09/01/2022
Foods from animals and plants contain many thousands of biologically active naturally occurring chemical compounds and the action of micro-organisms on these foods after they are harvested can add to the pool of active chemicals. Some of these active compounds may be resistant to stomach acids and are capable of penetrating an intact or damaged intestinal mucosa and causing an adverse reaction. In some cases failure to digest constituents of particular foods may result in the accumulation of abnormal levels of particular elements or compounds.
Adverse reactions to foods can be classified as allergies or intolerance.
Food allergies are caused by the presence of particular proteins in foods that provoke an immune response. Adverse reactions to foods that are not immune mediated can be classified as food intolerance.
Food intolerance
Food intolerance is an adverse reaction to ingested food that does not provoke an IgE mediated immune reaction. There are a wide variety of naturally occurring chemicals in foods that can provoke an adverse reaction in susceptible individuals, including the following;
* Vasoactive amines
* Monosodium glutamate occurs naturally in such foods as camembert cheese, Parmesan cheese, tomatoes, soy sauce and mushrooms.
* Salicylates are aspirin like compounds present in a wide variety of herbs and spices as well as apples, citrus fruits, strawberries, tomatoes, wine and some vegetables.
* Sulphites which occur naturally in some foods and are frequently added as a preservative to others , may cause an allergic like reaction in some individuals and have been shown to exacerbate existing allergies such as asthma or atopic dermatitis.
* Carbohydrates are a group of chemicals more commonly known as sugars and include simple sugars such as glucose, sucrose and lactose and more complex sugars such as glycogen and starch.
* Gliadin is a protein found in wheat, barley and rye. In some individuals an enzyme called tissue transglutaminase modifies the gliadin to produce antigenic components which provoke and autoimmune reaction against tissue in the small bowel.
SIGNS & SYMPTOMS
Symptoms will vary depending on the type and severity of the adverse reaction and the quantity of offending food consumed. Allergic responses tend to occur soon (usually a few to 30 minutes) after food is consumed and are usually evident and may be dramatic. Symptoms of food intolerance may take several hours or days to become evident, are less dramatic and may be subtle.
Food allergies
Presentation will vary depending on the type of allergy.
Oral food allergy Patients with this syndrome develop itching or tingling of the lips, tongue, palate, and throat following the ingestion of certain foods. In addition, swelling of the lips, tongue, and uvula and a sensation of tightness in the throat may be observed. This reaction is usually seen in patients with hay fever who consume raw fruit or vegetables
Exercise induced food allergy occurs after ingestion of a specific food before exercising. As exercise increases and body temperature rises, patients may experience itching, light headedness and a skin rash or hives. In more severe cases breathing may be impaired and a decrease in blood pressure may result in loss of consciousness. Crustacean shellfish, alcohol, tomatoes, cheese, and celery are common causes of exercise-induced food allergy reactions.
Eosinophilic esophagitis (EoE) is characterized by an allergic reaction in the oesophagus (the tube that connects the throat to the stomach) causing inflammation and accumulation of specialised immune cells called eosinophils. Symptoms of EoE include nausea, vomiting, and abdominal pain after eating. It may also cause reflux or difficulty swallowing.
Food allergy Symptoms tend to be more systemic, affecting particularly the GI tract and skin. Symptoms include itching or swelling of the mouth, abdominal cramps or pain, vomiting, diarrhoea and itchy skin rash. Patients may also experience some breathing difficulties and a drop in blood pressure.
A more severe reaction may result in anaphylaxis with a variety of symptoms including the following;
* Itching and swelling of the skin particularly the face and around the eyes. Skin rashes or hives.
* Itching and swelling of the lips, tongue and throat.
* Itching and swelling of nasal passages and runny nose.
* Difficulty breathing, wheezing, cough, chest pain and tightness.
* Vomiting, diarrhoea and abdominal pain or cramps.
* Drop in blood pressure, weak pulse, dizziness or loss of consciousness.
Anaphylaxis if severe and not treated promptly can result in inadequate blood pressure, reduced oxygen supply to vital organs and death.
Some food allergens have been shown to exacerbate asthma or ectopic dermatitis.
Food intolerance
Symptoms of food intolerance will also vary with the type and severity of reaction and the amount of reactive food ingested. Food intolerance can produce a variety of symptoms including the following;
* Abdominal cramps, pain or discomfort and diarrhoea.
* A feeling of heaviness or bloating with excess gas production.
* Loss of appetite, weight loss, fatigue, lack of energy.
* Headaches, runny nose, flushing, rapid heart beat.
* Numbness tingling or itching of the skin, or mucous membranes.
* Skin rashes or hives.
CONDITIONS WITH SIMILAR SYMPTOMS
Anorexia nervosa
Auriculotemporal syndrome
Bulimia
Crohns disease
Diverticulitis
Oesophageal disorders
Food poisoning
Gastritis
Gastroenteritis
Gastroesophageal reflux disease
Giardiasis
Hiatal hernia
Inflammatory bowel disease
Intestinal motility disorders
Irritable bowel syndrome
Urticaria
Ulcerative colitis
Wasp stings
Whipple disease
INVESTIGATIONS
-Blood for CAP RAST or CAP FEIA using specific food allergens. Blood for total IgE and eosinophils.
-Skin prick test using suspected allergens. Patch test using suspected allergens.
-Blood tests: FBC (Full blood count), anti-endomysial antibodies; anti-tissue transglutaminase antibodies; and anti-gliadin antibodies, Iron, Folate, Ca++, Vit B12, Vit D. and full biochemical profile.
-PH measurement of faeces, if the pH is less than 6 (acidic) the diagnosis is in favour of carbohydrate intolerance.
-Lactose tolerance test.
-Hydrogen breath test.
Faecal fats.
-Radiography of small bowel after barium meal.
-Endoscopy.
TREATMENT
The only recognised and proven treatment for food allergy or intolerance is identification of the offending food and subsequent avoidance.
PATIENT MGT.
If you have a serious allergy or intolerance of specific foods you should wear a bracelet or other device which identifies this allergy, in case of a medical emergency.
Foods from animals and plants contain many thousands of biologically active naturally occurring chemical compounds and the action of micro-organisms on these foods after they are harvested can add to the pool of active chemicals. Some of these active compounds may be resistant to stomach acids and are capable of penetrating an intact or damaged intestinal mucosa and causing an adverse reaction. In some cases failure to digest constituents of particular foods may result in the accumulation of abnormal levels of particular elements or compounds.
Adverse reactions to foods can be classified as allergies or intolerance.
Food allergies are caused by the presence of particular proteins in foods that provoke an immune response. Adverse reactions to foods that are not immune mediated can be classified as food intolerance.
Food intolerance
Food intolerance is an adverse reaction to ingested food that does not provoke an IgE mediated immune reaction. There are a wide variety of naturally occurring chemicals in foods that can provoke an adverse reaction in susceptible individuals, including the following;
* Vasoactive amines
* Monosodium glutamate occurs naturally in such foods as camembert cheese, Parmesan cheese, tomatoes, soy sauce and mushrooms.
* Salicylates are aspirin like compounds present in a wide variety of herbs and spices as well as apples, citrus fruits, strawberries, tomatoes, wine and some vegetables.
* Sulphites which occur naturally in some foods and are frequently added as a preservative to others , may cause an allergic like reaction in some individuals and have been shown to exacerbate existing allergies such as asthma or atopic dermatitis.
* Carbohydrates are a group of chemicals more commonly known as sugars and include simple sugars such as glucose, sucrose and lactose and more complex sugars such as glycogen and starch.
* Gliadin is a protein found in wheat, barley and rye. In some individuals an enzyme called tissue transglutaminase modifies the gliadin to produce antigenic components which provoke and autoimmune reaction against tissue in the small bowel.
SIGNS & SYMPTOMS
Symptoms will vary depending on the type and severity of the adverse reaction and the quantity of offending food consumed. Allergic responses tend to occur soon (usually a few to 30 minutes) after food is consumed and are usually evident and may be dramatic. Symptoms of food intolerance may take several hours or days to become evident, are less dramatic and may be subtle.
Food allergies
Presentation will vary depending on the type of allergy.
Oral food allergy Patients with this syndrome develop itching or tingling of the lips, tongue, palate, and throat following the ingestion of certain foods. In addition, swelling of the lips, tongue, and uvula and a sensation of tightness in the throat may be observed. This reaction is usually seen in patients with hay fever who consume raw fruit or vegetables
Exercise induced food allergy occurs after ingestion of a specific food before exercising. As exercise increases and body temperature rises, patients may experience itching, light headedness and a skin rash or hives. In more severe cases breathing may be impaired and a decrease in blood pressure may result in loss of consciousness. Crustacean shellfish, alcohol, tomatoes, cheese, and celery are common causes of exercise-induced food allergy reactions.
Eosinophilic esophagitis (EoE) is characterized by an allergic reaction in the oesophagus (the tube that connects the throat to the stomach) causing inflammation and accumulation of specialised immune cells called eosinophils. Symptoms of EoE include nausea, vomiting, and abdominal pain after eating. It may also cause reflux or difficulty swallowing.
Food allergy Symptoms tend to be more systemic, affecting particularly the GI tract and skin. Symptoms include itching or swelling of the mouth, abdominal cramps or pain, vomiting, diarrhoea and itchy skin rash. Patients may also experience some breathing difficulties and a drop in blood pressure.
A more severe reaction may result in anaphylaxis with a variety of symptoms including the following;
* Itching and swelling of the skin particularly the face and around the eyes. Skin rashes or hives.
* Itching and swelling of the lips, tongue and throat.
* Itching and swelling of nasal passages and runny nose.
* Difficulty breathing, wheezing, cough, chest pain and tightness.
* Vomiting, diarrhoea and abdominal pain or cramps.
* Drop in blood pressure, weak pulse, dizziness or loss of consciousness.
Anaphylaxis if severe and not treated promptly can result in inadequate blood pressure, reduced oxygen supply to vital organs and death.
Some food allergens have been shown to exacerbate asthma or ectopic dermatitis.
Food intolerance
Symptoms of food intolerance will also vary with the type and severity of reaction and the amount of reactive food ingested. Food intolerance can produce a variety of symptoms including the following;
* Abdominal cramps, pain or discomfort and diarrhoea.
* A feeling of heaviness or bloating with excess gas production.
* Loss of appetite, weight loss, fatigue, lack of energy.
* Headaches, runny nose, flushing, rapid heart beat.
* Numbness tingling or itching of the skin, or mucous membranes.
* Skin rashes or hives.
CONDITIONS WITH SIMILAR SYMPTOMS
Anorexia nervosa
Auriculotemporal syndrome
Bulimia
Crohns disease
Diverticulitis
Oesophageal disorders
Food poisoning
Gastritis
Gastroenteritis
Gastroesophageal reflux disease
Giardiasis
Hiatal hernia
Inflammatory bowel disease
Intestinal motility disorders
Irritable bowel syndrome
Urticaria
Ulcerative colitis
Wasp stings
Whipple disease
INVESTIGATIONS
-Blood for CAP RAST or CAP FEIA using specific food allergens. Blood for total IgE and eosinophils.
-Skin prick test using suspected allergens. Patch test using suspected allergens.
-Blood tests: FBC (Full blood count), anti-endomysial antibodies; anti-tissue transglutaminase antibodies; and anti-gliadin antibodies, Iron, Folate, Ca++, Vit B12, Vit D. and full biochemical profile.
-PH measurement of faeces, if the pH is less than 6 (acidic) the diagnosis is in favour of carbohydrate intolerance.
-Lactose tolerance test.
-Hydrogen breath test.
Faecal fats.
-Radiography of small bowel after barium meal.
-Endoscopy.
TREATMENT
The only recognised and proven treatment for food allergy or intolerance is identification of the offending food and subsequent avoidance.
PATIENT MGT.
If you have a serious allergy or intolerance of specific foods you should wear a bracelet or other device which identifies this allergy, in case of a medical emergency.
