Browse by intolerance

FODMAPs are fermentable carbohydrates (oligo-, di-, mono-saccharides and polyols) that are poorly absorbed by some people. In the colon they ferment quickly, drawing in water and producing gas — leading to bloating, abdominal pain and altered stools. They are a leading dietary trigger of IBS symptoms. Common high-FODMAP foods: onion, garlic, wheat, legumes, apples, milk, honey. Scientific approach: the Monash 3-step protocol is to AVOID all FODMAPs only for 2-6 weeks (elimination), then REINTRODUCE one subgroup at a time over ~3 days each to identify your personal triggers, then settle into a long-term diet that only restricts the subgroup(s) you actually react to. Eliminating all FODMAPs permanently is not recommended — it impoverishes the gut microbiota and is rarely necessary (Tuck & Barrett 2017; Whelan et al. 2018).

Lactose is the sugar found in milk and dairy. Most adults gradually lose the lactase enzyme that breaks it down — undigested lactose ferments in the colon, causing bloating, gas and diarrhea. Hard aged cheeses (parmesan, comté, cheddar) are nearly lactose-free; soft cheeses, milk and ice cream contain the most. Lactose-free alternatives and fermented dairy (yogurt) are often better tolerated.

Histamine intolerance is a deficiency of the DAO enzyme that normally breaks down dietary histamine. Symptoms: flushing, headache, hives, digestive upset, sometimes hypotension. Three categories matter: (1) histamine-rich foods — aged cheeses, cured meats, fermented foods, fish, alcohol; (2) liberators that trigger endogenous release — strawberries, tomatoes, citrus, chocolate; (3) DAO inhibitors that block clearance — alcohol, black tea, energy drinks. Important: the ratings here assume the food is consumed ultra-fresh. Histamine accumulates rapidly in protein-rich foods (fish, meat, leftovers, ripe cheese) as they sit — a safely-rated food can become risky within hours of cooking or a few days in the fridge. As a rule of thumb, avoid all fermented, aged or long-stored foods, freeze fish and meat immediately if not eaten the same day, and consume any prepared dish within 24h.

Gluten is the protein complex in wheat, rye, barley and crosses. Three distinct conditions involve it: celiac disease (autoimmune, requires strict avoidance, biopsy diagnosis), wheat allergy (IgE-mediated), and non-celiac gluten sensitivity (NCGS, symptoms without celiac markers). Hidden sources: soy sauce, beer, malt, some sauces and seasonings, oats unless certified gluten-free.

Fructose malabsorption (or hereditary fructose intolerance, much rarer) means fructose isn't fully absorbed in the small intestine. Excess fructose reaches the colon and ferments → bloating, gas, diarrhea. Often dose-dependent: small amounts tolerated, larger ones not. High-fructose sources: apples, pears, mangoes, honey, agave syrup, high-fructose corn syrup (sodas, processed foods). Tolerance improves when glucose is present (fructose is co-transported).

Oligosaccharides are a FODMAP subgroup: fructans (in wheat, onion, garlic, artichoke) and galacto-oligosaccharides / GOS (in legumes — lentils, chickpeas, beans). Humans lack the enzymes to digest them, so they reach the colon intact and are fermented by gut bacteria — producing gas, bloating and changes in stool. Soaking and cooking legumes thoroughly, and limiting onion/garlic in early reintroduction phases, can help.

Sorbitol is a sugar alcohol (polyol) used as a sweetener in sugar-free gums, candies and diabetic products. It is also naturally present in stone fruits — apples, pears, peaches, plums, prunes. Poorly absorbed in the small intestine, it draws water into the colon (osmotic diarrhea) and is fermented (gas). Daily intakes above 10g often cause symptoms even in non-sensitive people.

Sucrose intolerance (congenital sucrase-isomaltase deficiency, CSID) is the inability to break down sucrose (table sugar) and starches. Symptoms appear within 2 hours of eating sugar: bloating, watery diarrhea, abdominal cramps. Affects both children and adults — often underdiagnosed and confused with IBS. Hidden sources: sweet drinks, candy, cakes, fruit juices, many processed foods, plus all starches in CSID.

Tyramine is a biogenic amine that builds up in aged, fermented or improperly stored foods. In sensitive individuals (especially those taking MAO inhibitors) it causes hypertensive crises, migraines, flushing and palpitations. High-tyramine foods: aged cheeses (parmesan, blue), cured meats (salami, prosciutto), pickled or fermented foods (sauerkraut, soy sauce), beer, red wine, overripe fruit. Eating fresh dramatically lowers exposure.

Salicylates are natural plant compounds (aspirin's chemical cousin) used by plants for defense. Hypersensitive individuals develop hives, asthma, nasal polyps or digestive distress on exposure. High-salicylate foods: berries, oranges, tomatoes, peppers, herbs and spices (curry, paprika), honey, mint, tea, almonds. Often co-occurs with aspirin sensitivity. Pears, peeled apples and most fresh meats/fish/dairy are low-salicylate options.

Nickel allergy is the most common contact allergy (jewelry, belts). Systemic nickel allergy syndrome (SNAS) can also arise from dietary nickel: eczema flare-ups, hives, headaches, digestive issues. High-nickel foods: chocolate, cocoa, nuts, oats, soy, legumes, whole grains, canned foods (leached from cans), shellfish. Cooking in stainless steel can also leach nickel into acidic foods.

Oxalates bind to calcium in the kidneys and can form calcium-oxalate stones. If you're avoiding oxalates, limit salt (especially table salt) — high sodium increases urinary calcium excretion, raising stone-formation risk. High-oxalate foods: spinach, beetroot, rhubarb, almonds, cashews, chocolate, sweet potato, raw taro. Pair oxalate-rich foods with calcium (e.g. spinach + cheese) to bind oxalates in the gut before absorption.