Chapter 25: Medical Nutrition Therapy for Adverse Reactions to Food: Allergies and Intolerances Flashcards
adverse reactions to food
Encompass food allergies and food intolerances, both of which can involve multiple systems, cause diverse symptoms, and negatively impact health
food allergy
An adverse health effect arising from a specific immune response that occurs reproducibly on exposure to a given food
food sensitivity
A term used when it is unclear whether the reaction is immunologically related or due tot a biochemical or physiological defect
food autoimmune or immune reactivity
The concept that when the body’s normal tolerance of friendly antigenic substances is disrupted because of disease, injury, shock, trauma, drugs, or blood transfusion, the ingestion of foods containing antigenic substances with a composition similar to those of the body’s autoantigens can result in the production of antibodies that react to the food antigens and the body’s own tissues
sensitivity related illness (SRI)
A condition that occurs when an individual is exposed to some type of toxin or stressor and then becomes sensitive to a food, inhalant, or chemical, although the mechanisms are unclear
epigenetic
Modifications of the genome
atopic dermatitis
Hereditary eczematous rash
antibodies
Specialized immune proteins that are produced in response to the introduction of an antigen into the body
antigen
An allergen, toxin, or foreign substance
immunoglobulins (Ig)
Because of their association with the immune system, antibodies are referred to as immunoglobulins. Five distinct classes of antibodies have been identified: IgA, IgD, IgE, IgG, and IgM
lymphocyte
White blood cell
B-cells
A group of lymphocytes. Arise from stem cells in the bone marrow
T-cells
A group of lymphocytes. Originate from stem cells but later transported to the thymus gland where they mature
antigen-presenting cell (APC)
A cell that displays specific molecules of a material on their surfaces
epitope
The antigenic component displayed on the surface of antigen-presenting cells (APC)
cytokines
Chemical messengers
Th cells
Helper cells that adjust the system
Th1 cells
Regulate the activities of the B-cells to produce antibodies and direct damage to target cells, resulting in the destruction of antigens
Th2 cells
Mediate the allergic response by regulating the production of B-cells of IgE sensitized to food or other allergens
T-regulatory cells (T-reg cells)
Regulate the immune response so that there is tolerance of the foreign but safe molecule
T-suppressor cells
Regulate the immune response so that there is tolerance of the foreign but safe molecule
granulocytes
Cells that contain intracellular granules, which act as storage depots for defense chemicals or inflammatory mediators that, when released, not only protect the body from invading pathogens but also can produce allergic symptoms
mast cells
A type of granulocyte. Located in the lungs, skin, tongue, and linings of the nose and intestinal tract
basophils
A type of granulocyte. Are in circulation
eosinophils
A type of granulocyte. Found in blood and tissues and, when stimulated by cytokines produced by Th2 cells, migrate to the site of an allergic reaction
inflammatory mediators
Released when granulocytes degranulate. These mediators have a specific effect on local tissues and at other sites, resulting in the symptoms of an allergic reaction
oral tolerance
The mechanism by which potentially antigenic substances do not trigger an immune response and is the normal physiologic response to ingested antigens
dendritic cells (DC)
A type of antigen-presenting cell (APC)
B-regulatory (B-reg) cells
B-cells inhibit hostile immune reactivity. Act mainly through interleukin-10 (IL-10), an anti-inflammatory cytokine to reduce infection and allergic inflammation and to promote tolerance
sensitization
Can take place in the gastrointestinal tract, oral cavity, skin, and occasionally in the respiratory tract
microbiome
The collection of different types of microbes that live inside the gut
dysbiosis
When there is an imbalance in the microbial ecosystem
increased intestinal permeability aka “leaky gut”
The increased likelihood that intact food proteins and peptides will pass through the intestinal lumen and reach the lymphoid tissue, leading to immune sensitization and possible reactivity
gut-associated lymphoid tissue (GALT)
The largest mass of lymphoid tissue in the body and antigen penetration and presentation to the GALT drives food sensitization
IgE-mediated reactions
Occur when sIgE produced in response to the presence of the allergen attaches to matching sIgE antibodies on the mast cell or basophil, forming a “bridge” between them. This bridging activates the mast cell or basophil by a series of energy-requiring processes resulting in the cell’s degranulation and release of the inflammatory mediators, and the appearance of allergic symptoms
Non-IgE-mediated reactions
Based on the activation of cells other than IgE, such as eosinophils, and their degranulation and release of mediators. These reactions are present in delayed or chronic reactions to food allergen ingestion
cow’s milk protein allergy (CMPA)
An allergic response to proteins found in cow’s milk
anaphylaxis
An acute, systemic, often severe, and sometimes fatal immune response that usually occurs within a limited period following exposure to a food antigen. Multiple organ systems are affected. Symptoms include respiratory distress, abdominal pain, nausea, vomiting, cyanosis, arrhythmia, hypotension, angioedema, urticaria, diarrhea, shock, cardiac arrest, and death
food-dependent, exercise-induced anaphylaxis (FDEIA)
A rare distinct form of allergy in which an offending food triggers an IgE-mediated anaphylactic reaction only when the sensitized individual exercises within 2 to 4 hours after eating, or occasionally, before eating the food
galactose-alpha 1,3-galactose (“alpha gal”)
A delayed anaphylaxis response to mammalian meat (most commonly beef, lamp, pork, bison, buffalo, and venison). It involves IgE antibodies that the individual forms against the galactose-alpha 1,3-galactose oligosaccharide which is typically introduced into the person during bites from ticks, most commonly the lone star tick
oral allergy syndrome (OAS)
Now more commonly referred to as either pollen-food allergy syndrome or lipid transfer protein syndrome. IgE-mediated reactions characterized by oropharyngeal symptoms of itchy mouth; scratchy throat; swelling of the lips, mouth, uvula, or tongue; and throat tightness
pollen-food allergy syndrome (PFAS)
IgE-mediated reaction characterized by oropharyngeal symptoms of itchy mouth; scratchy throat; swelling of the lips, mouth, uvula, or tongue; and throat tightness. A milder reaction confined just to the oral cavity. Symptoms are rapid and appear within 5 to 30 minutes after ingestion of the allergen-containing food and most often subside within 30 minutes
lipid transfer protein syndrome (LTPS)
IgE-mediated reaction characterized by oropharyngeal symptoms of itchy mouth; scratchy throat; swelling of the lips, mouth, uvula, or tongue; and throat tightness. The reaction not only affects the oral cavity but also can become systemic with hives, wheezing, vomiting, diarrhea, and low blood pressure, or even anaphylaxis
cross-reactivity
Reaction to a protein that is similar to an allergen found in the food one is allergic to
latex-fruit syndrome or latex-food syndrome
Many people with latex allergies have IgE antibodies that can cross-react with antigens from food, mostly fruits, and cause allergic symptoms. Symptoms vary and may include anaphylaxis
systemic nickel allergy syndrome (SNAS)
Allergy to the mineral nickel begins as contact dermatitis. Individuals with nickel contact dermatitis can develop a secondary response of eczema or dermatitis when the nickel is present in an ingested food
eosinophils
Type of granulocyte. Capable of releasing inflammatory mediators
Eosinophilic esophagitis (EoE)
A gastrointestinal disorder which reflects a Th2 inflammation pattern. Symptoms of EoE vary depending on the age of the person and may include early satiety and inability to manage varied food textures in young children, to reflux-like symptoms and vomiting in school-aged children, and to dysphagia, refusal to eat, and food impaction in teenagers and adults
Eosinophilic gastroenteritis (EGE)
A gastrointestinal disorder which reflects a Th2 inflammation pattern. Symptoms vary depending on the portion of the GI tract involved, and the localized or widespread infiltration by eosinophils. Abdominal pain and nausea and vomiting are the most frequent presenting symptoms in children and adults. Adolescents may present with growth retardation, failure to thrive, and delayed puberty or amenorrhea
step up 2-4-6 food elimination diet
This approach begins with two-food elimination and steps up after 6 weeks of strict adherence with no remission. This is done again between the four-food and six-food groups if necessary. This approach usually results in prompt recognition of the majority of responders, reducing the number of endoscopies and costs, and shortening the diagnosis process
six-food elimination diet (SFED)
The elimination of cow’s milk, wheat/gluten, egg, soy, peanut/tree nuts, and fish/seafood
food protein-induced enterocolitis syndrome (FPIES)
A non-IgE mediated reaction to food. The major criterion is vomiting 1 to 4 hours after ingestion of a food with the absence of IgE-mediated skin or respiratory symptoms.
double-blind, placebo-controlled food challenge
Allergen is disguised and given orally and patient monitored for reaction; patient and physician blinded; also tested with placebo. “Gold standard” for allergy testing
food protein-induced proctocolitis or proctitis (FPIP)
Bloody and mucus-laden stools are seen in an otherwise apparently healthy baby, often about 2 months of age. Common food triggers are cow’s milk protein or soy protein from infant formula and their removal from the infant’s diet usually solves the problem
food intolerances
Adverse reactions to food that result in clinical symptoms caused by non-immunologic mechanisms including microbial, pharmacologic, GI, metabolic, psychological and behavioral or idiosyncratic
diamine oxidase (DAO)
An enzyme that when deficient can impact metabolism of histamine
histamine-N-methyltransferase (HNMT)
An enzyme that when deficient can impact metabolism of histamine
tyramine
A biogenic amine formed from the amino acid tyrosine that is found naturally in some foods, plants, and animals
FAILSAFE diet
A diet “free of additives, low is salicylates, amines, and flavor enhancers” designed by the Royal Prince Alfred Hospital in Australia. Intended to be used for the investigation and management of people with suspected food intolerance
food and symptom record
A record of the time food is eaten, quantity and type of food, and all ingredients if possible, and any symptoms that appear and the time of symtpoms
skin-prick test (SPT)
A type of immunologic testing. Drops of food extract are placed onto the skin and the skin is pricked with the food extract. The area is observed for development of the classic “wheal and flare” reaction
food allergen-specific serum IgE testing
Used to identify foods that may be causing allergic response. These tests measure the presence of IgE antibodies sensitized to various allergens
component resolved diagnostics (CRD)
A useful tool in assessing food allergy. CRD involves testing for IgE sensitized to specific component proteins in foods and not just the whole protein extract
elimination diet
Entails both an elimination phase and a systematic food challenge or food reintroduction period, is the most useful tool in both the diagnosis and management of adverse food reactions
food allergen labeling and consumer protection act (FALCPA)
Requires the top allergens to be clearly listed by manufacturers as an ingredient or following the ingredient list on food labels
precautionary allergen labeling (PAL)
Manufacturers may voluntarily list potential unintended allergens that may be present due to cross contamination in a clear way that does not interfere with the required food list
oral food challenge (OFC)
Conducted in a supervised medical setting. Foods are challenged one at a time on different days while the person is carefully observed in a medical setting for the recurrence of symptoms
dual allergen hypothesis
Proposes that allergic sensitization to foods may occur from a disrupted skin barrier early in life, as occurs in infantile eczema
atopic march
A pattern that describes a process in which atopic disorders progress over time from eczema to asthma to multiple allergic disorders including food allergy
allergen immunotherapy (AIT)
Aims to provide desensitization in a systemic stepwise process, was first described in the early 1900s. A procedure inducing tolerance to a specific allergen by repetitive administration of small amounts of an allergen, and it has been effective in respiratory allergy and venom hypersensitivity
