Food Allergy

Food Allergy

Defining Food Allergy

o  A food allergy is any adverse reaction to an otherwise harmless food or food component that involves the body’s immune system.

o  it is important to use the term “food allergy” or “food hypersensitivity” only when the immune system is involved in causing the reaction.

o  This reaction involves three primary components: food allergens , immunoglobulin E (IgE), and mast cells and basophils.

o  A food allergen is the part of a food that stimulates the immune system of food-allergic individuals.

o  A single food can contain multiple food allergens, the majority of which are likely to be proteins, not carbohydrates or fats.

Mechanism of hypersensitivity reaction

o  When allergic individuals eat certain foods, their immune systems are stimulated by the food allergens to make IgE specific to that food. Millions of IgE antibodies then circulate in the blood; they bind to blood cells called basophils and enter body tissues where they bind to mast cells.

o  When IgE antibodies on the surfaces of basophils and mast cells come in contact with food allergens, these cells stimulate the release of mediators such as histamine, prostaglandins and leukotrienes, which are powerful compounds that cause allergic reactions.

        

Epidemiology

• More prevalent in females than males (2:1)

• Tends to occur in children who have other allergic diseases

• Cross reactivity between certain foods and other substances such as latex

• Family history of food allergy is a major predisposing factor

• Specific food reactions vary across countries

Types of food allergy/intolerance

• Food specific IgE mediated reactions (Immune mediated)

                – Anaphylactic reaction

                – Urticaria/Rhinitis

• Non-IgE mediated reactions (Immune mediated)

                – Celiac disease (IgA mediated food induced enteropathy)

• Toxic food poisoning

                – Staphylococcal toxin

                – Salmonella toxin

• Pharmacological effects

                – Caffeine

                – Alcohol such as red wine

• Metabolic disorders

                – Lactase deficiency

NOTE: Some reference said that only immune mediated allergy considered as food allergy.

Types

Food Allergy Symptoms

o  Swelling of lips, tongue, throat, face

n  – Anaphylactic shock

o  • Rhinitis

o  • Hay fever

o  • Respiratory symptoms

n  Asthma

n  Wheezing

o  Skin problems

n  Hives

n  Urticaria

n  Eczema

o  Gastrointestinal

n  Vomiting

n  diarrhoea

o  Behavioural problems

n  Hyperactivity

Continue

o  Some specific symptoms patients might describe during an allergic reaction include:

n  Hot or burning tongue

n  Tingling in the mouth or tongue

n  Itchiness in the tongue

n  Sensation that something is stuck in the throat (or throat feels thick)

n  Tongue feels heavy

n  Tongue feels as if there is hair on it

n  Tongue feels as if there is a bump on the back of it

n  Lips feel tight

n  Ears feel itchy inside

n  Food is too spicy

The Big 8 Food Allergens

o  The eight most common food allergens cause more than 90 percent of all food allergic reactions.

o  The top eight food allergens are:

n  milk

n  shellfish (crustacea and mollusks)

n  eggs

n  wheat

n  fish

n  peanuts

n  soy

n  tree nuts (e.g. walnuts)

Food Allergy Management

o  Avoidance of the food

n  Complete avoidance of food itself

n  Avoidance of food contained in other products

n  Avoidance of people/utensils that have come into contact with the food

n   In young infants food needs to be reintroduced at regular intervals and many allergies are grown out of (with the exception of nut allergies and fish)

o  Medication – treatment for accidental ingestion

n  Adrenalin for anaphylactic reaction

n   Anti-histamine

n  Immunotherapy

o  Each elimination diet must take into account the individual’s ability to tolerate the offending food and the need to avoid nutritional deficiencies.

Is Your Baby Allergic to Your Breast milk?

o  Breast-feeding cuts food allergy risk But:

n  If a mother is allergic to any food the chances are her child may also be allergic to those foods.

n  Many mothers don't realise that they are allergic as they display little or no symptoms.

However, the allergic reaction can be much more pronounced in their suckling child.

What mother eats; baby eats. 

o  Women should avoid peanuts and tree nuts during pregnancy and while breast-feeding.

o  Mothers should supplement breast-feeding with a hypoallergenic formula (extensively or partially hydrolyzed).

o  Delay feeding these children solid foods until they're six months old.

o  Delay introduction of milk and egg until age 1 and peanut and tree nuts until age 3.

 

Prevention for children

o  Infants should be exclusively breastfed until they are at least 1 year old.

o  Infants should not be exposed to any solid foods until they reach 6 months of age.

o  Children should not have any contact with cow’s milk or other dairy products until they are several months old. Some physicians recommend waiting until a child is nine to 10 months old, while others suggest waiting a full year.

o  Eggs should be avoided for the first two years.

o  Peanuts, tree nuts and fish should not be introduced until a child is at least 3 years old.  

o  Parents need to be aware of any alternate names a problem food might be called, to better limit their child’s exposure to it.

o      Notifying the school of the child’s condition

o  Working with the school to find a plan that meets the child’s needs in the classroom, in the cafeteria and in any after-school or school-sponsored activities

o  Providing all contact information, medical documentation, written instructions and medications the school might need.

o  Not switching food with other students

o  Not eating those foods which they know to be risky or of an uncertain origin

o  Immediately notifying an adult if they believe they have eaten a food to which they are allergic, or believe they are having an allergic reaction

Facts about Food Allergy

o  FAC T: 

Although anyone can develop a food allergy, the ability to become allergic is inherited.

n  Children with one allergic parent have about twice the risk of developing food allergy than children without allergic parents. If both parents are allergic, a child is about four times more likely to develop food allergy than if neither parent is allergic.

n  Many children with food allergies also show sensitivities to inhaled allergens such as dust, cat dander and pollen.

n  In addition, people who develop food allergies often have histories of respiratory allergies such as allergic nasal symptoms or asthma.

 o      FACT

n  Most food allergy reactions are not life threatening. In fact, most cases of allergic reactions to food are relatively mild. But a small percentage of food - allergic individuals have severe reactions that can be life threatening.

n  In one study of severe allergic reactions to foods, most of the fatalities occurred away from home. All of the individuals involved accidentally ate a food to which they knew they were allergic. Other factors found in the study that contributed to the fatal reactions included a history of asthma, denial of symptoms, delay in obtaining medical treatment and the failure to administer epinephrine quickly after the reaction began.

                                                                 The End….