JPediatr(RioJ).2016;92(3):220---222
www.jped.com.br
EDITORIAL
Optimizing
bone
health
in
Brazilian
teens:
using
a
population-based
survey
to
guide
targeted
interventions
to
increase
dietary
calcium
intake
夽
,
夽夽
Otimizando
a
saúde
óssea
em
adolescentes
brasileiros:
utilizac
¸ão
de
um
levantamento
de
base
populacional
para
orientar
intervenc
¸ões
direcionadas
para
aumentar
a
ingestão
alimentar
de
cálcio
Neville
H.
Golden
SchoolofMedicine,StanfordUniversity,PaloAlto,UnitedStates
Calciumisnecessaryfor bonehealth,cardiovascular func-tion,nerveconduction,musclecontraction,andhemostasis. Calciumisthemostabundantmineralfoundinthebodyand 99%oftotalbodycalciumisfoundintheskeleton,whereit providesstrengthtotheunderlyingcollagenmatrix.During theadolescent growthspurt, demandfor calciumis high, bothforlongitudinalgrowthaswellasforaccretionofbone mass.1,2Peakbonemassisachievedtowardtheendofthe
seconddecadeoflifeandisanimportantpredictoroffuture fracturerisk.Theadolescentyearsthereforeprovidea win-dowofopportunityforinterventionstooptimizepeakbone massacquisition.
InthisissueoftheJournal,deAssumpc¸ãoetal. exam-ined calciumintake in adolescents in relation toa range ofsocioeconomic variablesand health-relatedbehaviors.3
Inacarefullyconducted,cross-sectional,population-based study of 913 adolescents living in Campinas, Sao Paulo,
夽 Pleasecitethisarticleas:GoldenNH.Optimizingbonehealthin
Brazilianteens:usingapopulation-basedsurveytoguidetargeted interventionstoincreasedietarycalciumintake.JPediatr(RioJ). 2016;92:220---2.
夽夽SeepaperbydeAssumpc¸ãoetal.inpages251---9.
E-mail:ngolden@stanford.edu
Brazil,using24-hourdietaryrecall,theinvestigatorsfound that88.6%ofadolescentshadadailydietarycalciumintake belowtheestimatedaveragerequirement(EAR)for adoles-centsaged9---18years.Consumptionwasloweringirls, in thosefromlowersocio-economicbackgrounds,andinthose wheretheheadofthefamilyhadalowerlevelofeducation. Lowcalciumintakewasalsoassociatedwithreduceddairy intakeaswellaslowintakeoffruitsandvegetables.
In its 2011 report, the Institute of Medicine (IOM) set the EAR, the recommendeddietary allowance(RDA), and the tolerable upper intake Levels (UL) as 1100mg/day, 1300mg/day,and3000mg/day,respectively,foradolescent boysandgirlsbetweentheagesof9and18years.4 These
recommendationswerebasedonmetaboliccalciumbalance studiesaswellasstudiesofbonemineralaccrualusingdual energyX-ray absorptiometry and similartechniques.5 The
EARistheaveragedailynutrientintakethatisestimatedto meettheneedsofhalftheindividualswithinthatagegroup. TheEARactuallyreflectstheestimatedmedianrequirement andassuch, bydefinition, theEAR isless thanthe needs of halfof thepopulation. In contrast,theRDArepresents the daily calcium intake that meets the requirements of 97.5%ofthepopulation.Accordingtothe2011Instituteof Medicinereport,theRDAforcalciumforadolescentsaged 8---19 yearsis 1300mg/day.4 Using the RDAinstead of the
http://dx.doi.org/10.1016/j.jped.2016.02.002
OptimizingbonehealthinBrazilianteens 221
EAR,theprevalence oflow calciumintakewouldbeeven higher.
Themajordietarysourcesofcalciumaredairyproducts, dark green leafy vegetables, legumes, nuts, and certain types of fish such as sardines and salmon. In the United States, approximately70% of dietarycalcium comesfrom dairy products and vegetables only contribute approxi-mately 7%.6 Each 8 oz. (240mL) serving of milk or cup
of yogurt and 1.5 oz. serving of natural cheese contains approximately300mgofcalcium.BothinBrazilandinthe UnitedStates,calciumisalsoavailableincertain calcium-fortifieddrinks andcereals.The bioavailabilityof calcium in greenleafy vegetablesisgenerally high,but the quan-tityofvegetablesneededtobeconsumedinordertomeet requirements is large. Based on the IOM’s recommenda-tions,adolescentsrequirefourservingsofdairyproductsor calcium-enrichedfoodsperday,andtheAmericanAcademy of Pediatrics recommends that pediatricians periodically assesscalciumintakeduringthegrowingyearsand encour-age increased intake,either by increasing the amount of dairy productsor by incorporatingcalcium-enrichedfoods intothediet.7
Although somestudieshavedemonstratedthatcalcium supplementationinchildrenandadolescentsincreasesbone mineral density,8,9 a recent meta-analysis of randomized
controlled trials found that routine calcium supplemen-tationonlyresultedinamarginalincreaseinbonemineral density and concludedthat this small increase would not likelyresultinaclinicallysignificant reductioninfracture risk.10Routinecalciumsupplementationisthereforenot
rec-ommended,butincreaseddietaryconsumptionoffoodsrich incalciumisrecommendedtoachieverecommendedintake levels.7
AsdeAssumpc¸ãoetal.havedemonstrated,itisnoteasy tomeetrecommendeddietarycalciumintake.Thefindings oftheBrazilianstudyaresimilartothosefromtheUnited Statesthatgenerallyshowlowercalciumintakeingirlsand reduced dairy consumption in all teens, but especiallyin girls.11,12Notreportedinthisstudy,bothintheUnitedStates
andinBrazilconsumptionofsoftdrinksandsweetened bev-eragesbyteenshasincreasedwhilemilkconsumption has declined, suggesting that soft drinks have replaced milk productsinthisagegroup.11---13Someadolescentgirls,
con-scious ofbody image concerns, incorrectly perceivedairy products to be fattening and tend to avoid them. One 8 oz.glassof skimmilk containsnofat and80kcals,andis agoodsourceofproteinandvitaminD.Incontrast,acanof softdrinkcontainsapproximately140kcalsandisdevoidof othernutrients.Pediatricianscanplayanimportantroleby educatingtheirpatientsanddispellingthenotionthatdairy productsarefattening.
In the de Assumpc¸ão study,the findings of the impact ofsocioeconomic classand parentaleducationoffer addi-tional insights into the complexity of the situation. Dairy products may be more expensive than high-calorie ‘‘fast foods’’ preferred by many teens, and calcium-enriched foodsmaycostmorethanfoodnotenrichedwithcalcium, placingadditionalburdenonthosefromlower socioecono-micgroupswhomayhavefoodinsecurity.ThedeAssumpc¸ão studyprovidesrichdataofferingopportunitiesfortargeted intervention.Unquestionably, improvementin socioecono-mic conditions is important, but this is not always easily
achievedifresourcesarelimited.However,nutrition educa-tioninterventionscanplayamajorroleinimprovingcalcium consumption by teens. These interventions can be in the formofpublic health campaignsabout the importanceof drinkingmilkanddairy products,ensuringthe availability ofmilkanddairy products,and limitingease ofaccessof softdrinksandsweetenedbeveragesinschoollunches, as wellasbyconductingclassroom-basednutritioneducation interventionsinschools.Thelatterhavebeen foundtobe effectiveinincreasingdietarycalciumintakeinadolescents livinginavarietyofdifferentcountries.14---17
FindingsfromthedeAssumpc¸ãostudydemonstratethat inadequatecalciumintakeinteensisassociatedwithother high-riskbehaviors,suchassmokingandinadequateintake ofotherhealthyfoodssuchasfruitsandvegetables.Lessons learnedfromthe de Assumpc¸ão study can guidetargeted interventionsaimed atthoseat greatestrisk andindicate thatthe interventionsshould address multiple health risk behaviors.
Conflicts
of
interest
Theauthordeclaresnoconflictsofinterest.
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