Do health-promoting schools improve nutrition in China?

Abstract

To demonstrate the effectiveness of health-promoting school framework to promoting healthy eating behaviours and nutrition knowledge among Chinese middle school students, their parents and school staff. Three schools were randomly selected from 15 rural middle schools, then were randomly assigned to either (i) school using HPS framework (HPS school), (ii) school with improved health education only (HE school) or (iii) school received no intervention (control school). Nutrition knowledge and eating behaviours were measured at baseline and 3-month after interventions, using the same instrument. Students and parents in the HPS school had the largest improvement in nutrition knowledge, from 4.92 to 8.23 and 4.84 to 7.74, followed by those in the HE school, from 4.98 to 8.09 and 4.78 to 5.80. School staff in the HE school had the largest improvement in nutrition knowledge (from 4.40 to 8.45), followed by those in the HPS school (from 5.20 to 9.15). Students in the HPS school had the largest improvement in eating behaviours (from 3.16 to 4.13), followed by those in the HE school (from 2.78 to 3.54). There was a statistical difference in the improvement of nutrition knowledge of all target population and of eating behaviours of students after interventions across three schools (p < 0.05). Both HPS framework and health education can increase nutrition knowledge among Chinese middle school students, their parents and school staff. However, HPS framework was more effective than health education only. Noticeably, HPS framework had a positive impact on students' eating behaviours, which should be in the subject of further research.

nutrition knowledge, eating behaviours, health-promoting school, China

INTRODUCTION

Adolescent years have been recognized as being critical in terms of rapidly changing body size, composition, functions and physical abilities and also in social and educational terms, as good nutrition and health can enhance students' educational performance and learning (McKenna, 2003). It is also the period when lifelong diet and eating behaviours are established (Türkan, 2011). Growing global concern about healthy diet and nutrition for adolescents has focused on both under-nutrition that can slow growth in height and weight and may delay puberty (Naidoo et al., 2009); and also overweight and obesity that can lead to chronic, long-term health problems such as coronary heart disease, type 2 diabetes and stroke (Story et al., 2000).

Studies indicate that nutrition-related health problems among youth are apparent in developing countries where over- and under-nutrition can paradoxically coexist. China represents an industrializing country currently experiencing a severe crisis in health and nutrition (Tudor-Locke et al., 2003). Studies over the last two decades have shown that nutritional deficiencies and over-nutrition are significant and growing problems in many parts of China (Fu et al., 2001). A national survey on diet and nutrition in 1992 revealed that the energy intake of young people aged 2–18 years reached 97% of the recommended daily allowance, but nutrient intake was unbalanced (Chen, 1999). Another survey conducted in eight Chinese cities in 1996 revealed an increase in obesity from 3.4% in 1985 to 7.2% among 7–18-year-old students (Yang et al., 2000). Statistics released by the Chinese Capital Institute of Pediatrics in 2011 (Xinhua News) show that among youth aged 0–18 years old in Beijing, 20% are overweight or obese and that the obesity rate has increased five- to seven-fold over the last 20 years. In addition, children and adolescents in rural areas of China, affected by poor living conditions and relatively low family income, have poor health awareness, low levels of health-related knowledge and unhealthy nutrition-related behaviour (Shi et al., 2006). Youth in rural areas also have a poorer nutrition and dietary intake pattern than their counterparts in urban areas of China (Wang et al., 2002).

Schools have been identified by the World Health Organization (WHO, 2003) as the ideal setting for promoting better health and nutrition. Improved health and nutrition may also take place across the broader school community, through student influence on parents and care-providers (Inchley et al., 2001; Massey-Stokes, 2002). The increasing power of peer group socialization and the amount of time spent at school add to the significance of the school years in terms of eating behaviours and diet (Moore et al., 2000; Derry, 2006). Recognition of the school as a critical setting for nutrition programs and services has been widely accepted both for the improved educational potential it offers directly to students and also for the development of a supportive environment for lifelong dietary, hygiene and exercise habits (WHO/FAO, 1998; MacLellan et al., 2010).

With this recognition, health promotion in schools has become a central feature of efforts to improve health, including nutrition. The model advocated by the WHO and established across many countries is that of the health-promoting school (HPS) (WHO, 2003). Underpinned by Bronfenbrenner's ecological theory (Bronfenbrenner, 1979), this model adopts a whole-school approach that integrates school activities, such as a sequential and planned nutrition curriculum; related aspects of the school environment, such as improvements in nutrition-related school policies and physical improvements to food-related areas; and engagement with families and the wider school community (Bowker et al., 1998). This model has increasingly been endorsed as an effective way to promote nutrition and health in the school setting (Lee, 2005).

Published studies evaluating the efficacy of using the holistic HPS approach to school-based nutrition promotion and comparing it with more traditional curriculum-only based approaches are, however, limited, particularly in China. This study seeks to demonstrate the effectiveness of applying a socio-ecological approach, as provided by the World Health Organization's HPS framework, to promote healthy eating behaviours and improve nutrition knowledge among middle school students, their parents and school staff in Chinese Middle Schools in rural areas and explores the extent to which this is an appropriate and effective model for nutrition promotion among students, their parents and school staff in Chinese Middle Schools.

METHODS

Study design and data collection

The study design was multi-factorial with repeated measures, at two points in time, of dependent samples from one control and two intervention schools. Three schools were randomly selected from 15 middle schools in rural areas of Mi Yun County to participate in this survey; these are labelled School A, School B and School C to preserve anonymity. The three schools were then randomly assigned to either (i) a holistic intervention school using the HPS framework (HPS school), (ii) to a partial intervention school with a modified Health Education curriculum (HE school) or (iii) to a school that does not receive either the HPS or HE intervention (control school). Nutrition knowledge and eating behaviours were measured at baseline and at 3 months' follow-up, with the same instrument. The baseline survey was conducted in July 2012, the intervention activities were implemented in pilot schools from September to November 2012 and then an evaluation survey was conducted in December 2012.

From each school 65 second-year students, a parent of each student and 20 school staff were randomly selected to complete the self-administered questionnaire. Each respondent was provided with full information about the study. Informed written consent was obtained from each school student and their guardians. The investigator was a Chinese national fluent in Mandarin, who had received prior training. A total of 195 students, 195 parents and 60 school staff were invited to complete the questionnaire. In all, 188 pairs of students and their parents and 60 school staff completed both baseline and follow-up questionnaires, and participated in interventions as required, with a response rate of 96.4 and 100%. The age of the 188 students ranged from 12 to 14 years (mean ± SD = 12.8 ± 0.45 years), with 91 males (48.4%) and 97 females (51.6%). The age of the 188 parents ranged from 32 to 54 years (mean ± SD = 40.53 ± 4.09 years), with 82 males (43.6%) and 106 females (56.4%). The age of the 60 school staff ranged from 26 to 52 years (mean ± SD = 41.05 ± 5.31 years), with 25 males (41.7%) and 35 females (58.3%).

The project received ethical clearance approval both from the University Human Research Ethics Committee in Australia (Reference No: PBH/14/12/HREC) and from the Peking University Institutional Review Board (Ethics Review Approval No: IRB00001052-12024).

Instrument

The instrument for the study was a 22-item, self-administered, structured questionnaire, designed in Chinese. The questionnaire was divided into three main sections to assess respondents' nutrition knowledge and eating behaviours. Section A (Personal Information) and Section C (Food Frequency Consumption) were derived from the Health-Related Behaviors Questionnaire for Chinese Youth (Middle School Students Version) designed by Ji Chengye, an expert in nutrition from Peking University. This questionnaire had been pre-tested on a small sample before being widely used in China. Section B (Nutrition Knowledge) was derived from two English questionnaires, both with good internal reliability with mean Cronbach's alpha scores of 0.73 (Oldewage-Theron and Egal, 2010), and 0.57 and a test–retest reliability of 0.80 (Turconi et al., 2003). These were translated into Chinese. Thus, Sections A and C had been used in China before and Section B had not.

Sections A and B comprised 10 questions, each with 5 response categories structured in different ways, with the ‘true’ response to each question receiving a score of one and zero for the other responses. The total score for this section was thus 10. The Section B nutrition knowledge questions addressed the main function of necessary nutrients, which food was richer in certain nutrients, and the symptoms and causes of food poisoning. Section C examined respondents' food frequency consumption, aimed at investigating weekly frequency of consumption of fresh fruit, vegetables, dairy products, breakfast, dessert, fried food and soft drinks. Respondents who ate breakfast, fresh fruit, vegetables and dairy products every day and who did not consume soft drinks, dessert and fried food over the previous 7 days received a score of one, with zero for the other responses. The total score for this section was thus 7.

Each questionnaire took ∼20 min to complete. Standardization of the questionnaire was also ensured by carrying out a pilot study on 70 students and their parents in a school randomly selected from the same rural areas (Mi Yun County) as the main study. Following the pilot study, minor adjustments, such as deleting unnecessary options in the questions and simplifying the language, were made to the questionnaire, prior to commencement of the study. The Cronbach's alpha of the student questionnaire was 0.89 and the Cronbach's alpha of the parent questionnaire was 0.91.

Interventions

The HPS school implemented a wide range of health promotion activities using the HPS approach, as indicated in Table 1. The HE school undertook a modified curriculum intervention only; the control school did not receive either the HPS or the HE intervention, but continued with standard school activities and curriculum. The core information component of the interventions in the HPS school and HE school contained the definition and importance of a balanced diet, the functions of the nutrients, nutrient deficiencies and their effects, how to supplement necessary nutrients reasonably, good hygienic practices and food safety.

Table 1:

Intervention components

HPS domains	Interventions
School environment and ethos	Formation of school nutrition group and nomination of group leader Regular school nutrition group meeting (every month) School staff nutrition training (one time, 90 min) Distribution of publicity resources for school staff (one time, before the training) Post-posters to publicise healthy diet and nutrition (change every month)
Modified curriculum	In-class curriculum (every week) Distribution of publicity resources for students (one time, before the first in-class curriculum) Peer support activities (every month)
Family/community involvement	Parents workshops (one time, 90 min) Distribution of publicity resources for parents (one time, before the workshop) Short message to parents (every month)

Statistical analysis

Using Epidata3.02 software, data were coded and entered onto a computer, and then logical error detection and verification carried out to exclude missing data and abnormal values.

Analysis was performed using SPSS 13.0 (SPSS Inc.) software. During data analysis, the baseline and follow-up questionnaires were paired and compared. Statistical analysis was conducted using mean and proportion to summarize respondents' basic characteristics. The χ² test of significance was used to identify the differences in socio-demographic characteristics of respondents by three schools. The impact of interventions on nutrition knowledge and dietary intake were assessed using the one-way ANOVA, all put at a p value of 0.05.

RESULTS

Study population characteristics

Of the 188 students, 62 came from the HPS school (33%), 65 from the HE school (34.6%) and 61 from the control school (32.4%); 165 (87.8%) were of Han nationality and 23 (12.2%) of Minority nationality. For parents in the study, 62 came from the HPS school (33%), 65 from the HE school (34.6%) and 61 from the control school (32.4%); 170 (90.4%) were of Han nationality and 18 (9.6%) of Minority nationality. Almost all (96.3%) parents were married, 2.7% were divorced and 1.1% was widowed. The education level of surveyed parents was in general not high, with the majority (68.1%) having graduated from middle schools, and only ∼5% having graduated from college or university. The relatively lower education level also related to their occupation type, with most of them (42.6%) employed as agricultural workers, followed by urban migrant workers (12.2%) and owners of small individual businesses (12.2%). Of 60 surveyed school staff, with 20 from each school, 54 (90%) were of Han nationality and 6 (10%) of Minority nationality, 59 (98.3%) were married and 1 (1.7%) was divorced, and all of them graduated from university or higher. There was no statistically significant difference in students, their parents or school staff in terms of age, gender, nationality, marital status, education level and occupation across the three schools (p < 0.05) (Table 2).

Table 2:

Study population characteristics

	HPS (n = 62)		HE (n = 65)		Control (n = 61)		Total (n = 188)		χ2
	n	%	n	%	n	%	n	%
Students
Gender
Male	30	48.4	29	44.6	32	52.5	91	48.4	0.679
Female	32	51.6	36	55.4	29	47.5	97	51.6
Age
Min	12		12		12		12		0.811
Max	13		14		14		14
Mean ± SD	12.73 ± 0.45		12.95 ± 0.37		12.70 ± 0.50		12.80 ± 0.45
Nationality
Han nationality	54	87.1	57	87.7	54	88.5	165	87.8	0.971
Minority nationality	8	12.9	8	12.3	7	11.5	23	12.2
Parents
Gender
Male	29	46.8	29	44.6	24	39.3	82	43.6	0.694
Female	33	53.2	36	55.4	37	60.7	106	56.4
Age
Min	32		33		35		32		0.337
Max	53		54		52		54
Mean ± SD	40.32 ± 3.96		40.15 ± 4.53		41.15 ± 3.71		40.53 ± 4.09
Nationality
Han nationality	57	91.9	57	87.7	56	91.8	170	90.4	0.651
Minority nationality	5	8.1	8	12.3	5	8.2	18	9.6
Marital status
Married	60	96.8	63	96.9	58	95.1	181	96.3	0.834
Divorced	1	1.6	2	3.1	2	3.3	5	2.7
Widowed	1	1.6	0	0	1	1.6	2	1.1
Occupation
Manager/leader	1	1.6	2	3.1	3	4.9	6	3.2	0.379
Professionals	3	4.8	7	10.8	6	9.8	16	8.5
Clerk	5	8.1	2	3.1	2	3.3	9	4.8
Individual businesses	7	11.3	8	12.3	9	14.8	24	12.7
Commercial and services personnel	5	8.1	5	7.7	3	4.9	13	6.9
Worker of non-agricultural registered permanent residence	7	11.3	5	7.7	0	0	12	6.4
Urban working farmers	9	14.5	8	12.3	6	9.8	23	12.2
Agricultural laborers	23	37.1	25	38.5	32	52.5	80	42.6
Temporary worker or redundant	2	3.2	3	4.6	0	0	5	2.7
Educational attainment
Junior school or lower	6	9.7	4	6.2	1	1.6	11	5.9	0.255
Middle school	40	64.5	43	66.2	45	73.8	128	68.1
High school	15	24.2	15	23.1	9	14.8	39	20.7
College	1	1.6	2	3.1	3	4.9	6	3.2
University or higher	0	0	1	1.5	3	4.9	4	2.1
	HPS (n = 20)		HE (n = 20)		Control (n = 20)		Total (n = 60)		χ2
School staff
Gender
Male	11	55	9	45	5	25	25	41.7	0.147
Female	9	45	11	55	15	75	35	58.3
Age
Min	33		26		30		26		0.484
Max	48		52		47		52
Mean ± SD	39.90 ± 4.24		42.45 ± 6.72		40.80 ± 4.58		41.05 ± 5.31
Nationality
Han nationality	18	90	18	90	18	90	54	90	1.000
Minority nationality	2	10	2	10	2	10	6	10
Marital status
Married	20	100	20	100	19	95	59	98.3	0.362
Divorced	0	0	0	0	1	5	1	1.7
Educational attainment
University or higher	20	100	20	100	20	100	60	100	1.000

Impact of interventions on nutrition knowledge

The results showed that students and parents in the HPS school had the largest improvement in nutrition knowledge, from 4.92 to 8.23 and 4.84 to 7.74, respectively; followed by those in the HE school, from 4.98 to 8.09 and 4.78 to 5.80, respectively. The school staff in the HE school had the largest improvement in nutrition knowledge (from 4.40 to 8.45), followed by those in the HPS school (from 5.20 to 9.15). Students, parents and school staff all had the least improvement in nutrition knowledge in the control school. As for different surveyed groups, the school staff gained the largest improvement (3.33 points) in nutrition knowledge, followed by students (2.59 points) and parents (1.55 points) (Table 3). In general, there was a statistically significant difference in the improvement of nutrition knowledge of students, parents and school staff after interventions across the HPS school, the HE school and the control school (p < 0.001) (Table 4).

Table 3:

Nutrition knowledge score and eating behaviour score of students, their parents and school staff in HPS, HE and control schools at baseline and follow-up survey

	Baseline	Follow-up	Improvement
Nutrition knowledge score
Students
HPS school	4.92	8.23	3.31
HE school	4.98	8.09	3.11
Control school	4.52	5.82	1.3
Total	4.81	7.4	2.59
Parents
HPS school	4.84	7.74	2.9
HE school	4.78	5.8	1.02
Control school	4.48	5.21	0.74
Total	4.7	6.25	1.55
School staff
HPS school	5.2	9.15	3.95
HE school	4.4	8.45	4.05
Control school	4.65	6.65	2
Total	4.75	8.08	3.33
Eating behaviour score
Students
HPS school	3.16	4.13	0.97
HE school	2.78	3.54	0.76
Control school	2.64	3.02	0.38
Total	2.86	3.56	0.7
Parents
HPS school	3.37	3.92	0.55
HE school	2.78	3.31	0.52
Control school	3.23	3.54	0.31
Total	3.12	3.59	0.46
School staff
HPS school	3.45	4.45	1
HE school	3	3.75	0.75
Control school	3.55	4.3	0.75
Total	3.33	4.17	0.83

Table 4:

Results of one-way ANOVA

	Sum of squares	df	Mean square	F	p
Improvement of knowledge score (students)
Between groups	151.526	2	75.763	35.564	0.000***
Within groups	394.112	185	2.130
Total	545.638	187
Improvement of behaviour score (students)
Between groups	10.994	2	5.497	8.452	0.000***
Within groups	120.325	185	0.650
Total	131.319	187
Improvement of knowledge score (parents)
Between groups	172.362	2	86.181	69.257	0.000***
Within groups	230.207	185	1.244
Total	402.569	187
Improvement of behaviour score (parents)
Between groups	2.087	2	1.044	2.657	0.073
Within groups	72.652	185	0.393
Total	74.739	187
Improvement of knowledge score (school staff)
Between groups	53.433	2	26.717	7.936	0.001***
Within groups	191.900	57	3.367
Total	245.333	59
Improvement of behaviour score (school staff)
Between groups	0.833	2	0.417	0.399	0.673
Within groups	59.500	57	1.044
Total	60.333	59

Impact of interventions on eating behaviours

Compared with the increase in nutrition knowledge, the improvement in eating behaviours was not big, with the largest increase among the school staff in the HPS school (from 3.45 to 4.45). Except for this group, the improvement in eating behaviour score in other groups was all less than 1 point. As for different surveyed groups, school staff gained the largest improvement (0.83 point) in eating behaviours, followed by students (0.70 point) and parents (0.46 point). There was a statistically significant difference in the improvement of eating behaviours of students after interventions across all three schools (p < 0.001), with students in the HPS school having the largest improvement in eating behaviours (from 3.16 to 4.13), followed by those in the HE school (from 2.78 to 3.54) and in the control school there was a small increase (from 2.64 to 3.02). There was no statistical difference in the improvement of eating behaviours of parents and school staff after interventions across the three schools (Tables 3 and 4).

DISCUSSION

This study was designed to demonstrate the effectiveness of a holistic HPS framework to promote healthy eating behaviours and nutrition knowledge among middle school students, their parents and school staff in Chinese Middle Schools and to investigate if this is an appropriate model for nutrition promotion among the target population. The results show that, although all target groups (students, their parents and school staff) whether in the HPS school, HE school or control school gained a nutrition knowledge increase over the 3 months of the intervention period, there was a significant difference in the extent of the improvement across the three target groups among HPS school, HE school and control school. Students and parents in the HPS school showed the largest improvement in nutrition knowledge, while the school staff in the HE school had the largest improvement in nutrition knowledge. Further, students and school staff both in the HPS school and the HE school showed a substantial increase in nutrition knowledge; however, only parents in the HPS school showed a large increase in nutrition knowledge. This is consistent with previous studies, for example, studies have shown that knowledge about diet and nutrition improved significantly after nutrition promotion interventions using HPS framework among students, such improvements ranging from the importance of eating a balanced diet (Malcolm, 2005), the concept of a balanced diet and healthy eating (Chan et al., 2011), the relationship between diet and health at present and in the future (Dixey et al., 2001), classification of foods (Sheila, 1995), the recommendations for fruit and vegetable intake (Griffin et al., 2010) and food hygiene knowledge (Eves et al., 2006). The merit of our study is that it not only indicates the effectiveness of using the HPS framework to promote nutrition knowledge among students, but also among parents and school staff, which amply reflects the purport of a ‘holistic’ approach to the school context.

Further, it is worth noting that except for the parents group, both students and school staff in the HE school showed an improvement in nutrition knowledge after intervention as substantial as those in the HPS school, which demonstrates the efficacy of health education in nutrition knowledge improvement, especially for those people in the immediate school environment. Generally speaking, nutrition education is about the provision of knowledge and skills for food consumers so that they can perform healthier eating and drinking behaviours. It may also include communications which are designed to motivate them to consume a healthier diet (Paul, 2003). Thus, our study found that nutrition promotion interventions using the HPS framework is the most effective model to improve nutrition knowledge for all target populations (students, teachers and parents), while for those in schools, particularly teachers, health education is also a highly effective way to improve nutrition knowledge.

This study found, however, that the improvement of eating behaviours was not as obvious as enhanced nutrition knowledge after the interventions. In the HPS school, only the students' eating behaviours had improved significantly after the intervention, while that of parents and school staff had not. Although the desired behaviour change across all target populations did not take place this is consistent with other studies, taking into account the complex nature of eating behaviour and that it is difficult to change (Lynagh et al., 1997; Freeman and Bunting, 2003; Bullen and Benton, 2004; Doak et al., 2006).

The interventions in our study had a modest, yet positive impact on our target populations' eating behaviours in general, with students, teachers and parents obtaining higher eating behaviour scores after the interventions compared with the baseline survey. These target populations in the HPS school achieved a larger improvement in eating behaviours than those in the HE school, which, in turn achieved a larger improvement in eating behaviours than those in the control school. In terms of effectiveness, the experience of this project serves to indicate that an integrated, comprehensive approach that includes students, their parents and the teachers, provides a ‘boosting’ effect over a more narrow approach that relies on education alone. A longer term project should help to illustrate the full extent of such a boost.

Limitations

The findings reported in this study should be considered in the light of a number of limitations. In particular, 3 months is a short intervention period and so it is not surprising that some of the changes in knowledge, attitudes and behaviour were of relatively limited size. A number of authors have identified the length of time in a school-based nutrition intervention study as critical (Odea and Maloney, 2000; Radcliffe et al., 2005; Morgan et al., 2010; Rana and Alvaro, 2010). It is likely, should the interventions be continued, that a stronger and more sustained intervention impact would be found.

Funding

This study was supported by Grant for Higher Research Degree students in School of Public Health, Griffith University.