Food allergies aren’t as common as you might think, but food intolerances can come and go. Here’s how to sort out the difference, a list of common culprits and where to go for help if you need it.
A well-educated woman brought her two small children to see me, asking me to diagnose their food allergies. I started with questions about the symptoms that made her suspect the children had food allergies.
She said she didn’t know of any symptoms, which was why she had come to see me! This mother had been led to believe that everyone was allergic to something.
What Are True Food Allergies?
They usually begin in infancy and involve the body’s immune system. Symptoms mostly occur within minutes of eating the offending food and may be quite severe – a sudden swelling of the throat, a sudden onset of asthma, vomiting and diarrhoea, or an outbreak of eczema.
The offending substance that produces the allergic reaction is called an allergen and even a tiny dose of the food containing the allergen causes white blood cells to produce antibodies.
When the allergen is consumed again, more antibodies are formed to fight the unwelcome substance and these cause symptoms.
True food allergies can be diagnosed with a blood test that shows increased levels of immunoglobulins.
Other reactions that do not involve the body’s immune system are sometimes called allergies, but are more correctly termed “food intolerances” or “food sensitivities”.
These are more common than true allergies and more difficult to diagnose because they do not involve antibodies and cannot be diagnosed with blood tests.
Some symptoms of food intolerance are obvious – for example, skin rashes, migraine, stomach pains and other gastrointestinal problems – but these can also have causes unrelated to food.
A runny nose in children is often attributed to foods (especially milk), but is more likely to be due to germs being shared, along with toys. Studies at Flinders Medical Centre in Adelaide have shown that children with post nasal drip or stuffy noses are not adversely affected by cow’s milk, although about 10 percent of asthmatic children have an allergic reaction to milk.
Even with asthma, however, 90 percent of children do not have milk allergy or intolerance.
Behavioural and mood changes are also attributed to food intolerance, but such symptoms are difficult to define and are more likely to be due to other factors, including “intolerance” problems with family, school or workplace.
Very few children classified as hyperactive or unruly have food intolerances. When foods are involved however, naturally-occurring salicylates in healthy foods such as fruits, vegetables and honey, are usually the culprits, rather than junk foods or sugar.
The only reliable way to diagnose food intolerances is with an Elimination Diet which excludes all foods usually responsible for such reactions.
Tests which use machines to diagnose food intolerances by measuring hand tremors, or reactions when substances are placed under the tongue are not accurate. Some of the allergy tests offered are shonky and their unscrupulous operators charge outrageous prices for worthless diagnoses.
Most true food allergies last for life, with the exception of milk allergy, which usually disappears at around three or four years of age. At this stage, a child’s digestive tract matures and intact milk protein molecules no longer pass through the intestinal wall.
Why Do Food Intolerances Happen?
Food intolerances can appear (and disappear) at any age or stage of life. They occur when you exceed a certain dose of a natural or added food chemical to which you are sensitive. The dose that causes problems may depend on other factors, and a food may have no adverse effect one day and produce a reaction the next.
For example, some women are sensitive to food chemicals only at certain stages of their menstrual cycle when there is an interaction between a food chemical and their hormone levels.
It is not easy to work out which foods cause intolerance reactions, because the total dose of a particular food chemical may be responsible, rather than individual foods.
Many people are aware that chocolate can cause migraines but are puzzled by the fact that they don’t always get a headache after eating it.
This is because chocolate contains amines, but so do other foods. If you have already had several foods high in amines, adding chocolate could be the last straw for someone sensitive to amines. But if you haven’t had other foods high in amines, chocolate might have no effect.
The Elimination Diet
The Elimination Diet omits all foods which contain substances known to cause reactions in sensitive people. If symptoms disappear on this diet, your child almost certainly has some food intolerance(s).
If there is no change, the symptoms are due to something other than food and there is no point in persevering with a restrictive diet.
For those who improve with an Elimination Diet, foods are added back in a systematic fashion to see which cause reactions. Many children have more than one intolerance.
Once you find out which foods are a problem, your child then needs a balanced diet which omits these foods. If some of the offending chemicals are a natural part of nutritious foods, your child needs alternatives that provide the same nutrients.
The Elimination Diet should be supervised by an Accredited Practising Dietitian or a doctor who understands food chemicals and likely reactions. They should also be able to help with alternative food selections, so your child still has an adequate diet.
Could It Be Something Else?
Sometimes food has nothing to do with the problem and is simply a scapegoat. With children, remember that some symptoms of food intolerance (such as pains in the tummy) are similar to those that occur in children who are being bullied at school.
Common Food Culprits
Problem food ingredients may have been added or they may occur naturally in foods. Some common offenders include:
- Salicylates – found in tea, coffee, herbs, spices, honey and many fruits and vegetables.
- Amines – found in such diverse foods as chocolate, tomatoes, cheese, mushrooms, bananas, avocados, pawpaw and red wines.
- Monosodium glutamate – additive 621 in many foods and also found naturally in soy sauce, tomatoes and tomato paste, some cheeses, pickled vegetables and flavoured snack foods. Glutamates have intense flavours. Additives 620 and 622-625 are also glutamate flavour enhancers.
- Sulphites – additives 220-228, used in dried apricots, pickled onions, wines, many fruit juices made from concentrates. (If you leave a packet of dried fruits open, some of the sulphur compounds evaporate.)
- Nitrites – additives 249-252, used in ham, bacon, corned meat, smoked fish and any “cured” products.
- Preservatives – including benzoates (additives 210-213, used in soft drinks), sorbates (additives 200-203, used in low-fat spreads, some cottage cheeses) and propionates (additives 280- 283) used in bread, muffins and crumpets.
- Colourings – additives 100-181, especially green or red, less commonly yellow.
- Wheat – may also cause allergies or food intolerance in some people, probably due to its proteins.