Frequently Asked Questions

Do you need more information about Food Detective™ or have questions about food intolerance? If so, you will find most of the answers here.


Food Intolerance

Are the tests covered by Medicare?
Medicare does not currently cover the cost of these tests.

Are the tests covered by Private Health Funds? 
Private Health Funds in Australia do not currently cover the cost of these tests.

What is the difference between food allergy and food intolerance?
A classical food allergy such as peanut or shellfish allergy is usually characterised by an immediate and often severe reaction to exposure to the offending food.

What do the borderline foods mean?
The borderline foods are slightly above the normal values and ideally should be reduced to a minimum in the diet. Therefore, we recommend that they rotate those foods showing a borderline result, once every 4 days if possible.

Is it possible to be affected by foods that are not detected by Food Detective
Some foods may cause a classical allergic reaction involving the production of a type of antibody called IgE. These will not be detected by any IgG food test. There are also many foods that can cause a reaction in the body without involving the immune system but produce symptoms similar to IgG reactions. For example, amines in chocolate, cheese and red wine may cause migraines; some food additives such as tartrazine can cause hives, rashes and asthma; monosodium glutamate in Chinese dishes produces sweating and dizziness; and ‘Nightshade’ alkaloids in potatoes, tomatoes and peppers can affect the joints. These are very difficult to test, but they should avoided if they are suspected of affecting the patient.


Technical and Clinical

Will any drugs affect the results?
Immunosuppressants which are generally given following an organ transplant will reduce the immune system’s ability to generate antibodies. High doses of steroids will also affect antibody production.

Do I have to collect the blood sample at any particular time of day?
No, samples can be collected at any time of the day.

Are there any research papers to support these tests?
Yes, a number of studies have implicated food IgG antibodies in the development of food intolerances and chronic illnesses such as eczema, arthritis, irritable bowel syndrome.

Have there been any trials to support these tests?
An independent audit, conducted in 1998, studied symptom reduction in over 2000 individuals following an elimination diet based on the food intolerance IgG test. The audit demonstrated that more than 70% of patients reported a significant reduction in symptoms after eliminating the foods giving high IgG levels in the test.

What is an IgG?
IgG stands for Immunoglobulin G. Immunoglobulins are antibodies which are produced by the immune system in response to foreign bodies entering the body. There are several different types of immunoglobulins with IgA, IgE, IgG, IgM being the most well known.

What is an antibody, and what is the difference between IgG and IgE antibodies?
An antibody is a specialised protein produced by the body’s immune system when foreign bodies (such as viruses, bacteria and toxins) enter the body. They are produced by special white blood cells called B-Lymphocytes as a defence against these foreign substances. IgE antibodies are a type of antibody mostly found in the skin, nose, lining of airways and lungs, and are usually produced in classical allergies. IgG antibodies are the type of antibodies that Food Detective tests for food intolerances. It has been shown by various studies, that if foods that are producing high IgG levels are eliminated from the diet, the symptoms of food intolerance can be reduced.

Why do foods cause an IgG response?
Generally, foods are broken down during digestion into their component parts e.g. amino acids, glycerides etc. These pass harmlessly through the gut into the bloodstream. However, occasionally small fragments of partially digested or undigested foods are able to pass through the gut wall into the bloodstream where they are recognized by the immune system as being ‘foreign’. The immune system responds by making antibodies (IgGs). In some patients, inflammation or irritation of the intestinal lining allows partially digested foods to leak into the bloodstream. This condition is called ‘leaky gut syndrome’ and patients with this condition typically have high levels of antibodies to multiple foods.

Why would some members of a food family come up positive (e.g. soya, haricot, kidney) even though not eaten for years, and yet have no reaction to other members (i.e. lentils, carob, peanuts, peas) that have been eaten?
While members of the same food family may be antigenically similar such that antibodies to one member will cross-react with another member, they will also exhibit antigenic differences depending on how closely related they are. Hence, it is possible that foods that have caused strong antibody responses which remain detectable even though they have not been eaten for years, do not cross react with other members of the same food family. Also, some antigens in foods are less able to initiate an immune response than others i.e. they are less immunogenic and, as a result, antibody production to them is less easily stimulated.

Why do we not test for sugar, alcohol etc?
Food IgG-based food intolerance is caused by proteins and the antibodies directed against them. Sugar and alcohol are not proteins.

Can IgG levels remain high even if not consuming any of that particular food? (i.e. for years?)
Antibody levels may remain detectable some several years after exposure. Because certain foods such as wheat, dairy and corn are widely used as additives in processed foods or cosmetics, IgG levels are more likely to persist in an individual who mistakenly presumes that such foods have been completely eliminated from the diet.

Is it possible to have high IgG levels and not experience symptoms?
Yes, some people do have high IgG levels to certain foods but do not have any symptoms at all. This is possibly due to their immune system being extremely efficient at clearing away the antigen-antibody complexes before they have chance to be deposited in the tissues and cause a problem.

Is there any evidence for complexes actually causing symptoms?
A study of infants with milk intolerance showed that symptoms appeared within hours of cow’s milk consumption and that this was accompanied by notable immune complexes appearing in the serum.

Does a Leaky Gut need to be repaired before those foods can be eaten again without symptoms?

If all food molecules get through, why do some lead to food intolerance and some not?
Two main factors govern the development of an IgG antibody-based food intolerance: the amount of a particular food in the diet and its ability to stimulate antibody production. Foods consumed in large quantities are more often associated with food antibody production, antigen-antibody complexes and symptoms. Some foods are more ‘immunogenic’ than others i.e. are more able to cause antibody production.

What determines which substances get through the leaky intestinal wall?
The composition of your diet and the size of the food particles. Also, minerals require carrier molecules which are often impaired in people with leaky gut. This can lead to mineral deficiencies in such individuals.

What is Leaky Gut Syndrome?
Leaky Gut Syndrome is a condition where large gaps develop between the cells of the intestinal wall causing large quantities of partially digested food to ‘leak’ into the bloodstream. The symptoms of Leaky Gut Syndrome are many and varied and include: abdominal pain, heartburn, insomnia, bloating, anxiety, gluten intolerance, malnutrition, muscle cramps and pains, poor exercise tolerance, food allergies.

Why do high IgG antibody levels cause symptoms?
When a food causes the body to produce high levels of IgG then these antibodies combine with the protein in the food to form an ‘antigen-antibody complex’. These complexes are usually eliminated by other cells in the immune system. However, if the immune system is overloaded, these insoluble molecules become deposited in various areas of the body, such as the head, lung tissue, gastro-intestinal tract, skin and joints where they produce symptoms such as headaches, asthma, irritable bowel syndrome, eczema and rashes, and arthritis.

How do we know that the complexes are deposited in certain areas?
Intestinal biopsy studies have shown evidence of immune complexes in patients with cow’s milk sensitive colitis. Other studies have demonstrated deposition of human IgG and cow’s milk proteins in lung tissue specimens taken from infants with pulmonary hemosiderosis.


Results and Questions

If they avoid foods that show a high IgG reading, how long will it take before the IgG level returns to a normal level?
Over time, the concentration of IgG antibodies to that particular food will gradually decrease. The half life of IgG in the blood stream is approximately 23 days. However, antigens that have been stored in the liver may be slowly released over several months, resulting in some persistent antibody production. The levels, however, will decline gradually, barring any new exposure.They started to avoid foods from their diet, and now they feel a lot worse, is this normal?
This is a normal reaction for many people in the first few days after excluding a food or foods, due to ‘withdrawal-type’ symptoms. It is quite common to feel worse for a few days, but this phase soon passes and an improvement is usually noticed after a week or two.


Milk Intolerance

What are the symptoms of lactose intolerance?
If the enzyme lactase is deficient, or low, then the ability to absorb lactose will be greatly reduced causing symptoms such as bloating, flatulence, diarrhoea and abdominal pain.

What is lactose intolerance?
Lactose intolerance is the inability to absorb lactose – the predominant sugar in milk – into the digestive system. If lactose is not absorbed properly, it ferments and this results in abdominal pain, a bloated stomach, stomach rumbling, increased wind and diarrhoea. Lactose is a disaccharide, which means that it is composed of two other sugars bound together. In order for lactose to be absorbed, it must be split into those two smaller sugars by an enzyme called lactase, which is present in the lining of the small intestine. If the levels of the lactase enzyme are low or absent, then that splitting does not occur and fermentation of the lactose occurs by bacteria in the large intestine. Lactase activity is high in babies and declines as the amount of milk in the diet decreases. Some people may have very low lactase levels but not have any symptoms. The reason for this is unknown. A lactose tolerance test, a hydrogen breath test, or a stool acidity test is required for a clinical diagnosis.

What are the main proteins in milk?
The total protein component of milk is composed of numerous specific proteins. The primary group of milk proteins are the caseins. All other proteins found in milk are grouped together under the name of whey proteins. The major whey proteins in cow milk are beta-lactoglobulin and alpha-lactalbumin.

If cow’s milk comes up positive, does that mean that they are lactose intolerant?
No. Lactose intolerance is the inability to digest lactose, the major sugar found in milk. It is caused by a shortage of the enzyme lactase, which is produced by the cells that line the small intestine.


Wheat Intolerance

Why has gluten come up positive but not wheat?
The wheat extract does not contain gluten but other proteins found in wheat such as seed storage proteins. The gluten extract does not contain these proteins but is a pure preparation of gluten. If there are antibodies to gluten but not to other proteins found in wheat, wheat will not show a positive result. Similarly, if there are antibodies to non-gluten proteins, wheat will show a positive result and in the absence of antibodies to gluten, gluten will remain negative.

What is durum wheat and why has that not come up positive, although wheat has?
Durum wheat and common wheat are different species of wheat. Durum wheat is very hard and is usually used to make flour and semolina for pasta. The protein content is different and therefore one can show up positive and not the other. Many people find that they can tolerate durum wheat if they are positive for wheat but negative to durum wheat.


Yeast Intolerance

If there is a positive to yeast, does this include brewers yeast?
Yes, the test includes both bakers and brewers yeast. If they come up positive to yeast, it is vital that they plan ahead as yeast is present in many different foods.

If the yeast comes up positive, does that mean they have Candidiasis?
No, not necessarily, the test just shows that there is an elevated level of antibodies to yeast in their blood.

What alcoholic drinks do not contain yeast?
All alcoholic drinks depend on yeasts to produce the alcohol, however distilling and filtering will tend to remove most of the yeast. Spirits, such as gin or vodka will have the lowest amount of yeast present compared with wines and beers.