Peanut Allergy Update by O7IG33

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									Peanut Allergy
   Update


Janice M. Joneja Ph.D., RD
           2006
                Peanuts and Anaphylaxis
    Peanuts are one of the most frequently cited causes of
     life-threatening anaphylactic reactions in Western
     countries
    Peanuts, tree nuts, fish, and shellfish are the foods
     most frequently identified as causes of anaphylaxis,
     and of these, peanuts seem to prompt the greatest
     concern
    The incidence of peanut allergy was reported to have
     doubled in American children less than 5 years of age
     in the five years between 1998 and 2003
_____________
Sampson 2003                                              2
            Incidence of Peanut Allergy
   One study reported that allergy to peanuts:
     Accounts for 28% of food allergies in children
      (72% of food allergies were to foods other than
      peanut)
     In peanut-allergic individuals, reactivity to peanut
      develops:
         Before one year of age in 46%
         Before 15 years of age in 93%

   The true incidence of peanut allergy in any
    population is largely a matter of speculation,
    based on questionnaires and occasional
    epidemiological studies
                                     _____________________
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                                     Moneret-Vautrin et al 1998
          Fatalities Due to Food Allergy
   2001 report of 32 fatal cases of anaphylactic reactions
    to foods in USA
       Peanut was responsible for 14 (67%) and possible cause in
        a further 6 (55%)
       Tree nuts the cause in 7 (33%) and possible cause in a
        further 3 (27%)
       Two cases thought to be due to milk and fish (1 [19%]
        each)
       Most of the victims were adolescents or young adults
       All but one were known to have food allergy before the
        fatal event
       All but one were known to have asthma
       Peanuts and tree nuts accounted for more than 90% of the
        fatalities
                                          _____________
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                                          Bock et al 2001
          Peanut Allergy in Populations
   Allergy to peanut is far less prevalent in China, despite the
    high rate of peanut consumption
   Allergy to all foods reported to affect only 3.4% – 5.0% of the
    residents of a select population in China
   Fish, shrimp, crab, and seaweed were the major allergens
   In 29 children aged 2 to 12 years with diagnosed food allergy
    in the Chinese population studied, none had signs of clinical
    allergy to peanut
   Peanut allergy in China is virtually non-existent, whereas in
    the USA about 3 million people report being allergic to
    peanuts
   The Chinese-American population living in the USA had an
    incidence of peanut allergy similar to that of the general US
    population
                                              _____________
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                                              Beyer et al 2001
         Peanut Allergy in the UK
   8 children under 16 years of age died from
    food allergy in ten years 1990 -2000 (= 1 death
    per 16 million children each year)
   Milk caused 4 deaths
   No child younger than 13 years died from
    eating peanuts
   One child died from an overdose of adrenaline
    used to treat a mild food reaction
_____________
                                                  6
Pumphrey 2000
   Incidence of Peanut Allergy in Canadian
                   Children
The prevalence of peanut allergy in children
  kindergarten through Grade 3 in randomly selected
  schools in Montreal:
 Between 1.5% and 1.76% of 4339 responding
  families
 Study based on:
      Questionnaire
      Skin-prick tests
      Measurement of peanut-specific IgE in blood
      Oral peanut challenge

   ______________
   Kagan et al 2003                                   7
 Processing of Peanuts and Allergenicity
   Roasting of peanuts has been demonstrated to
    increase their allergenicity, compared to the same
    variety of peanut when processed by other methods
   Roasting gives improved flavour and taste, and is the
    method used for processing peanuts and peanut butter
    in North America
   Roasted peanut is more likely to trigger a severe
    anaphylactic reaction than the fried or boiled peanut,
    which is the form in which people in countries such
    as China consume the food
______________
Maleki et al 2000                                        8
     Effect of Temperature on Allergenicity
    Much higher temperature reached in roasting in comparison to
     frying or boiling
    Peanut proteins are not degraded at high temperatures, and
     retain their potential to trigger an allergic reaction even after
     cooking (Class 1 allergens)
    Excessively high temperature changes the protein to a more
     insoluble form
    Increase in insolubility means that less of the protein will
     move into solution in the digestive tract, and will be more
     protected from digestive enzymes and destruction by gastric
     acid than a more soluble form would be
    Results in undegraded peanut protein being available as a
     continuous source of major allergens in the digestive tract long
     after the same protein in a more soluble form would have been
     removed from the system
______________
Kopper et al 2005                                                        9
Allergenicity due to Immune Interaction

   Method of heating the proteins significantly
    affects the interaction between the allergen and
    the antibodies produced by the allergic
    individual
   Increases the likelihood of the individual
    developing symptoms, and probably the
    severity of the symptoms in an allergic
    reaction
_________________
Mondoulet et al 2005                               10
        Factors in Allergenicity of Peanut

    Other factors that might affect the allergenicity
     of peanut proteins include:
       Type and variety of the peanut (of which
        there are about 14,000)
       Conditions under which the peanut has been
        grown
       Degree of maturation of the peanuts

______________
Chung et al 2003
                                                     11
               Peanut and Fat Content

   High fat content reduces reactivity to peanut
   Study of six people with a known peanut
    allergy; reactivity of four of the subjects
    significantly increased when the peanut was
    included in a lower-fat meal compared to when
    the food had a high fat content
   Subjects reacted to a dose equivalent to 23
    times less peanut with the low-fat recipe
    compared to the higher fat meal
_________________
Grimshaw et al 2003                             12
                         Legume Allergy
    There is no evidence to support the thinking that
     peanut-allergic individuals should avoid all legumes
    In laboratory experiments, cross-reactivity between
     peanut and soy is quite frequent, but in clinical trials,
     the cross-reactivity is quite uncommon
         One study reports only 2 out of 41 peanut-allergic patients
          reacted mildly to other members of the legume family
    Avoidance of legumes such as soy, chick peas, lentils,
     beans, peas, licorice, carob, and all other members of
     the Leguminoceae family, to which peanut belongs, is
     only necessary when allergy to the individual foods
     has been identified.
    _________________________
    Bernhisel-Broadbent et al 1989                                      13
                   Tree Nut Allergy
   Tree nuts are botanically unrelated to peanuts
   It is not necessary to avoid tree nuts such as hazelnuts
    (filberts), Brazil nuts, walnuts, almonds, macadamia
    nuts, pine nuts, pistachios, etc. unless the individual
    has an allergy to them
   Nuts in a nut mixture are very difficult to distinguish
    from each other
   Risk of tree nuts, especially nut mixtures, to contain,
    or to be contaminated by peanuts
   A person who has demonstrated allergy to peanuts is
    usually advised to avoid nuts of all types in the
    interests of safety

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                  Peanut and Soy Allergy
   Increase in the incidence of soy allergy, especially in
    children
   May be the result of exposure to the allergenic protein,
    in the form of soy-based infant formulas, in early
    infancy when the child is at highest risk for allergic
    sensitization
   Soy and peanuts contain a similar allergen, exposure to
    the soy allergen in infant formula could prime the
    child’s immune system to respond to the peanut
    allergen, even when he or she shows no signs of allergy
    to soy
   As a result, the child could exhibit allergic symptoms
    on an apparent first exposure to the peanut.
____________
                                                          15
Lack et al 2003
          Progression of Peanut Allergy
   Peanut allergy, like many early food allergies, can be
    outgrown
   In 2001 pediatric allergists in the U.S. reported that
    about 21.5 per cent of children will eventually
    outgrow their peanut allergy1
   Those with a mild peanut allergy, as determined by
    the level of peanut-specific IgE in their blood, have a
    50% chance of outgrowing the allergy2
   Only about 9% of patients are reported to outgrow
    their allergy to tree nuts3
__________________
1Skolnick et al 2001
2Fleischer et al 2003
3Fleischer et al 2005                                     16
      Maintaining Tolerance of Peanut

   When there is no longer any evidence of
    symptoms developing after a child has
    consumed peanuts, it is preferable for that
    child to eat peanuts regularly, rather than
    avoid them, in order to maintain tolerance to
    the peanut
   Children who outgrow peanut allergy are at
    risk for recurrence, but the risk has been
    shown to be significantly higher for those who
    continue to avoid peanuts after resolution of
    their symptoms              _________________
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                              Fleischer et al 2004
       The Peanut Safe Environment

Important measures for a peanut-safe environment
  should include:
 Ensuring that all personnel in a peanut-safe facility
  are well-informed about the dangers to the peanut-
  allergic person of accidental contamination
 Clear strategies for maintaining the facility in a
  peanut-safe condition, with strict rules about cleaning
 Informing everyone entering the facility to avoid
  introducing peanuts into the area, and the reasons for
  the restrictions

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     The Peanut Safe Environment continued

   Education of the peanut-allergic person concerning
    avoidance of their own exposure to peanuts,
    including:
       Avoidance of foods likely to contain, or be contaminated
        by, peanuts
       Being aware of all terms on food labels that would indicate
        the possible presence of peanut
       Carrying an Epipen of injectable adrenalin, and being
        familiar with its use in case of accidental exposure and an
        allergic reaction
       Wearing a MedicAlert tag or bracelet in case of loss of
        consciousness in an allergic reaction
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     The Peanut Safe Environment continued

   Informing all staff in the facility about emergency
    procedures should anyone in the area develop
    symptoms and require medical treatment.
   Such information should include:
       Familiarity with the use of the Epipen where appropriate
       Contacting key care-givers such as parents and guardians
        of children, and the person’s doctor or other health
        provider
       Instructions for transporting the individual to the nearest
        hospital in the quickest way possible

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                       Peanut Oil
 Highly refined peanut oil contains barely detectable
  amounts of peanut protein, and should be safe for
  consumption by most peanut-allergic individuals
 There is no guarantee that any peanut oil is
  completely free from peanut protein
 Threshold doses of peanut as low as 100 mcg
  reported to elicit (mild) symptoms in test subjects:
  may be below level of detection
 A person anaphylactic to peanut is strongly advised to
  avoid all types of peanut oil entirely
 Cold-pressed oils (also labelled “pure-pressed”,
  “expeller pressed” or “unrefined”) in particular
  should be avoided.
_________________
Hourihane et al 1997
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Probiotics, Prebiotics,
     Synbiotics

  Bacteria as Therapeutic Agents
             Microorganisms in the Bowel
   The healthy large bowel sustains a resident microflora
    of bacteria, fungi, and other harmless microorganisms
   Beneficial effects include:
       Synthesis of vitamins:
            Vitamin K
            Biotin
            Thiamin
            Folic acid
            Vitamin B12
       Interaction with immune cells to maintain a healthy
        epithelium
       Positive competition with invading pathogens to resist
        disease

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                 Resident Microflora
   Gut microflora of a breastfed infant is quite different
    from that of a formula-fed baby
   An individual’s bowel microflora is established at
    weaning
   Remains stable throughout life unless events
    intervene
   Individuals in the same household, eating the same
    diet, may have a vastly different bowel microflora
   After oral antibiotics several microbial species will be
    killed, but after about 6 months the previous strains
    become re-established and microflora returns to its
    pre-antibiotic state

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         Bowel Microflora and Allergy
   The type of gut colonization during the first weeks of
    life may predispose an individual to atopic disease
   The gut microflora influences:
      Resistance to infection
      Immunological environment for subsequent
        challenges, including food allergens
      May influence predominance of Th1 or Th2
        response
   Probiotics may alter the gut microenvironment by
    changing the types of microorganisms present and
    the cytokines produced by the local immune cells
_________________
Kirjavainen et al 1999                                   25
                     Probiotic

   Living micro-organisms within a food that is
    designed to provide health benefits beyond the
    food’s inherent nutritional value
   The types of micro-organisms used have
    certain characteristics to be of any value:
     Have a beneficial effect within the bowel
     Must be capable of living within the human bowel
      without causing any harm to the host.

______________
Thompson 2001
                                                     26
                Probiotic Characteristics

   Probiotic micro-organisms alter the gut
    microflora by competitively interacting with
    the existing flora by:
     Production of antimicrobial metabolites
     Modulating the local immune response to the
      indigenous micro-organisms
   Saccharolytic species:
     Use carbohydrates as substrate
     Produce beneficial metabolites
_____________
Shanahan 2000
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           Possible Use for Probiotics

   Trials in disease situations such as :
     Diarrheal diseases
     Re-establishment of normal intestinal microflora
      after antibiotic therapy
     Inflammatory bowel diseases

     Fungal disease (e.g. candidiasis)

     Cancers

     Cholesterol lowering

     Prevention of allergic diseases e.g. eczema

     Management of lactose intolerance
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                Why Probiotics?
   The desire by consumers to use natural
    methods for health maintenance rather than
    long-term chemotherapeutic agents (i.e.
    antibiotics)
   Expectation that food will become a source of
    prolonged well-being
   Speculation that the probiotic market will
    expand rapidly
   Depends on the reliability of claims for the
    effectiveness of these products in disease
    prevention and control
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    Micro-organisms Used as Probiotics

   Examples of bacteria:
       Lactobacilli
       Bifidobacteria
       Strains of enterococci
   Requirements for survival of probiotic strains:
       Must be able to survive passage through the hostile
        environment of the stomach and upper small intestine
       Resist the effects of intestinal secretions
       Attach to intestinal cells on reaching the large bowel,
       Thrive within its physiological and nutritional milieu.


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        Forms of Probiotic Agents

   Examples of food supplements containing
    live culture:
       Yogurts
       Fermented milks
       Fortified fruit juice
       Powders
       Capsules
       Tablets
       Sprays


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                       Prebiotics
   Non-digestible food ingredients that selectively
    stimulate a limited number of bacteria, to
    improve health
   Examples:
       Fructo-oligosaccharides (FOS)
       Lactulose
       Galacto-oligosaccharides (GOS)
   Provided in:
       Beverages and fermented milks
       Health drinks and spreads
       Cereals, confectionery, cakes
       Food supplements                               32
                      Synbiotics
   Combine prebiotics and probiotics
   Prebiotic substrate should enhance survival of
    probiotic bacteria
   Example:
       Bifidobacteria + fructo-oligosaccharide (FOS)
   In order to establish the new species, need to
    continue to provide live culture, and
    appropriate substrate

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      Probiotics and Lactose Intolerance

   Lactobacilli, bifidobacteria and Streptococcus
    thermophilus, assist in reducing the symptoms of
    lactose intolerance
   Produce the enzyme beta-galactosidase (lactase) in
    yogurt
   Microbial lactase breaks down lactose
   The fermented milk itself delays gastrointestinal
    transit, thus allowing a longer period of time in which
    both the human and microbial lactase enzyme can act
    on the milk lactose.

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        Microflora and Lactose Intolerance
   Lactose tolerance in people who are deficient in
    lactase may be improved by continued ingestion of
    small quantities of milk
   Does not improve or affect the production of lactase
    in the brush border cells of the small intestine
   Continued presence of lactose in the colon contributes
    to the establishment and multiplication of bacteria
    capable of synthesizing the beta-galactosidase
    enzyme over time
   Resident micro-organisms will break down the
    undigested lactose in the colon
   Reduces the osmotic imbalance within the colon that
    is the cause of much of the distress of lactose
    intolerance
                                        _________________
                                                              35
                                        de Vrese et al 2001
          Clinical Trials of Probiotics
   Not all probiotics have been tested in clinical
    studies with regard to allergy prevention or
    treatment
   L. bulgaricus seemed to have no effect on
    immune parameters, whereas it was associated
    with lower frequency of allergies
   L. acidophilus consumption accelerated
    recovery from food allergy symptoms
   These effects have also been observed in
    infants with eczema and cow's milk allergy
    using infant formulas supplemented with
    L. rhamnosus.
                                                  36
    Trials on Probiotics and Eczema Prevention

     Pregnant women took capsules containing Lactobacillus
      rhamnosus GG (LGG) during the last two to four weeks of
      pregnancy
     The newborn infants were given the same microorganism
      from birth to six months
     Breast-feeding mothers continued to take the capsules
      during lactation
     The babies were given the bacteria mixed with water by
      spoon
     Subjects taking the probiotic had a reduced risk of
      developing atopic dermatitis (eczema) compared to controls
      up to 4 years of age
     Other studies found no reduced incidence of eczema in
      babies treated with probiotics
    _________________
    Kalliomaki et al 2003                                      37
                    Prebiotics and Eczema
       A few preliminary studies suggested increased
        bifidobacteria may be associated with a decreased
        incidence of atopic dermatitis
       Stool of infants fed formula containing
        oligosaccharides (FOS and GOS) in comparison to
        infants not fed the test formula had:
          Increased numbers of bifidobacteria and lactobacilli
          Increased amount of short chain fatty acids
          Increased proportion of acetate
          Decreased proportion of propionate
          Lower stool mean pH
       This is closer to that seen in breast-fed infants
        compared to infants fed control formula
_______________                                        ____________
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Ben XM et al 2004                                      Knol et al 2005
     Effects of Probiotics on Intestinal Functions and
                    Immune Responses

    Probiotics have effects on a number of intestinal
     functions and immune responses that may be
     beneficial in food allergy management, such as:
         Repair of intestinal barrier function
         Repair of tight junctions
         Enhanced mucin production
         Effects on dendritic cell function
         Skewing of T cells towards Th1 rather than Th2
         Exclusion of pathogens by competition for substrate
         Suppression of intestinal inflammation
    _______________
    Saxelin et al 2005
                                                                39
        Status of Probiotics as Therapy
   Great care must be taken in transferring data from
    laboratory and experimental animal studies into
    human use
   Applies also to the use of known probiotics, some of
    which are already present in human nutrition, such as
    yoghurt
   Not all strains of bacteria in use as probiotics are
    completely harmless
   Their immune-modifying effects and possible
    antiallergic and anti-cancer actions require large
    clinical studies


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