Healing the Gut

What the science really says about the trend of “gut healing”

This post is from my previous newsletter, Food Psych Weekly.

This week’s question is from a reader named Becks, who writes:

Hi Christy, I’ve been dealing with extreme Hashimoto’s thyroiditis symptoms for about a year now (think hair loss, gut issues that got diagnosed as IBS, daily hives/rashes, and rapid weight gain) and was diagnosed about 10 months ago. While my antibodies are slightly elevated, my thyroid is functioning great otherwise.

I have been in eating disorder recovery since 2019 (active ED 2011-2019) and when I listened to episode 175 I had this great epiphany that maybe all of the physical issues I’m experiencing right now are my body still recovering physically from my eating disorder. In 2019 when I started refeeding, I was also diagnosed with IBS but was told there’s no solution other than over-the-counter medications, and so I’ve been dealing with gut issues since then. However the hair loss, rapid weight gain, and skin issues that are new are being blamed on the Hashimoto’s.

I have a dietitian who has Hashimoto’s who says I should cut out gluten and dairy. I also have an endocrinologist who, after a G.I. MAP test, says my gut is suffering from small intestinal bacterial overgrowth (SIBO) and leaky gut, so they’ve prescribed a whole slew of supplements to heal my gut over the next eight months. The endocrinologist says that healing my gut is the first step to healing my Hashimoto’s.

I’ve listened to your podcasts where you answered other listener questions about elimination diets, leaky gut, and treatment with supplements (episodes 211 and 186), so I guess my question is, what does the science say about “healing the gut?” And can healing my relationship with food without any restriction help me to heal physically? I’m feeling at a loss because I can’t find any RDs or doctors in my area that are looking at me as a whole person and considering my eating disorder’s role in all of my current issues. I would so grateful to hear your thoughts, and thank you for doing what you do.

Thanks, Becks, for that great question. Before I answer, just my standard disclaimer:

These answers are for informational and educational purposes only, aren’t a substitute for individual medical or mental health advice, and don’t constitute a provider-patient relationship.

First of all, I’m so sorry you’ve gone through all of this. As you probably heard me say on the podcast, I also have Hashimoto’s (an autoimmune condition that causes the body to attack its own thyroid tissue, resulting in hypothyroidism) and IBS or irritable bowel syndrome (a diagnosis for recurring gastrointestinal issues that don’t have a known physical cause), along with several other chronic conditions. The symptoms of Hashimoto’s or IBS alone can be debilitating, and the combination of both is often extremely painful, so I really empathize with your situation.

I’m also glad you’re considering the role of your eating disorder and subsequent recovery in triggering or exacerbating these symptoms. While you said you’re no longer in an active eating disorder, I’m sure you know that it’s a long road to recovery that often winds through disordered-eating territory for a while, so it’s possible you’re still engaging in some low-level disordered behaviors that are contributing to your symptoms. Letting go of all remaining diet-culture restrictions definitely can be the key to healing those symptoms for many people.

But it sounds like the providers you’re working with aren’t helping you do that. It seems like both your dietitian and your endocrinologist don’t specialize in disordered eating and are giving you recommendations that would be highly triggering for anyone in recovery. What’s more, their recommendations aren’t evidence based, and that’s what I want to address first.

As I discussed in the Food Psych episodes you mentioned (episodes 211 and 186), there’s no good scientific support for cutting out gluten and dairy for Hashimoto’s, unless the person also has celiac disease (a condition in which people are genetically unable to process gluten, affecting around 1 percent of the general population but more common among people with other autoimmune disorders) or lactose intolerance. The research I mentioned in those episodes, as well as more recent research (CW: food- and weight-stigmatizing language, problematic wellness-culture terms), has shown that there simply is no good evidence to support going gluten-free for Hashimoto’s, despite the trendiness of that advice.

A few other red flags with your providers’ recommendations:

• There’s also no good reason to recommend a gluten-free diet for IBS, according to a 2018 systematic review and meta-analysis (CW: specific diets mentioned).

• “Leaky gut” is a problematic phrase and not an accepted medical diagnosis, as I discussed in this newsletter.

• There’s definitely not enough evidence for the claim that “healing your gut is the first step to healing your Hashimoto’s.” Although there is a recently recognized correlation between certain gut microbes and Hashimoto’s, there’s no evidence that gut bacteria cause the disease. Indeed, as the authors of the above-linked meta-analysis explain, it could be that autoimmune thyroid diseases cause changes in the gut microbiota, not the other way around. The medical community is a very long way from being able to make definitive pronouncements like your endocrinologist did.

That brings us to another big issue: the GI-MAP test you mention, which is super problematic.

Granted, testing for gastrointestinal pathogens can have some value, such as in cases of infection with germs or parasites that are well studied and well known to cause infections. But this specific test, the GI-MAP, also tests for many microbes that just aren’t well understood and shouldn’t be used to make diet or supplement recommendations.

Even more concerningly, the test is riddled with false positives, making it unhelpful for diagnosing anything. In a 2020 laboratory study (which used an effective but slightly gross method to see how accurate the test was), researchers collected human feces that didn’t contain any of the bacteria or parasites that the GI-MAP tests for, and used seven samples of that feces as controls. They then divided the rest of the microbe-free feces into 16 samples and “spiked” each one with one of the germs that the test looks for. The GI-MAP test missed 20  percent of the spiked samples, and it produced false positives for a whopping 74 percent of the samples—meaning it claimed to detect specific microbes where they weren’t present.

This huge false-positive rate makes me question your endocrinologist’s use of the GI-MAP test, their diagnosis of SIBO, and their prescription of supplements to “heal the gut.” It sounds likely that this endocrinologist is coming from the world of functional medicine (as most of the doctors I’ve seen recommend the GI-MAP test do), which doesn’t have sufficient scientific support. I’d definitely recommend seeking out a second opinion from an endocrinologist who is not an adherent of functional medicine, so that at least you’ll have a better chance of getting more evidence-based recommendations for treating your Hashimoto’s.

Speaking of second opinions, it sounds like you haven’t been able to find any local providers who understand disordered eating, and finding an endocrinologist who does is definitely a tall order. But there are quite a few dietitians who do specialize in disordered eating, and who work remotely—and they may be able to help coordinate care with a local endocrinologist who won’t push diets or rely on non-evidence-based approaches. If you’re able to, I really recommend continuing to look for a dietitian and endocrinologist who’ll take your eating-disorder history seriously, as time-consuming and frustrating as I know the search for new healthcare providers can be. You deserve to get quality care that supports your recovery, not detracts from it.

Finally, one last thing that struck me about your question is the ongoing hair loss and skin issues you mention. You say that although your antibodies are slightly elevated, your thyroid is functioning great otherwise. Yet having hair loss and daily rashes isn’ta sign of great thyroid function (if the cause of those symptoms is indeed your thyroid). I wonder if there could be something else going on for you, or if your Hashimoto’s simply isn’t adequately medicated because you’re working with a care team that pushes supplements as a first-line treatment, which isn’t evidence-based (though a few specific supplements may be helpful in addition to medication). So I’d really encourage you to seek out another endocrinologist who’ll give you the proper testing and medication quickly, rather than putting you on a months-long supplement regime that isn’t likely to help in the end anyway.

I hope that’s helpful in thinking through these issues, Becks, and thanks again for the great question.

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