On food and cooking the science and lore of the kitchen ( PDFDrive ) 34
Bạn đang xem bản rút gọn của tài liệu. Xem và tải ngay bản đầy đủ của tài liệu tại đây (168.48 KB, 2 trang )
cow’smilkseemedagoodsubstitutefor
mother’smilk:morethanhalfofallsixmonth-oldsintheUnitedStatesdrankit.Now
thatfigureisdowntolessthan10%.
Physiciansnowrecommendthatplaincow’s
milknotbefedtochildrenyoungerthanone
year.Onereasonisthatitprovidestoomuch
protein,andnotenoughironandhighly
unsaturatedfats,forthehumaninfant’sneeds.
(Carefullypreparedformulamilksarebetter
approximationsofbreastmilk.)Another
disadvantagetotheearlyuseofcow’smilkis
thatitcantriggeranallergy.Theinfant’s
digestivesystemisnotfullyformed,andcan
allowsomefoodproteinandprotein
fragmentstopassdirectlyintotheblood.
Theseforeignmoleculesthenprovokea
defensiveresponsefromtheimmunesystem,
andthatresponseisstrengthenedeachtime
theinfanteats.Somewherebetween1%and
10%ofAmericaninfantssufferfroman
allergytotheabundantproteinincow’smilk,
whosesymptomsmayrangefrommild
discomforttointestinaldamagetoshock.
Mostchildreneventuallygrowoutofmilk
allergy.
MilkafterInfancy:
DealingwithLactose
Intheanimalworld,humansareexceptional
forconsumingmilkofanykindafterthey
havestartedeatingsolidfood.Andpeople
whodrinkmilkafterinfancyaretheexception
withinthehumanspecies.Theobstacleisthe
milksugarlactose,whichcan’tbeabsorbed
andusedbythebodyasis:itmustfirstbe
brokendownintoitscomponentsugarsby
digestiveenzymesinthesmallintestine.The
lactose-digestingenzyme,lactase,reachesits
maximumlevelsinthehumanintestinal
liningshortlyafterbirth,andthenslowly
declines,withasteadyminimumlevel
commencingatbetweentwoandfiveyearsof
