Is it a food allergy or a food intolerance? |21 July 2023

I can’t count the number of times I’ve heard someone say “I’m allergic to this”. Sometimes one has to wonder if it’s truly an allergy or is it actually an intolerance?

It might not always be clear what constitutes an allergy and what constitutes an intolerance since some of the symptoms are quite similar. This can cause someone to self-diagnose themselves with an ‘allergy’ which may not actually exist.

You might think that it’s not a ‘big deal’ and that these two terms can be used interchangeably. The truth however is that an intolerance can make you feel unwell for a period of time but then you’ll be okay. On the other hand, an allergy can make you sick and may also be life-threatening.

Differentiating between a food allergy and a food intolerance

So what’s the difference between these two terms. The biggest difference is the system involved when the ‘problem’ food is consumed.

A food intolerance involves the digestive system. When the food is consumed the body has difficulty to break it down. This may be because the body lacks certain enzymes or you are sensitive to certain additives or naturally occurring chemicals in the food.

It is also often dose-specific meaning that some people may be able to eat small amounts of the food without any adverse reactions. They would usually get symptoms if large amounts of the same food are eaten. The amount that leads to symptoms varies from one person to another.

Some common symptoms of food intolerances are nausea, diarrhoea, abdominal pain, excessive gas, heartburn and headaches. Symptoms may appear immediately or within 12 to 24 hours after eating the food.

Food allergy involves the immune system. The immune system which usually protects the body from foreign pathogens reacts to certain proteins in the food and sees it as an intruder.  An allergy is however not only limited to protein from foods but also from other sources such as pollen, animal fur or wool, house dusts and mould. These are all known as allergens.

While it may take a while for symptoms to appear in food intolerance the appearance of symptoms in an allergy is instantaneous. This can be due to even a microscopic amount of the allergen being consumed.

The symptoms of a mild to moderate food reaction includes swelling of lips, face and eyes, hives (raised red bumps on the skin) and tingling mouth. In a severe allergic reaction, known as anaphylaxis, a person may experience difficulty breathing, swelling or tightness in the chest, wheezing, persistent coughing, swollen tongue, dizziness or they may even collapse.

Causes of food intolerance

There are specific compounds in food that the body has difficulty breaking down leading to an intolerance. Some of the more common intolerances occur with consumption of milk, certain cereal products, certain food additives and other naturally occurring compounds in food products.

One of the most common intolerance is lactose intolerance. Lactose is a sugar found in milk and milk products. A person with lactose intolerance does not produce enough of an enzyme called lactase which is needed to digest lactose.

Gluten intolerance or non-coeliac gluten sensitivity is caused by the inability of the body to digest gluten which is typically found in certain cereals namely wheat, barley, rye and triticale. It is not the same as the autoimmune disease, Coeliac disease nor is it the same as wheat allergy which is an allergic reaction to wheat, despite them having certain similar symptoms.

Some people may also develop an intolerance to a compound called salicylate. It occurs naturally in many plant-based foods such as fruits, vegetables, herbs and spices. They are also a common ingredient in artificial flavouring or preservatives that are added to toothpaste and confectionary like sweets and chewing gum.

Histamine is another naturally occurring chemical which some people have difficulty breaking down. It is commonly found in cheese, avocado, banana, chocolate and wine.

A small number of additives added to processed foods can cause a reaction in certain people. This includes nitrates, a common preservative in processed meats like ham, salami, luncheon meat and corned beef; monosodium glutamate (MSG) – a flavour enhancer added in many sauces and snacks like crisps; and sulfites – a preservative used in wine, dried fruits, some jams and jellies.

Causes of food allergy

Food allergy is caused by an allergen, a protein present in certain foods. The most common foods that can cause an allergic reaction include peanuts, tree nuts, eggs, cow’s milk, wheat, sesame, fish, shellfish, soy and any products containing or made from them.

How do you know if you have a food allergy or food intolerance?

The only way to confirm the diagnosis is to see a health professional. There is no test for most intolerances. Once symptoms have been reported you will be advised to complete a food diary to keep track of food consumed and symptoms. This will enable identification of ‘problem foods’.

The next step may be an elimination diet whereby the suspect food is removed from the diet for a certain period of time and then reintroduced again later on. If symptoms appear when the food is reintroduced, then it is most likely that you have an intolerance to that particular food.

Managing food intolerances

The management of food intolerance is done by avoiding or limiting the foods that leads to symptoms. Some people find that they can tolerate small amounts of the food so may be able to continue to include them occasionally in their diet. Depending on the nature of the symptoms if they do occur certain over-the-counter medications can help.

In the case of those with lactose intolerance, they can try lactose-free milk and milk products. Otherwise if it is available in pharmacies you can try lactase pills before consuming milk or adding lactase drops directly to milk to help break down the lactose.  

Managing food allergies

The only way to manage food allergy is eliminating the offending food(s) from the diet. It is important however to only exclude the food to which you have a diagnosed allergy.

It is important to identify these foods in packaged foods as they may be there in small amounts and other terms may be used to describe them. For instance, in the ingredient list, milk may be written as casein, whey or lactose; eggs may be albumin or lecithin; wheat may be malt or bran; and soy may be hydrolysed vegetable protein, soy protein isolate or soybeans.

Strict regulations in many countries means that on the label of many of the foods that we import there is a declaration of these allergens whether they are used as an ingredient, an additive or processing aid. This makes it easier for you to know which foods you can avoid when doing your shopping if you are allergic to them.

If you’re still unsure whether you have a food allergy or food intolerance, then it is better to seek the help of a medical professional instead of unnecessarily avoiding certain foods which may otherwise be safe for you to consume.

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Yours in health

The E4OH team