Technical & 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



Do I need to completely fill up the capillary tube with blood?  

You need to fill the tube up to the black line with blood by touching the tube to the blood drop (don't squeeze), and then transfer all of the blood into the Solution A bottle by squeezing the bulb. This gives the correct amount of blood required for the test. If you do not fill up to the black line, then it is possible that any positive results will be weaker than they should be because of a greater dilution of the blood sample.   


I don’t seem to be able to collect enough blood to fill the capillary tube, what should I do?

In the unusual circumstances when there is insufficient blood to fill the capillary tube, and both of the lancets provided have been used, then it may be necessary to telephone us for a replacement tube and lancets. It is important to make sure that their hands are warm and that tthey have massaged the sample finger thoroughly before using the lancet. 


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.


Do I have to run the test immediately?

After you collect the blood sample, add it to the sample diluent bottle (solution A) and mix, it can be left at room temperature for up to 1 hour before running the test, or can be stored in a refrigerator for up to 7 days before testing. It is important for the sample/diluent mixture to be at room temperature before starting the test.


They have been avoiding a food for more than 3 months; will this food show up in the test?

It is possible that the antibody levels will have reduced significantly if they have been completely avoiding that food, and therefore highly likely that the food test will be unable to detect any antibodies.


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.