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Transcript
I.
Food Allergy Mania
 Instructor Resources: Unit 17 Nutrition Scoreboard transparency master
A.
B.
C.
D.
People use term “food allergy” for any food problem
Laity blame allergies for hyperactivity in children
Some health professionals deny food allergies exist
Food allergies now a health concern in U.S.
II. Food Allergies
A. Real ones are usually serious
1. Can cause a rash or upset stomach
2. Can result in death
3. Imagined food allergies lead to inadequate diets and other health problems
4. Many foods are falsely blamed for mental and physical health problems
B. Adverse Reactions to Foods
1. Food poisoning
2. Food allergies - immune response
3. Food intolerances - all other adverse reactions
4. In food allergies, immune system reacts to a substance in food (usually a protein)
a. Immune system not involved in food intolerances (all other adverse reactions)
C. Allergic Response
 Instructor Resources: transparency #47: Development of Allergic Reactions to Foods
1.
2.
3.
4.
Cells recognize food components; ones that trigger the immune system are food allergens
Exposure to an allergen triggers an allergic reaction
a. Immune system forms antibodies
b. Antibodies attach to cells
If allergen reappears, antibodies attach to it, and signal body to secrete histamine and
substances that cause physical signs of allergic reactions
Allergic reactions cause rash, diarrhea, congestion, or wheezing, or may be more serious
a. An allergen in peanuts, fish, and shellfish can cause anaphylactic shock
b. Can result in death, caused by cutoff of blood supply to tissues
c. Incidence of peanut allergy is increasing - 1 in 150 people affected
 Instructor Resources: Activity 17-2: Peanut Allergies
5. Symptoms occur in seconds after exposure, or up to two hours
6. Symptoms often disappear within two hours
D. Most Likely Foods
 Instructor Resources: transparency #48: Top 8 Foods that Cause Allergies
1. Most food allergies caused by 8 foods: nuts, eggs, wheat, milk, peanuts, soy, seafood, and fish
2. These are “the big eight” food allergies
E. Celiac Disease
1. Allergy to wheat gluten found in wheat and other grains
2. Affects 1 in 120–300 people
3. Differs from traditional allergies since localized in the lining of the small intestine
4. Difficult to diagnose because symptoms similar to other diseases
5. Treated by life-long gluten-free diet
F. Genetically Modified Foods
1. Genetically modified foods are tested for safety before they are sold
2. People allergic to Brazil nuts were allergic to GM soybeans with Brazil nut proteins
3. Due to testing procedures and FDA regulations possibility that GM foods have hidden
allergens is limited
4. True risks of allergic reactions from GM foods is unknown
G. Are Food Allergies Common?
1. Infants and young children have food allergies more often adults
a. 8% of infants and young children develop food allergy, often due to a protein in cow’s
milk
b. Cow’s milk and allergenic foods like peanuts, nuts, fish, seafood, eggs, and wheat not fed
to infants during the first year
c. Most infants outgrow allergy to cow’s milk or foods like milk, egg white, wheat, and soy
d. Rarely outgrow allergies to peanuts, nuts, fish, and shellfish
2. Incidence of food allergies in adults 1–2% and increasing
a. But over 30% believe they have food allergies
b. 60% of complaints are not confirmed
3. Popular wisdom misguided:
a. Allergies to sugar or food colors lead to hyperactivity
b. Yeast causes chronic fatigue syndrome
c. Dairy products, especially milk, cause phlegm
d. None documented by scientific studies
H. Diagnosis
1. Some people are sensitive to MSG but it doesn’t elicit an immunological reaction so it’s not a
food allergy
2. Illness due to the flu, food poisoning, lactose, sulfites, and foods that may cause gas and
bloating like dried beans and cabbage are often mistakenly attributed to food allergies
3. A variety of tests are used to diagnose food allergies, but there is only one “gold standard” that test is the double-blind, placebo-controlled food challenge
4. Other tests for food allergy are reliable to varying degrees
a. None is always accurate
b. Results of bogus tests not trusted at all
5. Skin Prick Tests
a. Skin prick tests common and useful for identifying the absence of a food allergy
b. Positive test results inaccurate 50% of the time
c. Few drops of food extract placed on the skin and skin is then pricked with a needle
d. At same time, another area of skin is pricked using water
e. Area around food skin prick more swollen than control means person might be allergic
f. Skin prick tests are useful to rule out allergies
6. RAST Test
a. RadioAllergoSorbent Test
b. Blood examined for immune substances
c. Not specific for individual allergens
I.
d. Does not reliably indicate a food allergy
7. Bogus Tests
a. A number of companies offer food allergy tests through the mail
b. Mail-order allergy tests do not use reliable assessment techniques
c. Other unreliable methods: hair analysis, cytotoxic blood tests, iridology, and sublingual
(under the tongue) and food injection provocation tests
Best Treatment
1. Identify food allergy
2. Eliminate food from the diet
a. Only treatment available for food allergies
b. If the food is important source of nutrients consultation with a registered dietitian is
recommended
c. People with allergies to peanuts, nuts, fish, or seafood eliminate the food for life
III. Food Intolerances
A. Food intolerance reactions do not involve the immune system; due to a missing enzyme or other
cause
1. Some are intolerant of lactose, sulfite, histamine
2. Separate real from unreal by double-blind, placebo-controlled food challenge
a. True food intolerances produce predictable reactions
b. Headache, diarrhea, swelling, or stomach pain occur every time a person consumes a
suspected food
B. Lactose Maldigestion and Intolerance
1. Lactose maldigestion is inability to break down lactose due to the lack of the enzyme lactase
2. Results in “lactose intolerance”
3. Symptoms are flatulence, bloating, abdominal pain, diarrhea, and “bowel rumbling”
4. Within several hours of eating more lactose than can be broken down by available lactase
5. Symptoms due to breakdown of lactose by bacteria in lower intestines and fluid
accumulation
6. Reduced intake of lactose-containing dairy products reduces lactose intolerance
a. Hard cheese, no-lactose milk, buttermilk, and yogurt contain low amounts of lactose
b. Small amounts of lactose-containing dairy products are tolerated
c. Ensure adequate calcium and vitamin D if milk and dairy product intake is restricted
7. Lactose maldigestion is very common
 Instructor Resources: transparency #25: Lactose Maldigestion
a.
Occurs in 25% of adults, incidence varies by population group
1. 62 to 100% of Native American adults
2. 90% of Asian Americans
3. 80% of African Americans
4. 53% of Mexican Americans
5. 15% of Caucasian Americans
C. Sulfite Sensitivity
1. Sulfite is a food additive used to keep vegetables and fruits looking fresh and to prevent
mold growth
2. Added to beers, wines, processed foods, and medications as a preservative
3. Small amounts cause anaphylactic shock and bring on asthma in sensitive people
D. Histamines and Migraines
1. Some get migraine headaches from red wine
2. Histamine in wine causes the headaches
3. People can’t break it down, it accumulates and causes headaches
4. Histamine is found in beer, sardines, anchovies, hard cured sausage, pickled cabbage,
spinach, and catsup
5. Tyramine in aged cheese, soy sauce, fermented products causes migraines in sensitive people
E. MSG
 Instructor Resources: Activity 17-1: MSG Disclosure
1.
2.
Monosodium glutamate (MSG) related to dizziness, sweating, flushing, headache, following
ingestion of foods, soups, food products that contain this flavor enhancer
Reaction called “Chinese Restaurant Syndrome” because Chinese foods often contain MSG
IV. Precautions
A.
B.
C.
D.
People with food problems must be careful
Should have plan ready if they develop reaction
Eating out, ask what is being served
Ingredients such as cow’s milk protein, egg white, sulfites, peanuts, and peanut oil are listed on
labels
E. Products that contain sulfites must be labeled
F. Genetically engineered foods must list known potential allergens such as soy or nut protein on
the label
G. People should carry preloaded syringe of epinephrine (“epipen”) and know how to use it
H. Know where to call for emergency help
I. Keep asthma inhalers and antihistamines readily available
J. Food allergies and intolerances are never caused by studying about them