Food additives that can cause allergic reactions

True allergy involves an allergen-antibody reaction. A food allergic reaction sets off a complex series of events when food allergen comes in contact with the immune system as it is passing through or being absorbed by the gastrointestinal tract.

There are several foods and food additives that can cause both immunologic and non-immunologic reactions indistinguishable from each other. For example, fish can act both a nonspecific histamine liberators and as true allergens.

Tuna, mackerel and certain cheeses contain histidine and tyrosine to such an extent that histamine and tyramine produced by decarboxylation from them can cause allergic-type symptoms in atopic people.

Any additives that contain proteins can cause allergic reactions, although these allergies are rare. Among food additives, annatto, a yellow color derived from a seed, and saffron, from the dried parts of a flower, which is used for color and flavor.

Cinnamon and nitrogen mustard are the most well-known causes of both allergic and non-allergic reactions.

Caviar or fish eggs allergy can occurs in people who tolerate fish. In China, allergies to bird’s nest soup, made in part from saliva of a bird, have triggered reaction. Carmine in food dye (red) that is derived from the dried body of a beetle, and it has also triggered allergic reactions.
Food additives that can cause allergic reactions 

Chinese restaurant syndrome

Because symptoms are reported to occur shortly after sensitive individuals eat Chinese food, sensitive to MSG has been dubbed the ‘Chinese restaurant syndrome’.

Monosodium glutamate is the sodium salt of the amino acid, glutamic acid. It is commercially synthesized by taking protein, typically derived from wheat or soy, through and acid wash to unravel the amino acids.

The neutralizing agent sodium hydroxide is then added to form the sodium salt of each amino acid, celled hydrolyzed vegetable protein which constitutes of MSG 10% to 30% of the mixture.

Symptoms associated with MSG sensitive include dizziness, sweating, flushing, a rapid heartbeat and a ringing sound in the ears. It appears within 20 min and last up to 2 hours.

In 1968, Dr Robert Kwok wrote a letter to the New England Journal of Medicine describing some mild by uncomfortable symptoms after dining at certain Chinese restaurants.

People who experienced headaches and general feelings of ill health after eating Chinese food suddenly realized that they were not alone.

Chinese restaurant syndrome, also called monosodium glutamate symptoms complex and it is commonly believed that monosodium glutamate is the cause.

More serious symptoms attributed to the syndrome have included swelling of the throat, chest pain, heart palpitations, and shortness of breath.
Chinese restaurant syndrome

Sulfite sensitivities

One of the common food idiosyncrasies is sulfite sensitivity. Sulfites are preservatives used most commonly in wine and dried fruits and vegetables.

Sulfite is used as food additives in a variety of foods. Sulfites exist in several forms: sulfur dioxide, sodium metabisulfite, potassium, metabisulfite, sodium bisulfite, potassium bisulfite and sodium sulfite.

Sulfite sensitivity is an idiosyncratic reaction of undefined mechanism associated with the ingestion of sulfites in foods and medications. The symptoms associated with idiosyncratic reactions can be form trivial to life threatening.

People who are sensitive to sulfite can have such severe reactions that range from shortness of breath to fatal shock.

Very small amounts of sulfites can cause anaphylactic shock and bring in an asthma attack in sensitive people. The FDA requires that processed foods containing sulfites list sulfites in the ingredient label.
Sulfite sensitivities

Basic of Sensitization in Atopic Allergy

Basic of Sensitization in Atopic Allergy
During the first year of life, allergic sensitization occurs readily via the intestinal tract because the protective immunologic mechanisms are not fully developed.

Breast milk offers passive protection during the vulnerable age but is also a possible route of sensitization.

Overproduction of IgE is characteristics of atopic allergy. Many healthy children develop IgE antibodies, against egg white for instance, during the first year of life.

These antibodies usually disappears in a few months and are probably a reflection of the normal humoral immunoresponse.

However, in those children who manifest a clinical allergy to egg white, antibodies disappear more slowly. It has been postulated that the function of cells, especially lymphocytes, controlling IgE synthesis is not in balance.

Atopy may be related to deficient or retarded maturation of cells suppressing IgE synthesis.

The protective mechanism of the intestinal mucosa, although their exact nature is not known, prevent sensitization effectively. From animal studies it is known that mice develop antibodies when given cow’s milk protein parenterally.

However, if the animal is fed cow’s milk before the injection, it develops immunotolerence and no antibodies can be detected.

The role of mucosal IgA is vitally important. Quantitative or qualitative deficiencies of IgA enhance the manifestation of circulation antibodies to foreign proteins as well as the formation of immunocomplexes.

If the permeability of the gastrointestinal or respiratory tract is increased for some reason, allergens penetrate the mucous membranes more easily and induce an immunologic response.

The function of the intestinal mucosal barrier is disturbed by infections, dietary habits, ingestions of alcohol and drugs and so fourth.
Basic of Sensitization in Atopic Allergy

Hypersensitivities Mechanisms

Hypersensitivities Mechanisms
Adverse reactions to food additives are caused by several mechanisms.

Food additives are ingested irregularly and in small doses. Additives are usually low by molecular weight chemicals, unlike many high molecular weight proteins which are potent allergens.

There is very little evidence of an immunological basis in reactions caused by food additives.

Adverse effects due to a various pharmacological or other mechanisms are much more common.

Many authors avoid the use of the terms allergy and atopy in connection with food additive reactions and prefer hypersensitivity or tolerance instead.

Terms such as false allergies, allergomimetic, reactions, or pseudoallergy have been suggested.

All these titles emphasize the nonspecific, nonimmunological nature of these reactions.

It has been observed in several studies that there is a dose response relationship with these reactions. A small amount of the agent is harmless, but a larger amount causes symptoms.

This better suits the concept of intolerance than immunologic sensitization.

Many patient suffering from food additives reactions have an atopic constitution and symptoms such as eczema and asthma.

Atopic subjects are more sensitive to numerous irritating environmental factors, including food additives, than the nonatopic population.

Atopic subjects have a particular tendency to release histamine after certain foods and additives that posses a histamine releasing action.

There appear to be more reactions caused by additives in adults than in children. The reason is obscure, but cumulative or slow development of intolerance may occur.

On the other hand, adults often have psychosomatic symptoms and are influenced by television programs and articles in journal and newspapers dealing with the adverse effects of food additives.
Hypersensitivities Mechanisms

Hypersensitivity Reactions

Hypersensitivity Reactions
Many people have uncomfortable reactions to various foods, and this is often considered to be due to food additives and other artificial chemicals such as pesticide residues, rather than to the food itself.

This discomfort is usually called allergy by nonmedical persons, but there are also nurses and doctors who use the term allergy when they mean various kinds of untoward reactions to foods without knowing the mechanisms of such reactions.

Strictly, an allergy is a harmful physiological reaction reaction caused by an immunologic mechanism.

If the mechanism is not allergic one but the reaction resembles allergic reaction, the term intolerance is often used.

The symptoms mimic those seen in allergic reactions, but the amount of agent producing the reaction is small enough not to cause a toxic reaction.

When the mechanism is not known, it is better to talk about hypersensitivity, which can mean both allergic and intolerance.

There are several foods and food additive that can cause both immunologic and non immunologic reactions indistinguishable form each other.

For example, fish can act both as nonspecific histamine liberators and as true allergen.

Tuna, mackerel and certain cheeses contain histidine and tyrosine to such an extent that histamine and tyramine produced by decarboxylation from them can cause allergic type symptoms in atopic people.

Among food additives, cinnamon and nitrogen mustard are the most well-known cause of both allergic and nonallergic reactions.

Terminology of Hypersensitivity Reactions
Hypersensitivity
A small amount of a substance produces symptoms that can be objectively verified and repeated.

Allergy
Immunologic mechanism are involved in the pathogenesis of symptoms.

Atopic allergy
The reaction is mediated by immunoglobulin E.

Intolerance
A small amount of substance produces a reaction similar to or closely resembling a true allergic reaction, but immunologic mechanisms not involved.

Hypersensitivity Reactions