FOOD ALLERGYFOOD ALLERGY

Lecture Material - Food SafetyInneke Hantoro

What is food allergy?What is food allergy?

• Food allergy is an abnormal response to a food triggered by the body’s immune system.

• The symptoms of an allergic reaction are caused by biologically active chemicals produced by the immune system in its attempt to protect the body from a foreign invader.

• Allergic reactions to food can cause serious illness or even death.

• Food allergy is different with food intolerance although both can show similar symptoms.

Types of food allergyTypes of food allergy

• IgE-mediated food allergy (immediate hypersensitivity)

– e.g. peanut allergy, cows’ milk allergy

• Cell-mediated food allergy (delayed hypersensitivity)

– involving sensitized immune cells in the small intestine, usually lymphocytes, that are sensitized to the specific substance that triggers the reaction inflammation on certain sites, symptoms appearing 24 hours or more after ingestion

– e.g. celiac disease

How do allergic reactions work?How do allergic reactions work?

An immediate allergic reaction involves two actions of our immune system:

1. Our immune system produces immunoglobullin E (IgE) – a type of protein that works against a specific food – antibody.

2. IgE attaches basophils (white blood cells) and to mast cells – cells found in all body tissues. The typical sites of allergic reactions include nose, throat, lungs, skin and GI tract.

How do allergic reactions work?How do allergic reactions work?

• Food allergens are proteins within the food that enter our bloodstream after the food is digested.

• Food allergen go to target organs such as skin, nose, etc and cause allergic reactions.

• An allergic reaction to food can take place within few minutes to an hour.

How do allergic reactions work?How do allergic reactions work?

• The symptoms of cell-mediated allergic reactions do not begin to appear until 6–24 hrs after ingestion of the offending food. These reactions develop slowly, reaching a peak at approx. 48 hrs and subsiding after 72–96 hrs.

• The mechanisms of cell-mediated food allergies are not nearly as well understood.

• They involve an interaction between specific food allergens and sensitized T lymphocytes - a major component of the gut-associated lymphoid tissue. Lymphocyte stimulation initiates the release of cytokines and lymphokines which produces a localized inflammatory response.

• Antibodies are not involved in these reactions.

Celiac diseaseCeliac disease

• Celiac disease, or gluten-sensitive enteropathy, is a malabsorption syndrome occurring in sensitive individuals upon the consumption of wheat, rye, barley, triticale, spelt, and kamut.

• The consumption of wheat or other offending grains or products made from these grains elicits inflammatory damage to the absorptive epithelial cells in the small intestine.

Celiac diseaseCeliac disease

• The loss of absorptive function along with the ongoing inflammatory process results in a severe malabsorption syndrome characterized by diarrhea, bloating, weight loss, anemia, bone pain, chronic fatigue, weakness, muscle cramps, and, in children, failure to gain weight and growth retardation.

• The inflammatory mechanism involved in celiac disease is mediated by intestinal T lymphocytes.

The allergic symptomsThe allergic symptoms

• Itching in mouth as we start to eat the food.• GI symptoms such as vomiting, diarrhea or

abdominal pain after the food is digested in stomach.• When the food allergens enter and travel through the

bloodstream, they may cause the blood pressure to drop.

• As the allergens reach the skin, they can cause hives or eczema.

• When the allergen reach the lungs, they may cause asthma.

Cross - ReactivityCross - Reactivity

• If we have a life-threatening reaction to a certain food, our body will show how to avoid similar foods that might trigger this reaction.

• For example: if someone has a history of allergy to shrimp, he/she will also show allergic reactions to crab, lobster and crayfish.

Cross contact allergenCross contact allergen

• Cross contact allergens occur when a residue or other trace amount of an allergenic substance is unintentionally added into a food not intended to contain that allergenic substance and where such occurrences are sporadic.

Common Food AllergiesCommon Food Allergies

• In adults:

Shellfish, peanuts, tree nuts (walnuts), fish, eggs, wheat, soy.

• In children:

Eggs, milk, peanuts, soy.

Tree nuts and peanuts can cause deadly food allergy reactions called anaphylaxis!

• Anaphylactic reaction is a severe reaction of rapid onset that involves most organ systems (multiple organ failure) and that results in circulatory collapse and a drop in blood pressure.

• The 1st symptoms usually are burning, itching, irritation of the lips, the inside of the mouth and the throat.

• Followed by nausea, vomiting, abdominal pain, and diarrhea.

Food AllergenFood Allergen

• The allergenic moiety of the food is usually a protein.• Allergenic proteins are usually not denatured under food

processing conditions and relatively resistant to digestion.

• Other foods can produce allergen as well, but not as often, e.g. strawberries.

• The foods to which adults or children usually react are those foods they eat often, e.g.: Soy and rice allergy in Japan Codfish allergy in Scandinavia Peanuts allergy in US

Types of Food AllergensTypes of Food Allergens

• Milk proteins: caseins, whey proteins (beta-lactoglobulin), serum proteins (albumin).

• Egg proteins: ovalbumin, conalbumin (ovotransferrin) and ovomucoid (heat stable).

• Grain proteins: gliadins, glutenins, albumins and globulins.

• Peanuts the most frequently cited causes of life threatening anaphylactic reactions!

• Soy bean• Seafood• etc

Food Allergy TestsFood Allergy Tests

• Skin testsIdentifying the type of IgE that is fixed to the skin mast cell. For example: scratch test.

• Blood tests analyze blood or blood serumRAST (radioallergosorbent test) or ELIZA ( enzyme-linked immunosorbent assay).These tests measure the presence of food-specific IgE in blood and the total IgE level in blood.

Food IntoleranceFood Intolerance

• Food intolerance is more common than food allergy, but it doesn’t relate to the immune system.

• Food intolerance is caused by the lack of our body’s ability to digest certain substances.

• Some people may have a food intolerance that has a psychological trigger.

Types of Food IntoleranceTypes of Food Intolerance

• Food poisoning: foods contaminated with microbes, such as bacteria and bacterial products (e.g. toxins).

• Histamine toxicity

A reaction like an allergic reaction when people consume histamine containing foods, such as in cheese, some wines, tuna and mackerel.

Types of Food IntoleranceTypes of Food Intolerance

• Lactose intolerance It caused by lactase deficiency. Lactase is an enzyme that is in the lining of the gut. Lactase breaks down lactose, a sugar found in milk

and most milk products. Lactose is used by bacteria to form gas which causes

bloating, abdominal pain and diarrhea. At least one out of ten people suffer lactose

intolerance.

Types of Food IntoleranceTypes of Food Intolerance

• Food additives, such as: MSG, when it is taken in large amounts can

cause some of the following signs: flushing, sensation of warmth, headache, chest discomfort and feeling of detachment.

Sulfites, in high concentrations can pose problem for people with severe asthma.

How to treat food allergy?How to treat food allergy?

• Avoiding to eat foods which can trigger allergic reaction.• Exercised- induced food allergy

The allergic symptoms may appear as exercise increases and body temperature rises. Therefore, it is required to avoid eating for a couple of hours before exercising.

• Taking medicine such as antihistamines to relieve GI symptoms, hives, sneezing and runny nose or taking bronchodilators to relieve asthma symptoms.

Consumer Protections & LabelingConsumer Protections & Labeling

• Food manufacturers are generally responsible about posting alerts concerning allergen contamination and recalling their products.

• Labeling of foods containing allergens have to be clear and consistent.

• The application of GMP in food manufacturing to avoid cross-contamination of food products by foreign allergens.

• The awareness of the consumers in checking the labels.

LabelingLabeling• The general labeling recommendations are:

– all allergen information should be grouped together to be easily identified and not hidden amongst other labeling information

– product description and representation should provide an accurate expectation of the product and should not be misleading

LabelingLabeling

– The print size should be big enough to be easily read, preferably at a minimum 1.5mm with sans serif font, and the font colour should contrast distinctly from the background. The use of lower or upper case will depend on the overall presentation of labeling information.

(FSZAN)

LabelingLabeling

• A consistent approach in the presentation of allergen information will help allergic consumers more quickly and easily identify foods of concern, helping to minimize accidental consumption of unsuitable foods.

• The recommended format consists of:– an ingredient list declaring in bold allergenic

substances and their derivatives; and– an allergen summary statement; and– a precautionary statement.

LabelingLabeling

References

• Food Allergy: An Overview. 2004. U.S. Department of Health and Human Services. Retrieved from www.niaid.nih.gov.

• Joneja, J. V.1998. Dietary Management of Food Allergens and Intolerances: A Comprehensive Guide 2nd Edition.J. A. Hall Publications LTD. Vancouver.