Stress and Your Heart-Brain-Axis

Dr. Shawn Talbott (Ph.D., CNS, LDN, FACSM, FACN, FAIS) has gone from triathlon struggler to gut-brain guru! With a Ph.D. in Nutritional Biochemistry, he's on a mission to boost everyday human performance through the power of natural solutions and the gut-brain axis.

A lot of people feel that stress is “inevitable” – we all experience it, it is all around us, and there is no way to avoid it.

While our exposure to stressful events might be somewhat out of our control and “guaranteed” these days, our response to stress is very much under our control.

I like to say that while we can’t really control the stress “out there” (our exposure to stress in the world around us) – we can absolutely control the stress “in here” (our response to stress – aka our “fight or flight” reaction).

You might find it interesting that a lot of our ability to control the stress that our brain experiences actually comes from our gut (our “2nd brain”) and our heart (our “3rd brain) – which are all connected to each other by the Vagus nerve and the immune system (which we refer to as the “axis”).

In this article – and the accompanying webinar video – we will cover how stress affects our heart (in honor of February – which is Heart Health Month) – and how we can naturally manage stress to help us feel and perform our best.

Why is Stress “Bad” (or is it)?

All of us have experienced “stress” in a number of different ways – including “psychological” stressors from our relationships, jobs, and finances – and from “physical” stressors such as narrowly avoiding a car crash, to jumping out of traffic, to the “good” stress of an intense workout. We’re also exposed (literally millions of times every day) to different types of “cellular” stressors related to imbalances in blood sugar balance (glycation), free radical exposure (oxidation), and cytokine signaling (inflammation) – all of which lead to an acceleration of the aging process.

All of these sources of stress are both “good” and “bad” – and the difference comes down to whether our exposure is short-term (“acute”) or long-term (“chronic”).

Acute stress is the type that appears and dissipates (like your weekly spin class) – while chronic stress is the type that appears and remains (like worrying every day about paying your bills).

During a stress response, there is an “activation” phase – where stress hormones (cortisol and catecholamines such as adrenaline/epinephrine), inflammatory signals (cytokines), energy molecules (glucose and free radicals), and physiological changes (blood pressure, heart rate, circulation, respiration, etc) all go up to get us into action.

Importantly, there us also a “recovery” phase to our stress response – where all of these stress-mediated changes go back “down” to normal to allow the body to recover, rebuild, and recuperate – and to actually come back stronger to better handle future stressors.

Unfortunately, we only experience this recovery phase when our stress is acute – we don’t have the recovery phase when our stress is chronic. During chronic stress, our exposure to cortisol, cytokines, glucose, free radicals, and all the rest is constant (think of it as always being “on”) – and that leads to cellular damage, tissue breakdown, and ultimately accelerated aging and increased diseases across every physical and mental parameter.

Even though these chronic stressors lead to damage in every cell in every part of our body, we are most likely to notice the earliest detrimental effects of stress in one (or all) of our “3 brains” – the 1st one in our head – the 2nd one in our gut – and the 3rd one in our heart.

Our last webinar talked about some new studies on “stress and your gut” – so today, we will focus on “stress and your heart” (I’m writing this on Feb 14 – Valentine’s Day).

How Chronic Stress Affects the Heart

  • Adrenal Hormones – your “fight-or-flight” hormones, including cortisol and catecholamines (adrenaline/epinephrine) – increase heart rate and blood pressure (adrenaline) while also elevating blood sugar, cholesterol, and triglycerides (cortisol), which can all physically damage the heart when prolonged.
  • Higher Inflammation – contributes to plaque buildup in the arteries – increasing the risk for coronary artery disease, heart attacks (myocardial infarction), abnormal heart rhythms (arrhythmias), and heart failure.
  • Poor Choices – we all know how we behave when we feel stressed – we’re more likely to smoke, drink too much, binge on comfort foods, skip our workouts, stay up too late scrolling Instagram, and generally say “F@#k it” to the healthy lifestyle that we know we should be doing instead.

Individualized Response

It’s important to understand that while science tells us that all chronic stress is “bad” – there is definitely an individualized experience of stress. What I mean by this is that different things stress out different people – and at the same time, different anti-stress solutions will appeal more or less to different people.

Using myself as an example, even though I understand that yoga can be wonderfully effective for reducing stress – it’s not really my thing – and I’d rather go for a run. Other people only want to run if they’re being chased – and would rather do a breathing exercise or vent to a friend or take a calming supplement. Different strokes for different folks – but luckily, we have lots of effective “anti-stress” approaches that can be good for our heart and all of our 3 brains.

“Wandering” Toward Stress Relief and Heart Health

The vagus nerve is one of the longest nerves in the body (number 2 – right behind the sciatic nerve) and the primary nerve of the parasympathetic nervous system (PNS – also referred to as the “Rest & Digest” part of our nervous system), which regulates many important body functions including mood, immune response, digestion, heart function, and many aspects of our stress response.

The vagus nerve gets its name from Latin (“vaga”) because it “wanders” (like a vagabond) from the brain to the heart, lungs, and gut. In fact, most (~90%) of the signals that it carries go “up” from the body to the brain – allowing our head-brain to receive information from our heart-brain and gut-brain. 

This communication “axis” is how the vagus nerve helps our brain monitor the rest of our body – but we can also modulate our vagal signals directly to help us regulate our stress response and help us shift out of “fight-or-flight” (SNS – sympathetic nervous system activation) and into “rest-and-digest” (PNS – parasympathetic nervous system activation). 

In fact, a great deal of our overexposure to chronic stress is due to being “stuck” in SNS activation (over-drive) and a poor ability to “down-shift” into PNS activation (relaxation).

Vagus Nerve Toning – Your New “Workout”

Just as we can train our muscles to become stronger – and our hearts to become more efficient – and our minds to become more flexible – we can also train our vagus nerve to enhance both mental fitness and physical performance. 

We think of “vagal tone” as both an indicator of our ability to cope with stress (resilience) and an overall marker for physical capacity, emotional regulation, and cognitive performance. Athletes with higher vagal tone can recover faster from hard workouts and are less likely to get sick/injured. People with demanding jobs and busy schedules are at a lower risk for depression, anxiety and burnout if they have higher vagal tone. Stimulating the vagus nerve has even been shown to increase cognitive function with improvements in memory and learning.

We can gauge vagal tone by tracking heart rate variability (HRV) – which reflects the millisecond-by-millisecond variation in time between individual heartbeats. In general, a higher HRV is “better” and indicates superior resilience across the entire Gut-Heart-Brain-Axis. HRV tends to drop as we age, when we’re stressed or depressed, before we get sick, when we’re sleep-deprived, and many other situations – and thus can be used as an “early warning signal” and an overall “systems check” for our body-mind-balance.

It sounds complicated, but it’s actually quite simple because if you have a WHOOP band, an Oura ring, or almost any smartwatch like an Apple watch, you’re already measuring HRV as an indicator of your overall “stress index” (or something similar, depending on your device). In our research studies, we use a “Heartmath” device that calculates HRV in a few different ways (heart rhythms and brain waves) and is sensitive enough to pick up changes in HRV in response to different interventions such as exercise, sleep, supplements, cold exposure, deep breathing, and other approaches to “toning” or “training” the vagus nerve.

People with higher HRV (indicating higher vagal tone) are at reduced risk for heart attacks and depression, and have lower indices of inflammation, oxidative stress, glycation (blood sugar imbalances). They might even live longer and better because higher HRV is related to a reduced risk of frailty with aging.

How to (easily) Increase HRV and Vagal Tone

Get a Massage – physical pressure (such as a neck massage) can stimulate the vagus nerve and stimulate the release of pain-releiving endorphins, stress-reducing endocannabinoids, and human-connecting oxytocin. No wonder a good massage leaves us feeling not only relaxed, but also calm and generally chill – it manually moves us out of SNS and into PNS activation.

Get the Right Vibes – monks have used mantras and chants for centuries to induce a state of calm by stimulating the vagus nerve with vibrations and contractions from the diaphragm and vocal cords. If “omming” is not your thing, then you can achieve the same effect with laughing, singing, humming, and deep breathing (because the vagus nerve innervates the vocal cords, diaphragm, and lungs). Interesting note – just a couple of days ago (Feb 9, 2024), a new study showed how Tai Chi (a series of slow gentle movements aligned with meditation) can reduce blood pressure even better than an exercise-only program, probably because of the body-mind combination of physical movement and mindfulness (

Jump in a Lake (as long as it’s cold) – the recent social-media trend of recoding your cold-plunges is actually backed by some emerging science where splashing cold water on your face, taking a cold shower, or submerging your whole body in a cold bath stimulates the vagus nerve. Try a 2-minute cold plunge (at around 40-50 degrees F) and you might never go back because the post-plunge sensations of resilience and calm-energy are almost addictive.

Embrace Hunger (temporarily) – because the vagus nerve is a hard-wired connection from the gut to the brain, anything that happens in the gut is transmitted instantaneously to the brain. This means that the brain knows when you eat – and what you eat – and also when you don’t eat – and some of those signals are related to vagal tone. Studies of intermittent fasting (IF – sometimes called “time-restricted eating”) have shown that a “16/8” pattern of eating (16-hour fast from 8pm-Noon the next day with an 8-hour eating window from Noon-8pm) can increase HRV (it is also good for your microbiome – but that is another story) – especially when compared to a high-calorie diet high in processed foods (which reduces HRV and thus can be viewed as a “stress” on the body). That said, “your results may vary” when it comes to IF – some people love it and thrive on it – and other people just feel awful when trying it. Personally, I practice IF about half the time (like right now while I’m writing), but sometimes will eat breakfast pretty soon after waking up (such as when I have a morning workout).

Supplement for Stress Resilience – sometimes, the most direct, effective, and impactful way to reduce stress and improve HRV is with a research-supported dietary supplement. Luckily, we have a number of options to choose from. Omega-3 fatty acids (“omega-3s”), particularly EPA/DHA from fish oil and fatty fish (salmon, mackerel, bluefish, sardines, anchovies, etc) can boost HRV and vagal tone (especially in pregnant women). An even more effective approach is the patented combination ( of palm fruit and astaxanthin (a reddish carotenoid from algae – it’s what makes salmon pink) that can increase HRV by ~20% and improve both mental and physical performance (better mood, higher energy, and enhanced exercise performance). I have that blend in my MentaHeart formula at Amare (

So there you have it – stress is bad for our entire Gut-Heart-Brain-Axis, but there are lots of simple and effective natural approaches that we can use to improve our stress resilience, boost our mood, and enhance our heart health.

Happy Valentine’s Day!


  • The Vagus Nerve Can Predict and Possibly Modulate Non-Communicable Chronic Diseases: Introducing a Neuroimmunological Paradigm to Public Health. J Clin Med. 2018 Oct 19;7(10):371. doi: 10.3390/jcm7100371.
  • Standardized massage interventions as protocols for the induction of psychophysiological relaxation in the laboratory: a block randomized, controlled trial. Sci Rep. 2020 Sep 8;10(1):14774. doi: 10.1038/s41598-020-71173-w 
  • The Effect of Cold Application to the Lateral Neck Area on Peripheral Vascular Access Pain: A Randomised Controlled Study. Journal of Clinical Medicine, 12(19). (2023)
  • Short-term fasting induced changes in HRV are associated with interoceptive accuracy: Evidence from two independent within-subjects studies. Physiology & Behavior, 241, 113558. (2021)
  • Dietary fish and omega-3 fatty acid consumption and heart rate variability in US adults. Circulation. 2008 Mar 4;117(9):1130-7. doi:10.1161/CIRCULATIONAHA.107.732826
About the Author

Exercise physiologist (MS, UMass Amherst) and Nutritional Biochemist (PhD, Rutgers) who studies how lifestyle influences our biochemistry, psychology and behavior - which kind of makes me a "Psycho-Nutritionist"?!?!

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