Environmental Sensitivities and MCAS: A Look at Their Fascinating Link

Jill Carnahan, MD

Imagine simply strolling through the store or sitting down to eat at your favorite restaurant and then boom – you’re hit with a barrage of unpleasant symptoms seemingly out of nowhere. This is the frustrating reality for a growing number of people struggling with environmental sensitivities – an extreme sensitivity and exaggerated response to low levels of chemicals or other irritants in the environment.

This overblown reaction to environmental triggers can seem confusing and random at first glance. But as it turns out, this rambunctious response may be triggered by an underlying culprit that’s simply a little confused. This confused culprit I’m referring to is a type of immune cell known as a mast cell in a condition known as mast cell activation syndrome.

Today we’re going to look at exactly what environmental sensitivities are, what mast cell activation syndrome is, and explore the fascinating link between these two conditions. Let’s dive in.

What Does It Mean to Be Environmentally Sensitive?

What exactly does it mean to be environmentally sensitive? In simplest terms, environmental sensitivity occurs when you experience negative symptoms in response to low-level exposure to an irritant in your environment. A sensitivity to something in your environment can trigger a constellation of tricky to pinpoint, vague, and seemingly unrelated symptoms. Just a few symptoms that can be triggered by an environmental sensitivity include:^1,2

Brain fog, forgetfulness, memory problems
Headaches
Sensitivity to light, sound, and/or touch
Difficulty sleeping or changes in your sleep patterns
Mood changes, anxiety, and/or depression
Fatigue, muscle weakness, and/or joint pain
Respiratory issues like persistent allergy symptoms or recurring infections
Digestive problems such as diarrhea, constipation, nausea, and/or vomiting
Skin issues like itching, rashes, blotching, and/or redness

What’s worse is that exposure to environmental toxins and irritants that you’re sensitive to can significantly exacerbate other underlying conditions like:^1,2

Neurodegenerative diseases such as Alzheimer’s, dementia, and Parkinson’s
Metabolic disorders like Type 2 diabetes, metabolic syndrome, and obesity
Epilepsy and other seizure disorders
Mental conditions like depression and anxiety
Autoimmune diseases
Cancer
Digestive disorders like gut dysbiosis, food sensitivities, celiac disease, and leaky gut syndrome
Respiratory conditions such as allergies, asthma, and COPD (chronic obstructive pulmonary disease)
Skin conditions like eczema and psoriasis

So, what on earth can trigger such perplexing and potentially problematic symptoms in response to low-level environmental exposures?

What Causes Environmental Sensitivities?

Environmental sensitivities can be triggered by a wide variety of potential irritants that we’re all commonly exposed to. Just a handful of environmental triggers that you can become environmentally sensitive to include:²

Toxic chemicals that are rampant in our environments like BPA’s, PCB’s, and microplastics
Noxious ingredients found in our homes like volatile organic compounds (VOC’s), mold, and heavy metals (click here to learn more about toxic chemicals that can be lurking in your home)
Air pollution from dust, wildfire smoke, cigarettes, etc.
Hormones, pesticides, herbicides, and fertilizers found in food
EMF’s and microwave radiation

If you have an environmental sensitivity, seemingly insignificant exposures to certain irritants can cause explosive symptoms. While we still don’t completely understand why some people experience chemical sensitivities and extreme reactions to their environment, more and more research is indicating that it might have something to do with a type of immune cell known as mast cells.

What Are Mast Cells?

Mast cells are highly evolved and complex immune cells. Despite their typically sparse numbers and scattered distribution throughout your tissues, these tiny cells can have a monumental impact on your immune response. You see, mast cells serve as sentinels, laying in wait and guarding the perimeters of your skin and other organs.³

When a threat is perceived, your mast cells spring into action – instantaneously releasing a cocktail of inflammatory mediators. These initial pro-inflammatory mediators initiate the immune response and signal other immune cells to join the battle. As additional immune cells migrate to the site of the threat, your mast cells continue creating and secreting more mediators – essentially reloading their weapons and continuing the cycle of inflammation.⁴

Now in a normal, healthy response, mast cells’ ability to instantaneously and continuously release these mediators is highly valuable. But if this delicate dance between mast cell activation and subsequent deactivation gets thrown off-kilter, it can spell trouble for your health – potentially triggering a condition known as mast cell activation syndrome.

What Is Mast Cell Activation Syndrome (MCAS)?

Mast cell activation syndrome, or MCAS, is a condition that occurs when you have a normal amount of mast cells drifting around in your body, but they aren’t functioning quite right. In mast cell activation syndrome your mast cells become highly dramatic and overactive. They essentially trigger your immune system to go haywire – setting off an inflammatory response that can spread throughout your body.

Because MCAS sends your hypersensitive mast cells into overproduction mode in response to some kind of trigger, you’ll typically experience flare-ups followed by periods of normalcy. One of the hallmark signs of MCAS is a cyclical waxing and waning of symptoms with varying degrees of intensity depending on what exactly triggers your misbehaving mast cells.^5,6

Understanding this intense, often explosive, and exaggerated response may be the key to understanding the underlying root cause of environmental sensitivities.

Mast Cell Activation Syndrome (MCAS) and Environmental Sensitivities: What’s the Link?

Research is finding that there is a crucial link between mast cell malfunction and environmental sensitivities. You see, mast cells’ evolutionary past stretches back to our most ancient ancestors. But our modern-day lives are a far cry from the lives our ancestors lived.

In today’s world, we’re constantly bombarded with unprecedented levels of chemical contaminants. And it seems our mast cells may be having trouble keeping up with our evolving toxin-laden world – with our vast exposure to environmental toxins provoking our mast cells to go haywire and inappropriately release this plethora of inflammatory mediators.

Exposure to a concentrated dose of environmental toxins or chronic low-level exposure to these toxic compounds can spark a process known as toxicant-induced loss of tolerance or TILT. As your immune system is exposed to these disruptive toxins, its tolerance steadily decreases until a tipping point is reached – throwing your mast cell so off-kilter that they begin malfunctioning.^7,8

So, How Are Environmental Sensitivities and MCAS Treated?

While there is clearly a distinct relationship between mast cell activation syndrome and environmental sensitivities, the details of this relationship are still murky. But the good news is, there are some promising treatment options that can help alleviate and even heal both of these conditions.

The treatment strategies for these conditions are far too extensive to cover in this blog post. But I’ve written some in-depth articles that dive deeper into answering the question of how we address these complex conditions. You can check them out below:

While we don’t have all the answers yet, we have made great strides in understanding and treating these complex and intertwined imbalances.

Are You Struggling With Environmental Sensitivities or Unexplained Symptoms?

If you’re struggling with environmental sensitivities, mast cell activation syndrome, or are in the trenches trying to find a cause for your persistent, unexplained symptoms, you are not alone. While these perplexing conditions are not always well understood in conventional medicine, there is help and there is hope for healing.

These conditions can be life-altering and debilitating. So if you’ve been diagnosed with either of these conditions or are concerned you may be experiencing symptoms of these conditions, these articles are a good place to start. But navigating these conditions can be tricky and arduous, so I strongly encourage you to seek out the guidance of an experienced Integrative and Functional Medicine Practitioner. They can help you identify the root cause of your symptoms and work with you to create a personalized plan for healing.

As a Functional Medicine Doctor myself, I’m dedicated to empowering my patients and readers to tap into true healing – not just masking their symptoms – and creating a vibrantly healthy and happy life. So if you enjoyed this article and are looking for more ways to prioritize and optimize your health, I’ve got loads of helpful articles to help you do just that over on my blog. And if you want to take it deeper, you can sign up for my weekly newsletter by entering your name and email address in the form below.

* These statements have not been evaluated by the Food and Drug Administration. The product mentioned in this article are not intended to diagnose, treat, cure, or prevent any disease. The information in this article is not intended to replace any recommendations or relationship with your physician. Please review references sited at end of article for scientific support of any claims made.

References

Published June 15, 2024

About the Author

Jill C. Carnahan, MD, ABIHM, IFMCP, was dually board certified in Family Medicine in 2006-2016 and in Integrative Holistic Medicine since 2005. She founded the Methodist Center for Integrative Medicine in Peoria, Illinois in 2009 and worked there as medical director. Then in 2010, she moved to Boulder, Colorado and opened Flatiron Functional Medicine where she has a widely sought-after medical practice with a broad range of clinical service including nutritional consultations, chiropractic therapy, naturopathic medicine, acupuncture, and massage therapy.

Dr. Jill is survivor of both breast cancer and Crohn’s disease and passionate about teaching patients how to live well and thrive in the midst of complex and chronic illness. She is also a widely sought-after inspirational speaker and travels around the world to teach physicians the principles of personalized and functional medicine. She has been featured in Shape Magazine, Parade, Forbes, MindBodyGreen, First for Women, Townsend Letter, and the Huffington Post as well as seen on NBC News and Health segments with Joan Lunden. She recently published her prescriptive memoir, Unexpected: Finding Resilience Through Functional Medicine, Science, and Faith, was published in 2023.