On food and cooking the science and lore of the kitchen ( PDFDrive ) 494

prestigeandavailabilitypushedgrains,
vegetables,andfruitstothesideoftheplate
andtheendofthemeal.Andfordecades,
nutritionalscienceaffirmedtheiraccessory
status.Fruitsandvegetablesinparticularwere
consideredtobethesourceofafewnutrients
thatweneedonlyinsmallamounts,andof
mechanicallyusefulroughage.Inrecentyears,
though,we’vebeguntorealizejusthowmany
valuablesubstancesplantfoodshavealways
heldforus.Andwe’restilllearning.
EssentialNutrientsinFruits
andVegetables:Vitamins

Mostfruitsandvegetablescontributeonly
modestlytoourintakeofproteinsand
calories,butthey’reourmajorsourcefor
severalvitamins.Theyprovidenearlyallof
ourvitaminC,muchofourfolicacid,and
halfofourvitaminA.Eachoftheseplaysa
numberofrolesinthemetabolismofour


cells.Forexample,vitaminCrefreshesthe
chemicalstateofmetalcomponentsinmany
enzymes,andhelpswiththesynthesisof
connective-tissuecollagen.VitaminA,which
ourbodiesmakefromaprecursormoleculein
plantscalledbeta-carotene(p.267),helps
regulatethegrowthofseveraldifferentkinds
ofcells,andhelpsoureyesdetectlight.Folic

acid,namedfromtheLatinwordfor“leaf,”
convertsaby-productofourcells’
metabolism,homocysteine,intotheamino
acidmethionine.Thispreventshomocysteine
levelsfromrising,causingdamagetoblood
vessels,andpossiblycontributingtoheart
diseaseandstroke.
GeneticEngineeringandFood
The most far-reaching development in
20th-century
agriculture
was
the
introduction in the 1980s of genetic
engineering, the technology that makes it
possible to alter our food plants and