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Why Food Sensitivities Can Be a Moving Target

Science Grade:

Do you have food sensitivities but don’t have a good handle on what you can and can’t eat because the reactions seem to always be changing?

This blog is for you.

One of the major issues those of us who can be prone to food sensitivity face is how to deal with social situations. You know that a cup of coffee, or a piece of cake, citrus fruit, cheese or whatever the offending food may be, will affect you differently than your friends and family, but it can be hard to get those closest to you to “buy in” and respect your culinary boundaries, especially when those boundaries are ever shifting.

Food sensitivity that stays in a state of flux is enough to make you doubt yourself and draw the ire of family members who don’t understand how a food you didn’t eat 6 month ago is now on your approved list. It’s one thing when you can draw a consistent line with an easy to understand food group, gluten being a great example. If you simply explain that you are on a gluten free diet and then stick with it, most reasonable people can get on board. However, when the list seems to be constantly growing and evolving, with a food you didn’t eat last month now back on the menu, things get frustrating.

My Experience With Food Sensitivity

I never would have guessed just how confounding food sensitivity could be until I moved to Austin, Texas.

I’ve written previously about my battle with histamine intolerance after arriving in Texas and have also published blogs on the link between anxiety and allergy as well as a list of strange conditions caused by allergy. It wasn’t until I saw first hand just how much living in Texas could cause reactions to food that I realized what some people go through with food sensitivity on a daily basis. I thank God that I am one of the “mild cases,” and that I was able to gain some degree of insight I can share with others.

So, let’s say you are someone who is reacting to a food one day, but feel fine eating it a month or two later. What gives? Why do your reactions to food seem to change with the wind?

First, some food sensitivity housekeeping. I want to start out by saying that I do believe elimination diets, which are the gold standard for identifying problems with food, can be helpful. Taking the step of doing an elimination diet is an important one. But, I also believe that food sensitivities are not set in stone. I think many issues with food are caused by harm to the gut coupled with an inability to tolerate certain physical environments. Elimination diets don’t usually focus on why a food is a problem in the first place.

There are some foods that certain people just can’t tolerate under any circumstances. For example, if you have elevated tissue transglutaminase antibodies you are likely sensitive to gluten, and that is unlikely to change over time. The same can be said for foods that elicit an “IgE reaction,” which is the hallmark of traditional allergic response. These are the foods you will have a problem with on a skin prick test delivered by an allergist. So, there are foods that will be a no go at all times. However, emerging research on the immune system, and specifically a class of cells called mast cells gives us clues into the shifting landscape of food sensitivity.

For example, when mast cells “degranulate” they release histamine and other inflammatory compounds called cytokines. Histamine relaxes blood vessels so the cytokines can get where they need to go to destroy what the body perceives as invaders.1 This is a great system for killing viruses.

But what if there was a foreign invader present in the environment at all times which keeps the immune system on high alert, meaning mast cells are spinning off their cocktail of goodies on a continuous loop?

When the body is in such a state, small additional insults, such as foods that contain histamine, or a man made toxin like glyphosate, push the immune system even further and the result is a sensitivity. When I lived in Austin, I lost a ton of weight and felt like I couldn’t eat anything. It was as if any food I tried wouldn’t agree with me, including supplements. When I left Austin, my symptoms went away, literally within a day. For example, an experiment I did with Lion’s Mane. Sitting in the Bay Area, where I was free of the brain fog, fatigue and general low energy moods I would get in Austin, especially on rainy days, I took Lion’s Mane. Amazing supplement. I felt great, clear. Now get me back to Austin where I take the exact same supplement at the same dose. Terrible and scary reaction, with my arm starting to itch and tingle.

Why the difference?

Lion’s mane increases the release of nerve growth factor, a chemical also released by mast cells when they degranulate.2 In California, with my immune system quieted down, the supplement presents no problems, but get me back to Texas, a place where I have severe allergies, and boom, I get a reaction as my NGF and histamine levels tip over a threshold my body can handle.

Location, Food Sensitivity and Mast Cells

Dr. Janice Joneja has written eloquently about this phenomenon in the context of histamine intolerance, explaining that patients with seasonal allergies can react to a food during pollen season that they never would have had a problem with when their allergic response was dormant. The combination of the histamine from the food plus the antigen rich environment puts them over the edge and into symptom territory. Their mast cells were too active to take on any additional small stress in the form of food. It’s worth noting here that the “cross reactivity” of certain foods with allergy to pollen is well documented. When a patient with a traditional IgE allergy experiences symptoms, they can become more sensitive to certain foods with proteins that body recognizes as similar to the “canonical” allergen.3

Consider this statement from the review Cross Reactivity Between Aeroallergens and Food Allergens:

Regarding the birch-fruit-vegetable-syndrome, about 70% of birch pollen-allergic patients develop symptoms of allergy to plant foods, most frequently involved being Rosaceae fruits (mainly apple), nuts (especially hazelnut), and vegetables from the Apiaceae family (mainly celery and carrot).

So, an allergy to birch pollen induces a sensitivity to some of the healthiest plant foods. I find this utterly fascinating. In essence, what you have is a food sensitivity that develops downstream of an insult to the mast cells that makes them hyper vigilant against a new “pseudo antigen.” Take away the state of high alert for the mast cells and you take away the food sensitivity. This means that in sensitive people, food sensitivity will fluctuate based on how “wired” their mast cells are.

These quotes from Dr. Neil Nathan’s new book Toxic are also instructive:

When mast cells become overly reactive, they lose the specificity of their response and can start reacting to ordinary stimuli that normally would not engage their attention.

Reactions to foods caused by mast cell activation depend greatly on the state of activation. During a flare up, virtually any food can cause a reaction, and during a dormant period, the same food may be well tolerated.

So, the key for each individual is to identify some of the core problems that activate mast cells and lead to food sensitivity. When these triggering events are removed, some people will see their food issues go away.

Causes of heightened immune response leading to shifting food sensitivity


Some people get very ill when they have been exposed to mold. Mold toxins are both lipophilic and hydrophilic, meaning they can travel through water and fat. This allows them to travel freely throughout the body. When a fungus has colonized the body, it releases toxins into the system which trigger a response from the immune system, whose job it is to kill the invader. However, fungal invaders are clever and they build protective cocoons called biofilms, which allow for the survival of the fungal colony.4 The result is the constant release of bad stuff like acetaldehyde, which taxes the liver and continues to excite the immune system.5 Now, with mast cells on red alert, they develop a “trigger finger,” reacting to the slightest provocation, including foods you used to eat with no problem.

Seasonal Allergy

Same principle at work here. Acetaldehyde, and presumably all sorts of other mold toxins, induce a reaction from mast cells. But so does plain old allergy. The impact of allergic triggers on mast cells is well known, and here’s the kicker: some of the molds that are recognized as dangerous in a home are also present in the air, in some cases in high spore counts.

Back to Austin.

By working with an allergist, I found an IgE allergy to mold. The normal suspect for mold problems is a contaminated home, but the ambient air can also have elevated mold spore count. Anything over 10,000 in mold spore count is considered very high. On rainy days, the mold count, which is always high in Austin, goes up, and can reach 20,000! Think about that for a second. That’s a huge number. Let’s say that like me you have an allergy to mold, which is common. You then encounter a 20,000 mold spore day in Austin. What do you think this does to the immune system? Things get especially bad if you have a reduced genetic ability to clear histamine via genes like AOC1, perhaps made worse by antibiotic and NSAID use, or other lifestyle factors.

Now you have a perfect storm where the body reacts to high histamine foods it never considered as troublesome before. The mast cell activation and lingering histamine produces zonulin, which can jeopardize the integrity of your gut wall. We know that mast cells are regulators of “epithelial barrier integrity,” which is a fancy way of saying they can compromise the gut when chronically inflamed.6 Under the theory of autoimmunity caused by leaky gut, a mast cell damaged gut wall lets all sorts of proteins into the blood stream that don’t belong there, further stimulating the immune system.7

Things get worse, more sensitivity develops, and on and on it goes, but you notice you feel better on a sunny day, or during a particular season, or on vacation, when allergies aren’t an issue. The whole mess begins with exposure to an environment you are poorly designed to live in. This is why you see conditions like interstitial cystitis, anxiety, prostate inflammation, sinus problems, gut issues like IBD, cognitive impairment etc. mediated in part by location and specifically by allergy. The conditions spring up in parts of the body where the mast cell count is greatest (gut, sinus, urogenital).

Environmental Toxins and Stress

Much of the literature on mast cells and histamine eludes to environmental triggers. This paper, titled The two faces of mast cells in food and allergy and allergic asthma: The possible concept of Yin and Yang, had this to say on the subject:

In the gastrointestinal tract, it has been demonstrated that non-specific mast cell activation (for example chronic stress) can lead to an increase epithelial permeability leading to a higher exposure to allergens and thus induction of sensitization to food allergens.

So, we strike on a common theme: there are a diverse range of factors which can trigger the immune system into an “inflammatory zone” that will result in downstream food sensitivity that is not of an IgE traditional allergic nature.

Mold and chronic infection can do this, but it is also plausible, at least for a growing number of sensitive individuals, that triggers in the physical environment, ranging from new and never before seen chemicals, to stress and even pollen can prime the immune system to start shooting at proteins it never before recognized as dangerous.

Key Takeaways

The immune system is in a constant state of flux.

When it goes on high alert in response to an irritant it can’t shake, downstream food sensitivities can develop.

When the irritant is removed, or lessened, the food sensitivities abate.

This is a possible reason why you’re sensitive to certain foods and supplements one day, but fine with the same products and foods the next.

John O'Connor

John O'Connor is the founder of Gene Food, host of the Gene Food Podcast and a health coach trained at Duke's Integrative Medicine Program. Read his full bio here.

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