Objective: To explore the prevalence of anemia and related factors among left-behind children in poverty-stricken rural areas in China, to provide basic information for anemia prevention and treatment for children. Methods: Data from the National Nutrition Improvement Program for Rural Compulsory Education Students in 2016 were used to express the prevalence of anemia among left-behind children. By using the multistage stratified random cluster sampling method, left-behind children of the 6-17-years-old in poverty-stricken rural areas were recruited in this study. Blood hemoglobin concentration of these students was determined by cyanmethemoglobin method. Anemia was judged by the WHO recommended standard and combined with the sea level elevation correction standard. Frequencies of food intake were collected through questionnaires. Data was then available for analysis including the level of hemoglobin and anemia rates. Relationship between anemia and food intakes as well as other influential factors was also analyzed. Results: The overall anemia prevalence (AP) was 11.6% among the participants. Rates of AP among the 6-, 7-, 15- and 16-17-years-old were 21.1%, 18.0%, 20.6% and 17.3%, respectively. Rates of AP among left-behind girls of 10-11-years-old and the 13-15-years-old were significantly higher than those in boys at the same age (P<0.01) group. Factors including: being girls (OR=1.34, 95%CI: 1.23-1.45), at grade 7 to 9 (OR=1.47, 95%CI:1.30-1.67) and mother being migrant worker (OR=1.32, 95%CI:1.16- 1.50) had higher proportions of getting anemia. Factors as living in the western area (OR=0.85, 95%CI: 0.78-0.93), taking breakfast every day (OR=0.70, 95%CI: 0.64-0.76), having meat more than twice per week (OR=0.84, 95%CI: 0.75-0.93) and having two kinds of vegetables per day (OR=0.85, 95%CI: 0.75-0.96) appeared protective. Conclusions Prevalence of anemia in left-behind children from the poverty-stricken rural areas was high, including junior middle school students from grade 7 to 9 at the early stage of youth development, girls and children with mothers as migrant workers. Anemia should be reduced by promoting the protective factors as having breakfast, increasing intakes of meat and fresh vegetables.

Objective: To analyze changes of school canteen construction and canteen meal provision in surveilled schools after the initiation of the National Nutrition Improvement Program for Rural Compulsory Education Student (NNIPRCES), therefore to provide data basis for improving efficacy of school canteen meals. Methods: From 2012 to 2017, among the 699 trial counties in 22 provinces under NNIPRCES, at least 10% of elementary schools and middle schools with each food supply model (canteen meals, enterprise meals, and family meals) were randomly selected in each county in each year. Questionnaire survey was conducted to collect school canteen construction and meal provision information. The sample size were around 8 000 to 11 000 schools every year. Results: From 2012 to 2017, the proportion of schools that have canteens only, have both canteen and dining room, as well as those have canteen and dining room with tables and chairs significantly increased with years(χ 2=3 043.95, 6 383.85, 6 731.17, P<0.01). The proportion of schools having canteen increased from 59.5% in 2012 to 87.0% in 2017. The proportion of schools with canteen providing breakfast, lunch or dinner varied across years(χ 2=51.85, 144.96, 189.19, P<0.01). The varieties of food groups of three meals all significantly increased during 2012, 2014 and 2017(χ 2=702.30, 892.38, 550.55, P<0.01). The canteen construction indicators, proportion of canteens providing three meals, and food groups included in three meals all significantly differed between elementary schools and middle schools, also between schools of central area and western area(P<0.05). The changing patterns with year were significantly different in elementary schools and middle schools, and in schools of central area and western area(P<0.05). Conclusion After the implementation of NNIPRCES, canteen construction and food variety in canteen meals significantly improved during 2012 to 2017. However, there are still gaps between changes of canteen construction and canteen meal provision. It is necessary to overcome obstacles to further increase the proportion of schools with canteen offering meals and the variety of food of meals.

Objective: To analyze the height changes among children who had received subsidies of the National Nutrition Improvement Program for Rural Compulsory Education Students (NNIPRCES) by comparing data from the year of 2012 and 2017. Methods: Among 699 counties where NNIPRCES was implemented, at least 10% of elementary schools and primary middle schools with different food supply modes (school canteen meals, company meals, and mix meals) in the county were selected randomly. Forty students from one or two classes from each grade (grade 1 to grade 9) were randomly selected, to ensure equal proportion of boys and girls in each grade were surveyed, data on height from 1 655 793 students measured in 2012 were compared with 1 419 281 students measured in 2017. Height was measured by metal height pole within 0.1 cm accuracy. Results: From 2012 to 2017, the average increase of height in boys and girls aged 6-15 years was 1.9 and 2.0 cm, respectively. Among them, maximum increment was found in boys at the age of 13 years and in girls at the age of 12 years, respectively, which was 3.0 and 2.8 cm. The average increase in boys from the central and western region was 2.1 and 2.2 cm, respectively, while increase in girls from the central and western region was both 2.2 cm. Compared with the results from 2012, height of boys with the 5th, 50th and 95th height percentiles in 2012 increased by 1.7, 2.0 and 2.1 cm, respectively in 2017, while the increase in girls was 2.1, 2.0 and 2.2 cm, respectively. The average increment of western students with the 5th and 95th height percentiles was higher than those of students from the central region. Conclusion The average height of students has increased after the implementation of NNIPRCES. However, the development was unbalanced between the central and western region, which requires more targeted intervening strategies to improve the nutritional status of students.

Objective: To evaluate snack consumption and the influencing factors associated with student participation in the Nutrition Improvement Program, and to provide a scientific basis for improving the program. Methods: Among the 50 monitoring counties that implemented the Compulsory Education Student Nutrition Improvement Program, two primary schools and two junior schools were randomly selected according to different food supply patterns (i.e., school, company, and mix). This study randomly selected one or two classes from each grade, which ranged from grade 3 to grade 9. A questionnaire, which addressed snack consumption and choice, was distributed to 27 374 students. Results: The findings revealed that 14.0% of students from poor rural areas in central and western regions consumed snacks two or more times per day, and 21.6% of students spent 3 yuan or more on snacks each day. The top three choices of snacks included fruit and vegetables (50.6%), biscuits and bread (50.1%), and puffed food (40.0%). Students who had mothers who worked outside the home, parents who worked outside the home, who consumed corporate meals, and who had access to a small shop on campus were more likely to consume snacks one or more times per day(OR=1.35，1.19，1.11，1.51，P<0.05). Conclusion The phenomenon of snack consumption among primary and middle school students from poor rural areas in central and western regions is common, and the selection of unhealthy snacks was identified as a problem. A health education system with comprehensive support and guidance from individuals, families, schools, and society should be established to guide students to opt for healthier snacks.

Objective: To evaluate temporal trend in food supply among pilot schools involved in the National Nutrition Improvement Program for Rural Compulsory Education Students (NNIPRCES). Methods: Ten percent of pilot schools were randomly selected and asked to report the information on food supplies. Daily intake of energy, carbohydrates and protein for each student were calculated and compared with the reference value in Nutrition Guidelines of School Meals (WS/T 554-2017). Results: Energy and protein supply increased among those pilot schools. The supply of energy increased from 1 566.5 kcal in 2012 to 1 927.4 kcal in 2017, protein increased from 49.0 g to 61.0 g. The energy ratio of fat increased from 31.9% to 34.9%, while energy ratio of carbohydrate decreased significantly (F=83.38, 128.36, 20.27 and 17.28, all P<0.05). The proportion of reasonable energy supply from carbohydrate and fat in 2017 were 17.5% and 26.8%, respectively. Conclusion The supply of energy and macronutrients in the pilot areas were unreasonable, more measures including dietary guide and monitoring need to be adopted to improve students nutrition status among rural areas.

Objective: To analyze the prevalence of stunting among students received subsidies of the National Nutrition Improvement Program for rural Compulsory Education Students (NNIPRCES) during 2012-2017. Methods: By using the data from 2012-2017 NNIPRCES survey, students aged 6-15 with valid height records were included. Stunting was defined according to the Screening Criteria of Malnutrition for School Age Children and Adolescents (WS/T 456—2014). To explore the association of the risk of stunting between different regions, gender or age groups in rural students. Results: The prevalence of stunting among students aged 6-15 who received subsidies of NNIPRCES during 2012-2017 were 8.0%, 7.9%, 6.9%, 6.5%, 6.0% and 5.3%, declined by 2.7, 1.8, 4.0 percentage points in average, as well as in central and western region, respectively. The prevalence of stunting declined with 2.7 percentage points for boys and ,2.9 percentage points for girls. The prevalence of stunting declined most at the age of 13, with 4.0 percentage points. Conclusion The prevalence of stunting of students has declined after the implementation of NNIPRCES from 2012 to 2017. However, the total prevalence of stunting was still high and the development was unbalanced between central and western region, which requires more target intervening strategies to improve the nutritional status of students.

Objective: To investigate the changes of school absenteeism among students received Nutrition Improvement Program for Rural Compulsory Education Student (NIPCES), and to provide basic data for further nutritional health improvement for rural students. Methods: Among 699 NIPCES monitored counties among 22 provinces across western and central China, 10%-30% of elementary and junior high schools were randomly selected as monitoring schools within each stratification according to the food supply pattern (school canteen, company and mix) in each county, school absenteeism information were collected and analyzed from 2012 to 2017. Results: The total rate of student absenteeism was 26.0 per 10 000. From 2012 to 2016, it dropped from 30.8 per 10 000 to 23.4 per 10 000 year by year, but it increased again in 2017(28.2 per 10 000). The rate of school absenteeism in the western region (29.4 per 10 000) was higher than that in the central region (21.5 per 10 000); The sick leave rate (15.0 per 10 000) of primary school students was higher than that of junior high school students (13.4 per 10 000), and the rate of personal leave absences (16.9 per 10 000) of junior high school students was higher than that of elementary school students(9.9 per 10 000); the absentees rate in mixed-food supply schools (28.5 per 10 000) was higher than that in canteen food supply schools(26.4 per 10 000), the latter was higher than that of company food supply schools(25.0 per 10 000). The rate of sick leave absenteeism was highest in December(18.4 per 10 000), and the rate of personal leave absenteeism in June was highest(14.6 per 10 000). Conclusion The rate of school absenteeism among students in the NIPCES area showed an overall downward trend year by year. The absentee rate of students varies by regions, grade, food supply patterns and school locations.