There is a lot of misinformation out there about the differences between allergies and intolerance. Unfortunately, a lot of this is perpetuated by healthcare professionals who don’t fully appreciate the complex diverse nature of the pathways reactions can take and the tremendous overlaps in the symptoms they can manifest in. This leads to many feeling dismissed or being given potentially dangerous advice to ignore symptoms if tests don’t confirm sensitivities. It is important to always remember that experience trumps tests – every time!
According to the world allergy association, “allergy” is defined “a hypersensitivity reaction initiated by proven or strongly suspected immunologic mechanisms”.
The most well known and understood of these immunological mechanisms, the ones that many professionals almost archaically consider as the only form of “true” allergy, are the ones that use the Immunoglobulin E reaction pathway. So much so that the understanding can be a bit muddied. Reactions can be separated into IgE and non-IgE allergies. Many calling non-IgE reaction pathways intolerances, when this is not scientifically accurate.
Non-Ige mediated allergies can involve different pathways including other immunoglobulins (like IgG, IgA), T-cells (FPIES), basophils, eosinophils and mast cell mediated reactions. Unfortunately since allopathic allergy testing typically only test for IgE allergies, unless exceptional circumstances or persistent patients pursue answers. This exclusivity of IgE can be very misleading and unhelpful. More integrative practitioners may consider IgG testing or ELISA testing.
Though in a linguistic sense, “in-tolerance” may mean lacking of tolerance and could be applied from anything from a food reaction that your body is obviously not tolerating to a lack of personal tolerance for things like different entertainment genres or social groupings. This does not help with distinguishing between types of food reaction and is not technically accurate medically.
Allergies are caused by the sensitisation of an immune pathway to a particular food or environmental trigger. When the body is exposed to a trigger, typically assumed to be protein though research is showing this can extend to carbohydrates (GOS). In the body’s attempt to fight off the threat, it triggers the release of inflammatory chemicals, primarily but not limited to histamine. Unfortunately these inflammatory chemicals can cause a whole host of scary and potentially life risking reaction symptoms.
Intolerances, aka pseudo-allergies, are typically caused by a metabolic deficiency preventing us from breaking down a particular food components like starches/sugars (lactose, FODMAP, CSID) or other compounds like oxalates, salicylates, glutamates and sulphates.
Histamine receptors and IBD.
Comprehensively expands on the different types of histamine receptors including GI tract involvement.
Comprehensive accumulation of current research covering the diverse nature allergic reaction pathways and accepted testing (long but informative read):