What is the difference between an allergy and an intolerance?

As far as your symptoms are concerned, there is little or no difference. In medical terms, however, a true allergy is a response by the part of the immune system known as immunoglobulin E (or IgE). People who have food allergies typically inherit this tendency to form that particular antibody, which triggers the body to release histamine when a certain food is eaten. An IgE response is more likely to produce immediate, strong reactions - hence the use of anti-histamines to calm certain symptoms. Your doctor can arrange for an IgE test to be done.

Intolerances, however, are triggered by a different immunoglobulin - IgG. If, therefore your IgE tests come back negative, it does not mean that a problem does not exist with a food, as had long been thought. An independent study by the University of York, UK, based on interviewing over 5,000 people who had had an IgG allergy test from Yorktest Laboratories, found consistent evidence that noticeable benefit was gained from removing offending foods from the diet. In this survey, 75.8% of those patients who rigorously followed their allergy (intolerance) free diet, as determined by a pin-prick blood test, had a noticeable improvement in their condition, with 68.2% of them feeling better within three weeks. The more strict they were with their diet, the better were the results. For those who followed their allergy elimination diet rigorously and reported high benefit, 92% felt a return of symptoms on reintroduction of the offending foods.

According to US medical expert Dr. James Brady, co-author of Hidden Food Allergies, "the conventional view that only IgE antibody reactions cause allergy is simply wrong. The evidence is that IfG reactions cause considerably more food allergies than IgE based reactions, and that food allergies are much more common than generally believed."

Reactions caused by food intolerances cause inflammation, which may manifest as pain, redness or swelling, and can trigger a whole host of chronic health problems - some severe, some less so. The symptoms are often masked, mimicking the symptoms of common problems such as headache, fatigue and joint pains. Occasionally, food intolerances will produce a different reaction each time - one day it may produce a headache; the next a rash. Weight gain is a common result of food intolerance. In order to "protect" itself, the body surrounds its cells with fluid, so that not all the weight you want to lose is fat. You might be holding as much as 30kg/14lbs - or even more - without knowing it. Also, the more often you are reacting allergically, the more resistant you become to insulin (see also). This is because the body releases masses of immune messengers called cytokines to deal with the allergy, and cytokines make you less responsive to insulin.

Repeated allergic reactions mean that more garbage ends up in your bloodstream as your immune cells fight off the invaders. All this has to be cleaned up by your liver, the body's organ of detoxification. Eventually, the liver's detox capacity gets overloaded. When this happens, the toxins are dumped in the least harmful place - your fat cells. The more toxic your fat cells become, the more weight you gain and the harder it becomes to shift those extra pounds. This is why people with allergies find it harder and harder to lose weight. Also, this continual process of over intoxication can turn a mild allergy into something more severe.

The good news about IgG - based allergies is that, if you avoid the offending food strictly for 3-6 months, the body forgets that it is allergic to it. This is due to the fact that there will no longer be any IgG antibodies to that food in your system. This is not the case with IgE based reactions.

Which foods or substances are the worst offenders?

The ones which cause masked reactions are often the ones to which we are exposed on a regular basis. In fact, you can even become addicted to the food causing the problem, so you then crave it and feel temporarily better for eating that food. In addition, IgG reactions are often delayed by up to 48 hours, so the sufferer doesn't associate the problem with the particular food causing it.

When I identify and intolerance, my patients often say "but I have eaten that food all my life, and never had a problem". The reasons why people "suddenly" develop problems with food are varied, but they are always related to a change in the immune response. This could be due to "leaky gut syndrome", in which molecules of food that should have been completely broken down and absorbed, and the remnants excreted, find their way through the gut wall and into the blood stream. As this is not the right place for such molecules, the body's defence system leaps into action, causing a variety of symptoms from eczema to arthritis etc. It could also be due to over-exposure to a particular substance, or to an increase in stress levels. (see also). Quite simply, the immune system is compromised and needs a break from the causative factor.

Some of the most common intolerances are:

Cow's milk	wheat	gluten
Eggs	nuts	soya
Peanuts	oranges	kiwi fruit
Coffee	chocolate	yeast
Corn	moulds	pollens

How do I find out what my intolerances are?

First of all, get your doctor to perform an IgE test It may be helpful to complete a food diary for a week to take with you. Download food diary here

Research IgG testing in NZ
York Test details

Alternatively, a nutritionist of naturopath can test using applied kinesiology or some other method (ask them).

The Pulse Test

Another very good guideline is a simple home test. Using a watch with a second hand, sit down and relax for a few minutes. When completely relaxed, take your pulse at the wrist. Count the number of beats in a 60 second period - a normal reading for children 1-10 could be 70-120 beats per minute; for children over 10 and adults, 60-100 beats per minute would be normal.

After taking your pulse, consume a quantity of the food that you suspect may be an allergen. After 20 minutes, take your pulse again. If you pulse rate has increased by more than 10 beats per minute, omit this food from your diet for one month, and then retest yourself.

For the purposes of this test, it is best to use the purest form of the suspected food available. For example, if you are testing yourself for an allergy to wheat, it is better to use a bit of plain wheat cereal rather than bread which contains other ingredients, including yeast and milk - two other common allergens.