choosing natural over pharmaceutical.

• "Every bug has a drug" — the right treatment depends entirely on what's actually present
• Some infections clear within three days on a pharmaceutical but may require 60+ days of herbal treatment
• Popular parasite cleanses and protocols can seem helpful but still leave underlying infections untreated
• Research exists on which herbal remedies are effective against which specific pathogens — it's not one-size-fits-all
• Herbal treatments aren't automatically safe for everyone; working with a knowledgeable provider is important

Dietary Triggers: What to Avoid When You Have IBS or Autoimmunity

Certain foods and additives consistently show up as gut disruptors, and removing them is often one of the first steps toward real relief — especially when you understand why they cause problems in the first place.

• Food additives and non-caloric sweeteners like sucralose/Splenda have been shown to trigger Hashimoto's; removing them can support remission
• Erythritol — found in many "healthy" keto products — can irritate the gut lining and trigger both IBS and IBD
• Gluten is a major trigger: up to 25% of people labeled with IBS may actually have celiac disease; others may react due to non-celiac gluten sensitivity, fructan sensitivity, SIBO, or systemic nickel sensitivity
• Dairy is another common culprit for both IBS and autoimmunity
• Raw, fibrous vegetables or high-fat foods can be difficult to digest for some — not because they're inherently bad, but because the gut needs more support
• The goal isn't permanent restriction — it's to identify root causes so you can eventually eat a fuller range of foods

SIBO: Why It Keeps Coming Back (and What's Really Driving It)

Small intestinal bacterial overgrowth is often treated as the root cause of IBS — but Izabella explains it's frequently a downstream result of something else entirely. Treating SIBO without addressing what's driving it means it almost always comes back.

• SIBO is present in roughly 50–70% of people with IBS and about 50% of people with hypothyroidism
• Upstream drivers include: hypothyroidism (slows gut motility), low gut muscle tone, deficiencies in carnitine, choline, or thiamine, gastroparesis, H. pylori infection (which suppresses stomach acid), and possibly parasitic infections that disrupt the ileocecal valve
• Treating SIBO with antimicrobials without fixing the underlying cause typically leads to recurrence
• The potential connection between GLP-1 agonists (which slow motility) and rising SIBO rates is worth watching as more data emerges

Izabella's Husband Got UC — and Into Remission in Under 8 Weeks

Izabella's husband Michael was diagnosed with ulcerative colitis right after the birth of their first child. Using a combination of functional medicine strategies and guidance from experts in their network, he got into remission within eight weeks and has stayed there for nearly eight years.

• Michael had subtle symptoms for a few years before diagnosis — digestive issues, bloating, body pain, irritability, and sleep disruption — but nothing that pointed clearly to IBD
• A colonoscopy confirmed ulcerative colitis; the family pursued both conventional medications and a functional medicine protocol simultaneously
• The protocol included Debbie Steinbach's squish and mushy diet and partial elemental diet approach, high-dose turmeric and anti-inflammatories, low-dose naltrexone, Boswellia, and serum-based immunoglobulins
• Things that can aggravate IBD — especially early in the healing process — include high-dose probiotics, berberine, erythritol, and some potent herbs
• Up to 10% of people labeled with IBS may actually have IBD — getting the right diagnosis is critical

Notable Quotes from this Episode

If you have an autoimmune condition, there's a good chance that you have that intestinal permeability piece. And in many cases, treating the gut can help not just those digestive symptoms, but it can also help a lot of the co-occurring conditions — from anxiety and depression to fibromyalgia to various types of autoimmune conditions.
Izabella Wentz

98% of people with IBS diarrhea had identifiable and treatable causes. That means 98% of the time he could figure out what was driving their IBS and treat it accordingly. Whereas the conventional medical approach that doesn't do any testing, less than 25% of people actually feel better.
Izabella Wentz

My goal for people is not to just be on an ice cube only diet and not to be fasting all day to feel better. My goal is to figure out what's triggering your symptoms — and yes, it could be foods, but some of these issues have driving factors behind them.
Izabella Wentz

Eat in a relaxed state. If you are stressed out when you're eating, there's a good chance that you're not going to digest your food properly — and potentially whatever microbes are in that food, you're not going to neutralize them with your stomach acid because stress reduces your stomach acid.
Izabella Wentz