Food allergy testing and food intolerances

Food allergy testing can be very helpful but is not always appropriate if the foods affecting you are not a true allergy.

The difference between food allergy and food intolerance

Food intolerance is a very generic term. It simply means that a particular food does not agree with you. Food allergy is a more specific term; it means your reaction to a particular food involved your immune system. Tests for identifying food allergies usually look for antibodies that your body’s immune system has made to bind to a specific food. This binding triggers the symptoms of allergy.

Food allergies

There are 2 types of antibodies believed to be involved in food allergy:

1.  IgE (stands for immunoglobin E)

      IgE is well accepted as being able to trigger the food allergy reaction. IgE reactions usually cause a fast, consistent and predictable allergic response to the offending food. As such, many people are aware they have the problem with the particular food. The reaction can be severe and in some cases life threatening. Such reactions may include anaphylaxis, hives and asthma. A nutritionist can order tests to explore IgE food allergies but you should definitely also seek your GP’s advice about any such concerns.

2. IgG (stands for immunoglobin G)

      This has been far more controversial as a cause of allergy. York Laboratories did a clinical trial that showed a relationship between individuals’ IgG antibodies to food and people’s symptoms. When the offending foods were avoided, the participants in this trial had a reduction in their IgG levels and an improvement in various aspects of well being. This included better intestinal health, improved ease of breathing, better ability to maintain a healthy weight, better mental clarity and well being, improvement in joint health, promoting an absence of headaches and muscle aches, better skin health and better energy and sleep.  Other than this there have been no trials. However, in my clinical experience, I have found IgG tests extremely useful. This has also been the experience of many others in the nutritional field.

      It is believed that IgG antibodies need to build up to a certain level before they trigger a response. IgG reactions may therefore take up to 2 days to manifest after the offending food’s been eaten. When you are tired, stressed, hungover, etc you may react, at other times when rested and in better form you may tolerate the food. Some people can tolerate small or infrequent portions but not large portions or not on a daily basis. In young children with eczema, I have most frequently found IgG antibodies to eggs. Avoiding egg white (rather than yolk) improved their skin condition. Less frequently other IgGs have been found.

      Sometimes, the aggravation caused to the gut by a dominant food intolerance/allergen seems to predispose an individual to acquiring new intolerances. Once the gut gets a rest from the irritating foods and its health improves, a much more varied diet can often, once again be enjoyed, as long as the dominant food allergen is restricted.

      We do an in house IgG food intolerance test which tests for 59 commonly occurring foods. More comprehensive tests can be ordered if desired and if it’s believed they’d be helpful.

Food Intolerances

Unlike food allergies, these do not need to be caused by a protein and do not necessarily involve the immune system. A nutritionist can often be very helpful, as they are familiar with different components in different foods.

Sometimes the root of an intolerance is in the gut. 

For example lactose intolerance is caused by an inability to break down the milk sugar lactose into its component sugars glucose and galactose. As a result the bacteria in the gut ferment it and symptoms are caused.

Lactose is meant to be digested by digestive enzymes in the gut lining. Occasionally, if the gut lining has been inflamed efforts to improve the integrity of the gut lining may improve tolerance to lactose. For example, after a gut infection or after too much boozing.  Sometimes improving the numbers of friendly gut bacteria, which are able to digest lactose, also brings an improvement in lactose tolerance. Generally speaking, the closer to the equator your ancestry is, the more likely that you have a genetic inability to digest lactose. This is simply because your gut lining has stopped producing the needed lactose-digesting enzyme, lactase. 

Sub-Optimal digestive function and gut health can leave an individual more susceptible to reacting to foods. 

Some people have found that it is not until they acquired a parasitic infection that they no longer could tolerate wheat or dairy or some other foods. If your food intolerance symptoms came on suddenly or after a holiday abroad, this is worth exploring. Your doctor can order you a stool analysis. Nutritionists can also order comprehensive stool analyses to check a variety of markers for digestive function and gut health.

Others find that digestive well being suffered after antibiotics. This is likely to be due to beneficial bacteria being knocked out, allowing a less friendly gut flora to flourish.

Good stomach acid production is important to gut health. It not only starts the tough job of protein digestion but also kills off unfriendly bacteria, yeasts and parasites, which might otherwise go on to contribute to food intolerances by aggravating the gut of fermenting foods. Some people report that after taking drugs that stop stomach acid production, other aspects of their digestive well being declined.

Good production of digestive enzymes is likewise important. Like the lactose example above, if the food is not digested properly, bacteria and yeast can then go on to ferment it or otherwise process it into aggravating compounds. An overgrowth of certain bacteria and yeasts can then compromise the health of your gut lining.

Certain unfriendly gut microbes enjoy certain types of food. For example yeasts favour sugars and starch, certain strains of clostridia enjoy polyphenolic foods and some people with ulcerative colitis find that foods with a high sulphur content aggravate them. This is also likely to be due to over-activity of specific microbes.

Some food intolerances have nothing to do with gut health or the immune system.

Our genetics are as varied as our appearances. Some of us simply find it harder to process certain chemicals.

Tyramine foods - Migraine suffers may find it harder to break down tyramine in foods. Often found in higher amounts in aged/matured foods. Red wine can aggravate the problem.

High sulphur foods - Other migraine sufferers may find sulphur harder to process, as found in higher amounts in white wines and champagnes. Asthma sufferers may also be less able to process sulphur.

High purine foods - People with gout/ high uric acid levels find it harder to process purine-containing foods like oily fish and organ meats. Booze, fructose and lead exposure could further aggravate the problem.

High/free glutamate foods - People with hyper tendencies or neurological challenges may be less able to process high-glutamate and glutamine containing foods. Glutamate excites your nervous system. Glutamate is found in high amounts in gluten, casein (dairy protein), gelatine, protein powders, and in MSG.

Oxalate foods - People prone to kidney stones are often less able to process oxalates, which then go on to form jagged crystals in the kidneys. Oxalate clearance may also be compromised by sub-optimal gut health. Rhubarb, spinach, dark chocolate, blackberries and celery are some of the foods which contain a high concentration of oxalates.

Manmade chemicals - There are also a multitude of new manmade chemicals which some people may be sensitive to. For example, some people intolerant of bread in the UK, report they have no problems when they eat a baguette bought in France. This could possibly be because in France far less additives are permitted in their bread making, whereas in the UK, the damper climate which affects flour, makes this harder to achieve. Synthetic colourants have been implicated as aggravating hyperactivity in susceptible individuals.

In all the above cases and more, a nutritionist can help in formulating a nutritional plan to not only help identify and minimise aggravating foods but also to optimise the levels of relevant nutrients that the body uses to efficiently process the offending dietary substances. In some instances there may also be an acquired predisposing factor that makes it harder for the body to detoxify the offending dietary substances and this can also be worked on to improve food tolerance.