Food intolerances and their symptoms

Food intolerances are reactions to certain foods that occur because the digestive system struggles to process specific ingredients. Unlike food allergies, which involve the immune system and can cause severe or even life-threatening reactions, food intolerances usually cause digestive and other mild-to-moderate symptoms, depending on the type and amount of food consumed.

What is a food intolerance?

A food intolerance occurs when the body has difficulty digesting specific foods or components within them. This can be due to enzyme deficiencies, sensitivity to certain chemicals, or reactions to additives. For example, lactose intolerance is common and arises from a lack of lactase, the enzyme needed to break down lactose, a sugar in dairy products.

What are the most common symptoms of food intolerances?

Food intolerances often lead to symptoms that affect the digestive system but may also produce symptoms in other areas of the body. These symptoms typically appear a few hours after consuming the offending food and may include:

• Bloating and gas: Feeling bloated or experiencing excessive gas is common, particularly with lactose or fructose intolerance.
• Abdominal pain or cramps: Cramping in the stomach or lower abdomen can result from indigestion or irritation caused by certain foods.
• Diarrhoea: Loose stools or diarrhoea may occur if food isn’t fully digested, especially with lactose or gluten intolerance.
• Constipation: Some intolerances can lead to slowed digestion and constipation, particularly those involving fibre-rich foods.
• Nausea: Some people feel nauseated after eating foods they can’t tolerate well.
• Headaches or migraines: Certain food intolerances, like those involving monosodium glutamate (MSG) or caffeine, may lead to headaches.
• Skin reactions: Itchy skin or mild rashes may sometimes be associated with intolerances, though these symptoms are more commonly seen with food allergies.

Common food intolerances

• Lactose intolerance: Affects people who have trouble digesting lactose in dairy products, often leading to bloating, diarrhoea and cramps.
• Gluten intolerance: This sensitivity to gluten, a protein in wheat, barley, and rye, can cause gastrointestinal discomfort. Non-coeliac gluten sensitivity differs from coeliac disease, an autoimmune condition.
• Fructose intolerance: Fructose, a sugar found in fruits and some sweeteners, can be poorly absorbed by the intestine, causing bloating, pain and diarrhoea.
• Histamine intolerance: Foods high in histamine, like aged cheeses, wine, and cured meats, can cause reactions in those with impaired histamine breakdown, leading to headaches, skin irritation and digestive issues.
• Food additives: Additives such as sulphites, MSG, and artificial sweeteners may trigger symptoms in sensitive individuals, including headaches, digestive upset, and skin reactions.

How do I manage food intolerances?

• Dietary adjustments: Avoiding or reducing the intake of trigger foods is often the most effective approach.
• Gradual reintroduction: Reintroducing foods slowly under medical guidance can help identify the tolerance level.
• Enzyme supplements: For some intolerances, like lactose intolerance, enzyme supplements may help improve digestion and reduce symptoms.

When should I see a doctor about a food intolerance?

If you suspect a food intolerance, consult a healthcare provider. They can guide you in identifying trigger foods through elimination diets, food diaries or specific tests, and help manage symptoms for a better quality of life.