RedisGood
Thebrainusescolortohelpuschoosewhattoeat
Redmeans"Greenlight,goforit!"Greenmeans:"hmm,betternot!"Likeanupsidedowntraffic
lightinourbrain,colorhelpsusdecidewhetherornottoeatsomething.This,accordingtoa
studyattheInternationalSchoolforAdvancedStudies(SISSA)inTriesteandrecentlypublished
inthejournalScientificReportsstatingthatvisionisthemainsenseweusetoguideusinfood
choices.Toevaluatecalorieintake,werelyona"colorcode."
"Accordingtosometheories,ourvisualsystemevolvedtoeasilyidentifyparticularlynutritious
berries,fruitsandvegetablesfromjunglefoliage,"saysRaffaellaRumiati,SISSAneuroscientist
andcoordinatorofthenewstudy.Thehumanvisualsystemistrichromatic:intheretina,the
light-sensitiveorganoftheeye,therearethreeclassesofphotoreceptors(cones)tuned
preferentiallytothreedifferentbandsofthevisiblespectrum.Thisimpliesthatwecanseealarge
numberofcolors(morethanmonochromaticanddichromaticanimals,lessthanthosewith4,
even5typesofphotoreceptor)."Weareparticularlyefficientatdistinguishingredfromgreen,"
saysRumiati.Thissophisticationtestifiestothefactthatweare"visualanimals,"unlikeothers,
dogs,forexample,whodependontheirsenseofsmell."Itismainlythecoloroffoodthatguides
us,andourexperimentsshowhow,"explainsRumiati."Todate,onlyafewstudieshavebeen
focusedonthetopic."
Whatdowelookforinfood?Nutrition,ofcourse,orcalorie-densecontent,andhighprotein."In
naturalfoods,colorisagoodpredictorofcalories,"explainsFrancescoForoni,SISSAresearcher
andfirstauthorofthestudy."Theredderanunprocessedfoodis,themorelikelyitistobe
nutritious,whilegreenfoodstendtobelowincalories."Ourvisualsystemisclearlyadaptedto
thisregularity."Theparticipantsinourexperimentsjudgedfoodswhosecolortendedtowardsred
ashigherincalories,whiletheoppositewastrueforgreens,"continuesGiulioPergola,a
researcherattheUniversityofBari,andoneoftheauthorsofthestudy."Thisisalsotruefor
processed,orcookedfoods,wherecolorlosesitseffectivenessasanindicatorofcalories."
Actually,thescientificliteratureshowsclearlythatcookedfoodsarefavoredovernaturalfoods
andthephenomenonhasbeenobservedeveninotherspeciesbesideshumans."Cookedfoods
arealwayspreferredbecause,comparedtonaturalfoods,thereismorenutritionforthesame
quantity,"explainsRumiati."Withcookedfoods,however,thedominanceofredovergreenno
longerprovidesreliableinformation,whichmightleadustobelievethatthebrainwouldnot
applytheruletoprocessedfoods.Onthecontrary,itdoes,whichhintsatthepresenceofancient
evolutionarymechanismsfrombeforetheintroductionofcooking."
AnothernodinfavorofthishypothesisisthefactthatthecolorcodeintheRumiatiand
colleaguesexperimentsdoesnotcomeintoplayforitemsotherthanfood:"Thepreferencefor
redovergreenisnotobservedwithnon-edibleobjects,"saysRumiati."Thismeansthatthecolor
codeofthevisualsystemactivatescorrectlyonlywithfoodstimuli."
Innertrafficlightforeatinghealthier
Ourfindings,besidesincreasingourknowledgeofthevisualsystem,offerinterestingpossibilities
onmanyfrontswhichcouldhaveanimportantimpactonthepublichealth:marketingfood,for
example,andtreatingeatingdisorders."Muchisbeingdonetodaytoencouragehealthier
eating,"notesRumiati."Forexample,tryingtoconvincethepeopletoeatfoodslowerin
calories.”Somecountriesproposebansoncertaintypesofproducts,suchascarbonatedsoft
drinksandhighfatfoods.Insomecases,thereisadisclaimeronthepackaging,aswith
cigarettes.Perhapsfoodcolorcouldbeusedtoproducesignificantresults,evenifartificial."
USEFULLINKS:
• OriginalpaperonScientificReports:www.nature.com/articles/srep37034
IMAGE:
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Credits:StacySpensley(Flickr:https://goo.gl/6nRHQA)
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