***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background Obesity has become a global public health problem , which also affects children . It has been proposed that the educational interventions during childhood could be a key strategy in the prevention of obesity . Objective To evaluate the efficacy of an intervention on food habits and physical activity in school children . Methods A 2-year cluster-r and omised prospect i ve study with two parallel arms was used to evaluate an intervention programme in children in their first year of primary schooling ( 5–6 years of age ) in schools in the city of Granollers . The intervention consisted of the promotion of healthy eating habits and physical activity by means of the educational methodology Investigation , Vision , Action and Change ( IVAC ) . At the beginning and at the end of the study ( 2006 and 2008 ) the weight and height of each child was measured in situ , while the families were given a self-report physical activity question naire and the Krece Plus quick test . Results Two years after the beginning of the study , the body mass index of the children in the control group was 0.89 kg/m2 higher than that of the intervention schools . The intervention reduced by 62 % the prevalence of overweight children . Similarly , the proportion of children that ate a second piece of fruit and took part in an after-school physical activity increased in the intervention group . In the control group , the weekly consumption of fish was reduced . Conclusions The educational intervention in healthy eating habits and physical activity in the school could contribute to lessen the current increase in child obesity Aims : To estimate the impact of school fruit tuck shops on  children ’s consumption of fruit and sweet and savoury snacks . Design : Cluster r and omised effectiveness trial with school as the unit of r and omisation . Setting : 43 primary schools in deprived areas in south Wales and south-west Engl and with a range of school food policies . Intervention : Schools operated fruit tuck shops throughout one academic year . Control schools did not do so . Measures : Repeated cross-sections of children aged 9–11 years completed a  computerised 24-hour recall question naire  at baseline ( n = 1902 ) and at 1-year follow-up ( n = 1924 ) , when a brief question naire was also completed ( n = 1976 ) . Results : Approximately 70 000 fruits were sold in the 23 intervention schools over the year , equivalent to 0.06 fruits per student per day . Children in intervention schools were more likely to report eating fruit as a snack at school ‘ often ’ ( OR 1.49 , 95 % CI 1.15 to 1.95 ) . There were no significant differences in children ’s intake of fruit or other snacks . There was a significant interaction ( p<0.02 ) between the intervention group and school food policy : where students were only allowed to bring fruit to school , fruit consumption was 0.37 portions per day ( 0.11 to 0.64 ) higher in intervention schools , compared to 0.14 portions ( −0.30 to 0.58 ) where no food was allowed and −0.13 portions ( −0.33 to 0.07 ) where there were no restrictions . Conclusions : In isolation , fruit tuck shops were not effective in changing children ’s snacking behaviour in schools . However , the results suggest that fruit tuck shops had a greater impact when reinforced by school policies restricting the types of foods students were allowed to bring to school Background Physical Activity Across the Curriculum ( PAAC ) is a 3-year elementary school-based intervention to determine if increased amounts of moderate intensity physical activity performed in the classroom will diminish gains in body mass index ( BMI ) . It is a cluster-r and omized , controlled trial , involving 4905 children ( 2505 intervention , 2400 control ) . Methods We collected both qualitative and quantitative process evaluation data from 24 schools ( 14 intervention and 10 control ) , which included tracking teacher training issues , challenges and barriers to effective implementation of PAAC lessons , initial and continual use of program specified activities , and potential competing factors , which might contaminate or lessen program effects . Results Overall teacher attendance at training sessions showed exceptional reach . Teachers incorporated active lessons on most days , result ing in significantly greater student physical activity levels compared to controls ( p < 0.0001 ) . Enjoyment ratings for classroom-based lessons were also higher for intervention students . Competing factors , which might influence program results , were not carried out at intervention or control schools or were judged to be minimal . Conclusion In the first year of the PAAC intervention , process evaluation results were instrumental in identifying successes and challenges faced by teachers when trying to modify existing academic lessons to incorporate physical activity This paper measures tobacco polices in statewide representative sample s of secondary and mixed schools in Victoria , Australia and Washington , US ( N = 3,466 students from 285 schools ) and tests their association with student smoking . Results from confounder-adjusted r and om effects ( multi-level ) regression models revealed that the odds of student perception of peer smoking on school grounds are decreased in schools that have strict enforcement of policy ( odds ratio ( OR ) = 0.45 ; 95 % CI : 0.25 to 0.82 ; p = 0.009 ) . There was no clear evidence in this study that a comprehensive smoking ban , harsh penalties , remedial penalties , harm minimization policy or abstinence policy impact on any of the smoking outcomes AIMS To determine the impact of a school-based harm minimization smoking intervention compared to traditional abstinence-based approaches . DESIGN , SETTING AND PARTICIPANTS A school-based cluster r and omized trial was conducted in Perth , Western Australia in 30 government high schools from 1999 to 2000 . Over 4000 students were recruited to participate and schools were assigned r and omly to either the harm minimization intervention or a st and ard abstinence-based programme . INTERVENTION The harm minimization intervention comprised eight 1-hour lessons over 2 years , quitting support from school nurses and enactment of policies to support programme components . Comparison schools implemented st and ard abstinence-based programmes and policies . MEASURES Cigarette smoking was categorized at two levels : regular smoking , defined as smoking on 4 or more days in the previous week ; and 30-day smoking as any smoking within the previous month . FINDINGS At immediate post-test ( 20 months post-baseline ) , after accounting for baseline differences , school-level clustering effects , socio-economic status , gender and family smoking , intervention students were less likely to smoke regularly [ OR = 0.51 , 95 % confidence interval ( CI ) = 0.36 , 0.71 ] or to have smoked within the previous 30 days ( OR = 0.69 , 95 % CI = 0.53 , 0.91 ) . CONCLUSION The school-based adolescent harm minimization intervention appears to have been more effective than the abstinence-based social influences programme at reducing regular smoking OBJECTIVE To examine change in high school students ' beverage consumption patterns pre- and post-intervention of reduced availability of sugar-sweetened beverages ( SSB ) and diet soda in school food venues . DESIGN A prospect i ve , quasi-experimental , nonr and omized study design . SETTING Public high schools . PARTICIPANTS A convenience sample from control ( n = 221 ) and intervention ( n = 235 ) high schools . INTERVENTION Schools aim ed to reduce ( n = 4 ) or not change ( n = 3 ) availability of SSB and diet soda in food venues for 1 school year . MAIN OUTCOME MEASURES Subjects ' beverage servings/day was determined from a food frequency question naire pre- and post-intervention . ANALYSIS Two-by-two mixed analysis of variance model compared pre- to post-intervention servings/day between control and intervention subjects , stratified by gender . RESULTS Consumption of SSB decreased in both intervention and control boys ( F = 53.69 , P < .05 ) and girls ( F = 22.87 , P < .05 ) . Intervention girls decreased  diet soda consumption as compared to control girls ( F = 6.57 , P < .05 ) . CONCLUSION AND IMPLICATION S Reducing availability of SSB in schools did not result in a greater decrease in SSB consumption by intervention as compared to control subjects . The impact of reducing availability of SSB at school may be limited . A better underst and ing of beverage consumption patterns may be needed to determine the efficacy of school food policies on those youth susceptible to obesity BACKGROUND . The prevalence and seriousness of childhood obesity has prompted calls for broad public health solutions that reach beyond clinic setting s. Schools are ideal setting s for population -based interventions to address obesity . OBJECTIVE . The purpose of this work was to examine the effects of a multicomponent , School Nutrition Policy Initiative on the prevention of overweight ( 85.0th to 94.9th percentile ) and obesity ( > 95.0th percentile ) among children in grade s 4 through 6 over a 2-year period . METHODS . Participants were 1349 students in grade s 4 through 6 from 10 schools in a US city in the Mid-Atlantic region with ≥50 % of students eligible for free or reduced-price meals .  Schools were matched on school size and type of food service and r and omly assigned to intervention or control . Students were assessed at baseline and again after 2 years . The School Nutrition Policy Initiative included the following components : school self- assessment , nutrition education , nutrition policy , social marketing , and parent outreach . RESULTS . The incidences of overweight and obesity after 2 years were primary outcomes . The prevalence and remission of overweight and obesity , BMI z score , total energy and fat intake , fruit and vegetable consumption , body dissatisfaction , and hours of activity and inactivity were secondary outcomes . The intervention result ed in a 50 % reduction in the incidence of overweight . Significantly fewer children in the intervention schools ( 7.5 % ) than in the control schools ( 14.9 % ) became overweight after 2 years . The prevalence of overweight was lower in the intervention schools . No differences were observed in the incidence or prevalence of obesity or in the remission of overweight or obesity at 2 years . CONCLUSION . A multicomponent school-based intervention can be effective in preventing the development of overweight among children in grade s 4 through 6 in urban public schools with a high proportion of children eligible for free and reduced-priced school meals The purpose of this study was to comprehensively assess the impact of school  tobacco policy intention , implementation and students ' perceptions of policy enforcement on smoking rates and location of tobacco use during the school day . Data were obtained from all students in Grade s 10 - 11 ( n = 22,318 ) in 81 r and omly selected schools from five Canadian provinces . Policy intention was assessed by coding written school tobacco policies . School administrators most familiar with the tobacco policy completed a survey to assess policy implementation . Results revealed policy intention and implementation subscales did not significantly predict school smoking prevalence but result ed in moderate prediction of tobacco use on school property ( R(2 ) = 0.21 - 0.27 ) . Students ' perceptions of  policy enforcement significantly predicted school smoking prevalence ( R(2 ) = 0.36 ) and location of tobacco use ( R(2 ) = 0.23 - 0.63 ) . The research findings emphasize : ( i ) the need to consider both written policy intention and actual policy implementation and ( ii ) the existence of a policy is not effective in controlling tobacco use unless the policy is implemented and is perceived to be strongly enforced This article presents the results of a mediation analysis of Project MYTRI ( Mobilizing Youth for Tobacco Related Initiatives in India ) , a r and omized , controlled trial of a multiple-component , school-based tobacco prevention program for sixth- to ninth- grade rs ( n = 14,085 ) in Delhi and Chennai , India . A mediation analysis identifies how an intervention achieves its effects . In MYTRI , changes in students ’ ( a ) knowledge about the negative health effects of tobacco , ( b ) beliefs about its social consequences , ( c ) reasons to use tobacco , ( d ) reasons not to use tobacco , ( e ) advocacy skills self-efficacy , and ( f ) normative beliefs about tobacco use were significantly associated with reductions in students ’ intentions to use tobacco and tobacco use behaviors . In contrast , changes in students ’ perceptions of the prevalence of smoking and chewing tobacco were significantly related to increases in students ’ intentions to use and use of tobacco . Implication s for intervention design are considered OBJECTIVES We assessed the effectiveness of a 2-year multicomponent , school-based intervention design ed to reduce tobacco use rates among adolescents in an urban area of India . METHODS Students from 32 schools in Delhi and Chennai , India , were recruited and r and omly assigned to an intervention or control group . Baseline , intermediate , and outcome data were collected from 2 cohorts of 6th- and 8th- grade students in 2004 ; 14,063 students took part in the study and completed a survey in 2004 , 2005 , or 2006 . The intervention consisted of behavioral classroom curricula , school posters , a parental involvement component , and peer-led activism . The main outcome measures were self-reported use of cigarettes , bidis ( small h and -rolled , often flavored , cigarettes ) , and chewing tobacco and future intentions to smoke or use chewing tobacco . RESULTS Findings showed that students in the intervention group were significantly less likely than were students in the control group to exhibit increases in 
    Output:
    
School policies were comparatively more effective in reducing unhealthy diet , tobacco use , physical inactivity and inflammatory biomarkers as opposed to anthropometric measures , overweight/obesity , and alcohol use .
Conclusion Mixed findings were observed concerning effectiveness of school policies in reducing NCD risk factors .