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The Ultimate Guide to Food Allergies & Intolerances

Discover the real difference between food intolerances and food allergies, plus 5 common causes that you can investigate, and practical tips to help manage your allergy or intolerance.


It is estimated that one-fifth of the population believe that they have a food intolerance. If you’re reading this article, you’re probably one of them. If you can’t quite put you finger on what food isn’t agreeing with you, then it’s time to get clued up – keep reading.

Food Allergies vs. Food Intolerences

Food allergies are a reaction by the immune system to a specific part of a food, usually one of the protein components.

Food allergies symptoms can include hives, swelling around the mouth, rashes and/or vomiting.  The worst case scenario is an anaphylactic reaction, which can be life threatening.  Food allergies do not disappear and are usually present from birth. Most commonly these reactions are to foods such as peanuts, cow’s milk, egg, tree nuts, soy, fish and shellfish, however it’s possible to be allergic to anything.

So you want to know ‘how to get over food allergies’? At this point of time there isn’t much we can do about it except for avoid the foods we react to, and be ready to administer first aid should exposure occur.

There is however, some hope for future treatment for allergy sufferers. A recent trial by the Murdoch Children’s Research Institute found that use of a certain strain of probiotics was able to reduce peanut allergy in 23 out of the 28 children studied. This is only a small study so far, so it’s unlikely that this will be a widely accepted treatment for a while to come, and it’s not recommended to try this at home due to the life-threatening nature of these allergies, however it does highlight the importance of keeping your gut healthy and also provides some hope.

You may be asking yourself “why am I developing food allergies?” and want to know how to tell if you have a food allergy, however you may not have an allergy, but rather an intolerance.

Recognising the difference between an allergy and an intolerance is important, as the incorrect use of these terms is often what leads to the general confusion about the whole area.

Food intolerances are reactions to foods that are not classed as an allergy. In some instances it can be due to a lack of enzyme such as in lactose intolerance, and in others it can be due to a reaction from the IgG or IgA immune cells. Unlike fructose malabsorption and coeliac disease, this is not a widely accepted phenomena and research into this area is still in its infancy.

Food intolerances are usually developed as a result of gut flora imbalances and/or damage to the lining of the digestive system (often referred to as intestinal permeability or leaky gut) however they can occur when a food is regularly consumed in large quantities.

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Food intolerances are not life threatening like an allergy, and the symptoms that can occur from eating something you are intolerant to are usually digestive (bloating, heartburn, diarrhoea, constipation, cramping and gas), however if you’re eating food you’re intolerant to, too frequently then it can create symptoms elsewhere in the body that are less likely to be related to food. These include brain fog, headaches, mood swings or weight gain.  Food intolerance symptoms are often delayed in their onset (they can come on 48 hours after eating) which means they are much harder to identify as the culprit for your symptoms.

Here are some common issues and causes – do you know the ins and outs of these?

1. Fructose Malabsorption

Fructose malabsorption can be a common issue for many people with digestive complaints, especially bloating, pain and diarrhoea.

It is estimated that up to 70% of people with IBS (irritable bowel syndrome) have fructose malabsorption.  The diet to manage this is known as the FODMAP diet.

The FODMAP diet was originally developed by Dr Sue Shepherd, an Australian dietician. She has proven, through her pioneering PhD research, that limiting dietary FODMAPs is an effective treatment for people with symptoms of IBS. Several research papers have confirmed her work and so this diet has become better known in the last few years, even being accepted overseas.

Fructose is a naturally occurring sugar found in certain fruits and vegetables, and in some people this sugar cannot be effectively processed in the small intestine.  As a result it is left to ferment, which can cause bloating, diarrhoea and/or constipation, flatulence, stomach pain, and even mood imbalances.

As wheat contains FODMAPs, some people attribute non-coeliac reactions to gluten to fructose malabsorption.

It is important to remember that high FODMAPs foods are not always the only culprit for IBS symptoms.

Consider being aware of your reaction to fatty foods, caffeine, alcohol, fibre (excess or lack of), medications and stress, which may also influence your symptoms. Hormonal problems and bacterial imbalances can also be responsible.

Contributing factors towards the development of fructose malabsorption include:

  • Diabetes (especially type 2)
  • Diets that are high GI (glycaemic index)
  • Stress
  • Certain medications including Corticosteroids and Metformin
  • Digestive damage from excessive alcohol, smoking and other factors

As you can see from the above list, fructose malabsorption is likely to occur from poor blood sugar regulation and digestive damage – commonly seen in inflammatory bowel disorders such as Crohn’s disease and ulcerative colitis.

RELATED: BOOK REVIEW: Heal Your Gut, by Lee Holmes

Fructose malabsorption diagnosis: You’d be surprised how many people Google ‘fructose malabsorption test’! Fructose malabsorption can be diagnosed using a fructose hydrogen breath test, which recognises unabsorbed fructose.

The FODMAP elimination and challenge diet is also a way of determining whether you react to FODMAPS, and narrowing down what types and how much. The FODMAP diet is very strict, so it’s not a long term solution but rather a means to identify which foods in this group you are reactive to.

FODMAPs are found in the following foods:

  • Fermentable Oligosaccharides (e.g. Fructans and Galactans)
  • Disaccharides (e.g. Lactose)
  • Monosaccharides (e.g. excess Fructose)
  • Polyols (e.g. Sorbitol, Mannitol, Maltitol, Xylitol and Isomalt)

The list of foods that are to be avoided in a full FODMAP diet is rather large, but it includes a lot of fruits, honey and some other sweeteners, wheat products, most dairy sources, soy milk, legumes, and certain vegetables including garlic, onion, mushrooms and asparagus.

2. Chemical Sensitivities

There are a number of substances that are naturally contained in foods that can cause reactions in some people, including rashes, headaches, fatigue, digestive symptoms, hyperactivity and irritability. The main food chemicals which can cause symptoms are salicylates, amines and MSG.

  • Salicylates can be found in a wide range of fruit (especially in unripened fruit) and vegetables (more concentrated in the outer leaves), as well as nuts, herbs and spices, jams, honey, yeast extracts, tea, coffee, bear and wines. Aspirin also contains salicylates.
  • Amines are high in foods such as deli meats (salami, bacon, ham, frankfurts), tinned fish and tinned meats, tomato paste and pasta sauces. They are also present in cheese, chocolate, wines, beer and yeast extracts.
  • MSG (monosodium glutamate) is well known for the reactions it can cause, particular when used as a flavour enhancer in some Asian cooking, soups, sauces and packaged snack foods. It is also found in high amounts naturally in some foods such as tomatoes, blue and parmesan cheese, mushrooms, broccoli and some meat and yeast extracts.

3. Sulphites Intolerance

Sulphites can cause a worsening of asthma symptoms, headaches and fatigue. The food additives to watch out for in this category are the numbers E220 – E224, E226 and E227. They are found in a lot of dried fruits, packaged salads and fruit salads, some dried foods such as garlic, ginger, potatoes, soft drinks and fruit drinks, pickles, sauerkraut and corn syrup. People who are very sensitive to sulphites may benefit from increasing their intake of the mineral molybdenum.

4. Histamine Intolerance

Histamine intolerance often mimics the symptoms of a food allergy, however it is an inflammatory reaction caused by an impaired ability to breakdown the chemical histamine, which is naturally present in many foods. Symptoms of histamine excess include hives and itching, racing pulse, anxiety, swelling of the face and throat, runny nose, conjunctivitis, headaches, digestive upset, fatigue, confusion and irritability. This problem is often developed after some form of disruption to the digestive system, usually an infection or course of antibiotics, but can also be triggered by stress and other digestive problems. Some medications such as painkillers, asthma medications and sleeping medications can also interfere with the enzymes that process histamine. Methylation problems can also affect histamine levels, and people who are in this category are more likely to experience mood disorders such as depression and OCD. Some of the main food triggers include red wine, fish (unless very fresh), smoked, processed or fermented meats, left-over foods, most cheeses, citrus fruits, pineapple, raspberries, prunes, tomatoes and tomato products, spinach, red beans, eggplant, olives, pumpkin, pickles and relishes, chocolate, soy sauce, most alcohol drinks and tea.

6. Coeliac Disease

Coeliac disease is one of the most well known forms of food intolerances. First discovered in the 1950s it was originally thought to only be a childhood disorder. The prevalence of this condition is increasing, however it is thought that there are many people with this condition who are still undiagnosed.

It is not an allergy or sensitivity, but rather an autoimmune reaction to gluten, which is often genetically inherited.

In people with coeliac disease the immune system causes severe damage to the cells of the small intestine, which causes digestive symptoms and significantly impacts on the absorption of nutrients, resulting in nutritional deficiencies. At a microscopic level, your digestive lining should be coated in hair like protrusions called vili – essentially it looks like a shag pile rug – and this creates lots of surface area to absorb nutrients. When damage has occurred in people with coeliac disease, these vili become flattened and fried, resulting in malabsorption problems.

Diarrhoea, cramping, bloating and constipation can be caused by celiac disease. However not everyone with coeliac disease experiences digestive problems, and so it can go undiagnosed for a long period of time, wreaking havoc in secret. Fertility issues, anaemia, osteomalacia, osteoporosis, autoimmune problems and mood disorders can all be related to undiagnosed coeliac disease.

Having the gene for coeliac disease does not automatically mean that you have the condition, but you cannot have coeliac disease without having the gene for it.

If you suspect that you have coeliac disease but have been avoiding gluten, then you can get yourself tested for the coeliac genes first.  If you do have the genes, you will need to eat gluten containing foods for 6-8 weeks before doing the antibody tests (as these would not be accurate without having eating gluten previously).  This will confirm whether you have coeliac disease or not. In some cases your doctor may refer you to get a biopsy performed, which is considered to be the most conclusive diagnosis.

Many people who are avoiding gluten have not been adequately screened for coeliac disease before commencing a gluten free diet and so coeliac disease often goes undetected.

In people with gluten intolerance/sensitivity or fructose malabsorption they can often handle small amounts of gluten without experiencing problems, however with coeliac disease you might get away without experiencing symptoms, but the damage to the vili will always happen. This means that having the diagnosis of coeliac disease gives you the knowledge of whether you need to be 100% strict with gluten avoidance or not.

Tips For Managing Food Allergies & Intollerances

Whether you have been diagnosed with an intolerance or allergy, or you’re dealing with food intolerance in babies and children, it can be very overwhelming and stressful to get a diagnosis of a food intolerance or allergy, particularly if it is a common food such as wheat or dairy. Thankfully due to the magic of the internet there is more help than ever for people trying to manage their diet around food intolerances.

  • Join a support group. There are plenty of Facebook groups and online forums dedicated to specific food intolerances, and often the people in these groups have done plenty of research so will be able to share resources and recipes with you.
  • Research food substitutions. Instead of giving your favourite recipes the flick, try substituting ingredients you can’t have for foods which will create a similar effect. For example, eggs, which are commonly used to bind dishes can be replaced with a little corn meal or extra kneading; cheese can be replaced with ‘vegan cheese’ which is often made with cashews and nutritional yeast; cow’s milk can be replaced with oat, nut or seed milks and wheat flour can be replaced with several gluten free flour options. Keep your pantry stocked with these and that way you won’t be disappointed if you get a whim for cooking a particular dish.
  • Plan your meals in advance. Meal planning and prepping can make life easier for everyone, but especially so for those dealing with food intolerances. Create a list of meals that you can have and rotate through these. Try a new recipe each week and eventually you will have a big repertoire of recipes that you are familiar with.
  • Call ahead. If you’re going out to eat, call ahead and advise of any food intolerances so that the kitchen can have options prepared.  It can be a good idea to ask if they’re okay for you to bring your own gluten free bread or milk alternative.
  • Educate your friends and family. Share this article and other information with friends and family who might be struggling to understand, and discuss with them what foods you can and can’t handle and how much you can tolerate, if any. Most people will be happy to accommodate your requirements as long as they understand.
Alison Mitchell Naturopath

Alison is a practicing Naturopath, based in Windsor and Dural, NSW. She also offers consultations via Skype. She is passionate about helping people reclaim their health and vitality by blending traditional healing methods with the latest research. She is thorough and caring in her approach and believes in an individualised approach to treatment and diet. She is a foodie and an advocate of the 80/20 rule, and she believes that life is meant to be enjoyed and that good health is one of the best ways to do this.

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