Food Allergy

Food allergies, unheard of a few decades ago, are now frequently diagnosed or self-diagnosed. Food allergies, food sensitivities, food intolerances – call them what you will. You may as well, because there is still massive confusion about terminology in the medical literature, where the very idea of anyone being allergic to food was pooh-poohed until recently. While the debate and semantics continue, there does, however, seem to be an increase in people’s reactions to foods, broadly broken down as follows.

  1. Food allergy – immune mediated
  2. Food sensitivity – immune mediated
  3. Lactose intolerance – non-immune mediated
  4. Fructose malabsorption – non-immune mediated
  5. Chemical sensitivity – non-immune mediated

1. Food allergy

This is a true allergy, calling on recruiting antibodies produced in the body known as IGE (Immunoglubulin E). As quickly as seconds to minutes after the ingestion of the culprit food, a violent reaction occurs – the results of which can be fatal. Common allergens in this group are crustaceans, eggs, fish, milk, peanuts, soybeans and treenuts – although any food can be a potential trigger. You don’t even have to eat the offending allergen, a chaste kiss on the lips has been known to cause an anaphylactic reaction.


  • Hives.
  • Asthma attack.
  • Swelling of the airways including throat, lips and tongue.
  • Drop in blood pressure.
  • Feeling lightheaded.
  • Anaphylaxis – a shutdown of the heart and lungs.

What causes it?

  • Leaky gut hypothesis. In theory, the barrier between the intestine and the bloodstream should be virtually impenetrable. Only the smallest of molecules should be able to cross over. So, when there are larger particles in the bloodstream, the immune system responds as if there is a pathogen (eg virus, bacteria) and responds as such. However, the particle in question is a fragment of partially digested food, not a pathogen.
  • Starting young. For a few months after birth the baby’s digestive tract is relatively ‘leaky’, allowing bigger than normal molecules to cross from the intestine to the bloodstream. One reason for this leakiness is to allow antibodies from mum’s breastmilk to pass freely and kickstart the infant immune system. Therefore, from an evolutionary point of view, human babies are meant to drink only mother’s milk for some time. In industrialised countries such as our own, babies are often weaned at six months (if not earlier), when the digestive tract is still allowing the passage of large molecules. Often the first foods we start babies on include cow’s milk, soy foods, orange juice and wheat – all major players in the food allergy stakes.
  • A susceptibility to allergy can be inherited.
  • The straw that breaks the camel’s back. In the normal course of events, our immune system is able to deal with a certain level of sensitivity to food allergens. However, when the immune system is under challenge – during stress, infections, or not eating or sleeping well – the food sensitivity becomes the ‘straw that breaks the camel’s back’ and a ‘new’ food allergy appears. This explains why people in their 30s, 40s and 50s can suddenly become ‘allergic’ to a food to which they have never previously reacted.
  • Familiarity breeds contempt. Today’s supermarkets offer a vast range of options, yet every week our shopping trollies are predictably full of the regulars – even the cat gets the same tuna titbits in jelly. What did you have for breakfast? Chances are it was the same as yesterday, and the day before that. Human beings are creatures of habit. The foods that are most often implicated in food allergies include wheat, milk, oranges, eggs, peanuts and tomatoes. It is no coincidence that some of these foods form the basis of many people’s diets. Our digestive tract was not designed for such dietary monotony and has not changed substantially for hundreds of thousands of years – unlike our diet. Before the advent of agriculture about 10 000 years ago, we roamed the countryside nibbling on anything and everything we could get our hands on: flowers, seeds, roots, fruits, insects and mastodons. Our ability to eat from a wide variety of foods substantially improved our survival prospects. If, for example, our diet had consisted solely of mastodon chops, when the mastodons snuffed it, so would we. Humans have always been masters of adaptation.
  • Addictive allergy. Sometimes a food allergy does not cause a reaction, but suppresses one. This phenomenon, called an ‘addictive allergy’, is when the allergic molecule attaches to receptor sites in the brain, much like our very own brain chemicals called endorphins, which act as natural opiates. If deprived of these chemicals, the receptor sites will remain empty and addictive symptoms may result such as craving the food, irritability and mood changes. Milk is a common addictive allergy. If you are particularly devoted to a food and cannot bear the thought of life without it, quite possibly, that food is the problem.

What to do

Due to the potential severity of reactions to these foods, strict avoidance of these foods is the only way. Don’t touch them with a barge pole. (Although it has been known for children to grow out of them, they should always be regarded with extreme caution if and when these foods are reintroduced into the diet.) If prescribed by your doctor, it is recommended that you carry your epi-pen with you at all times. Should you encounter the food by chance, a quick jab of adrenaline with the epi-pen will open up airways and potentially save your life. (Epi is short for epinephrine, the other name for adrenaline.)

2. Food sensitivity

The type 2 reaction is also immune mediated, but not as dramatic as type 1. Symptoms can take hours or days to appear after the food has been ingested, which can make these food reactions more difficult to identify. Common foods in this group include eggs, soybeans, fish, crustaceans, peanuts, milk, wheat, tree nuts and sesame seeds.

What causes it?

See type 1. Food Allergy


  • Digestive system: mouth ulcers, chronic diarrhoea, constipation, duodenal ulcer, flatulence, gastritis, irritable bowel syndrome, cramping, mucus on stools.
  • Urinary system: chronic cystitis, bed-wetting.
  • Immune system: chronic infections such as colds and frequent ear infections.
  • Mental/emotional: anxiety, depression, hyperactivity, inability to concentrate, insomnia, irritability, mental confusion, personality change.
  • Muscular/skeletal: joint pain, tender muscles.
  • Respiratory tract: asthma, chronic bronchitis, wheezing, itchy nose or throat, sinusitis.
  • Endocrine: diabetes, thyroid problems.
  • Skin: acne, eczema, hives, itching, skin rashes.
  • Weight: weight gain, weight loss.
  • Other: rapid heartbeat, water retention, bloating, fatigue, headaches, migraines, hypoglycaemia.

What to do


  • Avoid the suspect food(s) for a month (also known as the four-week allergy program). Be strict. Using wheat as an example, obvious foods to exclude are bread, pasta and pastries, but many processed foods also contain wheat, such as soups and crumbed foods. Look for allergy-based recipe books and websites to help with planning meals.
  • Keep a diary of your symptoms starting a week before you begin the program so that you can accurately compare before and after. Mention all physical and psychological symptoms, even if they don’t appear to relate to the allergy. It is advisable to record other influences such as weather changes, emotional upsets and menstrual period. This diary will be invaluable in assessing the degree of allergy.
  • When the month is up, it is time to take the ‘challenge’. Eat a portion of the suspected allergy food 3 times on the same day. For example, if wheat is the suspected allergen, have toast and weeties for breakfast, a sandwich for lunch and pasta for dinner. Refrain from the food for 2 days after the challenge as symptoms such as eczema may take that long to reappear.
  • Recovery. Once you have ascertained that a particular food is a problem, continue fairly rigorous avoidance for a further 3 months. It is necessary to ‘heal’ the gut to prevent further allergic substances from passing over the intestinal barrier. Additionally, it is wise to stabilise the immune system.
  • After 3 months on the program, start to reintroduce the allergen very slowly. No more than 1 serve every 4 days. Again, record any reactions in your food diary.


These remedies are designed to help in several ways: to improve the digestive process, support the immune system and repair and fortify the intestinal wall.

For your digestion

  • Take 1 teaspoon of herbal bitters in a small glass of water and sip before dinner. Herbal bitters stimulate the bitter taste buds. This in turn stimulates the vagus nerve, which helps improve the functioning of the entire digestive system. It also increases stomach acid which can help properly break down protein structures.
  • If your digestive system is on the weak side (ie you experience burping, flatulence, bloating, constipation or diarrhoea), take 1 digestive enzyme tablet and 1 betaine hydrochloride tablet with each meal.
  • Take probiotics. In addition to the repair of your digestive tract, the good microflora will also help digestion.

For your immune system

  • Echinacea is known as an immune-system modulator. Perfect for when the immune system is underactive or overactive as it is in the case of allergies. Take 500–1000 mg of echinacea twice a day in tablet or tincture form. Other herbs that can help include those for allergies such as albizia and baical skullcap.
  • Lactoferrin is an iron-containing protein that is found in colostrum, the first breast milk, and has excellent gastrointestinal and immune system benefits.
  • Avoid coffee, sugar and alcohol. These put extra stress on an already fragile immune system.

For repair and fortification of your intestinal wall

  • Glutamine is an amino acid that helps repair intestinal cells.
  • Probiotics are necessary to create a healthy intestinal environment, decreasing intestinal permeability. The probiotics you choose need to contain at least lactobacillus and bifidobacterium spp.
  • Zinc is needed for cellular repair.
  • Herbs that help inflammation include ginger, turmeric and aloe vera and those that repair include golden seal, calendula and aloe vera.

Food rotation

If you are a sensitive soul (and those who are sensitive to food are often sensitive by nature), you will do well to adopt a form of food rotation. It is easy to fall into the habit of eating the same food day in, day out. As mentioned previously, this may be a reason for the explosion of allergies. Food rotation means eating different foods more often, or, allergenic foods less often. For instance, not eating the same grain every day. The most common example here is wheat. Breakfast cereal made from wheat. Morning tea biscuits made from wheat. Lunch sandwiches made from wheat. Dinner pasta, made from you know what. Get funky and include other grains like rice, quinoa, barley or try not having any grains for a day a week. Same idea for nuts, fruits, vegetables, meats and milk.

Food rotation takes a while to get used to, but your expanded repertoire of food choices will have a positive impact on your health.

3. Lactose intolerance

Not an immune-mediated reaction at all, lactose intolerance is the result of a missing enzyme, lactase. Lactose intolerance is one of the most common food intolerances in the world. In fact, 20 per cent of Caucasians are affected and over 60 per cent of some other ethnic groups including Asians and Africans. This reflects the fact that dairy foods in general, and milk in particular (which has the highest amount of lactose), are not universally consumed.

Lactose intolerance can be diagnosed via a hydrogen breath test, but just removing dairy from your diet for a few days will give you an idea as to whether this is a problem for you.

What causes it?

  • Common in those of Asian, African and Mediterranean descent.
  • A bowel infection of viral, bacterial or parasitic origin often creates lactose intolerance as the lactase-producing bacteria are wiped out by the infection.
  • Bowel surgery.
  • Gluten intolerance.
  • Pre-term infants are often lactose intolerant.

Lactose is milk sugar, a double sugar comprised of galactose and glucose joined together by a chemical bond. In the healthy intestine, certain bacteria create an enzyme called lactase. Lactase has the ability to break the bond between galactose and glucose, and send the two merrily on their way across the intestinal wall into the bloodstream. (Galactose gets converted to glucose somewhere on this journey.) Without lactase, lactose is unable to be absorbed and will, via osmosis, draw fluids from the body causing diarrhoea and bloating – classic lactose intolerance symptoms. [end box]

There are two kinds of milk-sensitivity problems. The first is to lactose, or milk sugar. This is a deficiency of the lactase needed to break down and digest lactose. The second is a casein sensitivity. Casein is a major protein in milk products. This is more of an immune response Type 2 reaction.


  • Abdominal pain.
  • Abdominal bloating.
  • Flatulence.
  • Diarrhoea.

What to do


  • For a month, avoid all food containing lactose – milk (cow, goat and sheep), yoghurt, ice-cream, ricotta and cottage cheese, cream. Hard cheese and butter have negligible amounts of lactose.
  • After a month of avoiding lactose and taking the probiotic supplement, begin by eating a small amount of milk product. The first one to try would be a spoonful of good quality natural yoghurt. Each day, increase your intake in small amounts of different dairy foods, for as long as you are symptom free.


  • Take probiotics, especially lactobacillus spp.

4. Fructose malabsorption

Fructose malabsorption is the most recent food sensitivity on the scene. Researched by Australian dietician Sue Shepherd, fructose malabsorption is the difficulty in digesting fructose, a sugar found in fruits and vegetables. If not adequately digested, fructose (and fructose-like molecules) travel down the intestine where they ferment. Many people with IBS respond well by decreasing fructose foods from their diet. Fructose malabsorption can be detected by a hydrogen breath test.

A diagnosis of fructose malabsorption is a controversial one, as fructose containing fruits and vegetables have been part of mankind’s diet since God was a boy, and fruit and vegetables happen to be extremely good for you in all other ways, being chock-full of vitamins, minerals, phytonutrients, antioxidants and fibre while still being low in kilojoules. It is more than likely the problem has arisen in recent times as food manufacturing has increased the amount of fructose added to processed foods. This, combined with dysbiosis (the wrong bugs in the wrong place in your gut), has predisposed some individuals to this condition.


  • Reflux.
  • Constipation and/or diarrhoea.
  • Bloating.
  • Flatulence.
  • Abdominal pain.
  • Vomiting.
  • Depression.

What to do?


  • Avoid or reduce the following foods: fruit juice, tinned and dried fruit, grapes, guava, apple, coconut milk and cream, honeydew melon, mango, nashi fruit, papaya, pear, quince, star fruit, tomato, watermelon, Lebanese cucumber, sweet potato, tomato paste, relish, sweet and sour sauce, BBQ sauce, fructose corn syrup, fructose, honey, fortified wines, globe artichokes, asparagus, garlic, green beans, onions, leek, shallots and wheat.

The preceding list includes some very beneficial foods, and it would be a nutritional crime to be bereft of them for life. The best way to tackle the problem, if your symptoms are indeed made worse by these foods, is to remove them from your diet for a month while improving your intestinal microbiome with a course of probiotics and perhaps some digestive enzymes with each meal. Once all symptoms have abated, gingerly begin to reintroduce fructose-rich fruit and vegetables (leaving aside the processed fructose products) and hopefully, you will once again be able to enjoy these nutritious foods.


  • Take a probiotic supplement daily.
  • Take a digestive enzyme tablet with each meal.

5. Chemical sensitivity

Common chemicals include:

  • Histamine (red wine, soy sauce).
  • Salicylates (spices, herbs, berries).
  • MSG (packet soup).
  • Sodium benzoate (prunes, tea, soft drinks).
  • Sulphites (dried fruit, processed meats).


  • Difficulty in breathing.
  • Wheezing.
  • Headache.
  • Nasal congestion.
  • Runny nose.
  • Skin rash.
  • Hives.
  • Itching.
  • Swelling of the hands, face and feet.
  • Inflammation of the eyes.
  • Stomach pain.
  • Nausea.
  • Burning or itching sensation in the mouth.
  • Flushing of the skin.
  • Diarrhoea.
  • Blood pressure changes (both high or low possible).
  • Dizziness and fainting.
  • Fluid retention (oedema).

What to do

These reactions are not immune mediated.


  • Avoid or reduce the chemical in your diet as much as you can.

Behind the scenes

Our immune system is programmed to respond to substances foreign to, or not recognised by, the body. These substances are often bacteria or viruses, which are made up of molecules of protein. When a protein molecule that our body does not recognise manages to escape our defence systems, the immune system is placed on alert. This happens in the case of hayfever. When a person inhales pollen (a protein), it causes an allergic reaction, often sneezing and mucus production. Food allergy is similar, except the allergic substance, known as an allergen, is absorbed across the intestinal wall during the course of digestion. For the person with an allergy to milk, when a fraction of the milk protein (casein) is absorbed, their immune system will react.


No testing method, laboratory or other, is 100 per cent accurate in diagnosing a food allergy. However, a cytotoxic blood test, whereby a sample of blood is analysed for IgG antibodies to specific foods may be undertaken.

The ‘gold standard’ for diagnosing a food allergy is the method of food avoidance and challenge. This requires strictly eliminating the suspect food from your diet for 2 weeks. After this time, there should be a noticeable reduction in symptoms and the suspect food should stand out like a sore thumb. Mostly, it will be a food that you eat every day, like wheat, oranges (orange juice) or milk (cheese, etc). Note: people with a type 1 reaction should never undertake this challenge as it can be be life-threatening.

At a glance

Good food

Foods you are not allergic to. Try and rotate them anyway.

Food to avoid

Foods containing the allergen plus coffee, sugar and alcohol.


  • Echinacea, probiotics, digestive enzymes.
  • Lifestyle.
  • Stress management.
  • Mind–body alignment. A food allergy could represent a conflict within. Who or what in your life are you allergic to?


Treating food allergies in children is much the same as for adults: take out the offending food and improve immunity. Some children ‘grow out’ of their food allergies and are able to tolerate the food after a year or so. When patients come to see me with possible food allergy symptoms, I always quiz them to see if they had allergies as a child. If they were allergic to a specific food then, chances are they might be again.

Taking good food out of a child’s diet is problematic. Firstly, you need to ensure that any of the positive nutrients that the particular food supplied is replaced in some way (eg in the case of dairy; calcium and protein). Secondly, a restricted diet places a strain on the family, most often mum who needs to find new recipes and school lunches. And finally, having a food allergy is difficult socially. Some children can be cruel and not being able to eat the same foods as your peers and/or being seen as different may negatively affect your youngster’s psyche. Nevertheless, sometimes it is necessary to go the hard yards. Supplements for children are similar (except ditch the bitters), just adjust the dosage to suit.