Food Sensitivities: How They Develop, What They Drive, and How to Identify Yours
Food sensitivities are distinct from food allergies and significantly more common. They involve delayed immune reactions (primarily IgG-mediated) to foods that are otherwise considered healthy, and they drive a wide range of symptoms including gut dysfunction, skin conditions, brain fog, fatigue, joint pain, and hormonal symptom amplification.
The Difference Between Allergies and Sensitivities
• IgE allergy: immediate (within minutes), potentially severe, mediated by IgE antibodies. Examples: peanut allergy, shellfish allergy.
• IgG food sensitivity: delayed (hours to days), less severe but cumulative and chronic, mediated by IgG antibodies. Symptoms are diffuse and hard to link to specific foods without testing or elimination.
• Non-immunological food reactions: enzyme deficiencies (lactase, DAO), chemical sensitivities (salicylates, amines), or FODMAPs in SIBO or IBS.
Why Food Sensitivities Develop
Food sensitivities develop primarily as a consequence of intestinal permeability. When the gut barrier is compromised, partially digested food proteins enter the bloodstream, triggering an immune response. Once sensitised, the immune system reacts to those foods even after the gut has healed, unless the exposure period is sufficient to allow tolerance to re-establish.
Drivers include SIBO, dysbiosis, chronic stress (cortisol directly disrupts tight junctions), NSAID use, and alcohol.
Common Food Sensitivities
The most commonly identified food sensitivities in clinical practice include:
• Gluten and wheat (particularly in women with autoimmune conditions including Hashimoto's)
• Dairy (casein most often, not always lactose)
• Eggs
• Soy
• Corn
• Nightshades (tomato, pepper, potato, eggplant) in inflammatory conditions
• High-histamine foods in women with histamine intolerance
Testing for Food Sensitivities
IgG food sensitivity testing (Cyrex Array 10, Great Plains, or similar panels) identifies elevated antibody responses to specific foods. These tests are most clinically useful when gut permeability is suspected and symptoms are broad and multi-system. They should be used as a tool alongside clinical judgement, not as the sole diagnostic criterion. See functional testing for context.
The gold standard for identifying food sensitivities remains the elimination-reintroduction protocol: removing the suspected foods for 4 to 6 weeks, then systematically reintroducing them one at a time and monitoring symptoms.
The Treatment Protocol
Simply eliminating trigger foods without healing the gut addresses symptoms but not the cause. The clinical approach involves:
• Remove identified trigger foods for a therapeutic period (minimum 4 to 6 weeks)
• Heal intestinal permeability through targeted nutritional support
• Restore the gut microbiome through fibre diversity and fermented foods
• Systematically reintroduce foods after the healing phase to establish which remain problematic
Reacting to foods that should be healthy and not sure where to start?
Book a Clinical Case Assessment with Kirstie to assess your gut health picture and develop a structured food sensitivity protocol.
