Food allergies and intolerances

Allergies and intolerances can be extremely frustrating and really affect people’s quality of life. Especially if these allergies and intolerances are from perfectly healthy foods.

Allergies and intolerances can manifest in not only digestive discomfort and digestive symptoms, but they also commonly manifest in and exacerbate existing skin issues, hay fever symptoms, hormonal disruption (especially in females), fatigue/lethargy and immune conditions.

Identifying allergies and intolerances

Sometimes allergies and intolerances are very easy to pinpoint. People can recognise the intake of a particular food and a flare up of their symptoms. While people may sometimes know what foods they react to, they may not understand what all of these foods have in common, hence they may not understand what component of the foods they are reacting to. People may think they know based on Dr. Google, but most of the time, in my experience, the assumption is incorrect. 

On the other hand, some food allergies and intolerances may not manifest in symptoms immediately after ingestion. This can make it hard for people to pinpoint what foods they are reacting to. This is because certain components of various foods that a person may have an allergy and intolerance to, may take time to build up in their system before they manifest in symptoms. This can also lead to people pinpointing the wrong foods. These types of food allergies and intolerances are due to an accumulation in the body of components that are contained in foods, due to an increased intake and poor breakdown of these food components. This is usually a result of a disruption in a person’s gut microflora. An example of this, which I commonly see and treat in practice is histamine intolerance.

People can also pinpoint the wrong foods if they forget about the context in which they are consuming the food. For example, a person may think they react to a certain food they ate at a restaurant, but they don’t realise that it actually may have been the cooking oils and sauces they are reacting to. Home cooked foods are very different from takeout. This is why cooking your own food is so important for your health so you can control ingredients, especially when identifying allergies and intolerances. 

What drives food allergies and intolerances?

Most food allergies and intolerances are driven by our gut bacteria. Within the gut, there are billions of colonies of bacteria, both good bacteria and bad bacteria. The good keeps the bad in check. It is all about balance within the gut. 

Poor diet and lifestyle habits, as well as the overuse of medications such as antibiotics, can cause the bad bacteria to overrun the good bacteria. Once this happens, the bad bacteria release inflammatory molecules that cause inflammation in the digestive system, thus affecting proper digestion and absorption of food. When food is not digested and absorbed properly in the gut due to inflammation, it can lead to food intolerances. Food intolerances are when certain foods are not digested and absorbed properly, therefore they linger in the gut where bacteria excessively ferment them. The by-product of fermentation is gas, which is then responsible for the symptoms of bloating, wind, pain, reflux (due to increased abdominal pressure) and stool issues. 

Digestive disorders like Chron’s disease, ulcerative colitis, celiac disease and irritable bowel syndrome (IBS) are characterised by inflammation in the digestive tract due to overgrown bad bacteria, which is why these people tend to commonly suffer from food intolerances.

Furthermore, 80% of the immune system is located in our gut. Our gut bacteria play a really important role in regulating our immune system and governing healthy immune function. An overgrowth of bad bacteria can cause immune dysregulation, which can contribute to and exacerbate lots of immune related health issues like autoimmune conditions, eczema, psoriasis, asthma, hay fever and of course food allergies. Food allergies are a hypersensitivity of the immune system, where it reacts to proteins in certain foods. Food allergies is where the body mounts an immune reaction to proteins in food because it perceives these proteins as foreign and dangerous. This is because the immune system is not being regulated properly by the gut bacteria. Immune reactions to harmless protein in food causes inflammation in the gut and immune system, hence exacerbating existing health conditions. 

What is the best way to pinpoint food allergies and intolerances?

The best way to pinpoint food allergies and intolerances is firstly to work with a practitioner who can help you identify commonalities between foods you may think you are reacting to. Based on your symptom picture, they may be able to identify reactions to food groups that you may be unaware of. 

Once the potential culprits are identified, removal of the foods in question and then re-introduction of those foods in dose dependent amounts, is the gold standard of identifying food allergies and intolerances. This is because it has real world applicability. We want to find out what a person reacts to, in what amounts and if this amount is allergy and testing methods can’t do this. 

What about food allergy and intolerance testing? Is it reliable?

Food intolerances are usually tested by giving a person the component of certain foods they may be reacting to. Their symptoms are then monitored, and some tests use breath testing, where the amount of gas in a person’s breath is measured upon the ingestion of a food component that they may be reacting to. This is to test the amount of malabsorption and bacterial fermentation of the food component. The more gas means poorer absorption and increased fermentation, therefore indicating an intolerance.

However, this can be unreliable as people eat food, not components of food. For example, giving someone a pure fructose and glucose solution as part of a test is different to consuming these molecules within foods. All foods are structurally different, which is why people often don’t react to all the various types of food that contain a particular food component they may struggle to digest. Food structure also changes due to things like cooking, which is also why some people may react to certain foods raw compared to cooked. 

For example, someone might be diagnosed with fructose malabsorption/intolerance due to high levels of gas production on a breath test after consuming a fructose-based solution. However, this usually does not mean they will get digestive symptoms after eating every food that contains fructose. 

They may only experience digestive symptoms after eating certain types of fruit and vegetables with fructose in them, while other types with high amounts of fructose may not be an issue. Every person is different, and every food is different, even if some foods contain similar molecules that some people may struggle to digest if they have inflammation in their guts. 

It is all individual based, which is why food removal and reintroduction is so helpful because it allows us to find out exactly what foods a person reacts to of a particular food group. We can also identify the amounts they react to as well, as some people react to certain foods in a dose dependent manner. This is real world applicability.   

Allergy testing on the other hand usually involves taking a blood sample and measuring immune molecules to certain foods that are located in the blood. Sometimes the allergenic food is administered to the person in high amounts and then a blood test is taken afterwards. These tests can be unreliable because immune molecules may show in the blood but not actually cause a reaction in the body, therefore giving false positives. These tests have also been shown to lack accuracy, validity and reliability in scientific research. Pin pricks are often used as well, but unless it is an environmental allergen, people eat “allergenic” food through their gut, not through their skin. 

We eat food through the gut not via the skin….

Lastly, allergy and intolerance testing can lead to conclusions that lead to the removal of whole food groups. This is because they don’t help identify what specific foods a person is reacting to. This is not ideal. If a person does not react to a certain food, then there is no need to remove it. This is why food removal and reintroduction is so important. Whole food group removal can lead to two major problems that are not ideal for a person suffering from allergies and intolerances.


  1. Whole food groups removal is often unnecessary and can cause a lot of stress on the individual. Especially when they are told all the things they can’t eat, but not given any guidance on how to keep a healthy diet based on what they can eat. Increased stress levels are counterproductive as stress causes disruptions to the gut bacteria that drives allergies and intolerances.
  2. Removal of whole food groups can lead to the decreased intake of nutrient dense foods, leading to potential nutrient deficiencies. Also, removing lots of wholefoods can affect the gut bacteria composition. The good bacteria in the gut need healthy foods to feed on and thrive. When people go on restrictive elimination diets, this can have negative effects on the gut bacteria, therefore causing one problem while trying to solve another. A common example of this is the commonly prescribed low FODMAP diet and “anti-candida” diet. These diets often lead to the removal of foods that are very high in nutrients (e.g. prebiotics) that feed the good bacteria in the gut, which is important for the treatment of the conditions that these diets are trying to solve.


Based on all of this, how do we treat food allergies and intolerances?

Once we identify the foods in question, we can then remove them for a certain period of time, which varies from person to person. This gives time for inflammation to decrease. During this time, it is vital to re-shape the gut bacteria and help to increase good species that will help digestion and re-balance the immune system. Re-balancing the immune system via the gut will also help with environmental allergies like hay fever. 

This is done via changing diet and lifestyle habits that effect gut bacteria composition, as well as evidence based herbal and nutritional supplementation. Diet changes must focus on what a person can eat, instead of focussing on what they can’t. 

Once we do this and a person’s symptoms have settled, it is possible to re-introduce certain foods in dose dependent amounts (note: this does not apply for anaphylaxis). This is important for the gut bacteria as well.

More often than not, people will start being able to tolerate the intake of higher amounts of foods they once reacted to.