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Food Allergies


The Health Index

Unfortunately, there is much confusion around several similar terms; food allergy, intolerance, and sensitivity are all widely used and frequently used interchangeably.

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True food allergies are those that trigger the formation of IgE (immunoglobulin E) antibodies. Reactions tend to occur immediately after exposure and can be life-threatening (anaphylactic shock). Typical symptoms are swelling of the mucous membranes, respiratory symptoms, skin rashes, redness, and itching. Common food allergens are nuts, peanuts, fish, stone fruit, celery, eggs, dairy and more. 


Food intolerance is a digestive system response rather than an immune-system response. It occurs when something in food irritates your digestive system or when you are unable to properly digest the food. Intolerance to lactose, which is found in milk and other dairy products, is the most common food intolerance. Others are fructose, gluten or histamine intolerance. Food sensitivities are immune reactions, but the antibody produced is called IgG (rather than IgE, as in true food allergies).


Symptoms are not life-threatening but can be incredibly varied, ranging from digestive symptoms (e.g. abdominal pain, diarrhoea, constipation, heartburn, flatulence) to headaches and migraines, insomnia, depression, anxiety, joint pain, and skin rashes. They do not typically occur immediately after ingestion and can take up to 72 hours to manifest, which makes it very difficult for the person affected to know which food may have triggered it. 


The most common IgG-triggers are yeast, cow’s milk, gluten, wheat, egg yolks or egg whites, but at the end of the day, we can be sensitive to any food. The most likely culprits are those we eat frequently, even every day.

What are the causes?

Allergies are autoimmune conditions caused by the immune system wrongly identifying certain proteins in a food as harmful. The body then launches a range of protective measures, including releasing chemicals like histamine, which causes inflammation. If you are allergic to food, even minute quantities can cause a reaction. The foods in question must be avoided completely.

Food sensitivities activate the immune system, but rather than being IgE-mediated like a food allergy, they are mediated by IgG and IgA antibodies. IgG- and IgA-mediated food intolerances are thought to be related to increased gut permeability (“leaky gut”) and are often implicated in Crohn’s disease and other gastro-intestinal conditions. If the gut is permeable, partially digested food molecules can enter the bloodstream through the intestinal wall and provoke an immune response.

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What are the symptoms?


With a food allergy, symptoms typically occur within minutes of exposure. However, they can also take a few hours to manifest. Symptoms include:

  • Swelling of the tongue, mouth, or face

  • Difficulty breathing

  • Blood pressure drop

  • Vomiting, diarrhoea

  • Hives

  • Itchy rash


In severe cases, a food allergy can cause anaphylaxis. Symptoms that can come on very quickly include an itchy rash, swelling of the throat or tongue, shortness of breath, and low blood pressure.

Symptoms of food sensitivity can take between a few hours to a couple of days to develop, which makes it difficult for the person affected to pinpoint the food that may have caused the reaction. Symptoms of intolerances can be, among others:

  • Asthma

  • Digestive symptoms (e.g. diarrhoea, constipation, bloating, stomach cramps)

  • Skin problems (e.g. rashes, hives, acne, eczema)

  • Headaches, migraines

  • Joint pain or stiffness

  • Weight gain or loss

  • Tiredness or fatigue 

  • Depression, anxiety

  • Brain fog

  • Lethargy

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How can a nutrition practitioner help?

A nutrition practitioner will ask questions about your overall health and health history, diet, lifestyle and exercise habits. They will look at your food diary to see which foods could be causing problems. They may also recommend functional testing to find out which foods you may be sensitive to and/or to assess the health of your digestive tract.


Whether you suffer from allergies, intolerances, or sensitivities, your gut is the place to start in order to strengthen your immune system and improve the way you feel. Sometimes, sensitivities or intolerances even disappear once the gut has healed, or foods that you have had to avoid completely can be tolerated again in small quantities.


If you know which foods you must avoid, a nutrition practitioner can advise you on how to create nutritious and yummy meals without the offending ingredient(s).  Your nutrition practitioner will develop a customised diet, supplement and lifestyle plan that works for you.

Find your Food Allergy


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