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Food Allergy

Diagnosis of an adverse reaction to a food may be easy if the person consistently exhibits the same symptoms after eating a food. However the diagnosis is most usually more complex as the person is reacting to more than one food, there may be a time delay before the onset of symptoms, and many symptoms can have other causes than an adverse reaction to a food. The same foods can cause different symptoms to different persons, and even with the same person the range of symptoms can change on different occasions. It is therefore important for a patient who believes that they are suffering from an adverse reaction to a food to consult an Allergist or other suitably qualified and experienced specialist doctor who can determine whether the symptoms are indeed related to a food, or is there some other cause.

1. Physical Examination
The diagnosis starts with a complete physical examination followed by laboratory tests to exclude any medical condition not related to adverse reactions to foods.

2. Medical History
It is very important for the doctor to determine the medical history of the patient in order to ascertain the type and severity of the symptoms, to try to rule out any other medical cause of the symptoms, and to try to determine the identity of the problem food(s).

3. Family History
The family history is also important as allergies tend to run in families, so if one or more parents or siblings are allergic, even if with different symptoms to inhalant allergens, then this would increase the chance of the patient also being allergic. Similarly, it is believed that other types of intolerance such as Non-IgE Mediated Immune and Enzymatic Intolerance may also be familial linked.

4. Food History
Information on the personal food pattern is necessary and patients may be required to keep an accurate diary of foods eaten and symptoms experienced over a certain period.

5. Supplementary Tests
After the Medical, Family and Food History have been established, and adverse reaction to food is suspected, then supplementary tests are needed to reach a final and reliable diagnosis. For a patient with a food allergy, as the immune system has been activated and IgE has been produced, then measurement of allergen-specific IgE is used to prove food allergy. Therefore for the diagnosis of food allergy, skin tests and blood tests (Specific IgE) are used to provide further information.

For Food Intolerance, there is no evidence that the immune system is involved, and so the skin and blood tests do not give a positive answer. For the diagnosis of food intolerance, the medical, family and food history, and a selective elimination diet, may give evidence supporting the diagnosis.

5(a) Skin Prick Test
Different types of skin tests can be used to diagnose food allergy. In the skin prick test, a diluted extract or fresh part of the suspected food is placed on the skin of the forearm or the back, which is then scratched or punctured. The skin test is more sensitive and reproducible when fresh food items are used, rather than extracts from commercial manufacturers. The fresh food is punctured with a special needle and then the skin. This is called the "prick-prick method". If, after the prick, a local swelling (wheal) surrounded by redness (flare) forms within 15 minutes, similar to a mosquito bite or larger, then the skin test is positive and the person may be allergic to the tested food. Because food allergen extracts are not standardised, and their stability often remains poorly established, it is important that only experienced doctors interpret results of skin tests. Skin prick testing should be performed only in places equipped to treat anaphylaxis in case of a risk of a systemic reaction. Skin tests are unreliable if a patient has extensive eczema. Another problem can be medication that will interfere with the result of a skin test and that cannot be discontinued for 2 to 14 days because of the severity of the illness, for example antihistamines.

5(b) Blood Test ("ImmunoCAP® Specific IgE")
It is vitally important to distinguish between the blood tests that are used routinely world-wide for the diagnosis of IgE-Mediated Food Allergy, and the unconventional blood tests claiming to identify Food Intolerance.

The blood test used routinely world-wide and in South Africa by thousands of doctors and the medical opinion leaders for the diagnosis of food allergy and the identification of the problem food allergens is the Pharmacia ImmunoCAP® Specific IgE test. This test was originally developed by Pharmacia Diagnostics of Uppsala Sweden in 1972 and has been developed into it's present form. The ImmunoCAP® Specific IgE test is today acknowledged to be the best diagnostic test in the world to measure allergen-specific IgE and is used exclusively throughout all South African pathology laboratories. The ImmunoCAP® Specific IgE test and it's predecessor from Pharmacia have been evaluated over the past 25 years by thousands of independent clinical researchers and their results published in tens of thousands of medical publications throughout the world.

This ImmunoCAP® Specific IgE test measures quantitatively the amount of allergen specific IgE produced by the patients' immune system against any particular food allergen. There is a range of over 200 different food allergens that can be tested for with the ImmunoCAP® Specific IgE test. These ImmunoCAPR Specific IgE food allergen tests include various meats, dairy products, nuts, seeds, beans, cereals, shellfish, fish, molluscs, spices, vegetables, fruits, etc. There are in addition a range of over 200 other allergens that are not of food origin, for example, grass pollens, weed pollens, tree pollens, moulds, epidermals, drugs, occupationals, etc. A positive result with any ImmunoCAP® Specific IgE test clearly and reliably indicates that the patient has IgE directed against that allergen (food) and is therefore sensitised against that food. However, this does not necessarily mean that the patient will exhibit clinical symptoms against that food, especially when the result is only weakly positive. This may mean that the patient is about to develop symptoms. This is why a positive result should be used to identify those allergens to which the patient should then be challenged in an elimination - reintroduction diet. Conversely, a negative ImmunoCAP® Specific IgE result reliably shows that there is no allergen-specific IgE directed against that food, and the patient is therefore not sensitised against that food and the patient is therefore not allergic to that food. This can be very useful information indeed for small babies who appear to be allergic to many foods and it then becomes important to find some foods to which they are not allergic.

In addition to this vast range of individual food allergens with the ImmunoCAP® Specific IgE test, there are various mixes of related foods, such as mixed cereals, mixed seafood, mixed nuts, mixed spices, etc. A particularly useful mixed food allergen test is the Paediatric Food Mix fx5 that tests for allergy to the commonest foods to which a baby or small infant may react, namely egg white, cow's milk, fish, wheat, soya and peanut. These mixed allergen tests are used to screen a blood sample for that type of allergen and a negative result excludes all of those individual components, whereas a positive result would be followed up with tests for the individual component allergens.

ImmunoCAP® Specific IgE test results are expressed in classes from 0 to 6 and fully quantitatively in units of kilo units per litre IgE, (kU/l IgE) and is standardised against the World Health Organisation standard.

In addition to ImmunoCAP® Specific IgE tests to identify food allergens, there are some other blood tests that can be used in the diagnosis of allergy.

The test for Total IgE is a fully quantitative assay that measures the total amount of IgE in the patient, whether it be directed against one or more foods or against inhalant allergens, or drugs or any other allergens. This test is used to give an indication of the degree of allergen load that the patient is being subjected to. For example, a slightly raised Total IgE would indicate that the patient is moderately allergic to just one or a few allergens, whereas a very highly elevated level of Total IgE would indicate that the patient is either highly allergic to one or a few allergens, or is allergic to many allergens. However, due to it's clinical limitations, the test for Total IgE is gradually being replaced by the Phadiatop test and the ImmunoCAP® Specific IgE Paediatric Food Mix fx5.

The Phadiatop® test is a qualitative test (i.e. yes or no) that indicates very reliably if a patient is sensitised to one or more inhalant allergens. Although inhalant allergens are not foods, it must be remembered that many foods are also found as inhalant allergens, for example wheat is a grass that produces pollen that can cause an inhalant allergy. In addition, many infants with food allergy go on to develop inhalant allergy after a few years.

ImmunoCAP® Specific IgE tests have certain advantages over skin prick tests. ImmunoCAP® Specific IgE tests are:

completely unaffected by the symptoms of the patient (e.g. even severe eczema cases)
completely unaffected by drug therapy (e.g. anti-histamines)
are as sensitive as skin tests (i.e. very few false negative results)
are more specific than skin tests (i.e. fewer false positive results)
comprehensive range of allergens that can be tested for (over 200 individual allergens)
screening tests of mixed allergens (over 40 different mixes)
Whether ImmunoCAP® Specific IgE tests or skin prick tests are used depends on the choice of the individual doctor who will base his decision on his own experience and the individual circumstances of each case. Most usually the ImmunoCAP® Specific IgE tests are used due to the advantages stated above, though they are more expensive than skin testing. In South Africa the Total IgE, the Phadiatop and the Specific IgE tests are all fully reimbursed by all Medical Aid Schemes.

5(c) Elimination - Reintroduction Diet
When food allergy to one or more foods is suspected based on the results of the history, supported by skin and/or Specific IgE tests, elimination - reintroduction diets can be used to confirm the diagnosis and the identification of the offending allergens, for two reasons:

the allergens for skin or Specific IgE tests can be affected by loss of allergenicity during manufacture
a substantial number of patients, although demonstrating IgE to that particular food and are therefore sensitised, do not exhibit any clinical symptoms.
An elimination diet is used to remove the suspected foods from the diet for a period of two weeks, even including minute quantities of the suspected allergens. Sometimes the patient is asked to follow an oligoallergic diet that excludes almost all-possible potential allergens. During this period the patient keeps a careful record of the foods consumed and any clinical reactions. If the symptoms do not clearly improve within two weeks then it is most unlikely that food allergy is involved, or there could be multiple sensitivities. If however the symptoms do clearly improve, then it is most likely that the offending food allergens have been correctly identified. An open oral challenge is then performed when the suspected food is re-introduced into the diet or is given under controlled circumstances in the doctors rooms (a challenge test). An adverse reaction then confirms the diagnosis and the identification. If the open challenge is positive the result should ideally be confirmed by a Double Blind Placebo Controlled Food Challenge Test (DBPCFC) where neither the patient nor the doctor are aware of whether the patient is being challenged with the suspected food or with a placebo. As this technique removes any psychological effect and any bias by the doctor, it is regarded as the gold standard for food challenge tests. It is however seldom done in clinical practice due to the inconvenience involved. For the diagnosis of Food Intolerance and the identification of the offending foods, DBPCFC is the only proven test that provides reliable results.

Provocation tests should only be carried out by an experienced doctor with resuscitation equipment readily available, as a severe reaction and even anaphylactic shock is possible.

Diagnosis of Food Intolerance
If the defence (immune) system is not involved, food intolerance cannot be diagnosed by a skin or blood (Specific IgE) test. These IgE tests only detect IgE against a food such as is found with food allergy, and do not give positive results when food intolerance is involved. Therefore food intolerance is diagnosed with the help of the medical history, and food history, followed by elimination and reintroduction or provocation of the suspected food or groups of food. DBPCFC is also of great importance for the diagnosis of food intolerance.

Unconventional Diagnostic Methods
Diagnostic methods used by "clinical ecologists" and others to diagnose and treat patients with the so-called environmental illness (or food and chemical sensitivity / environmentally induced disease / ecologic illness / total allergy syndrome) are expensive and lack scientific foundation in detecting adverse reaction to food, and should be avoided. The theory is that food and chemical sensitivity leads to common somatic complaints such as headache, fatigue, malaise, disorientation and dizziness, among others. This theory has not been proven.

There are in South Africa, and in a very few other countries in the world, some of these tests that are promoted for the diagnosis of food intolerance and the identification of the problem foods. The proponents of these tests claim to identify foods to which a patient is intolerant, and a subsequent exclusion diet will relieve a very wide range of symptoms from migraine to irritable bowel syndrome to chronic fatigue syndrome, and including obesity! These tests are being heavily promoted directly to the public, with largely unsupported medical claims, but against the advice of the vast majority of medical opinion leaders and medical researchers. The most widely publicised of these tests are based on the concept of leukocytotoxic testing, whereby a sample of blood is mixed with the food in question, in a test tube, and the subsequent reaction can be measured by a change in the size of the blood cells. This clinical concept and these tests have over the years been evaluated by local and international opinion leaders in medicine and laboratory pathology and the overall conclusion is that these methods are not recommended for use. They are:

- not supported by mainstream, conventional doctors and researchers
- lacking a scientific rationale,
- not reproducible (i.e. are inconsistent)
- expensive (approximately R2,000 for a standard panel of 130 tests)

These tests are therefore to be regarded as the last line of investigation when all other traditional diagnostic procedures and tests have been used, but to no avail.

Treatment
Once the diagnosis of food adverse reaction has been established and the problem foods reliably identified, then the only proven therapy is to avoid or eliminate the offending food. This means giving up the food that causes the symptoms. In some special situations, the use of prophylactic medications can be beneficial.

If there are several offending foods, or if the foods are a more or less essential part of the diet, such as milk, then a doctor or dietitian with expert knowledge in this area must be consulted. A dietician can be of great help with providing long-term meal planing and can make suggestions for alternative foods or ingredients.

Long term dietary guidelines are only justified after a proper diagnosis has been made. In children, the diagnosis should be considered as temporary and should be re-evaluated at intervals as very young children can "out-grow" many food allergies. For milk and egg allergy, this re-evaluation should be done yearly, while peanut allergy is usually life-long. However, whilst one food allergy can disappear, other food allergies can appear. Also, other types of allergy symptoms can develop and sensitisation to other allergens such as to house dust mites, grass pollens, cats and dogs, etc. (inhalant allergens) can arise.

The Role of the Dietitian
The dietician can play a vital role not only in the treatment (i.e. avoidance) of the offending foods, but even in the diagnosis of the type of food hypersensitivity, and the identification of the problem foods. The dietitian is trained and has many years' experience of food hypersensitivities and their management, whereas the great majority of clinicians, even specialist Allergists, will not have this depth of experience. The value of the dietician in the management of the food allergic patient can therefore not be overstated.

Food Allergy Prevention

There are three main elements to the prevention of food allergy

1. Pre-disposition to Allergy
Children with parents or siblings who suffer from allergies will be more inclined to have allergies themselves. (include graphic here of children and percentages)

2. Breast Feeding
Breast-feeding for a period of 6 months should be encouraged for all new-borns. This becomes clinically important if that child has an allergic pre-disposition, and even after that period known allergenic foods should ideally be avoided if possible. Proteins from potentially allergenic foods such as cow's milk, and egg can be transferred from the mother to the bay in the breast milk, so it is also advisable for the breast-feeding mother to also avoid these potentially allergenic foods. If breast-feeding is not successful or not possible, then a child with an atopic pre-disposition should be given a hypoallergenic formula. Soya milk is not a good alternative as approx. 10% of cow's milk allergic babies are also allergic to soya. (include graphic of breast feeding).

3. Avoidance of Tobacco Smoke and Inhalant Allergens
Passive smoking by a baby or infant is to be strongly discouraged, as this can irritate and sensitise the baby's lungs. Similarly, the exposure to inhalant allergens such as pets and house dust mite, should be avoided as much as possible.

Chemical and/or Food Sensitivity

Chemical Sensitivity: A new Mechanism of Disease?
Multiple chemical sensitivity (MCS) is an ailment, or a family of ailments, that has very real consequences for tens of millions of Americans.

In various large surveys 15% to 30% of Americans (37 to 75 million people) report that they are unusually sensitive or allergic to certain common chemicals such as detergents, perfumes, solvents, pesticides, pharmaceuticals, foods, or even the smell of dry-cleaned clothes. An estimated 5% (13 million people) have been diagnosed by a physician as being especially sensitive. Many of these people react so strongly that they can become disabled from very low exposures to common substances.[1,pgs.232-233]

Typical symptoms include

prolonged fatigue,
memory difficulties,
dizziness,
lightheadedness,
difficulty concentrating,
depression,
feeling spacey or groggy,
loss of motivation,
feeling tense or nervous,
shortness of breath,
irritability,
muscle aches,
joint pain,
headaches,
head fullness or pressure,
chest pains,
difficulty focusing eyes,
nausea, and more.

This group of symptoms is known as environmental illness or, more commonly, multiple chemical sensitivity (MCS), meaning "sensitivity to many chemicals."
MCS has been recognized by its symptoms for 50 years because MCS sufferers in many geographical areas, researchers studying them, and doctors treating them, have reported a remarkably consistent picture of disease. However, because MCS sufferers react to chemicals at levels that are hundreds or thousands of times lower than allowable occupational exposures, traditional toxicology dictates that their symptoms cannot be caused by chemical exposures. Nor is MCS a true allergy because there are no IgE-mediated reactions involved, so allergists don't know what to make of it.

In sum, because MCS does not fit any of the three currently-accepted mechanisms of disease --infectious, immune system, or cancer --traditional medicine has not known how to explain MCS, and so has often labeled it "psychogenic" --originating in the patient's mind. This has left MCS sufferers in limbo. Told they are crazy, or imagining their disease, or making it up, they find themselves passed from physician to physician without any satisfactory answers and often without relief from their very real distress. (Some MCS sufferers DO have psychological symptoms, but that doesn't necessarily mean their disease ORIGINATES in their mind.) Forty percent of MCS sufferers report having seen more than 10 medical practitioners.

MCS came to the attention of mainstream science and medicine forcibly in 1987 when U.S. EPA (Environmental Protection Agency) installed 27,000 square yards of new carpeting and painted and remodeled office space at its Waterside Mall headquarters in Washington, D.C. Some 200 agency employees developed symptoms associated with "sick building syndrome"[1,pgs.174,76-77] --and several dozen EPA employees later reported developing MCS. The National Research Council has now accepted that "sick building syndrome" is a real phenomenon, producing MCS-like symptoms.

Most recently, MCS has been in the news because there are two new, large populations of people who exhibit some or all of the symptoms of MCS: Gulf War veterans, and women with silicone breast implants.

Since 1990, progress has been made defining and understanding MCS, though there is still a long way to go. Nevertheless, real progress has been made. A new book --a second, updated edition of CHEMICAL EXPOSURES; LOW LEVELS AND HIGH STAKES, by Nicholas A. Ashford and Claudia S. Miller[1] --offers a lucid, thoughtful description of the current science and medicine of MCS, suggests a hypothesis (which could be tested) about the origins of the disease(es), and offers real hope to sufferers that one day their ailments will be understood and treated, possibly even prevented.

The stakes are enormous, and the chemical industry knows it. If a clearly-defined disease emerges from research on MCS, with chemical causes that are understood, then it can't be too many decades before chemical corporations will have to face liability and compensation claims from millions of victims harmed by their products. Who knows where this might lead in the relationship between corporations and an angry public?

Like the tobacco companies before them, the chemical corporations are bent on casting doubt on the serious medical research now being conducted to discover the causes and physiologic mechanisms of MCS. The chemical corporations have labeled such research "junk science," and they have funded a new research arm of their own (modeled on the Tobacco Research Institute?) called the Environmental Sensitivities Research Institute (ESRI). DowElanco, Monsanto, Procter and Gamble, the Cosmetic Toiletries and Fragrances Association, and other companies and trade associations involved in the manufacture of pharmaceuticals, pesticides, and other chemicals, each pay $10,000 per year to keep ESRI going. The head of ESRI is Dr. Ronald Gots, who also runs something called the National Medical Advisory Group, which provides expert witnesses to defend the chemical corporations in tort lawsuits. Dr. Gots has published no original peer-reviewed research on MCS, yet he and ESRI specialize in claiming that MCS is a mental disorder.

Dr. Gots says, "Everything that is known about MCS to date strongly suggests behavioral and psychogenic explanations for symptoms."[1,pg.280] In other words, if you exhibit some or all of the symptoms of MCS, you are probably crazy and if your doctor thinks otherwise, he or she is probably a charlatan. Such a claim has special staying power because it cannot be tested scientifically. As long as anyone is around to assert its validity, such a claim surrounds MCS research with an aura of controversy --and controversial topics have trouble attracting mainstream funding.

Here is a typical "advertorial" by ESRI from the February, 1996 issue of THE MERCHANDISER (Spring Grove, Pennsylvania):

Multiple Chemical Sensitivities: Fear of Risk or Fact of Life?
"Scientists are increasingly concerned that a doubtful new diagnosis--supposedly caused by everything 'man-made' in the environment--is unnecessarily making thousands of Americans miserable each year. One of these so-called 'modern diseases' is called MCS, for Multiple Chemical Sensitivities. Many established scientists and physicians doubt MCS actually does exist; it exists only because a patient believes it does and because a doctor validates that belief. For information on MCS, write the Environmental Sensitivities Research Institute, 6001 Montrose Road, Suite 400, North Bethesda, MD 20852."

The authors of the new book on MCS are highly qualified. Nicholas Ashford is professor of technology and policy at Massachusetts Institute of Technology (MIT) with advanced degrees in chemistry and law. Claudia Miller is a medical doctor with a masters degree in environmental health; she teaches at the University of Texas Health Science Center in San Antonio. Their 1989 report on MCS, funded by the New Jersey Department of Health, won the prestigious Macedo award of the American Association for World Health. Their new book is a pleasure to read. It is clear, thoughtful, intelligent, and carefully written. It makes an important contribution to our understanding of chemical sensitivity.

In reviewing several hundred studies --not all of them of good quality --Ashford and Miller describe the common themes that emerge from the good ones: MCS seems to be a disease (or family of diseases) that occurs in two stages. MCS is "initiated" by a high exposure (for example, a chemical fire, or spill) or by repeated moderate exposure to pesticides or solvents or some other strong chemical(s) such as those found in chemical dumps or used in remodeling homes or offices, including new carpeting. After the "initiating" exposure, symptoms are then "triggered" by extremely low exposure to many different chemicals, such as those found in fragrances, or tobacco smoke, pharmaceuticals, or foods. Not everyone exposed to chemicals gets MCS, just as not everyone stung by a bee goes into anaphylactic shock. A certain portion of the population seems predisposed to react strongly to chemicals after an initiating event.

The mechanisms of MCS are not understood, but recent evidence suggests that the nervous system (or perhaps the nervous and immune systems together) somehow become sensitized by an initiating exposure. Thereafter, low exposures to common chemicals bring on major symptoms way out of proportion to the size of the stimulus.

Ashford and Miller suggest that MCS is not really the best name for this ailment or family of ailments because it fails to reflect the importance of the initiating chemical exposure. They suggest that the name Toxicant-Induced Loss of Tolerance (TILT) better describes the true nature of the illness(es) --initiated by a toxic exposure which leads to the loss of tolerance for common chemicals. They suggest that different initiating events may give rise to somewhat different ailments, all of which cause sensitivity to chemicals --just as different infectious diseases can all cause a fever.

The scientific community has held several symposia on MCS (or TILT) since 1990 and a scientific consensus has been reached on the double-blinded, placebo-controlled research that needs to be conducted to define this disease (or disease family).

Despite this consensus, the research is not being conducted because the needed facilities do not exist. A special "environmental medical unit" needs to be built, preferably in a hospital, to test MCS patients by exposing them to chemicals under controlled conditions and observing their responses. Despite numerous recommendations that such a unit should be built --including a recommendation from the National Research Council --the funding is not there.

Without naming him, authors Ashford and Miller blame Ronald Gots and others like him for the logjam: "...those who continue to promote untested and untestable psychogenic theories for MCS are part of the problem. Their lobbying of policymakers and others in this regard has contributed to widespread governmental inertia on this issue, making it near impossible to obtain funding for essential studies specifically directed toward MCS. Many of those who advocate psychological explanations in government-sponsored meetings and in the scientific literature are paid corporate spokespersons or consultants with financial conflicts of interest. Yet these conflicts generally are not revealed when these individuals appear in scientific meetings, author scientific articles, serve on official panels or boards, or serve as reviewers of grant proposals. Policymakers and publishers of scholarly journals need to recognize and remedy this appalling injustice."[1,pg.256]

These are not academic questions. Seventy thousand Gulf War veterans, alone, have sought help. They are told they must prove their disease exists --but without research they have no proof. The same is true of tens of thousands of women whose breast implants have left them with many of the symptoms of MCS. (David Kessler, when he was head of the Food and Drug Administration (FDA) said, "We know more about the life of a tire than a breast implant.") These and millions of other people are genuinely suffering, yet they are told --with no research basis --that there is nothing medically wrong with them--it's all in their minds. Only research can find the truth.

Quite possibly, MCS or TILT is a new, fourth disease mechanism parallel to infections, immune disorders, and cancer. Those suffering its symptoms cannot gain relief from their torment until the needed research is done. Those who are being paid by chemical corporations to stand in the way of that research deserve the labels inhuman and inhumane. Would criminal be too strong a word?

Peter Montague
(National Writers Union, UAW Local 1981/AFL-CIO)