School Children’s Heightin Beijing

1. Introduction This joint report by a group of noted human biologists in Beijing examines secular growth of school boys and girls, 7 to 17 yearsofage,inBeijing,overthehalfcentury,1955to2010,by10year interval, based on derived data from published researches for the periodof1955to1975andChineseNationalSurveysofStudents ConstitutionandHealthfortherestoftheperiod.Thereportplac- es the greatest concerns on statistical developments in height and weightandaccruedBMIamongchildreninBeijing,withlittlein- terest on “inputs to health”, such as school lunch programs, gymnasticprogramsandsoforce,andtothereviewer’sregret,chang- es in per capita consumption of selected food products, such as meat,milk,vegetablesbyagegroupsofchildren,0~4,5~9,10~14, 15~19(Mori, 2022[3]). As shown inTable 1, as transcribed fromTable 1, EHB, with SD omitted,theaverageheightof17-year-oldboysreached175.4cm in 2010, not quite that of theirAmerican counterparts (176.3 cm) but greater than that of 17-year-old boys in European countries lying along roughly the same latitude as Beijing, such as France (174.1 cm), Italy (174.48 cm) and Spain (175.3 cm), and signifi- cantly taller than those in Japan (170.7 cm) and South Korea (173.4 cm) (Mori, Cole and S. Kim, 2021[4])As for the 17-yearoldgirlsinthestudy,thetrendwasthesame,withoneexception: there was no significant difference between their average height andthatoftheirAmericancounterparts(p.214).Femalelateteens in Beijing proved not shorter in mean height than theirAmerican peers in 2010(p.214). Those boys in age 17 were 168.7 cm in 1975, 0.1 cm shorter than in 1965; those girls in 14-15 years of age in 1975 were slightly shorterthanin1965,forexample,consequencesoftheGreatFam- ine, caused by the Great Leap Forward (1958-60). On the other hand,childreninallagesin1985aresubstantiallytallerthanthose in 1975, either sex, partially reflecting “compensatory growth” (p.215,leftcolumn;Mori,2018[5]).Thereviewerwon’targue.As mentionedattheoutset,thedatafortheperiod,1955to1975were derivedfrompublishedresearches.Inanalyzingthegrowthdevelopment of urban children’s height in China, C. Tian and JIC Ye, 2013[6],classifiedurbanChinaintothreegroups,GroupI(coastal bigcities),II(otherbigcities),andIII(moderateandsmallcities). BeijingisincludedinGroupI,whichisknownforthebettersocioeconomic development than the rest of city groups. Table 2, based on FAOSTAT food balance sheets [7]*1, demonstrates that per capita supply of cereals, meat & fish, egg & milk, vegetables&fruit,intermsofkg/year,changedfrom131.4,15.9, 4.5, 52.6 in 1973 to 174.3, 22.4, 7.0, 76.3 in 1983, with animal productsincreasedonlyslightlyinChinabetweentheearly1970s and the early 1980s, as compared to the later periods. Seemingly largeincrementsinchildren’sheightbyagegroupsbetween1975 and 1985 should have come from inconsistent data sources to unignorable extent.

Keywords: China; Children’s height; BMI

2. Pointsof Interest It is widely taken that Asians should be appreciably shorter genetically in height than Europeans (Gerald J. van den Berg et al.,2011[8]). In the end of the 19th century, the Dutch, the currently the world tallest, the young men at 183 cm, were recorded 167 cm, only 1.5 cm taller than the French counterparts (Mori, 2022,FNS[9]).TheaverageIndonesianyoungmenare161.5cm in 2010(Mori, South EastAsia, 2022[10]).As we will see below, Indonesia is substantially lower than China, South Korea and Japaninrespectofpercapitasupplyofmeat-fish,milk-eggs,vegetables-fruit in 2000~2010 (Table 2). What is concerned in the leading countries lately in Asia is obesity: should children eat more animal products, without reducing cereals,theywouldgrowbigger,nottallerinheightbutheavierin weight(Tables3).InS.Korea,17-year-oldboyswere173.0cmin height, 65.3 kg in weight in 2000, 173.8 cm in height, 68.1 kg in weight in 2010, and 173.7 cm in height and 71.1 kg in weight in 2017, accompanied by steadily increasing BMI from 21.8, 22.6 and 23.4, accordingly. On the other hand, in the case of children in Beijing, 17-year-old boys were 173.4 cm in height and 63.4 kg inweightin1995,173.5cmand67.6kgin2005,and175.4cm and66.8kgin2010,resultingin21.1,22.4,and21.7inBMI, accordingly. The report attributes these stable BMI in the case of children in Beijing to the city government’s guidance in promoting physical activitiesinandoutschool.Thereviewerhascomeacrossreports onprohibitionofsoftdrinkvendingmachinesonthepublic-school campuses to successfully keep children away from sugar-rich productsinseveralcitiesinUS.Theaudienceshouldbeimpressed to realize that China has been very low in per capita consumption of sugar: one tenth that of USAand one fifth that of South Korea in2010(Table4).Aboy,70kginweight,consumesapproximately 350kcal,whenhejogshalfanhour.Percapitasupplyofsug- ar, 368 kcal/day in South Korea in 2010, should be equivalent to running about 5 km/30 minutes. If one takes one or two cans of naturally sweetened soft drinks, without matching physical exer- cises, increases in BMI will be natural outcomes. Soft drinks are more than good for thirsty throat but most effective in putting up body weights. Encouraging various sports in and out school curriculums should be accompanied by sufficient dressing facilities for students. As the economy expands, food consumption tends to increase, animal products, in particular. Japan and South Korea have successfully met the increasing demands for meatand milk in two ways: importing feed grains and finished products; meat and dairy products from overseas. China is very large in population: 1,062 million in 1985 and 1,360 million in 2010, as compared to 120 and 127 million (Japan) and 40.5 and 48.5 million (S. Korea), respectively.AsshownbyTable5,Chinahasmanagedtofeedtheir people,withoutheavilyrelyingonimportsfromoverseas.AdministratorsandfarmingcommunitiesinChinashouldbecongratulat- ed for their achievements in successfully keeping high and robust self-sufficiencies in the basic food supply

3. SupplementalComments―GrowthExaminedin Practice: Cross-Sectionalvs Longitudinal Onebornin1978, forexample, grew to one year old in 1979, 7-year-old in 1985, --, 17-year-old in 1995. To determine growth from7- year-oldto17-year-old,sayin1995,itispreferableto compare 17-year-old in 1995 with 7-year-old in 1985, following the same birth cohort. In practice where students’ health examinationsurveystakeplaceevery10years,longitudinaldataarenot available.Inmostdeveloped/stabilizedcountries,includingJapan, no big differences accrue, whether longitudinal data or cross-sectional data applied. The reviewer suspects, however that unmissable differences might accrue, in two approaches in the case of China,rapidlyexpandingsocio-economicsocieties(Mori,Growth Charts-Curves, 2022[11]). What the reviewer could suggest is simple: compare 7-year-old in 1975 with 17-year-old in 1985, diagonally, tracing the same birth cohort, born in 1968. In human biology, the importance of “early years of life” is emphasized in determiningfutureadultheight(ColeandMori,2017;A.Deaton, 2007[12;13]).

BriefSupplements Authorsareallmedicalresearchers.Oneoftheirgreatestconcernsliesunderstandablyintheworldwidetendencyof children’soverweight.Thereviewer came across a short statement, p.215, left-hand column, the 2010 ChinaHealthandNutritionSurveyshowedthatoverthepreviouseightyears Beijing’sresidentsdecreasedtheirconsumptionofoil,animalproducts,and cerealsby33.7%,27.6%,and15.4%,withoutmodifyingtheirconsumption ofvegetablesandfruit(BeijingMunicipalGovernment,2014).Thedrastic reductionofanimalproducts,inparticular,isnotconfirmedbyFAO’sfood valancesheets,attached.Intherealmofhumanbiology,animalproteinshould beoneofthekeydeterminantsofadultheight.Thereviewerassumesthat the authors ofthe report may not disagree.

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Hiroshi Mori. School Children’s Heightin Beijing. Annals of Clinical and Medical Case Reports 2023