Allergy

Statistics

For reasons that are not entirely understood, the diagnosis of food allergies has apparently become more common in Western nations in recent times.[4] In the United States food allergy affects as many as 5% of infants less than three years of age[26] and 3% to 4% of adults.[27] There is a similar prevalence in Canada.[28]

The most common food allergens include peanuts, milk, eggs, tree nuts, fish, shellfish, soy, and wheat - these foods account for about 90% of all allergic reactions.[citation needed]

[edit] Differing views

Various medical practitioners have a differing views on food allergies. Irritable Bowel Syndrome (IBS) patients have been studied with regards to food allergies. Some studies have reported on the role of food allergy in IBS; only one epidemiological study on functional dyspepsia and food allergy has been published. However, since 2005 several studies have demonstrated strong correlation between IgG and/or IgE food allergy and IBS symptoms[29][30][31] The mechanisms by which food activates mucosal immune system are incompletely understood, but food specific IgE and IgG4 appeared to mediate the hypersensitivity reaction in a subgroup of IBS patients. Specific chemicals and receptors have been demonstrated to be critical in food allergy development in murine models.[32] Exclusion diets based on skin prick test, RAST for IgE or IgG4, hypoallergic diet and clinical trials with oral disodium cromoglycate have been conducted, and some success has been reported in a subset of IBS patients.[33]

Studies comparing skin prick testing and ELISA blood testing have found that the results of skin prick testing correlate poorly with symptoms of irritable bowel syndrome that correlate with food allergies demonstrated through ELISA testing and dietary challenge.[34]

Extensive clinical experience has demonstrated significant improvement of patients with IBS whose ELISA-based food allergy testing is positive and where treatment includes a careful exclusion diet.[35]

In addition, many practitioners of alternative medicine ascribe symptoms to food allergy where other doctors do not. The causal relationships between some of these conditions and food allergies have not been studied extensively enough to provide sufficient evidence to become authoritative. The interaction of histamine with the nervous system receptors has been demonstrated, but more study is needed.[36] Other immune response effects are commonly known (swelling, irritation, etc.), but their relationships to some conditions has not been extensively studied. Examples are arthritis, fatigue, headaches, and hyperactivity. Nevertheless, hypoallergenic diets reportedly can be of benefit in these conditions, indicating that the current medical views on food allergy may be too narrow.

[edit] In children

Milk and soy allergies in children can often go undiagnosed for many months, causing much worry for parents and health risks for infants and children. Many infants with milk and soy allergies can show signs of colic, blood in the stool, mucous in the stool, reflux, rashes and other harmful medical conditions.[citation needed] These conditions are often misdiagnosed as viruses or colic.

Some children who are allergic to cow's milk protein also show a cross sensitivity to soy-based products.[37] There are infant formulas in which the milk and soy proteins are degraded so when taken by an infant, their immune system does not recognize the allergen and they can safely consume the product. Hypoallergenic infant formulas can be based on hydrolyzed proteins, which are proteins partially predigested in a less antigenic form. Other formulas, based on free amino acids, are the least antigenic and provide complete nutrition support in severe forms of milk allergy.

Seventy-five percent of children who have allergies to milk protein are able to tolerate baked-in milk products, ie., muffins, cookies, cake.

About 50% of children with allergies to milk, egg, soy, and wheat will outgrow their allergy by the age of 6. Those that don't, and those that are still allergic by the age of 12 or so, have less than an 8% chance of outgrowing the allergy.[38]

Peanut and tree nut allergies are less likely to be outgrown, although evidence now shows[39] that about 20% of those with peanut allergies and 9% of those with tree nut allergies[40] will outgrow their allergies. In such a case, they need to consume nuts in some regular fashion to maintain the non-allergic status.[citation needed] This should be discussed with a doctor.

Those with other food allergies may or may not outgrow their allergies.

[edit] Labeling laws

In response to the risk that certain foods pose to those with food allergies, countries have responded by instituting labeling laws that require food products to clearly inform consumers if their products contain major allergens or by-products of major allergens.

[edit] United States law

Under the Food Allergen Labeling and Consumer Protection Act of 2004 (Public Law 108-282), companies are required to disclose on the label whether the product contains a major food allergen in clear, plain language. The allergens have to clearly be called out in the ingredient statement. Most companies list allergens in a statement separate from the ingredient statement.[41]

[edit] See also
Food portal

* Lactose intolerance
* Oral Allergy Syndrome
* Medical emergency
* Mast cell