Childhood obesity is a major public health concern in the UK [1
]. Today, 30% of children aged 2 to 15 in England are overweight or obese [2
], and children who are becoming overweight or obese at earlier ages are likely to stay obese for longer [3
]. Inequalities in child obesity have been increasing among children aged 10−11. The gap in obesity prevalence between the least and most deprived areas among 10−11 year olds increased by 5% between 2006/7 and 2017/18 [4
The causes of obesity among children are complex and multifactorial, and a combination of measures is required to tackle them. Factors associated with overweight and obesity include unhealthy diet and insufficient physical activity [5
]. There is evidence that a sufficient intake of fruits and vegetables is related to decreased risk of non-communicable diseases (NCD), including type-2 diabetes, cardiovascular disease and cancer [7
]. Childhood is considered to be an important period for the development of healthy eating behaviours, including vegetable consumption, and children who adopt healthy eating behaviours at an early age continue to eat healthy diets into their adulthood [9
]. The World Health Organisation (WHO) recommends eating at least 400 g or five portions of fruits and vegetables per day to reduce the risks of NCDs [11
]. The European PRO-GREENS cross-sectional survey of 8158 eleven-year-old children from ten countries in Europe reported that the mean total fruit intake ranged between 114 and 240 g/d and vegetable intake between 73 and 141 g/d per day. The Health Behaviour in School-Aged Children (HBSC) study indicates that only 39% of 11 year old children consume vegetable and fruits on a daily basis, drawing on data from 44 countries in Europe and North America [12
Again, benefits of regular physical activity (PA) for the current and future health of children and young people (5−17 years old) have been well researched and acknowledged by the World Health Organisation. WHO [13
] recommends at least 60 minutes of moderate to vigorous physical activity for all children aged 5–17 years and the inclusion of vigorous and resistance activities at least three times a week. Yet, urban children are less active than the recommended levels in many countries, including the UK [14
]. According to the HBSC study, only 50% of the children participated in two or more hours of vigorous physical activity per week [12
]. Low vegetable and fruit intake and inadequate physical activity indicate the need for interventions for children that will encourage them to eat healthily and be more active on a regular basis.
Primary schools are typically the first formal institution where children spend most of their waking hours during term time. Hence, it is important that children have the opportunity to spend time outdoors and be active in this setting. The UK Government’s ‘Childhood Obesity: A Plan for Action: Chapter 2’ states “We must ensure that schools are equipping children with the knowledge they need to lead healthy lifestyles and creating environments which encourage their pupils to eat healthily and be physically active (page 27)
]. Again, physical activity and spending time outdoors is positively associated with mental health and academic performance [17
]. Hence, a ‘whole-school approach’ would support children’s health and well-being.
Different school-based programmes introduced in the past decade to tackle childhood obesity focus on either dietary intake or improvement of physical activity. Interventions focusing on the promotion of healthy eating or improving physical activity have had limited effects on reducing childhood obesity. In contrast, complex interventions potentially addressing both diet and physical activity may show more promising results in tackling obesity [20
]. The types of interventions included educational, environmental, and multicomponent, combining educational with environmental. The effect of school-based interventions including only an educational component (i.e., classroom-based activities) or only an environmental component (i.e., fruit and vegetable distribution) on children’s healthy eating is limited and not conclusive [23
]. On the other hand, multicomponent interventions (including both educational and environmental components), show more promising results in increasing children’s fruit and vegetable consumption [20
The experiential learning approach taken in this study by setting up a school garden and creating awareness about eating healthily, incorporates both the environmental and educational components addressing both dietary intake and physical activity. The health and well-being impacts of school gardens on children’s health and well-being are reported in the systematic review conducted by Ohly and colleagues [26
]. School gardens can positively influence children’s vegetable and fruit intake [27
] and their physical activity [30
]. However, in many of these interventions, the gardening activities were not linked with their meals. Knowledge of nutrition and the reference daily intake and self-efficacy have been found to be positively associated with fruit and vegetable intake [32
]. The benefits of school gardening can be amplified by incorporating hands-on learning of growing fruits and vegetables with curricular learning and school meals, making a connection between what children eat with what they could grow in their school gardens.
This study was conducted within the framework of INHERIT. (INHERIT is a Horizon 2020 project aiming at identifying and implementing policies/practices/innovations that promote health, reduce health inequalities and improve the environment). This study aimed to increase children’s physical activity and improve their attitudes to healthy eating by combining activities in the school gardens with provision of a plant-based meal once a week. The activities in the garden were run by a Schools and Community Education Project Officer (SCEO) from the Green Gym with support from class teachers, and resources from the Meat-Free Monday UK campaign. The Green Gym ® is a group outdoor activity offered by The Conservation Volunteers (TCV) to help people get physically active and make a difference to the local environment with an emphasis on health and fitness. Anyone can join free outdoor sessions where volunteers are guided in practical activities such as planting trees, sowing meadows and establishing wildlife ponds.), The Meat Free Monday campaign aims to raise awareness of the detrimental environmental impact of animal agriculture and industrial fishing, and encourages people to slow climate change and improve their health by having at least one plant-based day each week. The study was approved by the University College London Research Ethics Committee and consent was gained from both parents and children before the study commenced. The project identification code is 12543/001, date of approval is 3rd July 2018.
The ‘INHERIT model’ [33
] underpinned the conceptual framework for this research study, and is a relational model built on concepts used in the long-established DPSEEA (Drivers, Pressure, State, Exposure, Effect, Actions) model [34
] and behaviour change wheel (BCW) [35
]. The INHERIT Model comprises interconnected components and offers the basis for design, planning and evaluation of INHERIT case studies/interventions to frame, describe and assess the relationship between environment, human health and well-being and other factors. The model further facilitates the understanding of how interventions and actions can affect lifestyle behaviours by showing the causal pathway.
In the present study, an intervention is designed to change behaviour by offering opportunities to participate in gardening activities, to build capacity by learning about gardening and plant-based healthy diets, and to increase motivation amongst both teachers and children by incorporating these activities into regular curricular lessons of the school. The intervention thus enables three essential conditions: capability, opportunity, and motivation (what is termed as the ’COM-B system’ forming the hub of the BCW) [35
]. The intervention was carried out in a public primary school in North-East London in the United Kingdom. Using a pre-post design the study investigated the impact of the above-mentioned activities (gardening with provision of plant-based meals once a week) on children’s physical activity and the key determinants of fruit and vegetable intake (FVI), i.e., attitudes to and preferences in healthy eating and knowledge of nutrition and plant science. An intervention group (IG) and a control group (CG) were selected in the same school, where the former received the intervention and was compared against the CG, who were not exposed to gardening activities during the period of the experiment. The following hypotheses were examined quantitatively:
The intervention group (IG) would report significantly less sedentary behaviour (SB) and more moderate to vigorous physical activity (MVPA) compared with the control group (CG).
The IG would report significantly more daily consumption of fruits and vegetables than the CG. Significant difference is also predicted between the two groups’ attitudes to and preferences in eating fruits and vegetables.
The IG would have significantly better knowledge of nutrition and plant science compared with the CG.
Qualitative methods were used to understand the underlying reasons behind any difference between the two groups and how the intervention might have contributed to any change in the intervention group.
2. Materials and Methods
A quasi-experimental mixed methods study was conducted in a public primary school in the London Borough of Redbridge in North-East London. The borough is diverse in its profile with 11 neighbourhoods amongst the 20% most deprived in England and another 11 amongst the 20% least deprived in England [36
]. The borough is the 21st most deprived out of 33 local authorities in London, and 15.5% of children in this borough come from low-income families. The children in the school also come from diverse backgrounds, where 4.2% come from the 10% most deprived families of the borough, and 1.3% come from the 10% least deprived families of the borough. 12.3% of children are eligible for free school meals (see Table 1
In terms of the physical environment of the school, there is a tarmac playground with a playhouse, a shaded area with picnic tables, some seating areas, planters and a mound area. The mound area has 7 raised garden beds of different sizes, 2 compost bins, a small seating area and a small pond (see Figure 1
and Figure 2
a). The school also has access to a green field and woodland adjacent to the school premises; however, this area is not used on a regular basis. There is an outdoor classroom/seating area along a trail in the woodland (see Figure 2
b). Before intervention, the mound area was overgrown with weeds and the children were not engaged in any outdoor learning sessions there.
2.1. Study Participants
Sixty children (9−10 years old) from Year 5 participated in the study, where 30 children in one class were the intervention group (IG) and the other parallel class of 30 children acted as the control group (CG) (random group assignment). Children had been randomly allocated by the school to these two classes at the beginning of the school year. Both groups included children with different learning abilities and included children with autism and hearing impairment. Children aged 9−10 were selected for two reasons. Firstly, the research methods used in this study would be developmentally appropriate for children of this age (i.e., questionnaires and focus groups), and secondly, the obesity rate among Year 6 children (10−11 years old) in England is of public health concern [4
]. Therefore, identifying potential routes to obesity and overweight management among children closer to this age is crucial.
The intervention was a collaboration between the UCL Institute of Health Equity, TCV and the Meat-Free Monday Campaign UK (MFM), and included leading children outdoors for activities related to gardening, growing of food and environmental improvement and conservation every Monday afternoon during the school term for two hours. The intervention was planned to run for one school year, where the intervention group (IG) had access to the gardening activities outdoors run by the TCV for the first half of the year (September 2018 to February 2019) when the control group (CG) received their usual classes indoors. They (IG) also received one Meat-Free Monday session run by the MFM UK campaign manager (30 min), focusing on the environmental and health benefits of plant-based meals. The activities focused on encouraging children to eat more vegetables and fruits, and taste and try new vegetables; they were also encouraged to eat a plant-based meal at least once a week. For the second half of the year (February 2019 to July 2019), the CG children would have access to gardening activities and one Meat-Free Monday session. This paper reports results based on the data collected after five months of intervention in February 2019. TCV led the outdoor activities based on their experiences and guided by evidence generated from previous Green Gym evaluation studies [37
]. The UCL research team facilitated the activities, liaising with the school and ensuring access to resources needed for the intervention, and assessed the feasibility and impact of the intervention.
On the first day of gardening sessions, the SCEO introduced herself as a facilitator of the gardening activities rather than the leader. During the first few weeks, children mapped the outdoor area and suggested changes and improvements that could be made to the school ground. The Green Gym activities in the school ground were then based around the suggestions made by children that included preparing raised beds for spring crop growing by weeding, covering and refilling with newly dug leaf mulch and compost from school grounds (Figure 3
b). Children also sowed seeds of cress and lettuce in toilet rolls in their green house to transport later on to the garden beds. Children worked on creating a dead hedge as a safety barrier by collecting, sawing, hammering and weaving the wood themselves. They worked together to use slabs to create an accessible path to the garden shed, cleared the field path, removed small trees and relocated the mini-beast (insect) hotel and the compost bin. Children learned how to light small fires with no matches or lighter, collected twigs for fuel and lit kettles to heat the water for a festive hot chocolate treat before Christmas. They also tasted a wide variety of fruits and vegetables during one session.
2.3. Outcome Measures
Baseline assessments (before the intervention) were carried out at the beginning of Year 5, a week before the gardening session started. The outcome assessment was completed immediately after the intervention (middle of Year 5). Identical protocols and procedures were used at both assessments. They were undertaken by trained researchers who had completed enhanced Criminal Records Bureau/Disclosure and Barring Service checks.
Children were asked to wear a GENEActiv accelerometer (GAwrist, Activinsights, Cambs, UK) on the non-dominant wrist for seven consecutive days. The instruction was to wear the devices at all times including during sleep and water-based activities. Devices were set to record at a frequency of 100 Hz.
A self-reported questionnaire was used to measure children’s attitudes to, frequency of and preferences in eating fruits and vegetables. This reliable and valid questionnaire was developed to assess dietary patterns associated with positive energy balance and food behaviours, attitudes, knowledge and environments associated with healthy eating among Year 5, 6 and 7 children [38
]. As the current study only assessed attitudes to, frequency of and preferences in fruit and vegetable consumption, only these questions were kept in the questionnaire. The questionnaire further included items to measure children’s knowledge of plant science and nutrition used by Wells et al. [39
]. The children completed the questionnaires in their regular classroom environment. Children were given instructions on how to complete the questionnaires to ensure sufficient understanding. For questionnaire items and the response scale see Table 2
2.4. Qualitative Method
In order to gain insight into the underlying reasons behind any change due to intervention and the children’s experiences of gardening, what worked and what did not, qualitative information was sought through three focus groups with children after the intervention. Each focus group comprised four to six participants. The focus group discussion (FGD) was semi-structured and explored topics around the children’s experiences of gardening outdoors, whether gardening helped or deterred their learning and whether or how gardening had any positive/negative impact on their behaviour, physical activity and attitudes to eating fruits and vegetable. FGDs also explored children’s views of how the activities can be improved.
Teachers and instructors from Green Gyms responded to a set of open-ended structured questions in written format. The questionnaire included ten questions asking about their experiences of gardening, what went well and what did not go well and how the intervention could be improved further.
2.5. Data Analysis
GENEActiv wrist data were downloaded using the GENEActiv software version 3.2 and saved as binary files. Files were then processed in R following van Hees et al. [40
]. Days with ≥10 hours of wear time were considered valid. Sleep time was considered as the hours between midnight and 06:00 and was excluded from analyses. Children with at least 3 valid days were included in analyses. Data were segmented into the whole day from 06:00 until midnight and school time from 09:00 and 15:00 on weekdays. Daily averages were then calculated for each activity threshold across the whole day (06:00 to 24:00 H) and during school time (SH: 09:00 to 15:00). The data from the first day of wearing the devices was excluded because of potential reactivity to the measuring equipment, while the remaining wearing days were checked for validity.
Prior to all analyses, all outcome measures were checked for normal distribution (skewness and kurtosis between −2 to 2). The data from all the children from two groups have been explored together on each of the variables. All outcome measures were normally distributed. Descriptive statistics (using SPSS 24.0 for Windows (IBM Corp., Armonk, NY, USA)) were computed to describe the sample characteristics. Independent sample t-tests were conducted at baseline (T1) to assess whether there was any difference between the two groups at baseline. To assess the effectiveness of the intervention, parametric tests (one-way ANCOVA) were selected to compare the groups. In addition, a parallel samples t-test was conducted for the intervention group to measure any improvement between baseline (T1) and follow-up (T2). The data from the focus groups and structured questionnaires with teachers were analysed using thematic analysis. Qualitative data analysis software Quirkos 2.4 (Quirkos Software, Edinburgh, UK) was used for the analysis.
The present study investigated the impact of a gardening intervention aided with a Meat-Free Monday session on children’s healthy eating, physical activity and knowledge of nutrition. Results suggest that school gardens help to reduce children’s sedentary activity and promote PA. The analysis of data collected using accelerometers indicated that compared to children not engaging in any gardening activities, children having a weekly two hour session of gardening reported a greater reduction (though not significant) in their usual daily sedentary activity during the school hours. Though measures of MVPA during school hours and waking hours reduced for both groups, this reduction was less among children engaged in gardening activities, indicating a positive impact on MVPA due to intervention; however, a causal connection should be made with caution as the difference is not significant. Though there is little prior research examining the effects of school-based gardening interventions on PA, our findings are consistent with the previous study by Wells et al. [30
The qualitative findings from the study indicate a positive impact on children’s physical activity, children reported being more active than before, building muscles and improving their gross motor skills. This aligns with findings from previous studies [30
] that reported that children moved more and sat less on days when they were gardening.
Regarding healthy eating, the findings of the study indicated no effects on children’s vegetable consumption and attitudes to eating vegetables, although the existing literature indicated that school-based complex interventions and experiential learning approaches are more effective in influencing children’s healthy eating [24
]. The finding from this study resonates with the findings from a recent study by Huys and colleagues [44
]; however, it contrasts with the findings from the above-mentioned studies [24
]. The findings from the quantitative analysis also did not indicate any significant impact on fruit consumption, attitudes to and their preferences in eating fruits. However, children have shown some improvement in their familiarity with new vegetables and fruits and interest in tasting new ones.
The focus groups with children, however, indicated that they were more motivated to taste vegetables, that in many cases they thought it was acceptable to eat some vegetables, and that the taste was somewhat acceptable in more cases after intervention than before. It was also indicated in the focus group conversations with children that if they had the opportunity to grow fruit and vegetables, and taste them in the school gardens, that might have had an impact. This resonates with the findings from the qualitative study by Sarti and colleagues [45
], who explored children’s perspectives on school gardening and vegetable consumption, where children stated that they ate vegetables because they had grown them with their own hands.
Regarding knowledge about nutrition and plant science, findings from this study indicate some improvement in children’s knowledge of nutrition and plant science because of the intervention, although the difference is not significant. The positive impact on children’s knowledge is harmonious with previous studies [27
]. The qualitative findings also indicated more opportunities for social interactions and making friends with other pupils.
It is not surprising that findings from the accelerometer data did not reveal statistically significant effects considering the relatively short five month intervention period and a small sample size. Although school gardening is expected to activate children to do activities outside school hours, it seems unlikely to happen within the short timeframe of this study. In addition, the post intervention data were collected in winter, when people usually spend more sedentary time because of shorter days and longer nights. Reduction of sedentary behaviours is associated with decreases in percentage overweight and obesity and decreased risk of cardio metabolic diseases [47
]. While the approximately four minute increase in MVPA during the school hours among intervention children was modest, they do contribute to daily MVPA and they may help to counteract the tendency toward greater inactivity with age. If gardening is integrated within the school curriculum as a pedagogical tool, and a health strategy, more time could be spent gardening and engaging in garden-based lessons, possibly yielding a stronger effect. Changes in other accelerometry-measured levels of PA during the school hours and the waking hours of the day were in the predicted direction, though not statistically significant. In addition to school gardens contributing to a reduction in usual sedentary activities and nudging children’s at-school MVPA a bit higher, our results suggest that while participating in gardening activities, children engaged in diverse physical movements and postures, using their muscles in activities such as raking, using shovels, chopping and pushing trolleys. On the other hand, children spent most their time sitting in indoor class-based lessons. Allowing children to spend more time in garden-based activities can play a role in children’s gross-motor development and strengthen muscles and bones [30
Our study findings from the questionnaire reveal no significant impact on children’s frequency of, attitudes to and preferences in eating vegetables and fruits. Similar studies have found a positive impact of gardening on eating fruits [49
] but findings related to impacts on eating vegetables remain contradictory and inconclusive [44
]. However, results from qualitative data indicate some levels of acceptance on the part of children in terms of finding vegetables ‘ok’ or ‘fine’ and also some interest in trying new vegetables as opposed to not eating any vegetables. The willingness to taste new vegetables is an important objective and is the first step for the development of healthy eating behaviour among children. Our study also indicates an improvement in children’s knowledge of nutrition and plant science. Although the effect is not significant, repeated exposure to vegetables and knowledge about nutrition within the school environment through gardening may increase vegetable intake in the long run [51
4.2. Strengths and Limitations of the Study
The study design was carefully developed to take account of known sources of bias in an experimental study. We developed the intervention taking into account the determinants of overweight/obesity and also according to guidelines for complex interventions. The use of qualitative methods help to understand the underlying reasons for any changes or no changes due to the intervention. Similar studies are mostly quantitative or purely qualitative, and very few studies explored the qualitative insights along with the quantitative evaluation. However, the study has several limitations. Firstly, the study was implemented in only one school, and hence comprised a small sample. This might explain the not significant effect of the intervention on the outcome measures. However, this study can be considered as a pilot experiment and can lead to the development of future interventions and a randomized control trial with larger samples. Secondly, the study has a short intervention timeframe and was implemented only in colder periods of the year (between September and February) when not many vegetables and fruits grow. Therefore, the activities were directed more towards conservation and maintenance of environment than growing of fruits and vegetables, hence children had limited experience of the whole growing process and were not able to harvest their grown food within that period. Although programmes as short as 10 weeks showed measurable changes in preferences for vegetables [27
], an intensive programme of one whole school year could have been more effective in adequately addressing all the areas of gardening from preparation of the site to harvesting and management.
Thirdly, children on the autism spectrum and children with hearing impairment were included in the analysis. There might be debate as to whether this was appropriate, but on balance, we felt that given the inclusive nature of the study and that many children with autism spectrum disorder are in mainstream education in the UK context and they participate in the usual activities along with their peers, hence the outcomes being measured are not likely be affected by these conditions.
Fourthly, there was limited engagement of teachers in the design and planning of gardening activities and linking them with the curriculum, whereas integration in the curriculum is one of the most important success factors for school gardening programmes [26
]. In addition, involvement from the Meat-Free Monday campaign was limited to one interactive session. Although online lesson plans were available on the Meat-Free Monday website, more time from teachers for direct involvement in the planning and design of activities and having some training on outdoor learning could have improved the quality of the implementation. This would also be important for later implementation and potential upscaling. Finally, one important factor possibly playing an important role in the lack of measurable effects is the fact that parents or the community were not involved in the project. Parents play a key role in children’s fruit and vegetable consumption, and the involvement of parents in school-based programmes is as important as the involvement of teachers [53
] and can potentially contribute to the success of the programme [23