Whenit’sanallergy
AllergyUKsaysupto10%of
adultsandchildrenmayhavea
foodhypersensitivity(allergy),yet
asmanyas20%ofadultsreport
havinghada reactiontofood.In
fact,a truefoodallergyinvolvesa
reactionfromtheimmunesystem.
Whenit perceivesfoodsasa
threat,it releasesImmunoglobulin
E (IgE)antibodiestocells,whichin
turnreleasechemicalsthatcause
anallergicreaction.Sohowdowe
knowif thisis what’shappening?
‘Symptomsofa truefood
allergyusuallycomeonfairly
soonaftereating– mostlywithin
minutes,’explainsPatrick.These
includeswellinginthemouth,an
itchyrashand,inseverecases,
breathingdifficultyandcollapse.
It’susuallyfairlyobviouswhat’s
happening.Skin-pricktestsdone
inallergyclinicsonly pick up
thesereactions.
‘However,thereis a second
groupofallergysymptomsthat
donotinvolvetheimmune
system(callednon-IGmediated
symptoms),wherereactionsare
delayedbyseveralhours.These
includestomachupsets,rashes
andasthma-typesymptoms,’says
Patrick.‘Becauseofthetime
delay,it canbelessobvious
what’sgoingon.Unfortunately,
thereis nodiagnostictestfor
these,sotheyaredifficultto
proveonewayortheother.’This
makesit alltooeasyforpeopleto
self-diagnoseortoturntotests
thatgiveunreliableresults(See
Testsyoucantrust,right).Whenit’sanintolerance
Theterms‘foodintolerance’
or‘foodsensitivity’areunspecific
andnotmedicallyrecognised,
accordingtoPatrick.TheBritish
DieteticAssociation(BDA)says
foodintolerancesdonotinvolve
theimmunesystemandarerarely
life-threatening.Yetsomepeople
clearlydohavesymptomsafter
ingesting certain compoundsFood allergy or intolerance?Whattodoif you
suspecta food
allergy...
●Seekmedical
advice– dial 999
if youexperience
swellingand
breathing
difficulties,
whicharesigns
ofanaphylaxis.
●Askfora referral
toanallergy
specialistfortests
(seeopposite).
●Ifanallergyis
confirmed,seea
registereddietitianor
nutritionistregistered with
theAssociationfor
Nutritiontohelpyou
createa well-balanced,
appropriate diet.5THINGSYOU
NEEDTO
KNOWABOUT
ORALALLERGY
SYNDROME(OAS)
1 ALSOKNOWNAS
pollen-foodsyndrome,
OASiscausedbycross-
reactingallergensfound
inbothpollenandraw
fruits,vegetablesandsome
treenuts.
2 THEIMMUNESYSTEM
recognisesthepollenand
similarproteinsinthefood
anddirectsanallergic
responsetowardsthese.
3 THOSEAFFECTEDby
oralallergysyndromecan
usuallyeattheproblemfruits
orvegetablesincookedform.
Thisisbecauseproteins
changeduringtheheating
process,sotheimmunesystem
nolongerrecognisesthem.
4 SYMPTOMSTYPICALLY
BEGINinteensandyoung
adultswhomayhavebeen
eatingthefruitsorvegetables
inquestionforyearswithout
anyproblems.
5 ITAFFECTSthose
whohaveallergyto
birch,ragweedor
grasspollens.RAGWEEDsuchasfoodadditives,histamine,
salicylateandsulphites,andthese
reactionscanvaryenormously
betweenindividuals.Sowhen
shouldtheseintolerances be
causeforconcern?
‘Sincethere’salwaysa risk
ofa severereactionsuchas
anaphylaxis,whichcanbe
life-threatening,it’simportant
togetanynegativereactions
tofoodcheckedoutwithyour
doctor,’saysPatrick.It couldbe
a full-blownIgEallergy,andyou
mayneedtocarryanEpiPenof
adrenalineforemergencies.
‘Evenif it’s“just”anintolerance,
it canbeusefultoidentifywhich
foodsarecausingyouproblems.
Beawarethatsymptomssuchas
bloatingmayhaveothercauses
thatareunconnectedtoallergies,
suchascoeliacdisease,Irritable
BowelSyndromeorlactose
intolerance(anenzyme
deficiency),’ he adds.28 HEALTHY FOOD GUIDEMAY 2019