Understanding the root causes: your immune system, your gut, your food, and your city

Dr. Michele Renee, DC, MAc, LMT | Stockheart Whole Health, Minneapolis | 8 min read | Part One of Two

In this post: Immune Dysregulation · Foods That Feed the Fire · Food Sensitivities · Your City and the Pollen Problem

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*“Allergies aren't a malfunction. They're your immune system doing exactly what it was built to do, just doing it a little too enthusiastically."*

Every spring, I watch people come in with itchy eyes, foggy heads, and sinuses packed tight as a river delta during flood season. They've tried every antihistamine on the shelf. They're exhausted, frustrated, and honestly a little embarrassed that something as simple as pollen is flattening them.

Here's what I want you to know: your body is not failing you. Your immune system learned somewhere along the way that certain substances are a threat, and now it's doing its best to protect you. That response is real. The suffering is real.

But here's the question conventional medicine rarely stops long enough to ask: why is your immune system reacting this way in the first place? And why does it seem to get worse every year? The answers live in a few places most people haven't looked, including your gut, your plate, and the trees lining your street.

It Starts With Immune Dysregulation

In a functional medicine framework, allergies aren't just a seasonal nuisance. They're a sign that the immune system has lost some of its regulatory capacity, that it's reading threats where there aren't any, or amplifying responses that should be mild. Before we can address the symptoms, it helps to understand what's feeding that dysregulation.

Gut microbiome imbalance

About 70 to 80 percent of your immune system lives in your gut. That's not a metaphor; it's anatomy. Dysbiosis, an imbalance in the gut bacterial community, is strongly associated with allergic disease. When the gut microbiome is disrupted by antibiotics, stress, processed food, or other factors, immune regulation suffers downstream. Healing the gut often means calming the immune system, sometimes dramatically.

Intestinal permeability

When the lining of the small intestine becomes compromised, particles that should stay in the digestive tract get into the bloodstream. The immune system mounts a response to them, and that low-grade, chronic activation amplifies reactivity to other triggers, including environmental allergens. It's a compounding effect, and most people have no idea it's happening.

Nutrient deficiencies

Vitamin D, zinc, magnesium, and omega-3 fatty acids all play direct roles in immune regulation. Many people with chronic allergies are running low on one or more of these. Supplementing blindly is a shot in the dark. Testing gives you a map.

Chronic stress and cortisol dysregulation

Stress hormones directly influence mast cell activation and histamine release. If your allergy symptoms reliably get worse during high-stress periods, that's not a coincidence. The immune system and the nervous system are in constant conversation, and when the nervous system is dysregulated, the immune system follows.

Histamine intolerance

Some people have difficulty breaking down histamine from food and other sources. When that capacity is reduced, environmental histamine load, the pollen, the mold, the dust, stacks on top of dietary histamine load and the total burden tips over into symptoms. A low-histamine diet trial can be clarifying when nothing else explains the picture.

Foods That Feed the Fire

Certain foods actively promote mucus production and systemic inflammation. During allergy season especially, they add to a burden the body is already struggling to manage. These aren't permanent restrictions for most people, but during a bad flare, pulling back on them can make a real difference:

Dairy (milk, cheese, ice cream, sneaky food additives)
Refined sugar and sugary drinks
Gluten and refined wheat
Alcohol, especially red wine, cider, sake, and beer
Processed and fried foods
High-histamine foods: aged cheeses, cured meats, fermented foods
Artificial additives and food dyes
Refined vegetable oils (soy, canola, corn)
Bananas and citrus, which cross-react with certain pollens
White bread and wheat-based pasta

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**What to eat more of:** Dark leafy greens, colorful vegetables, wild-caught fish, ginger, turmeric, garlic, onions (quercetin-rich), bone broth, and omega-3-rich foods actively support immune regulation and help the body clear mucus naturally. And hydration matters more than people realize. Water thins mucus, plain and simple.ever it is, the way you tell your story online can make all the difference.

When It's Not Allergies, It's Sensitivities

Here's a question worth sitting with: if you're congested most of the time, not just during pollen season but year-round, food sensitivities may be driving more of that than you think.

This is different from the mucus-promoting foods we just covered. Food sensitivities are immune reactions, often low-grade and delayed, that don't show up on a standard allergy test. That's because they involve IgG antibodies rather than the IgE antibodies that classic allergy testing measures. The reaction can happen hours or even a couple of days after eating the offending food, which makes it genuinely hard to connect the dots on your own. You just know you're always a little stuffy, a little foggy, a little off.

Common culprits include dairy, gluten, eggs, soy, corn, and tree nuts, but sensitivities are individual. What drives excess mucus and inflammation in one person may be completely fine for another. Food sensitivities and environmental allergies also compound one another, creating reactions that seem disproportionate to either trigger alone.

Two paths worth exploring: An elimination diet, done properly over four to six weeks with a careful reintroduction phase, is the gold standard for identifying food sensitivities. It takes patience and structure, but it gives you real, personalized information. An IgG food sensitivity panel is another option, a blood test that screens for delayed immune reactions across a broad range of foods. It works best when interpreted alongside symptoms and clinical history, not in isolation. At Stockheart, we use both approaches depending on where someone is starting from. If you've been congested since you can remember and nothing has fully explained it, this is worth exploring.

Why Your City Might Be Making It Worse

Here's something that doesn't get nearly enough attention: the environment you live in may be actively loading the dice against you, and not because of nature, but because of decisions made by city planners decades ago.

The male tree problem

Most tree species produce both male and female specimens. Male trees produce pollen. Female trees capture it, using it for seed production. In a balanced urban forest, pollen has somewhere to go. But starting in the mid-twentieth century, city planners and landscapers began preferentially planting male trees for a reason that now reads as almost absurd: they're tidier. No fruit, no seeds, no dropped pods to sweep off sidewalks.

The 1949 USDA Yearbook of Agriculture explicitly recommended that when used for street plantings, only male trees should be selected, to avoid the nuisance from the seed. Cities followed that guidance. Nurseries responded by propagating almost exclusively male cultivars, often labeled simply as fruitless or litter-free. Horticulturist Tom Ogren documented what he called botanical sexism, the systematic overplanting of pollen-producing male trees in urban landscapes, which left city air with an enormous pollen load and almost nothing to absorb it.

Female trees produce no pollen. They trap and remove it from the air as part of their reproductive process. A landscape with a healthy mix of female trees is, in a very real sense, a lower-pollen environment. Cities that planted almost exclusively males created what Ogren describes as pollen corridors, streets lined with nothing but high-output pollen producers, with no female trees to balance the load.

The science is nuanced. Most tree species (roughly 75 percent globally) produce flowers with both male and female parts, so the framework doesn't apply universally. But for dioecious species, those with distinct male and female trees, including willows, poplars, ash, silver maples, mulberry, and certain junipers, the imbalance is real and measurable. Some cities have passed pollen control ordinances requiring better male-to-female ratios in new plantings. Albuquerque and Berkeley have both done this. Minneapolis has not.

Oak trees lining walking path in manicured green space. Healing, wellness, wellbeing, thriving, holistic health care, integrative care Minneapolis MN

Lack of biodiversity compounds the problem

Urban forests tend to be low in diversity, often dominated by just a handful of species. Research published in Scientific Reports found that when a city's canopy is concentrated in a few genera, pollen exposure risk estimates can vary wildly. The fewer the species, the more volatile the risk, and the less buffer there is when a single species has a bad year. Diverse urban forests dilute the allergenic load, spread bloom windows across more of the season, and reduce the chance that any one tree dominates the air.

Climate change is lengthening the season

Warmer temperatures mean plants begin pollinating earlier in spring and continue later into fall. Pollen concentrations in North America have increased more than twenty percent over the last two decades. Elevated carbon dioxide causes some plants to produce more pollen per season. The allergy season you remember from ten years ago is not the one you're living through now.

Air pollution and pollen interact

Urban air pollution doesn't just irritate airways on its own. Research suggests that pollutants alter the composition of pollen grains, making them more allergenic, and cause pollen to break into smaller particles that penetrate more deeply into the lungs. Living near high-traffic corridors or areas with poor air quality compounds pollen exposure in ways that regional pollen counts don't capture.

What this means for you: Your allergy symptoms are not purely personal. They are partly a public health outcome of how your city was designed. That doesn't make the symptoms less real, and it doesn't mean there's nothing you can do individually. But framing allergies as a purely individual immune problem misses something important. Advocating for diverse, balanced urban tree planting and understanding your local canopy are part of the bigger picture.

Understanding the why changes everything.

When we stop treating allergy symptoms as random bad luck and start seeing them as signals, patterns emerge. Your gut, your food, your stress load, and the trees outside your window are all part of the picture. None of these factors work in isolation, and no single intervention fixes everything. But once you understand what's driving the reactivity, you have somewhere to start.

In Part Two of this series, we get into exactly that: what you can actually do about it. From herbs and acupuncture to chiropractic care, mucolytics, and saline rinses, there are more tools available than most people know, and they work better when we understand the terrain they're working in.

Up next: Treating Allergies Holistically: Root Causes, Real Relief. We'll walk through herbal allies, acupuncture, the C1 chiropractic connection, mucolytic agents, and why a simple saline rinse might be the most underrated thing you're not doing.

With warmth,

Dr. Michele Renee, DC, MAc, LMT

Stockheart Whole Health | Minneapolis, MN

Why Are My Allergies So Bad?

Understanding the root causes: your immune system, your gut, your food, and your city