Causes of Food Intolerance
The causes of food intolerance are often related to the body’s inability to properly digest or absorb certain components in food. Food intolerance may result from enzyme lack, chemical sensitivities, or underlying stomach disorders. Unlike food allergies, food intolerances do not trigger an immune reaction.
Enzyme Deficiencies
Many intolerances stem from a lack of enzymes needed to break down specific food substances:
A lack of lactase, the enzyme that digests lactose (milk sugar), causes lactose intolerance
Fructose malabsorption results from the inability to absorb fructose effectively in the small intestine
Sucrose intolerance, though rarer, involves issues withdigesting common table sugar
Without these enzymes, large sugars ferment in the gut, producing gas, blocks, and diarrhoea.
Chemical Sensitivities
Some people react to natural chemicals in food, such as:
Caffeine in tea, coffee, or chocolate
Histamine in aged cheeses, smoked meats, and wine
Salicylates, found in many fruits, vegetables, and spices
Tyramine, present in foods that have fermented
These reactions can cause head-aches, flushes, irregular heart activity, or irritability, and are often dose-related.
Additives and Preservatives
Certain food additives are known to cause intolerance-like symptoms:
Sulphites (used in dried fruits, wine, and processed meats)
Monosodium glutamate (MSG)
Artificial sweeteners, like sorbitol and xylitol
These additives can cause headaches, hives, or digestive upset in sensitive individuals.
Gastrointestinal Conditions
People with underlying gut conditions may be more likely to develop food intolerances:
Irritable bowel syndrome (IBS) often overlaps with intolerance to FODMAPs (fermentable sugars)
Coeliac disease, although immune-mediated, can be confused with gluten intolerance
Small intestinal bacterial overgrowth (SIBO) may worsen intolerance symptoms
Causes of Food Intolerance
Understanding the causes of food intolerance helps guide dietary changes and supports better gut health, allowing people to enjoy food with fewer symptoms.
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