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  • Writer's pictureZoey Hughes

Decoding Your Body: The Science Behind Food Allergies and Intolerances

Allergy vs intolerance blog image with eggs, nuts, prawns and a logo for Zoey M. Hughes health and nutrition coaching

In the realm of food reactions, the terms 'allergy' and 'intolerance' are often used interchangeably but they are not identical and cause drastically different effects in your body. It's time to demystify these terms and lay out their differences, symptoms, and underlying biological reactions.


Understanding Food Allergies

A food allergy is an immune system response where the body perceives a certain food as harmful and reacts by releasing chemicals to fight the intruder, including histamine (hence anti-histamines to deal with minor allergies). This can occur within minutes to hours after consuming the allergenic food which can make it difficult to pinpoint what the offending food was. The severity of symptoms can range from mild reactions (itchy mouth, hives) to severe and potentially life-threatening conditions like anaphylaxis which may cause difficulty breathing and a drop in blood pressure.


I have significant personal experience with allergies, but consider myself lucky as I have dramatically visible and quick reactions. Fun fact: I discovered I was allergic to melon after three instances in which I turned bright red after a single mouthful!


Understanding Food Intolerance

Food intolerance, on the other hand, is a digestive system response where the body finds it difficult to digest a particular food, often because it lacks the necessary enzymes. This typically leads to gastrointestinal symptoms such as bloating, gas, diarrhea, or constipation. Symptoms of food intolerance generally appear a few hours after eating the problematic food and, unlike allergies, are not life-threatening, just uncomfortable and occasionally embarrassing.


The Biological Reactions: Allergies vs. Intolerance

In a food allergy, the immune system mistakenly identifies a food protein as a threat and produces antibodies known as Immunoglobulin E (IgE). Upon subsequent exposure to the food, these IgE antibodies trigger the release of chemicals like histamine, causing allergic symptoms. This is why even a tiny amount of allergenic food can cause an allergic reaction (Please note that while micro-dosing can be an effective strategy to reduce allergy symptoms, this must always be done under medical supervision).


Food intolerance, however, is not an immune response but rather a physiological reaction. It often occurs due to the lack of an enzyme required to fully digest a food. For example, lactose intolerance is caused by a deficiency of the enzyme lactase, which is needed to break down lactose, a sugar found in milk and other dairy products. Without enough lactase, lactose is fermented by bacteria in the colon, leading to symptoms like bloating, gas, and diarrhea.


Unfortunately, I also suffer from lactose intolerance. I don't miss the ill effects enough to ever try it, but if you are lactose intolerant and simply have to have some cheese, you can buy supplemental lactase, which may minimise your discomfort.


Telltale Symptoms: How to Differentiate

Food allergies often cause immediate, consistent, and reproducible symptoms every time the allergenic food is consumed, regardless of the amount. Symptoms may include skin reactions (itching, hives, swelling), respiratory symptoms (wheezing, nasal congestion, difficulty breathing), gastrointestinal symptoms (nausea, vomiting, diarrhea), and cardiovascular symptoms (dizziness, fainting).


Allergy symptoms - Skin reactions, respiratory distress, gastrointestinal issues, cardiac issues

Food intolerance symptoms are usually dose-dependent and may not occur unless you eat a large portion of the food or eat it frequently. This may mean you can get away with a birthday meal with minimal downsides as long as you keep your portion size under control. Intolerance symptoms are primarily gastrointestinal and include bloating, gas, cramps, diarrhea, and occasionally can also cause symptoms outside the digestive system like headaches and migraines.


Mindful Eating

If you're struggling with unknown digestive issues, you may well have an underlying intolerance (although it may be a case of chronic inflammation instead). Understanding the difference between food allergies and intolerances is crucial for appropriate management and treatment. While they may share some symptoms, the underlying causes, and the potential severity of reactions are vastly different. If you suspect you have a food allergy or intolerance, it is advisable to consult a healthcare professional for diagnosis and guidance. Avoid consumption of any food you believe you are allergic to and minimise exposure to those you are intolerant to until you have explored the issue with your healthcare professional.


Remember, each individual's response to food is unique, and what works for one person may not work for another. It's all about understanding your body and finding what works best for you.

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