On food and cooking the science and lore of the kitchen ( PDFDrive ) 35

ageandcontinuingthroughadulthood.
Thelogicofthistrendisobvious:it’sa
wasteofitsresourcesforthebodytoproduce
anenzymewhenit’snolongerneeded;and
oncemostmammalsareweaned,theynever
encounterlactoseintheirfoodagain.Butifan
adultwithoutmuchlactaseactivitydoes
ingestasubstantialamountofmilk,thenthe
lactosepassesthroughthesmallintestineand
reachesthelargeintestine,wherebacteria
metabolizeit,andintheprocessproduce
carbondioxide,hydrogen,andmethane:all
discomfortinggases.Sugaralsodrawswater
fromtheintestinalwalls,andthiscausesa
bloatedfeelingordiarrhea.
Lowlactaseactivityanditssymptomsare
calledlactoseintolerance.Itturnsoutthat
adultlactoseintoleranceistheruleratherthan
theexception:lactose-tolerantadultsarea
distinctminorityontheplanet.Several
thousandyearsago,peoplesinnorthern
Europeandafewotherregionsunderwenta


geneticchangethatallowedthemtoproduce
lactasethroughoutlife,probablybecausemilk
wasanexceptionallyimportantresourcein
colderclimates.About98%ofScandinavians
arelactose-tolerant,90%ofFrenchand
Germans,butonly40%ofsouthernEuropeans
andNorthAfricans,and30%ofAfrican

Americans.
Coping
with
Lactose
Intolerance
Fortunately, lactose intolerance is not the
same as milk intolerance. Lactase-less adults
can consume about a cup/250 ml of milk per
daywithoutseveresymptoms,andevenmore
ofotherdairyproducts.Cheesecontainslittle
or no lactose (most of it is drawn off in the
whey, and what little remains in the curd is
fermented by bacteria and molds). The
bacteria in yogurt generate lactose-digesting
enzymes that remain active in the human
small intestine and work for us there. And
lactose-intolerant milk fans can now buy the