Can Allergens & Irritants Impact The Health Of The Body?

Last week our Healthy Living Blog post by Sarah, “Allergy or Intolerance” introduced the difference between an allergy and an intolerance, and linked both to gut health.

An allergy refers to the body’s reaction to the proteins within the eaten food (immune system). This food is harmless to most people.1

An intolerance or sensitivity is considered a ‘chemical’ reaction (digestive system) to a substance, commonly food, and does not show up on a traditional allergy test.

Why should I care? I can cope with the symptoms of my intolerance!

It’s not as simple as a tummy ache, bowel changes, or even a mild rash. Regularly exposing your body to allergens or irritants can have significant impacts on the health of the body.

Exposure to an allergen creates an inflammatory response in the digestive system, creating an increase in intestinal permeability (aka Leaky Gut Syndrome). This increase in gut permeability creates a change in the way our metabolic and neuroendocrine systems function.

The metabolic system is responsible for life sustaining chemical reactions, which ultimately fuel the body’s energy and chemical needs.

The neuroendocrine system involves the interaction between the brain and the body’s hormonal regulation and helps to regulate and balance our body’s daily functions. 

Changes in these two systems result in a pro-inflammatory state, which can contribute to immune system dysfunction and the development of a wide range of chronic conditions3.

The intestinal microbiome has been identified as a triggering/mediating factor in autoimmune conditions4 (including Graves’ disease, Hashimoto’s thyroiditis, multiple sclerosis, type 1 diabetes, systemic lupus erythematosus, and psoriasis); some rheumatoid conditions5 (rheumatoid arthritis and spondyloarthropathies), and potentially some types of cancers6.

It’s not all bad news. By choosing healthy lifestyle factors we may better promote a healthy gut microbiome2.

Where possible, avoid processed foods. The additives and preservatives often contained in processed foods are designed to slow the growth of microflora and bacteria. They are designed to prolong the shelf life of a product, however once ingested, can also wreak havoc on the balance and growth of the bacteria integral to a healthy gut microbiome. By consuming a wide variety of foods, you may increase the diversity of nutrients and microflora your gut is exposed to; thus helping to maintain a balance of the 2100+ organisms7 that make up our gut microbiome.

Illustration: Mitch Blunt

There are a range of supplements and programs that can be followed to improve gut health and potentially reduce not only the symptoms of your intolerance but also help to address the root cause.

Speak to you practitioner to find out what approach would be best in your situation.


[1] Metagenics Allergy and Reactivity Reduction Program: Clinical Guide
[2] Shanahan F, van Sinderen D, O’Toole PW, Stanton C. Feeding the microbiota: transducer of nutrient signals for the host. Gut. 2017;66(9):1709-1717.
[3] Fitzgerald, F. and Hodges, R., 2021. The Role of the Microbiome in Immune-Related Diseases | IFM. [online] The Institute for Functional Medicine. Available at: 
[4] Opazo MC, Ortega-Rocha EM, Coronado-Arrázola I, et al. Intestinal Microbiota Influences Non-intestinal Related Autoimmune Diseases. Front Microbiol. 2018;9:432
[5] Yeoh N, Burton JP, Suppiah P, Reid G, Stebbings S (Mar 2013). “The role of the microbiome in rheumatic diseases”. Current Rheumatology Reports(Review). 15 (3): 314
[6] Fasano A (Jan 2011). “Zonulin and its regulation of intestinal barrier function: the biological door to inflammation, autoimmunity, and cancer”. Physiological Reviews (Review). 91 (1): 151–75 
[7] Thursby, E., & Juge, N. (2017). Introduction to the human gut microbiota. The Biochemical journal474(11), 1823–1836.