1. Food Allergies and Intolerances
Unit 17

2. Food Allergy
Food allergies are a major health concern in the US and other Westernized countries
Food allergy (food hypersensitivity)
Adverse reaction to a normally harmless substance in food that involves the body’s immune response

3. Adverse Reactions to Foods
Food intolerance
Adverse reaction to a normally harmless substance in food that does not involve the immune system
Immune system
Body tissues that provide protection against bacteria, viruses, and other harmful substances

4. Adverse Reactions to Foods
Foods that often cause adverse reactions:

5. Allergy and the Immune System
In people with allergies, body cells identify some components of food as harmful and trigger the body’s immune system
Food allergen
Substance in food (usually protein) that the body identifies as harmful and that elicits an allergic reaction from the immune system

6. Allergy and the Immune System
In response to an allergen, the immune system forms antibodies
Antibodies
Proteins the body makes to fight harmful invaders such as viruses, bacteria, or (in the case of food allergies) allergens

7. Allergy and the Immune System
Antibodies are formed on first exposure to an allergen – when the allergen reappears, an allergic reaction occurs
Histamine
Substance released in allergic reactions
Causes blood vessel dilation, itching, hives, drop in blood pressure, release of stomach acids
Counteracted by antihistamines

8. Development of Allergic Reaction

9. Food Allergy Symptoms

10. Anaphylactic Shock
In highly sensitive people, exposure to trace amounts of an allergen can cause anaphylactic shock – a massive immune reaction that can result in death

11. Key Terms Anaphylactic shock
Reduced oxygen supply to the heart and other tissues due to the body’s reaction to an allergen in food or other “foreign” substance
Symptoms may include abdominal cramps, vomiting, chest tightness, paleness, weak and rapid pulse, difficulty breathing
Can result in death
Treated with epinephrine injection

12. Foods Most Likely to Cause Allergy
Food ingredient labels are required to state whether a food contains one or more of the “big eight” food allergens
Nuts
Eggs
Wheat
Milk
Peanuts
Soy
Shellfish
Fish

13. Foods Most Likely to Cause Allergy

14. Wheat Allergy (Celiac Disease)
Celiac disease (celiac sprue or gluten sensitive enteropathy)
An autoimmune disease characterized by inflammation of the small-intestine lining resulting from a genetic gluten intolerance
Causes diarrhea, fatty stools, weight loss, vitamin and mineral deficiencies
Treated with gluten-free diet

15. Gluten in Foods

16. How Common Are Food Allergies?
5% of infants and children develop a food allergy, often to cow’s milk or egg white
For children at risk:
No cow’s milk before age 1
No eggs before age 2
No peanuts, nuts, fish, shellfish before age 3

17. How Common Are Food Allergies?
2-3% of adults have food allergies, and the number is increasing
About 1/3 of Americans believe they have food allergies – but usually, allergy is not confirmed by testing

18. Diagnosing Food Allergy
Double-blind, placebo-controlled food challenge
Test used to determine the presence of a food allergy or other adverse reaction to a food
Neither patient nor care provider knows whether the suspected food or a placebo is being tested
Undertaken under medical supervision

19. Other Tests for Food Allergy
Immunoglobin-E test
IgE protein produced in response to an allergen
Doesn’t identify allergen
Skin prick tests
For absence of food allergy only – positive results don’t prove an allergy exists
Positive skin-prick test

20. Bogus Tests
Companies that offer food allergy tests through the mail do not use reliable techniques and are a waste of money
Other unreliable tests:
Hair analysis, cytotoxic blood tests, iridology, sublingual food injection provocation

21. Treating Food Allergies
Allergy shots for food allergens are not yet available
After an allergy is confirmed, the only treatment is to eliminate the food from the diet

22. Food Intolerances Food intolerance does not involve the immune system
Produces reactions similar to food allergy, but by different mechanisms

23. Lactose Maldigestion Lactose maldigestion
Characterized by reduced digestion of lactose due to low availability of the enzyme lactase
Occurs in 25% of US adults; incidence varies by population group
Results in lactose intolerance

24. Lactose Intolerance Lactose intolerance
GI symptoms resulting from consumption of more lactose than can be digested with available lactase
Flatulence, bloating, abdominal pain, diarrhea, “rumbling in the bowel” due to breakdown of undigested lactose by intestinal bacteria
Restricts intake of lactose-containing products

25. Sulfite Sensitivity
Sulfite is a food additive (preservative) used in many foods and medications
Small amounts can cause anaphylactic shock in sensitive people

26. Red Wine, Aged Cheese, and Migraines
Histamine in some foods may cause migraine headaches in sensitive people
Red wine, beer, sardines, anchovies, cured sausages, pickled cabbage, spinach, catsup
Tyramine may cause similar symptoms
Aged cheese, soy sauce, and other fermented products

27. “Chinese Restaurant Syndrome”
MSG (monosodium glutamate) is used as a flavor enhancer in soups, stews, and many Chinese food items
“Chinese restaurant syndrome”
Sensitivity causes dizziness, sweating, flushing, rapid heartbeat, and ringing in the ears

28. Precautions
People with food allergies or intolerances must be very careful about what they eat
They should have a plan of action ready in case a serious reaction develops

29. Take Action to Prevent Anaphylaxis
For those at risk of anaphylactic shock:
Learn how to avoid foods that trigger reactions
Ask your doctor what to do if symptoms appear
Fill and carry prescriptions for any needed medications (EpiPens, antihistamines, inhalers) – and learn how to use them
Wear an ID bracelet with allergy information