Vagus Nerve Support, Wearables and EMFs, Heart Rate Variability

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: Is Your Vagus Nerve Sabotaging Your Thyroid Health?

• Podcast Review: Is there a relationship between DHEA and thyroid health?

• Understand Your Tests: Understanding Heart Rate Variability

• Ask Dr. Eric: How much EMFs do wearable devices emit?

Is Your Vagus Nerve Sabotaging Your Thyroid?

Many people—including natural healthcare practitioners—overlook the critical role of the parasympathetic nervous system (PNS) in overall health. As one of two branches of the autonomic nervous system (the other being the sympathetic nervous system, or SNS), the PNS is responsible for the “rest and digest” response, while the SNS governs the “fight or flight” reaction.

Ideally, we should spend most of our time in a parasympathetic state, where healing, digestion, and recovery can occur. However, in today’s fast-paced world, it’s common for people to remain stuck in sympathetic dominance, which can have wide-ranging effects—including on thyroid and gut function.

The Vagus Nerve: A Parasympathetic Powerhouse

The vagus nerve is the primary nerve of the parasympathetic nervous system. It is the longest and most complex of the twelve cranial nerves and has far-reaching influence over multiple systems of the body, including the digestive, immune, and endocrine systems.

When it comes to thyroid health, the vagus nerve plays an indirect but important role. Although it doesn’t control the production or secretion of thyroid hormones, it influences the vasculature of the thyroid gland, helping to regulate blood flow and communication between the nervous and endocrine systems. Both the SNS and PNS innervate the thyroid, but the vagus nerve is the main parasympathetic pathway.

Vagus Nerve Dysfunction and Gut Health

If you dive into the research you’ll see a relationship between low vagal tone and gut-related conditions such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and small intestinal bacterial overgrowth (SIBO).¹ The vagus nerve also stimulates stomach acid secretion, which is essential for protein digestion, nutrient absorption, and protection against pathogens.

When chronic stress suppresses vagus nerve activity, stomach acid production may decline, resulting in hypochlorhydria, dysbiosis, and even intestinal permeability (leaky gut)—a key contributor to autoimmune conditions like Graves' disease and Hashimoto's thyroiditis.

How to Activate the Vagus Nerve and Support Thyroid Health

If you're looking to shift out of "fight or flight" mode and into a more parasympathetic state, focusing on vagus nerve stimulation is essential. Here are several science-backed ways to enhance vagal tone:

Mind-body practices: Incorporate deep breathing, meditation, yoga, or qigong for at least five minutes daily.

Gargling: Gargle vigorously with water for 2 minutes several times per day.

Singing out loud: Singing in the shower or car can engage the vocal cords and stimulate the vagus nerve.

Cold exposure: Try contrast showers—alternating hot and cold water—or finish your showers with 30 to 60 seconds of cold water to stimulate vagal tone.

Heart rate variability (HRV) training: Use biofeedback tools like HeartMath to increase HRV, an indirect marker of vagal function. A higher HRV reflects better adaptability and stronger parasympathetic activity.

Conclusion

Vagus nerve health plays a crucial role in both thyroid and gut function, making it an essential focus for anyone dealing with autoimmune conditions like Graves' disease or Hashimoto's. Chronic stress and poor vagal tone can lead to downstream effects, including low stomach acid, gut dysbiosis, and leaky gut—all of which may fuel autoimmunity.

The good news is that simple, daily practices like gargling, deep breathing, and cold exposure can improve vagal tone and restore balance to the autonomic nervous system. When the vagus nerve is functioning well, the body is better equipped to digest, detoxify, and defend itself—three vital functions for healing autoimmune thyroid conditions.

 Which Hyperthyroid Healing Diet Should You Follow?

There’s no single diet that everyone with hyperthyroidism should follow. Diet selection is a highly personal choice that must consider individual health conditions, lifestyle, and preferences.

In my book, The Hyperthyroid Healing Diet, I explore three different diets in detail, explaining what each involves and how you can start implementing the right one for you. This book will benefit those with Graves' disease, toxic multinodular goiter, and subclinical hyperthyroidism.

There is a lot of confusion when it comes to the foods people with hyperthyroidism should eat and which ones they should avoid, and the truth is that there isn’t a single diet that fits everyone perfectly. That’s why The Hyperthyroid Healing Diet doesn’t just focus on one diet, but instead gives multiple diet options, while at the same time guiding you towards the one most suitable for your situation and condition.

Note: those who purchase The Hyperthyroid Healing Diet will also gain access to the online resources, which includes dozens of recipes, checklists related to the different diet options, and a few bonus chapters not included in the book.

By reading this book you will discover the following:

✅ The ideal diet for Graves’ disease, toxic multinodular goiter, subacute thyroiditis, and subclinical hyperthyroidism

✅ Hidden sources of common allergens and other ingredients to avoid 3 ways to detect specific food triggers

✅ How much protein those with hyperthyroidism should consume on a daily basis

✅ The truth about food sources of iodine

✅ How to increase muscle mass and bone density

✅ What diet you should follow if you’re a vegan or vegetarian

✅ Addressing weight loss and weight gain concerns

✅ What you need to do to achieve optimal adrenal health How to optimize your adrenals, improve sleep quality and duration, and heal your gut

✅ And much, much more!

Click Here to Order the Hyperthyroid Healing Diet

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 Q & A podcast episode I answered the question “Is there a relationship between DHEA and Thyroid Health?” In this episode, we dive into the overlooked connection between DHEA and thyroid health—especially how it influences autoimmunity, adrenal function, and your body’s ability to regulate inflammation and stress. When I dealt with Graves’ disease I had low DHEA, and I also find this to be the case with a lot of my patients with hyperthyroidism and Hashimoto’s.

You’ll find out why low DHEA is so common in thyroid conditions, what silently depletes it, and the key things to know before considering supplementation. For anyone stuck in a cycle of symptoms or slow progress, this episode offers fresh insight into what your body might really be asking for. It’s the missing link you didn’t know you needed.

Tune in to discover how supporting this one hormone could change your thyroid health.

Understand Your Tests

Measuring Heart Rate Variability (HRV)

This week’s Understand Your Tests section will be a little different, as I won’t be focusing on blood or functional medicine tests, but instead will discuss how to measure heart rate variability. And unlike past issues of this newsletter there won’t be any images.

As I mentioned earlier, a healthy heart is characterized by greater variability in the time intervals between beats—a measurement known as heart rate variability (HRV). This variation is a powerful indicator of autonomic nervous system balance and overall well-being. In fact, research shows that reduced HRV is associated with a higher risk of cardiovascular disease, increased inflammation, stress-related disorders, and even premature mortality.^2,3

But how exactly can you measure HRV? Thanks to advancements in wearable technology and mobile apps, it's now easier than ever to track your HRV over time—both for general wellness and as a tool to monitor vagus nerve activity and recovery capacity.

Popular Devices for Measuring HRV

Here are some of the most widely used and trusted tools for measuring HRV:

HeartMath Inner Balance. HeartMath’s Inner Balance device uses an ear-clip sensor that connects to your smartphone. It not only tracks your HRV in real time but also guides you through biofeedback exercises like deep breathing and heart-focused meditation designed to increase HRV and resilience. I personally have been using the Inner Balance from HeartMath for many years.

✔️Ideal for stress reduction and nervous system training

✔️Offers visual coherence scores and breathing prompts

✔️Great for beginners wanting to improve vagal tone

Oura Ring. The Oura Ring is a sleek, compact wearable ring that tracks HRV during sleep, along with sleep quality, body temperature, and readiness scores.

✔️Provides detailed overnight HRV trends

✔️Offers daily "readiness" scores based on HRV, sleep, and recovery

✔️Particularly useful for those looking to optimize recovery and performance

WHOOP Strap. The WHOOP strap is a favorite among athletes and fitness enthusiasts. It provides continuous HRV tracking and uses this data to calculate strain, recovery, and sleep metrics.

✔️Offers 24/7 HRV data and personalized recovery scores

✔️Includes coaching insights to guide physical exertion and rest

✔️No screen – syncs with an app for streamlined data review

Apple Watch. The Apple Watch collects HRV data using the electrocardiogram (ECG) feature and through regular optical heart rate measurements.

✔️HRV data is stored in the Apple Health app

✔️Useful for spotting trends over time, especially if combined with third-party apps (like HRV4Training)

✔️Ideal for casual users already within the Apple ecosystem

Fitbit Devices. Many Fitbit smartwatches and trackers now support HRV tracking, especially during sleep.

✔️Accessible via Fitbit’s Health Metrics Dashboard

✔️Tracks overnight HRV to monitor stress, recovery, and autonomic balance

✔️Simple and user-friendly for beginners

Which HRV Device Do You Use?

If you're already tracking your HRV, I’d love to hear which device or app you’re using. There are always new technologies being developed, and I’m sure there are several tools I didn’t mention here. Your feedback may help others find the right HRV solution for their needs.

Ask Dr. Eric

During every issue I'll answer a few questions 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: CONCERNS WITH EMFS AND WEARABLE DEVICES

Dr. Eric, how much EMF exposure does one get when using wearable devices such as the oura ring or Apple watch?

Thanks for your question! EMFs are invisible areas of energy produced by electricity. They are classified into two types:

Low-frequency EMFs, such as those emitted by power lines and household appliances.

Radiofrequency EMFs, which are emitted by wireless devices like smartphones, tablets, and wearables.

Although EMFs are considered "non-ionizing" (meaning they don’t carry enough energy to break DNA bonds), some research suggests that prolonged, close-range exposure may disrupt cellular processes, increase oxidative stress, and interfere with sleep and circadian rhythms.

For a deeper dive, consider listening to my podcast interviews with EMF experts Lloyd Burrell and Nicolas Pineault, who explain the biological impact of EMF exposure and provide practical strategies for reducing it.

Wearable Devices and EMF Exposure

Wearables are becoming a staple in health optimization. They offer insights into sleep, heart rate, blood oxygen levels, body temperature, HRV (heart rate variability), and more. However, the trade-off may be continuous EMF exposure due to their wireless capabilities, Bluetooth connectivity, and proximity to the body.

Let’s review some of the most popular devices and the current concerns regarding EMFs:

Oura Ring

Functionality: Tracks sleep, temperature, HRV, readiness score, and activity.

EMF Concern: The Oura Ring has an airplane mode that allows users to sync the ring only when needed. In this mode, EMF exposure is minimal, making it one of the safer wearable options from an EMF standpoint.

Whoop Strap

Functionality: Offers detailed data on sleep, recovery, and strain. Designed for athletes and high-performers.

EMF Concern: Whoop transmits data continuously via Bluetooth. Currently, it does not offer an airplane mode. This means that EMF exposure is persistent unless the band is removed.

Apple Watch

Functionality: Tracks heart rate, activity, sleep, blood oxygen, ECG, and even enables calls/texts.

EMF Concern: The Apple Watch emits continuous RF radiation due to its cellular and Bluetooth capabilities. Even when not actively in use, it pings nearby devices to maintain a wireless connection. There is no true "off" mode unless the device is powered down completely.

Fitbit

Functionality: Measures heart rate, sleep, and steps; newer models also monitor oxygen saturation.

EMF Concern: Like the Apple Watch, most Fitbits use Bluetooth for continuous data transmission. Some models allow the Bluetooth signal to be turned off manually, although this can limit functionality.

How Much of a Concern Are EMFs from Wearables?

Current evidence suggests that low-level EMFs from wearables are far less potent than those from cell phones or Wi-Fi routers. However, proximity and duration matter.

Even low-level radiation may be problematic when in constant contact with sensitive areas of the body (e.g., wrist, fingers, or chest), especially during sleep when the body is meant to regenerate.

A 2024 review noted that while the EMF levels from most wearables are low, the long-term health implications are still unknown. The authors emphasized the importance of more research on chronic exposure and biological effects at close range.⁴

Tips to Reduce EMF Exposure from Wearables

Use Airplane Mode: Choose wearables that allow you to disable Bluetooth or sync manually.

Remove During Sleep: Consider removing your wearable at night to give your body a break from 24/7 EMF contact.

Alternate Hands or Wear Intermittently: Switch sides or reduce wearing time throughout the day.

Measure EMFs Yourself: Use an EMF meter to determine exposure levels from your specific device.

Optimize Your Environment: Turn off Wi-Fi and Bluetooth when not in use and avoid keeping wearables near your head (such as sleeping with an Apple Watch under your pillow).

Additional Thyroid-Related Resources

Click Here for Electronic Pollution and Thyroid Health with Lloyd Burrell (episode 73)

Click Here for The Hazards of Electronic Pollution with Nicolas Pineault (episode 137)

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

Click Here to work with Dr. Eric and his team

References:

(1) https://pmc.ncbi.nlm.nih.gov/articles/PMC5808284/ 

(2) https://pmc.ncbi.nlm.nih.gov/articles/PMC2587932/ 

(3) https://pubmed.ncbi.nlm.nih.gov/36243195/ 

(4) https://www.sciencedirect.com/science/article/pii/S2772671124000901

That’s a wrap