Alyssa Luck

Polyvagal Theory: A Critical Appraisal

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Pressed for time? Jump to Summary and Conclusions.

Update 25 April 2023: Added section “”Asocial Reptiles” and “Social Mammals”: A False Dichotomy”.

If you’ve ever seen the terms “ventral vagal” or “dorsal vagal” outside of an advanced anatomy textbook, you’ve probably encountered polyvagal theory. This theory, introduced by psychologist Stephen Porges, makes specific claims about the evolution, anatomy, and physiology of the vagus nerve and autonomic regulation of the heart, and parlays those claims into hypotheses about the interplay between the autonomic nervous system and human psychology and sociality.

Polyvagal theory as an explanatory model, while receiving little to no acceptance in the fields of autonomic physiology or neurobiology, has become – dare I say – gospel in the communities of “trauma-informed” somatic and psychotherapy. (6, 7, 8)

Polyvagal theory also makes frequent appearances in communities that promote “rewiring” the autonomic nervous system as a way to treat illnesses such as chronic fatigue syndrome, POTS, and various autoimmune diseases.

I’ve even seen it in health and wellness spaces that aren’t focused on trauma or illness – for instance, on the Bulletproof YouTube channel, or in the Instagram posts of “pro-metabolic” nutrition influencers. It seems that polyvagal theory has become relevant for just about anyone interested in human health.

The comments below the Dave Asprey video give an idea of the enthusiasm and gratitude with which polyvagal theory is most often received by the public. However, the theory has been criticized by scientists, most notably psychosomatic researcher Paul Grossman.

The exchanges between these two researchers have been largely unproductive, and I suspect this is in large part due to the fact that Grossman is critiquing polyvagal theory purely at the level of biology, while Porges conceptualizes the theory primarily within the contexts of experimental psychophysiology or broadly integrative “mind-body” research. Thus, I propose that polyvagal theory and its attendant controversy cannot be understood through analysis at the level of biology alone.

As such, in this article I’ll provide a critique of polyvagal theory as biology, as a model for psychophysiology, and as a biopsychosocial framework. I also include two additional levels of analysis that reflect the sociocultural roles that polyvagal theory has taken on: as direction and justification for clinical therapies, and as an “illness myth.”

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Lymphatic Support for Ulcerative Colitis and Crohn’s Disease

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Yet another topic I’d like the time to delve more deeply into, but for now, I’ll share a couple references! I’m still new to this topic, so I’ll have more/better resources to share in the future, but for now, the main person I’m aware of who shares at length about the role of lymph in health is Perry Nickelston of Stop Chasing Pain. Leah from Lymph Love Club also shares interesting information (including the second reference below!).

Nikolakis et al. The Role of the Lymphatic System in the Pathogenesis and Treatment of Inflammatory Bowel Disease. Int J Mol Sci. 2022.

D’Aiessio et al. Targeting lymphatics in inflammatory bowel disease. Oncotarget. 2015.

Heart Rate Variability 101: What It Is, How It’s Measured, and Controversies in the Literature

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Updated September 26, 2022; text and figure added in Does HRV index autonomic tone?, and text added in Respiratory sinus arrhythmia.
Updated August 10, 2022; text added in “Measuring RSA” section.

Heart rate variability (HRV) is a fascinating metric. It’s been around for over a century in the clinical and research space, and has exploded in popularity both in research and household settings because it can be measured easily and noninvasively, providing a window into the complexities of physiological and psychological processes without perturbing the underlying systems. Athletes use it to optimize training and recovery, doctors use it to predict patient outcomes, and psychologists use it to measure a whole host of cognitive activities…yet still today, nobody seems to be able to agree on precisely what these measurements actually mean.

As I’ll explain below, HRV is not a single measurement but rather a biological phenomenon that can be quantified in a number of different ways, which one needs a fair bit of technical and mathematical expertise to correctly interpret. A thorough understanding of the physiology underlying HRV has lagged well behind enthusiasm for its potential, which has led to a number of very persistent misunderstandings and a glut of unhelpful or misleading research. Reading through recent reviews and editorials, you often get the sense that the experts in the field are sighing with exasperation at the fact that controversies that ought to have been laid to rest in the late 1990s are still alive and well today.

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Autonomic Nervous System 101: Anatomy and Physiology

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The autonomic nervous system (ANS) is responsible for controlling all of the unconscious (autonomous) functions of the body. These autonomous functions maintain internal homeostasis, and also prepare the body to support appropriate voluntary (ie, non-autonomous) responses to external stimuli.

As such, dysfunction in the ANS can contribute to problems maintaining internal homeostasis in general (including problems with digestion, heart rate, and blood pressure, among others), but also problems involving maladaptive responses to external stimuli.

Many levels of control and regulation ultimately feed into control of the ANS, so by no means is this “autonomous” system detached from conscious and voluntary thoughts and behaviors, but understanding the inner workings of the ANS is very helpful as a foundation for understanding the physiological regulatory processes of the body, including emotional and cognitive processes.

To that end, this article will provide a general overview of the structure and function of the ANS, and a brief discussion of some problems with the common “fight or flight” versus “rest and digest” dichotomy of ANS function.

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Vitamin A Detox Diet for Ulcerative Colitis and Crohn’s Disease

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I have not yet had time to delve as deeply into this theory as I’d like, so in a moment I’ll be directing you to other sources for your own exploration, but I wanted to give a brief introduction to the topic and a few of my own thoughts.

Back in 2014, a man named Grant Genereux (an engineer, unassociated with the science or medical fields) introduced a radical new hypothesis about the underlying cause of eczema, which he later expanded to include all autoimmune diseases and most other “diseases of Western civilization” as well: vitamin A toxicity. He even goes so far as to argue that vitamin A is not a vitamin at all, but a toxin.

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Brain Retraining: How to Choose a Program?

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Edit 30 November 2023: I just stumbled across a randomized controlled trial showing positive results from an “amygdala and insula retraining” intervention for long COVID. The paper was published this year, and links to other trials using the same program, plus some related research that looks interesting (like this paper). Would be a fun rabbit hole for anyone interested in nervous system/brain retraining.

“Brain retraining” has become an increasingly common approach to chronic illness. It’s especially popular for conditions like multiple chemical sensitivities, EMF sensitivity, chronic fatigue syndrome, fibromyalgia, and POTS, but people have had success with an enormous range of chronic mental and physical conditions, from depression and anxiety to IBD and other autoimmune disorders.

I’m a bit biased because this is where my focus currently is for my own health, but I do think brain/nervous system approaches are the missing piece for many with chronic illness, especially people who have tried every diet and supplement regimen under the sun and still haven’t seen much improvement.

The central ideal of these approaches is that it isn’t the environment that’s the problem – it’s the way your body is responding to it. Maladaptive response patterns can be conditioned into us in a number of different ways and at any point in our lives, but the common denominator is that the body has learned to operate from a “threatened” mode, rather than a “safe” mode. It’s not quite as simple as the classic dichotomous “fight or flight” vs. “rest and digest,” but that idea does roughly get at what’s going on.

The body does not heal efficiently when it feels threatened, so all these programs use various tools to teach the body that foods and social experiences and exercise and other environmental stimuli do not need to be defended against; that it is safe. (If this sounds a little intangible or pseudosciencey, I hear you – one of my current research goals is to bring some concreteness to these approaches!)

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Dynamic Neural Retraining System: Can DNRS Work for IBD?

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Summary: The Dynamic Neural Retraining System was created by Annie Hopper to heal herself from severe multiple chemical sensitivities (MCS), and since 2008 has been widely used by others with MCS and other “mysterious” chronic illnesses such as fibromyalgia, chronic fatigue syndrome, and even long-COVID, with seemingly miraculous results. The program is built upon the premise that at the root of all these illnesses is a maladaptive brain response to environmental stimuli, causing the body to react as if harmless stimuli are life-threatening. Although DNRS is not widely used or marketed for IBD, evidence indicates that maladaptive nervous system responses are likely a component of the disease, and at least one IBD patient has reported success using DNRS. Although DNRS is not designed with IBD patients in mind, the principles it teaches may very well be the missing piece for many people who have tried just about everything else.

This article is part of the IBD Index. Last updated on May 5, 2022.

The Dynamic Neural Retraining System, or DNRS, is one of those programs that appears to toe the line between “this is totally miraculous” and “this is total bullshit.” How could someone possibly go from, say, being wheelchair- and house-bound, and only able to eat a few foods, to being totally and completely healthy, just by doing some mental exercises?

It sounds like magic, but this is the promise of neuroplasticity. It’s not easy, but it’s powerful. And for many with ulcerative colitis or Crohn’s disease, it could be the missing piece – the reason that all of the drugs and diets and supplements haven’t worked, despite great effort and dedication.

Table of Contents:
What is DNRS?
How does DNRS work?
Do people with IBD have limbic system impairment?
Can DNRS work for ulcerative colitis or Crohn’s disease?
How much does DNRS cost? Is it worth it?
Helpful resources

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Ketone Supplements for Ulcerative Colitis and Crohn’s Disease

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Summary: There are a few mechanisms by which having elevated blood ketones could be therapeutic for IBD, and one case report demonstrated benefit of ketone salts in the context of a low-carb (but not ketogenic) diet for Crohn’s disease. Exogenous ketones can reliably elevate blood ketones as well as or better than a ketogenic diet, without the potential attendant downsides of such a diet. Ketone esters elevate blood ketone levels more than ketone salts, and may be better tolerated, but are also more expensive. MCT oil (particularly pure caprylic acid) can promote ketogenesis in the liver, but has a limited ability to do so compared to exogenous ketones. All of these supplements have various strengths and weaknesses and may be worth experimenting with for someone with IBD who is attempting to achieve therapeutic ketosis, whether in the context of a ketogenic diet or not.

This article is part of the IBD Index. Last updated on May 2, 2022.

In my (rather lengthy) article about the ketogenic diet, I discussed the background, risks, and potential benefits of a ketogenic diet in the context of IBD. Ketone supplements have become popular as both an adjunct to a ketogenic diet and as a way to get some of the benefits of ketone metabolism without the stringent dietary restrictions. But do they actually work? Are they safe? And are they worth trying if you have ulcerative colitis or Crohn’s disease?

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Ketogenic Diet for Ulcerative Colitis and Crohn’s Disease

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Summary: Ketogenic diets have exploded in popularity for weight loss and overall health optimization. While we are still sorely lacking in clinical research on ketogenic diets for IBD, there are a few compelling mechanisms – particularly modulating intestinal immunity and overcoming energy starvation in colonocytes – indicating that ketosis could be a helpful therapeutic strategy for some people. However, there are also some risks, with a potential increase in hydrogen sulfide production being a particular concern since hydrogen sulfide is often already elevated in people with IBD. Therapeutic effects of the diet are likely mediated both metabolically (by emulating fasting) and via the microbiome, but both of these mechanisms appear to be highly context-dependent, contributing to significant disparity in results across the existing literature on ketogenic diets in health and disease. In the context of IBD, my current assessment is that a strict ketogenic diet could be helpful as a short-term strategy for certain people, but is unlikely to be an optimal long-term strategy.

This article is part of the IBD Index. Last updated on April 27, 2022.

As the name would suggest, a ketogenic diet is a diet that promotes the metabolic state of ketosis. This is generally accomplished by consuming very few carbohydrates, a moderate amount of protein, and getting most calories from fat.

Note that I discuss the carnivore diet separately, because while a carnivore diet is necessarily ketogenic, its defining feature is the elimination of all plant foods, which is not necessary on a non-carnivore ketogenic diet.

For information about exogenous ketones (including brands), MCT oil, and some comments about breath vs. urine vs. blood testing for ketosis, check out my article on ketone supplementation.

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Carnivore Diet for Ulcerative Colitis and Crohn’s Disease

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Summary: The carnivore diet has become increasingly popular for everything from weight loss to general health, and many with IBD have reported miraculous results, including one written up and published as a case report. However, a strict carnivore diet (especially with our modern tastes) is not a tried and true strategy for humans: populations that have traditionally subsisted on mostly animal foods do still eat some plant foods, and usually have very specific dietary patterns that most modern carnivores don’t come close to replicating. A carnivore diet could absolutely still be worth trying for IBD, especially if nothing else has worked, but care should be taken to monitor for any issues related to hydrogen sulfide overproduction or metabolism and general health. Certain strategies, such as keeping the fat-to-protein ratio supportive of ketosis and including specific microbiome-supporting foods like cranberries, could help minimize risk and maximize chances of success.

This article is part of the IBD Index. Last updated on April 15, 2022.

The carnivore diet is like the sexier, more exciting cousin of the ketogenic diet (which I covered in the linked post). Rather than hewing to a certain macronutrient ratio, a carnivore diet simply eliminates any food that comes from a plant, only including foods that come from animals. This makes it far simpler to follow, and also more fun (if you’re the type of person who enjoys all the connotations of being a “carnivore” and feeling superior for eschewing lame plant foods).

Many people with IBD have reported miraculous results from adopting a carnivore diet, but many also claim that a stint of carnivore dieting ruined their health. So what are the considerations surrounding a carnivore diet in the context of IBD?

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