By Greg Fors, D.C., IBCN - Chief Science Consultant, Biospec Nutritionals
By Greg Fors, D.C., IBCN - Chief Science Consultant, Biospec Nutritionals
Why your body may be overreacting to spring, and what you can do about it
Every spring, millions of people brace for the same routine: sneezing, congestion, itchy eyes, fatigue, brain fog, poor sleep, and the feeling that your body is fighting the outside world. Allergic rhinitis is extremely common, but common does not mean normal. [1]
The standard approach is usually to suppress symptoms with antihistamines, nasal sprays, or decongestants. Sometimes that helps, but for many people it is incomplete. The symptoms keep returning, the fatigue lingers, and every year feels like a repeat of the last.
In functional medicine, we ask not only what are you reacting to, but also why is your immune system so reactive in the first place?
This is where the concept of immune terrain becomes important. Your body does not respond to pollen in isolation. It responds through the lens of your inflammation levels, your gut health, your nutrient status, your blood sugar regulation, your stress load, and your ability to clear histamine. A growing body of research links allergic rhinitis with immune dysregulation, microbiome changes, gut barrier dysfunction, and broader systemic inflammation rather than a simple “pollen problem” alone. [1-4]
The following guide walks you through seven key issues that may explain why your “allergy bucket” keeps overflowing.
Issue 1: Trigger vs. Cause — Pollen May Be the Trigger, Not the Root Cause
Most people blame the pollen, the ragweed, the mold, or the neighbor’s cat. In functional medicine, we call those triggers. A trigger is real, but it is not always the deeper cause.
Think of your immune system as a bucket. Throughout the year, that bucket fills with stress, poor sleep, processed food, blood sugar swings, gut irritation, environmental exposures, and chronic inflammation. By the time spring arrives, the bucket may already be nearly full. Then pollen lands on top of that already strained system, and the bucket spills over.
That overflow becomes sneezing, congestion, sinus pressure, itchy eyes, fatigue, brain fog, and sometimes even worsening asthma or skin issues.
This matters because it changes the goal. Instead of just avoiding pollen, we work to calm the immune system itself. Allergic rhinitis is an immune-mediated condition, and current research increasingly supports the idea that microbiome balance, epithelial barrier function, and whole-body immune regulation influence who reacts strongly and who does not. [1-3]
Issue 2: Nutrient-Poor Diets, Blood Sugar Swings, and the Insulin-Inflammation Connection
If your diet is heavy in sugar, refined carbohydrates, ultra-processed foods, and low-quality fats, you may be feeding inflammation long before allergy season starts.
Frequent blood sugar spikes drive repeated insulin release. Over time, insulin resistance and hyperinsulinemia are tied to elevated inflammatory signaling, endothelial dysfunction, and broader metabolic stress. That does not mean sugar directly “causes” every allergy symptom, but it can amplify the inflammatory background that makes the immune system more reactive. [5-7]
There is also emerging population-level evidence that more pro-inflammatory dietary patterns are associated with a higher likelihood of allergic rhinitis. In other words, the way you eat may influence how loud your allergies become. [8,9]
A calmer immune system usually starts with a calmer metabolic environment:
- fewer refined carbohydrates
- less added sugar
- more fiber
- more phytonutrients
- more protein balance
- healthier fats
- fewer ultra-processed foods
You do not need a perfect diet. But if your blood sugar is on a roller coaster, your immune system often is too.
Issue 3: Gut Health, Leaky Gut, and the SIBO Connection
One of the most important functional medicine concepts in allergy care is this: The gut and the immune system are deeply connected.
A large share of the body’s immune activity is associated with the gut and mucosal immune system. The microbiome helps train immune tolerance, maintain barrier integrity, and regulate inflammation. When that system is disturbed, immune balance can shift in the wrong direction. [3,4,10]
If the gut lining becomes irritated or overly permeable, bacterial byproducts and poorly digested compounds may provoke immune activation. This is one reason functional medicine doctors pay close attention to gut symptoms in people with chronic allergies.
A particularly important problem is Small Intestinal Bacterial Overgrowth, or SIBO. In SIBO, excess bacteria grow in the small intestine, where they do not belong in high numbers. This can lead to bloating, gas, abdominal discomfort, altered bowel habits, food reactions, and increased intestinal irritation. Breath testing is commonly used in the right clinical setting, though it is not perfect. [11]
Not every person with seasonal allergies has SIBO. But when bloating, food intolerance, constipation, diarrhea, reflux, or abdominal fullness travel with allergy symptoms, gut dysfunction deserves a closer look.
Issue 4: Why “Normal” Labs May Not Tell the Whole Story
Many patients are told, “Your labs are normal,” while they are still exhausted, foggy, congested, inflamed, and miserable. This is by far one of the biggest frustrations in conventional care.
Standard lab work is often designed to detect established disease. Functional medicine tries to identify dysfunction earlier, before it becomes a full diagnosis.
Depending on the individual, a broader workup may include:
- basic inflammatory markers such as hs-CRP
- vitamin D status
- metabolic markers tied to blood sugar regulation
- stool testing for microbiome balance
- breath testing for SIBO
- targeted nutritional markers when clinically appropriate
Vitamin D is especially important because it helps regulate immune signaling. Research on vitamin D and allergic rhinitis is mixed, but low vitamin D status has been linked in multiple studies to worse allergic patterns or chronic rhinitis in at least some populations, and recent meta-analyses suggest supplementation may help certain patients, though not uniformly. [12-15] This is why we do not treat a lab value in isolation. We treat the patient in front of us.
Issue 5: The SIBO-Histamine Loop and Why Some “Allergy” Symptoms Start in the Gut
Histamine is one of the major chemicals involved in allergic symptoms. Interestingly, some people may not only be reacting to pollen. They may also be dealing with a higher internal histamine burden. Certain gut microbes can produce histamine, and histamine intolerance is increasingly being studied as a gut-linked condition. The intestinal enzyme DAO (diamine oxidase) helps break down histamine in the gut. When gut function is impaired, histamine clearance may be reduced. [16-19]
This can create what I often call a histamine bucket:
- pollen adds histamine pressure
- certain foods add more
- gut dysfunction lowers your ability to clear it
- symptoms become louder and harder to control
This may help explain why some people feel worse after fermented foods, aged cheeses, processed meats, leftovers, alcohol, or spinach, especially during allergy season.
To be clear, histamine intolerance is not the same thing as a classic IgE food allergy, and the science is still evolving. But clinically, this gut-histamine connection is very real for some patients and should not be ignored. [17,18]
Issue 6: Natural Ways to Build a Stronger Immune Terrain
Natural allergy relief is not about pretending symptoms do not exist. It is about helping the body regulate itself better.
This typically starts with the foundations:
- improve diet quality
- steady blood sugar
- support sleep
- reduce the inflammatory load
- identify gut dysfunction
- correct nutrient deficiencies
- lower the body’s total histamine burden when appropriate
In some patients, targeted nutritional support is likely to improve immune reactivity.
Vitamin D3
Vitamin D plays an immune-modulating role and may be helpful when deficiency is present, though response varies. [12-15]
Quercetin
Quercetin has been studied for anti-allergic and mast-cell-stabilizing effects, with encouraging mechanistic data and some supportive early clinical evidence, though it should be viewed as supportive rather than a stand-alone cure. [20,21]
Vitamin C
Vitamin C has antioxidant and histamine-related effects, and newer reviews continue to explore its role in allergic support, although protocols vary and the evidence is not uniform. [22]
Stinging nettle
Stinging nettle has a long history of traditional use for seasonal allergy symptoms, and small clinical studies suggest it may offer supportive benefit in some people. [23,24]
Probiotics
Several probiotic strains have led to improvements in seasonal allergy symptoms in various human clinical trials. These findings should not come as a surprise when considering the interplay between the gut microbiome and immune system. However, it’s worth noting that improvements in seasonal allergy symptoms are not a universal finding for all probiotic supplements. Results can only be attributed to specific probiotic strains, like Lactobacillus Rhamnosus GG (LGG) for example, which has shown to exert specific influence over immune function and seasonal allergy symptoms [25].
Essentially, the key is to use the right tool for the right person. Supplements work best when they are part of a bigger plan, not used as a substitute for finding the cause.
Issue 7: The Big Takeaway — Stop Chasing Symptoms and Start Rebuilding Resilience
If you only treat the pollen, you may miss the deeper reasons your body is reacting so strongly. Seasonal allergies are often the visible tip of a larger iceberg:
- inflammation
- gut dysfunction
- blood sugar instability
- poor nutrient status
- microbiome imbalance
- impaired histamine clearance
- chronic immune overactivation
This is why one person walks outside and barely notices spring, while another feels exhausted, swollen, foggy, and miserable for weeks.
The goal of functional medicine is not just to quiet the noise for a few hours. The goal is to improve the terrain so the body becomes less reactive in the first place. This is how real progress happens. If you are tired of the cycle of sneezing, congestion, brain fog, sinus irritation, and fatigue every spring, it may be time to stop asking only, “What am I allergic to?” and start asking, “Why is my immune system so overwhelmed?”
This is where deeper healing begins.
Biospec Nutritionals — Medical & Educational Disclaimer
This content is provided for educational and informational purposes only and is not intended to provide medical advice, diagnosis, or treatment. It is not a substitute for individualized guidance from a qualified healthcare professional. Always consult your physician or other qualified healthcare provider before starting, stopping, or changing any supplement, medication, diet, or exercise program.
† FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
References
[1] Akhouri S, House SA. Allergic Rhinitis. StatPearls. Updated 2023.
[2] Hu Y, et al. Association Between Gut and Nasal Microbiota and Allergic Rhinitis. 2024.
[3] Wiertsema SP, et al. The Interplay between the Gut Microbiome and the Immune System. 2021.
[4] Takiishi T, et al. Intestinal barrier and gut microbiota: shaping our immune responses throughout life. 2017.
[5] Freeman AM, et al. Insulin Resistance. StatPearls. Updated 2023.
[6] Berbudi A, et al. Interplay Between Insulin Resistance and Immune Function. 2025.
[7] Giannakopoulou SP, et al. The Impact of Dietary Carbohydrates on Inflammation-Related Disorders. 2024.
[8] Wang Q, et al. Association between the dietary inflammatory index and allergic rhinitis. 2024.
[9] Su L, et al. Association between energy-adjusted dietary inflammatory index and allergic rhinitis. 2024.
[10] Pierre JF. The gastrointestinal immune system. 2015.
[11] Sorathia SJ, et al. Small Intestinal Bacterial Overgrowth. StatPearls. Updated 2023.
[12] Kim YH, et al. Vitamin D levels in allergic rhinitis: a systematic review and meta-analysis. 2016.
[13] Kawada K, et al. Vitamin D Supplementation and Allergic Rhinitis: systematic review and meta-analysis. 2025.
[14] Park SC, et al. Vitamin D Deficiency as a Contributing Factor to Chronic Rhinitis. 2024.
[15] Tian HQ, et al. The role of vitamin D in allergic rhinitis. 2017.
[16] Comas-Basté O, et al. Histamine Intolerance: The Current State of the Art. 2020.
[17] Jochum C, et al. Histamine Intolerance: Symptoms, Diagnosis, and Beyond. 2024.
[18] Schnedl WJ, et al. Histamine Intolerance Originates in the Gut. 2021.
[19] Sánchez-Pérez S, et al. Intestinal Dysbiosis in Patients with Histamine Intolerance. 2022.
[20] Jafarinia M, et al. Quercetin with the potential effect on allergic diseases. 2020.
[21] Mlcek J, et al. Quercetin and Its Anti-Allergic Immune Response. 2016.
[22] Vitamin C in Allergy Mechanisms and for Managing Allergic Disease. 2025.
[23] Bakhshaee M, et al. Efficacy of Supportive Therapy of Allergic Rhinitis by Stinging Nettle. 2017.
[24] Bhusal KK, et al. Nutritional and pharmacological importance of stinging nettle. 2022.
[25] Mishra T, et al. Efficacy of Lactobacillus and Bifidobacterium in Allergic Rhinitis: A Narrative Review. 2025.
