Food Allergy, Intolerance and Aversions: What’s the Difference?
There are different ways to classify adverse reactions to food depending on the mechanism, these terms are commonly confused or used incorrectly. The terms ‘food allergy’, ‘food hypersensitivity’ and ‘food intolerance’ are often used interchangeably, yet they describe very different types of reactions to food.
There are two ways to classify adverse reactions to food:
Immunological reactions. These are reactions to a protein in the food and involve the immune system. This type of reaction, often called a food allergy, is quite uncommon. These responses are always reproducible and reliable responses to particular foods, irrespective of the volume ingested. For example someone who suffers from an egg allergy will always react to ingestion of egg, whether it is from eating a whole egg or a small amount cooked into a cake. The reaction will always be the same.
Non-immunological reactions. These reactions do not involve the immune system and are usually referred to as food intolerances. They are very common. These reactions can vary and depend on the amount consumed, timing of meal and other meals consumed that day. For example someone who suffers from lactose intolerances may be able to consume a small amount of lactose (e.g. a dash of lactose containing milk in tea) but will experience symptoms if they consume a large volume of lactose (e.g. a milkshake containing milk, ice-cream and yoghurt).
FOOD ALLERGIES
Allergies occur when an overactive immune system produces proteins called IgE antibodies against substances in the environment that are otherwise harmful – pollen, house dust mites, moulds, animal hair (dander), and in some cases specific food proteins. Food allergy is mainly a problem of infants, toddlers and young children. Adults are usually allergic to a single food such as peanut or shellfish, but children are commonly allergic to two or three foods, sometimes more. The most common food allergens are:
Peanut and other nuts
Egg
Milk
Seafood
Sesame
Wheat
Soy
New food allergies can occasionally arise in adult life, usually crustaceans and other more exotic foods that are often not eaten in childhood. Reactions to fruits, vegetables, herbs and spices are due to chemical intolerances rather than allergies. Skin prick tests or blood tests can detect IgE antibodies in people with allergies, but are of no value for the diagnosis of intolerances.
Common symptoms of food allergy include:
Itching, burning and swelling of the mouth
Runny nose
Skin rash
Diarrhoea
Abdominal cramps
Breathing Difficulties
Vomiting and Nausea
In severe cases symptoms can be life threatening – a reaction called anaphylaxis, in which the circulatory system collapses.
FOOD INTOLERANCE
Food intolerances do not involve the immune system. They are the most common trigger of gut symptoms but can also cause other symptoms such as headaches and fatigue. There are a few main ways food intolerances can cause gut symptoms:
By causing bowel distension and therefore triggering gut symptoms. Foods containing poorly absorbed fermentable sugars or FODMAPs (naturally occurring in many foods including fruits, vegetables, dairy products and some grains) are common triggers.
Lactase deficiency (metabolic food intolerance) can cause gut symptoms as it results in lactose intolerance (the body doesn’t produce enzyme to digest lactose).
By specific responses to foods containing high levels of bioactive substances and food chemicals that are either naturally occurring in foods or added during food processing. This can cause pharmacological type reactions. Common examples of triggers include caffeine, salicylates, amines, glutamate, preservatives and colours.
COMMON SYMPTOMS
Almost any system in the body can be affected by food intolerance. Symptoms can depend on the volume of food ingested and can also occur due to a ‘threshold’ affect. Common symptoms include:
Gut symptoms (diarrhoea, constipation, bloating, excess flatulence, cramping etc)
Headaches
Fatigue
Behavioural changes and problems
Asthma, hives and swelling
DIAGNOSIS
Hydrogen breath tests or implementing a Low FODMAP diet is used to diagnose food intolerances related to bowel distension. Chemical related intolerances are diagnosed by undergoing a chemical elimination diet.
FOOD AVERSION
Food aversion compromises food avoidance, where the person avoids food for psychological reasons such as distaste or desire to lose weight, and psychological intolerance.
Psychological intolerance can cause similar symptoms to true food intolerance but is caused by the emotions associated with the food, rather than the food itself. Psychological intolerance symptoms will normally occur when a food is recognised and consumed under normal circumstances, but will not occur if the food is given in an unrecognisable form (i.e. the person isn’t aware they consumed the ‘problem’ food).
WHY IS IT IMPORTANT TO KNOW THE DIFFERENCES?
Allergies can be life threatening, yet food intolerances albeit cause adverse symptoms, do not pose a danger to one’s life. Those with allergies should not be exposed to any food allergen in any circumstance, yet those with food intolerances maybe able to tolerate small volumes of the trigger food and therefore don’t need to severely restrict their diet in comparison to someone with a food allergy.
HOW TO ESTABLISH WITH A RESIDENT IF IT’S AN ALLERGY OR INTOLERANCE
To help establish if a resident suffers from a food allergy or intolerance, the following questions need to be asked:
When was the onset of the allergy/intolerance? Was it in childhood?
What are the types of symptoms that occur? Are they at risk of anaphylaxis?
Is the food trigger one of the 7 common food allergens? (refer to list above)
Can the person tolerate small volumes of the problem food?
If they can tolerate small amounts of the food (i.e. they can have milk baked into a cake, but not a large glass of milk), the food trigger is not a common food allergen and the symptoms experienced are not ‘immunological’, it is more likely to be an intolerance rather than an allergy.
STRATEGIES FOR MANAGEMENT OF ALLERGY & INTOLERANCES IN AGED CARE
Establish if the resident suffers from an allergy or intolerance.
If an intolerance, establish if the resident can eat small amounts of the problem foods. This can allow for more variety with meals provided.
Document the allergy or intolerance and the symptoms it elicits in the residents care plan.
Advise the kitchen of the resident’s requirements. Be specific in terms of how much they can tolerate or how strictly the resident needs to avoid the problem food.
Ensure nursing staff and PCA’s are aware of requirements.
Advise visitors of any allergies if bringing in food to the facility.
Advise the treating doctor and ensure medications prescribed do not contain allergens.
Monitor for symptoms and devise a treatment plan with the resident’s doctor.
Liase with the facility Dietitian for meal planning input if required.