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Food Intolerance- The What, Causes & Management

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Food intolerance’s are common. According to some estimates, they may affect 15–20% of the population.

A person with a food intolerance has difficulty digesting certain foods. It is important to note that a food intolerance is different than a food allergy. While a food allergy results from an immune system reaction to a specific food, food intolerance’s usually involve the digestive system, not the immune system.

Food intolerance’s are more common in those with digestive system disorders, such as irritable bowel syndrome (IBS). According to the IBS network, most people with IBS have food intolerance’s.

This week’s article looks at the causes, types, symptoms, and diagnosis of food intolerance’s and explains how people can manage them.


A person with a food intolerance will often experience discomfort soon after eating certain foods. The symptoms are varied and usually involve the digestive system. The symptoms of food intolerance’s can take a while to emerge. The onset may occur several hours after ingesting a food, and the symptoms may persist for several hours or days.

Common symptoms of food intolerance include:

  • bloating
  • excess gas
  • stomach pain
  • diarrhoea
  • migraine
  • headaches
  • a runny nose
  • malaise, which is a general feeling of being under the weather

In people with a food intolerance, the amount of the food that the person eats determines the severity of their symptoms. It can be difficult to determine whether someone has a food intolerance or an allergy because the signs and symptoms of these conditions overlap.

Causes & Types

Food intolerances arise if the body is unable to digest a certain food. This impairment may be due to a lack of digestive enzymes or a sensitivity to certain chemicals.

Foods commonly associated with food intolerance include:

  • milk
  • gluten
  • food colourings and preservatives
  • sulfites
  • other compounds, such as caffeine and fructose

The next section look’s at the various causes and types of food intolerance’s:

Milk (Lactose)

Lactose Intolerance

The body uses digestive enzymes to break down foods. If a person lacks certain enzymes, they may be less able to digest certain foods.

Lactose is a sugar that occurs in milk. People with lactose intolerance do not have enough lactase, an enzyme that breaks lactose down into smaller molecules that the body can easily absorb through the intestine.

If lactose remains in the digestive tract, it can cause spasms, stomachache, bloating, diarrhoea, and gas.

honey image
Honey (Fructose)

Fructose Intolerance

Fructose is a sugar present in fruit, some vegetables, and honey. Fructose intolerance can also be due to the lack of an enzyme, although this is rare. In such cases, it is known as hereditary fructose intolerance.

Fructose malabsorption, in which the body is missing a protein that allows it to absorb the sugar from the intestine, is much more common.

In these individuals, the fructose in foods ferments in the gut, leading to gas, fullness, bloating, cramps, and diarrhea.

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Bread with gluten

Gluten Intolerance

Gluten is a protein that occurs in some cereals, including wheat, barley, and rye. A person with gluten intolerance experiences discomfort, such as pain, bloating, or nausea, after eating foods that contain gluten. Gluten intolerance is also associated with non-digestive symptoms, such as:

  • brain fog
  • headaches
  • joint pain
  • fatigue
  • depression
  • anxiety
  • a general lack of well-being

Gluten intolerance is different than celiac disease, which is an autoimmune system response to gluten, and wheat allergy, which is an allergic response to wheat. However, the symptoms of these conditions may be similar. Gluten intolerance is also known as non-celiac gluten sensitivity. The symptoms of celiac disease and gluten intolerance typically improve when a person eliminates gluten from the diet but return when they reintroduce it.

spices image

Salicylate Intolerance

Salicylates are compounds that occur in many plant foods, including fruits, vegetables, herbs, and spices. They are also common in artificial flavorings and preservatives, including those in toothpaste, chewing gum, and candies.

Most people can tolerate moderate amounts of salicylates in their diet, but some people have a reduced tolerance.

Symptoms can include:

  • hives
  • rashes
  • stomach pain
  • diarrhoea
  • fatigue
  • a runny nose
  • wheezing

Food additives and intolerance

Of the thousands of additives that the food industry uses, experts believe that only a relatively small number cause problems. The following food additives can cause adverse reactions in some people:

  • Nitrates: These preservatives are common in processed meats, and the symptoms of an intolerance can include headaches and hives.
  • Monosodium glutamate (MSG): This flavor enhancer can cause headaches, chest tightness, nausea, and diarrhea in those with an intolerance.
  • Sulfites: Common sources of these preservatives include wine, dried fruits, fresh shrimp, and some jams and jellies. People with an intolerance may experience chest tightness, hives, diarrhoea, and sometimes, anaphylaxis.


Food intolerance’s and food allergies can have similar symptoms, so it can be tricky to diagnose these conditions. Diagnosis is also complicated when a person has several food intolerance’s.

People can keep a food diary to document which foods they eat, the symptoms that appear, and their timings. These data can help people and their healthcare providers work out which foods are causing adverse reactions.

Apart from lactose intolerance and celiac disease, there are no accurate, reliable, and validated tests to identify food intolerance’s. The best diagnostic tool is an exclusion diet, also known as an elimination or diagnostic diet.

The doctor may recommend a skin prick test or blood test to rule out a food allergy.

A blood test can measure levels of immunoglobulin E (IgE) antibodies. High levels can indicate an allergy.

Some people find that if they stay off the specific food for a while, they have no reaction when eating it again. This is known as tolerance. Maintaining tolerance is often a question of working out how long to abstain from eating the food and how much of it to eat when reintroducing it. A healthcare professional can help.


Food intolerances arise when the body cannot properly digest certain foods. Lactose intolerance and gluten intolerance are common types.

There is currently no cure for food intolerance’s. The best way to avoid symptoms of a food intolerance is to avoid certain foods or eat them less often and in smaller amounts. People can also take supplements to aid digestion.

Balanced Healing can offer a screening service and we provide:

  • Blood Test for IgE’ s indicating intolerance’s covering 90 or 240 foods,
  • Access to an Allergy Specialist at the Allergy Clinic



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