Food Sensitivities and Elimination Diets

These three terms are frequently conflated in popular culture but have distinct mechanisms, severity profiles, and diagnostic approaches.

Feature	Food Allergy	Food Intolerance	Food Sensitivity
Mechanism	IgE-mediated immune response	Enzymatic or chemical (non-immune)	Non-IgE immune or gut-mediated; poorly defined
Onset of symptoms	Minutes to 2 hours	30 min – 48 hours	Hours to days
Dose dependency	Even trace amounts can trigger	Dose-dependent — small amounts often tolerated	Varies; often dose-dependent
Severity	Potentially life-threatening (anaphylaxis)	Uncomfortable but not dangerous	Chronic; debilitating but not acutely dangerous
Symptoms	Hives, throat swelling, anaphylaxis	Bloating, gas, diarrhea, headache	Fatigue, brain fog, skin, GI, joint symptoms
Diagnosis	Skin prick test, specific IgE blood test, oral food challenge	Symptom history, breath tests (lactose, fructose)	Elimination diet + reintroduction
Valid test	IgE testing (allergy specialist)	Lactose: hydrogen breath test; Histamine: clinical history	Elimination-reintroduction (gold standard)

The popular IgG food sensitivity test sold by commercial labs lacks clinical validity — elevated IgG antibodies to foods indicate exposure, not pathology, and are found even in healthy individuals who regularly eat those foods. Major allergy societies (AAAAI, BSACI) do not recommend IgG testing for food sensitivity diagnosis.

Warning: If you suspect a true food allergy (especially to nuts, shellfish, or sesame), see an allergist before attempting elimination — an anaphylactic reaction during unsupervised reintroduction can be life-threatening.

While any food can theoretically cause sensitivity in an individual, certain foods and food components account for the majority of reported reactions. Many sensitivities are actually to specific components within a food rather than the whole food.

Trigger	Mechanism	Typical symptoms	Estimated prevalence
Lactose	Lactase enzyme deficiency → undigested lactose ferments in colon	Bloating, gas, diarrhea (30–120 min after dairy)	~65% of adults globally; higher in East Asian, African, Hispanic populations
Gluten (non-celiac)	Not fully understood; may involve innate immunity or FODMAP fructans	GI symptoms, fatigue, brain fog (distinct from celiac disease)	~1–6% of population (contested)
FODMAPs	Fermentable carbohydrates (fructose, lactose, fructans, galactans, polyols) ferment rapidly	Bloating, gas, pain, altered bowel habits — particularly in IBS	~10–15% of population (IBS prevalence)
Histamine	Diamine oxidase (DAO) enzyme insufficiency; dietary histamine exceeds clearance capacity	Headache, flushing, hives, nasal congestion after aged foods	~1–3% of population; poorly studied
Fructose (malabsorption)	GLUT5 transporter limitation → excess fructose in colon	Bloating, loose stools, pain especially after fruit, honey, HFCS	~30–40% of adults have some degree
Salicylates	Aspirin-like compounds in many fruits, vegetables, and spices	GI symptoms, skin reactions, asthma-like symptoms in sensitive individuals	Rare; ~0.1–2%

Tip: Celiac disease is an autoimmune condition, not a sensitivity — it requires strict, lifelong gluten avoidance and must be diagnosed with blood tests (anti-tTG IgA) and intestinal biopsy before starting a gluten-free diet.

The elimination diet is a structured diagnostic tool, not a permanent way of eating. The goal is to remove potential trigger foods for 3–6 weeks until symptoms resolve, then systematically reintroduce them to identify which food (or food component) is causing the problem.

The most comprehensive version is the low-FODMAP diet (for IBS) or the broader six-food elimination diet used in eosinophilic esophagitis (removing milk, wheat, eggs, nuts, soy, and seafood). For general sensitivity investigation, a more practical two-stage process is standard:

• Stage 1 — Elimination (3–6 weeks): Remove all suspected trigger foods completely. Consume only whole, minimally processed foods from a base list. Keep a detailed symptom diary throughout.
• Stage 2 — Reintroduction: Reintroduce one food group at a time, every 3 days, while monitoring symptoms. If symptoms return, remove that food and wait for symptoms to clear before testing the next.

Phase	Duration	Allowed foods	Goal
Elimination	3–6 weeks	Rice, quinoa, most vegetables, chicken, turkey, lamb, non-citrus fruits, olive oil, coconut oil	Achieve symptom remission as baseline
Reintroduction	6–12 weeks (testing each group)	One new food group every 3 days	Identify specific triggers
Personalized diet	Ongoing	All tolerated foods + avoiding confirmed triggers	Maximum dietary variety without symptoms

Warning: Elimination diets are nutritionally restrictive and can easily lead to deficiencies in calcium, vitamin D, B vitamins, and fiber if poorly planned. Do not extend the elimination phase beyond 6 weeks unnecessarily.

The reintroduction phase is where the diagnostic value is gained — and where most people go wrong by reintroducing multiple foods simultaneously or not waiting long enough between tests. Patience and systematic testing are essential for reliable results.

• Test one food or food group at a time — combine a trigger food with a baseline meal, not with other new introductions.
• Use a structured dose escalation — a small portion on day 1, a medium portion on day 2, a full portion on day 3, then observe for 3 days before testing the next food.
• Document carefully — use a symptom diary scoring 0–10 for each symptom category (GI, skin, energy, cognition) at the same times each day.
• Wait for symptoms to clear before testing another food after a positive reaction — residual symptoms confound results.

Reintroduction order (low-FODMAP example)	Foods tested	Wait before next group
Lactose	Milk, soft cheese, ice cream	3 days if no reaction
Fructans (wheat)	Wheat bread, pasta (2 portions)	3 days if no reaction
Fructose (excess)	Honey, mango, apple juice	3 days if no reaction
Galacto-oligosaccharides	Chickpeas, lentils, cashews	3 days if no reaction
Polyols (sorbitol)	Avocado, peaches, stone fruits	3 days if no reaction
Polyols (mannitol)	Mushrooms, cauliflower	3 days if no reaction

Tip: A positive reaction in the reintroduction phase means that food is a trigger at that dose — not necessarily that it must be avoided forever. Many intolerances are dose-dependent, and ongoing testing over months can reveal how much you can tolerate without symptoms.

Self-directed elimination diets carry real risks: nutritional deficiencies (especially in children), unnecessarily prolonged restriction, and incorrect attribution of symptoms to the wrong food. A registered dietitian (RD) or accredited practising dietitian (APD) significantly improves outcomes.

A dietitian provides:

• Nutritional adequacy review — ensures the elimination diet still meets calorie, protein, calcium, vitamin D, and fiber requirements.
• Symptom diary interpretation — identifies patterns that may not be immediately obvious to the individual.
• Guidance on specific protocols — the FODMAP approach, for example, is complex and requires professional training to implement correctly; Monash University's low-FODMAP app is dietitian-developed.
• Psychological support — food restriction can trigger anxiety around eating; a dietitian supports a healthy relationship with food throughout the process.

Resource type	Use	Notes
Registered dietitian	Whole-protocol supervision	Essential for children, pregnant women, complex symptoms
Monash FODMAP app	Low-FODMAP food guide	Research-backed; updated regularly; small cost
GP / gastroenterologist	Rule out celiac, IBD, SIBO before starting elimination	Bloodwork and endoscopy may be needed first
Symptom diary apps	Consistent daily logging (e.g., mySymptoms, GI Monitor)	Improves pattern recognition; share with clinician

Tip: Before starting an elimination diet, have your GP check for celiac disease antibodies (anti-tTG IgA), thyroid function, and complete blood count — many non-specific symptoms blamed on food have other, easily diagnosed causes.