Effects of school-based interventions on Food and Nutrition Literacy (FNLIT) in primary-school-age children: a systematic review

Abstract

This study systematically reviewed the evidence on interventions seeking to improve Food and Nutrition Literacy (FNLIT) functional, interactive and critical skills in primary school-aged children. Electronic databases, including PubMed/MEDLINE, SCOPUS, Web of Science, Cochrane, Pro-Quest and Google Scholar were systematically searched. Randomised and non-randomised controlled trials, pre-/post-test and case–control designs were included. The primary outcomes were three levels of FNLIT: functional, interactive and critical. All citations, full-text articles and abstract data were screened by two independent reviewers. Any conflicts were then resolved through discussion. The quality of the included studies was individually evaluated using the Effective Public Health Practice Project (EPHPP) quality assessment tool. Two reviewers extracted data from the included studies, and a descriptive analysis was performed. The quality of all eligible studies (n 19) was rated as moderate/weak. A wide variety of skill-building activities were introduced by programmes, including recipe skills/food preparation, food label literacy, food tasting, gardening harvesting, and supporting cultural practices and ethnic foods. Only four studies measured food literacy (FL) (food label literacy) via a valid measure. Most interventions focused on the functional level of FL, except for two programmes (one scored weak and one scored moderate). In most of the studies, delivery of intervention content was facilitated by teachers (n 15). Promising interventions were tailored to the needs and interests of students, incorporated into the existing curriculum and facilitated by teachers. The successful intervention strategies led to improvements in functional, partly interactive and critical skills. Future interventions should focus, holistically, on all aspects of FNLIT, especially interactive and critical skills.

Food/nutrition literacy is an important topic in public health research; indeed, the growing attention towards food/nutrition literacy is because it is considered as bridging the gap between food, nutrition and well-being in communities. In addition, it can serve as a fundamental step towards the capacity building to effectively use nutritional knowledge and skills, specifically in meeting children’s current and future health⁽¹⁾.

A myriad of definitions and conceptualisations of food/nutrition literacy are provided in the research; however, a widely cited definition describes food literacy (FL) as a collection of inter-related knowledge, skills, and behaviours required to plan, manage, select, prepare, and eat foods to meet needs and determine food intake. FL is the staging that empowers individuals, households, communities and nations to protect diet quality through change and support dietary resilience over time⁽²⁾. Some studies have characterised FL as the ability to search and understand nutrition-related information⁽³⁾. In a review of 173 studies, Krause and colleagues⁽⁴⁾ classified FL into three conceptual elements of Nutbeam’s health literacy definition⁽⁵⁾, including functional, interactive and critical FL. Doustmohammadian et al. have also previously defined Food and Nutrition Literacy (FNLIT) based on Nutbeam’s model of health literacy, to which the cognitive and skill domain has been added; indeed, based on this study, the cognitive domain included knowledge and understanding, while skill domains included food choice, functional, interactive and critical skills⁽⁶⁾.

Childhood and adolescence are critical periods of life in which many eating habits are formed and generally continue into adulthood⁽⁷⁾. Promoting FNLIT in children empowers them to control the determinants of nutritional health⁽⁸⁾. Available evidence shows that most children and adolescents do not follow dietary guidelines’ recommendations. For example, fruit and vegetable consumption in 5–18-year-old children is less than the recommended level, whilst only 15 % of students consume the recommended intake of milk and dairy products^(9,10) . A general shift in children’s dietary patterns has been noted towards the lower intake of fruit and vegetables, fibre-rich foods, and dairy products⁽¹¹⁾, as well as increased consumption of high-energy-dense foods⁽¹²⁾. Thus, FNLIT along with other environmental factors may be a crucial factor in promoting food choices and eating behaviours among children and adolescents^(1,13) .

According to the extant literature, early prevention programmes are recommended to best influence children’s learning skills and increase the possibility of more successful behaviour stabilisation to maintain healthy dietary habits into adulthood⁽¹³⁾. Indeed, paying attention to FNLIT promotion among children may be essential in improving dietary patterns, health and well-being. Schools have direct contact with students for about 6 h a day and up to 12 critical years of intellectual, psychological, social and physical development⁽¹⁴⁾. The WHO identified the school setting as ideal for nutrition education and promoting healthy eating practices in children⁽¹⁵⁾; however, the lack of documented policies and programmes relating to FNLIT is a preponderant issue in developing countries.

Kelly et al. reviewed the efficacy of FL interventions, without focusing on the quality of the studies, in elementary schoolchildren aged 4–12 years old and concluded that few interventions (28 %) addressed critical FL⁽¹⁶⁾. The other limitation of the aforementioned study was the lack of grey literature searched. Furthermore, the authors just focused on FL and did not consider the wide and multifaceted topic of FNLIT^(6,17) in their search strategy and review.

The multi-dimensional nature of the concept of FNLIT necessitates multi-level interventions to improve FNLIT^(2,18) . The first step to develop such interventions includes referring to the evidence and successful modelling examples⁽¹⁹⁾. Unfortunately, most studies in the field of food/nutrition literacy are correlational⁽²⁰⁾, and there is a lack of convincing studies to demonstrate the change in FNLIT as the outcome of interventions. Therefore, this systematic review aims to identify interventions targeted at promoting children’s FNLIT in the school setting. The current study aims to identify: (1) strategies and principal components of FNLIT promotion, (2) the implementation methods of the interventions, and (3) the effectiveness of interventions in promoting FNLIT among primary schoolchildren.

Methods

This systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines⁽²¹⁾. The current systematic review was registered with PROSPERO, the International Prospective Register of Systematic Reviews (CRD42019135118). The authors published a more detailed systematic review protocol in addition to the online registration⁽²²⁾.

Inclusion and exclusion criteria

Eligible study designs were quantitative studies, including case–control studies, pre- and post-interventions, post-test only, randomised and non-randomised controlled trials that allocated students individually or in clusters (i.e. teachers, classrooms and schools), and quasi-randomised trials examining the effectiveness of interventions for FNLIT promotion in primary students aged 5 to 12 years.

Any studies available in full-text and English-featuring interventions that contained one or more dimensions of the skill domain of food/nutrition literacy, including functional, interactive and critical food/nutrition literacy that targeted children aged 5–12 years old in elementary schools, or other equivalent educational settings, were searched for and included accordingly. Nutritional interventions focused on diabetes, obesity and other non-communicable diseases were excluded.

Referring to Nutbeam’s model of health literacy^(5,23) , the primary outcomes in the review consisted of FNLIT in skill domains, including functional, interactive, and critical FNLIT. Based on the available evidence, components of each dimension of the skill domain are presented in Table 1.

Table 1. Study eligibility and exclusion criteria based on the PICOS elements

PICOS, Population, Intervention, Comparison, Outcome, Setting⁽²⁶⁾

We considered interventions whose reported outcomes increased FNLIT skills (functional, interactive and critical) or both dimensions of food/nutrition knowledge and skills.

Interventions that were solely aimed at food and nutrition knowledge improvement were not considered. Successful interventions and those that included theories and hands-on activities to enhance literacy were taken into account.

Secondary outcomes included diet quality improvement (e.g. healthy eating index)⁽¹⁾, nutritional indicators (e.g. dietary diversity score), weight loss⁽²⁴⁾ and lifestyle health promotion⁽²⁵⁾.

All positive and negative outcomes were considered in the study.

Search strategy

The review team (AD, NO and MHS) designed a search strategy and implemented the suggested query or search strategy suited to the environment of data banks for multiple databases. According to the PICOS format (Participant, Intervention, Comparison, Outcome and Setting)⁽²⁶⁾ and the MeSH database, a draft of the search strategy can be found in Supplemental Table S1.

The primary source of literature was a structured search of major electronic databases, up to 1 October 2021, including PubMed/MEDLINE, SCOPUS, Web of Science, Cochrane and Pro-Quest. Google Scholar as a source of grey literature was searched up to page 20 (first 200 results) for title searches using the following keywords and was performed in duplicate: ((FL) or (nutrition literacy) or (health literacy) or (functional literacy) or (critical literacy) or (interactive literacy) or literacy or food or nutrition)) AND (education or school or student or teaching or training or class or curriculum or lesson or instruction) AND (garden or harvest or cook or taste or label or skill).

Hand-searching of the reference lists of included studies, relevant reviews, and documents were conducted to identify other relevant studies.

Study selection

All citations were imported into Endnote X7 citation manager⁽²⁷⁾ and were systematically de-duplicated, and a merged library was created. The de-duplication process was validated by Systematic Review Assistant-Deduplication Module (SRA-DM)⁽²⁸⁾. Based on the pilot-tested inclusion criteria checklist, two review authors (AD and MK) independently screened studies for eligibility by their titles and abstracts. The full texts of all the potentially relevant papers were then retrieved and assessed independently by the two review authors (AD and MK). The final decisions were made according to the inclusion criteria checklist, and the reasons for article discarding were documented (online Supplementary Table S2).

At all stages, disagreements were resolved by seeking a third review author’s view (NO). The PRISMA flowchart⁽²¹⁾ was used to document the selection process.

Data extraction

A pilot-tested standardised form was used to extract data from each study report. We extracted the following data: author (s), publication year, target group (age, sex and number of participants), intervention description (name, study design, comparison or control groups, components, duration, and follow-up of intervention), FL/nutrition literacy validated tools (if any), theory basis of intervention (if any) and FNLIT outcomes.

Two reviewers (AD and MK) performed data extraction independently, and potential conflicts were resolved through discussion. As necessary, original authors of primary publications were contacted for data clarifications or missing outcome data.

Quality appraisal

Two reviewers separately evaluated the risk of bias in the included reports by the validated quality assessment tool for quantitative studies (online Supplementary Table S3). This tool was developed by the Effective Public Health Practice Project (EPHPP)⁽²⁹⁾ to assess the quality of included studies in systematic reviews relating to public health topics⁽³⁰⁾. Seven elements of the quality assessment tool were included: selection bias, study design, confounders, blinding, data collection methods, withdrawals/dropouts and analysis, leading to an overall rating of strong, moderate or weak⁽³⁰⁾: (a) strong (when there were no weak rating); (b) moderate (when one factor was rated as weak); and (c) weak (when two or more factors were rated as weak).

The quality assessment of all the included studies was conducted by two authors (AD and MK) and was reported in Supplementary Table S3. Potential conflicts were resolved through discussion.

Synthesis of results

The quantitative analysis (meta-analysis or statistical pooling) was not considered due to the lack of sufficient studies with similar outcome measures or similar interventions; therefore, only a descriptive analysis was performed.

Results

Study selection

Our literature search yielded 7809 publications between 1997 and 2020 (PubMed = 1057, SCOPUS = 1880, Web of science = 4535, Cochrane = 98, Pro Quest = 123, and Google Scholar = 116). After removing duplicates, 102 articles were screened based on title and abstract review. Of these, 64 publications were excluded for the following reasons: no full text available (n 29), thesis (n 26), the paper was not in English (n 2), book, conference abstract (n 5) and review (n 2). The full texts of the remaining thirty-eight publications were retrieved for further assessment, of which nineteen failed to meet the inclusion criteria. The main reason for excluding full texts was that they were not school-based interventions (Fig. 1, online Supplementary Table S2). Finally, nineteen articles were included, such that their characteristics are summarised in Table 2. The quality assessment of each of these studies is depicted in Fig. 2.

Fig. 1. PRISMA diagram.

Table 2. Key characteristics of reviewed studies (n 19)

FL, food literacy; NL, nutrition literacy; NS, not stated; SCT, Social Cognitive Theory; TPB, Theory of Planned Behavior.

Fig. 2. Quality assessment (using the EPHPP) of reviewed studies (n 19).

Study characteristics

The main theoretical models of behaviour change used in developing food/nutrition literacy interventions were Social Cognitive Theory (n 5, 26·31 %)^(31–35) and Theory of Planned Behavior (n 1, 5·26 %)⁽³⁶⁾. Theory-based interventions mainly improved functional food/nutrition literacy (Table 3).

Table 3. Summary of intervention description in terms of content, facilitators, cooking course association setting and its effect on the FNLIT dimensions and its components by the quality level of study

Four studies (21 %) were randomised controlled trials^(35,37–39) , and four (21 %) used a case–control design^(36,40–42) . In three studies (15·78 %), two groups were compared pre- and post-test^(33,43,44) , but most studies (n 8, 42·10 %)^{(31,32,34,45–49)} used the same group tested pre- and post-intervention.

Fifteen out of nineteen studies (78·94 %) had not used a valid scale to measure FNLIT and its components. Only four studies (%) measured food label literacy by valid measures^{(32,43,48,50)} . In one study, a change in knowledge of food labelling was assessed by asking individuals whether a food label was present on a product⁽³²⁾. Validated multi-item ‘food label literacy’ tools to evaluate the food label literacy of students were used only by two studies^(43,50) . Treu et al. ⁽⁴³⁾ evaluated knowledge of healthy food choices in the form of food label literacy in school-aged children by the Food Label Literacy and Nutrition Knowledge (FLLANK) questionnaire, which previously underwent validation testing in the Independence School District (ISD)⁽⁵¹⁾.

Eighteen of the nineteen studies were set in high-income countries, as classified by the World Bank economic classification⁽⁵²⁾. Of these, fifteen studies were conducted in the USA^{(31,33–36,38–40,42–46,48–50,53)} , two in Australia^(33,37) , one in the UK⁽⁴¹⁾ and one in Spain⁽⁴⁷⁾.

Of the included studies, ten targeted children aged 7–10 years^{(31,35,37,38,41–44,47,49)} , four studies targeted children aged 11–15 years^{(32,33,40,48)} and five studies targeted children aged 8–15 years^{(34,36,39,45,46)} .

Seven out of nineteen studies (36·84 %) included parents in the interventions^{(31,35,37,38,42,46,47)} .

Quality assessment of included studies

The results mainly came from uncontrolled studies and were often based on non-validated outcome measures with no proper adjustment for confounders, which led to the weak global rating for ten studies based on the EPHPP assessment tool⁽²⁹⁾. The quality of nine studies was rated as moderate, and none of the studies were judged as strong.

The data collection method was rated weak for most studies (n 11), largely because there was no information on the measurement instrument’s validity and reliability.

Blinding of students and education providers was generally not possible in the studies. Task outcomes were directly assessed and not likely to be influenced by lack of blinding. Therefore, we assessed blindness as moderate in most studies. The quality assessment of included studies is summarised in Fig. 2 (online Supplementary Table S2).

Strategies and components used in the interventions

Five basic types of strategies were used in interventions aimed at improving FNLIT, including gardening⁽⁴⁰⁾, recipes skill building/cooking^(31,41,47) , food label reading^{(32,42,43,48,50)} , food tasting⁽³⁸⁾ and multi-component interventions^{(33–37,39,44–46,49,53)} . Multi-component interventions included a combination of strategies from gardening/harvesting to food preparation/cooking, recipe skill-building, supporting cultural practices and ethnic foods, food tasting, and food labelling interventions (Table 2).

The variety of skill-building activities introduced by studies is as follows:

Recipe skill building

Two interventions offered recipe skill-building to children and preadolescents (aged 9–15 years)^(41,45) . These included interventions that allowed a child to develop competency in recipe reading. Recipes were purposefully written for children with limited food skills and resources and reflected proper considerations, such as low cost, basic ingredients, basic/simple kitchen equipment, standardised format, numbered preparation steps, core recipes with variations, repetition, and progression of skills, exposure to a variety of foods, dietary guidelines principles, and involved local foods. Workstations were provided for an individual child or a team of two persons with the opportunity to skill-build and gain the confidence to perform the task independently. Working in a small group provided opportunities for peer-to–peer and supportive adult interactions. Additionally, by providing a ‘core’ recipe with simple ingredients, the choice was a practice of the learning experience, allowing youths to make food by their selected ingredients. For example, the ‘create a-flavor’ allowed changes in ‘Apple Cinnamon Toast’ by variations in the type of fruit, bread and seasonings⁽⁴⁵⁾. In addition, opportunities for conversations about food choices, such as the advantages of whole-grain choices, were provisioned. Overall, these programmes were well received by students.

Food label literacy

Food label literacy interventions were usually part of multi-component school module(s) to promote the skills of use and understanding food label information, as well as informed food choices presented entirely in a one-off session^(34,50) or as part of a healthy eating intervention⁽⁴³⁾. Food label literacy interventions focused on enabling students to (1) explain topics such as nutrients, balanced diets, harmful effects of high fat, sugar and salt foods, and why making informed food choices can benefit their health; (2) recognise deception on packages of food products; (3) identify mandatory information on the labels, aspects they considered while buying packaged foods, defining DV and calculating DV% with differing serving sizes, and key points to make healthy food choices; (4) demonstrate the location of the nutrition facts panel, the ingredient list on food packages, nutrient content declaration (energy, fat, sugar and salt), manufacture, expiration, and best-before dates, and quality symbols; (5) determine foods’ healthfulness according to their labels, nutrition facts panels and the ingredient list on their packages; and (6) grocery store tours^{(32,34,43,48,50)} .

Food preparation/cooking classes/clubs

Cooking classrooms and cooking clubs, either embedded into the school curriculum^{(31,35,37,38,44,45,49,53)} or delivered in the form of an after-school food club^{(34,39,41,47)} , are another approach used to promote food skills (Table 3). Food clubs were held over several weeks (e.g. 20 weeks). The length of cooking classes or courses varied from a few hours per week to multiple days of training. Classroom-based activities focused on science, health, nutrition, literature and field trips to grocery stores, restaurants, nature centres and cultural events. Children were involved in an in-depth demonstration focused on specific food/ethnic foods⁽⁵³⁾ or skills, such as preparing delicious foods, identifying food safety and self-efficacy. Students became more confident and independent by learning the importance of healthy nutrition and hands-on skills in a kitchen setting. In the interactive cooking classes, students cook along with a chef and their peers in real time. Designed to look and feel like they were cooking in their own home, each student had his/her own cooking station, complete with sinks, aprons and cookware sets. Interventions offered hands-on skills, along with food-knowledge building^{(31,37,39,41,44,47,53)} . One intervention used cooking demonstrations using the ‘Cooking Up Healthy Choices’ curriculum. Cooking Up Healthy Choices was a series of five cooking demonstration sessions that allowed students to get familiar with a variety of vegetables, observe cooking methods, understand related nutrition concepts and experience the preparation of recipes using all five senses⁽³⁵⁾.

Food tasting

Students participated in communal food activities that impacted food knowledge and fostered positive food nature^{(33,34,38,44)} . Students brought new food to the class and talked with each other about how they tasted. They were encouraged to notice and enjoy the sensory characteristics of food and eagerly shared their pleasure with their peers. In the ‘Cooking With Kids (CWK)’ intervention, students were exposed to tasting lessons⁽⁴⁹⁾. Through these sessions, students would learn to try new food as one of the components of functional skills of FNLIT (Table 3).

Gardening/harvesting

Seven studies specifically focused on gardening/harvesting interventions^{(33,35,37,40,44,46,53)} . These programmes were carried out as gardening lessons in the classroom curriculum. Children assigned to gardening groups received weekly lessons focused on garden activities and the food system. They were engaged in either doing crafts (e.g. photography) or gardening in the afternoons. Volunteer adolescents sold their planted products in the farmers’ market during the weekends. They also went to the ‘Farm Camp’ and learned how a small-scale, organic, cooperative farm operates.⁽⁵³⁾.

Supporting cultural practices and ethnic foods

Some programmes consisted of strategies to increase children’s willingness and cognition towards ethnic and indigenous foods. Students were introduced to an ethnic meal prepared by young cooks in this programme and tried ethnic and unfamiliar foods^(46,53) . Understanding diverse ethnic and cultural practices related to meal preparation and consumption is one layer of FL⁽²⁾.

Implementation methods of the interventions

The educational/training sessions were presented mainly by lectures, pictorial booklets, and posters, accompanied by power points, videos, and short animation films to engage, motivate and inform the students. Also, some group activities were performed, for example, assigning teams of students to search through a grocery bag containing food products, such as cereals, crackers, or snack bars, and decide which products are healthful ‘clued-in’ and which are less healthy ‘clue-less’⁽⁵⁰⁾. Other teachings and learning activities included take-home challenges and parents’ newsletter, role-playing, playing together, grocery store tours, hands-on activities, doing crafts (photography) and animation film for entertainment education.

Delivery formats of interventions in the fifteen of the nineteen studies (78·94 %) were by teachers^{(31–33,35,37–44,46,47,49)} . Investigators supplemented information only when it was necessary. Some other interventions (n 4) were facilitated by community health educators⁽³⁴⁾, registered dieticians⁽⁴⁸⁾, as well as community members involved in the programme⁽⁴⁵⁾.

Interventions in the promotion of Food and Nutrition Literacy dimensions

Functional Food and Nutrition Literacy

Fifteen studies (78·94 %)^{(32–36,38–45,47,49)} were interventions to improve health outcomes, which described the specific effects on some components of functional FNLIT and knowledge aspects. These interventions resulted in a significant increase in functional skills of FNLIT, including food preparation (cooking and safety), planning and managing, food selection, recognition ability, reading and using nutrition facts labels, self-efficacy, and confidence, and trying ethnic and unfamiliar food (see Table 3 for details).

Critical Food and Nutrition Literacy

In a study by Hawthorne et al. ⁽⁴⁸⁾, the subjects’ scores in serving size modification calculations and nutrition label understanding (calculating %DV with differing serving sizes and defining DV) as critical food/nutrition literacy skills were significantly improved.

The Farm to School programme⁽⁴⁶⁾ is comprised of a tailored approach and presented according to students’ needs and interests. The intervention evaluation showed an improvement in advocacy for local and sustainable foods and mobilising FL for increased public engagement with issues of social justice and equity in food systems.

Integrated aspects of Food and Nutrition Literacy (functional and interactive)

No intervention included measurement of all FNLIT components or the three emphasised dimensions of Nutbeam’s hierarchical model of health literacy; however, two out of nineteen studies (10·52 %)^(31,37) did incorporate two dimensions of the skill domain, including functional and interactive literacy. Block et al. ⁽³⁷⁾ presented the Stephanie Alexander Kitchen Garden programme results. The following components of FNLIT were improved:

• confidence and skills in relation to cooking and gardening, and increasing child willingness to try new foods (functional skills);

• school social environment, increasing school community connections (interactive skills).

The Stephanie Alexander Kitchen Garden (SAKG) was a national programme based on a health-promoting schools framework that used a multi-level, multi-strategy approach through the school policies, curriculum, staffing and environment sought sustainability^(54–56). The teaching methods comprised enjoyable hands-on food education through gardening, harvesting, preparing, and sharing fresh, seasonal, healthy, and delicious food. Teachers facilitated the programme. The specialist staff planned and supervised each class, and children worked in small groups assisted by adult volunteers⁽⁵⁷⁾.

iCook 4-H was a curricular programme focusing on families cooking, eating and playing together. Miller et al. ⁽³¹⁾ reported the following improvements in FNLIT functional and interactive skills in the iCook 4-H intervention:

• cooking skill confidence, desire to cook more meals at home, and fewer fast-food meals, 100 % fruit juice, vegetable soup, and whole-grain consumption (functional skills)

• adult–youth feeding interactions by shared parent–child decision-making related to food choice and effective management in food-related conflicts (interactive skills)

Effectiveness of interventions

Because of the low quality of the studies, we can draw no firm conclusions regarding the effective components of food/nutrition literacy interventions. However, the following common factors were noted within the interventions successful in more than one dimension of FNLIT, especially interactive and critical aspects, which were identified as promising. Four out of nineteen studies included the following factors (21·05 %):

• the interventions which tailored their activities and presented information to the needs and interests of students⁽³⁷⁾;

• the interventions that were incorporated into the existing curriculum and facilitated by teachers^(31,37,46) ;

• interventions mainly used promising strategies/methods, including pleasurable hands-on food education, school gardening programmes, kitchen classrooms, family cooking, eating and playing together, and supporting cultural practices and ethnic foods^{(31,37,46,48)} that led to improvements in functional, partly interactive and critical skills.

Discussion

In this systematic review, for the first time, interventions aimed at improving food/nutrition literacy were identified and assessed. To our knowledge, there has been no study to have directly examined food/nutrition literacy interventions. However, we looked for relevant studies focused on food skills or functional aspects of FNLIT. All the studies reviewed here effectively improved one or more dimensions of FNLIT skills, especially functional FL. However, the interventions partially considered improved interactive and critical skills and were implemented among students from different grades and through various delivery formats, study designs, FL measurement instruments, and outcomes.

Three factors were identified as promising within the reviewed interventions: (1) those that tailored their activities and presented information to the needs and interests of students; (2) the interventions that were incorporated into the existing curriculum and facilitated by teachers; and (3) the interventions that mainly used strategies/methods such as pleasurable hands-on food education, school gardening programme, kitchen classroom, family cooking, eating, and playing together and supporting cultural practices and ethnic foods that led to improvements in functional, and partly interactive and critical skills (instead of just knowledge). These findings are concordant with those from the review by Berkman et al. ⁽⁵⁸⁾ and other studies^(59–61), demonstrating that the effectiveness of interventions could be determined by a combination of tailored activities and appropriate strategies.

Because of the studies’ overall low quality, no firm conclusions could be drawn on the effectiveness and the affective component(s) of food/nutrition literacy interventions. Besides, FL was operationalised and measured differently in the interventions, thus impeding the comparability of the results. Furthermore, most studies did not use a validated tool for measuring FL. Due to the novelty of the FL concept, over the preceding decades, a limited number of studies on the development, translation and validation of (both subjective and objective) food/nutrition literacy measurement instruments have been published^(6,62–65) . The development of precise tools for measuring FL and taking a unified approach will provide a foundation for developing effective FNLIT programmes⁽⁶⁶⁾.

The three most common strategies used by programmes were gardening, food preparation/cooking and food tasting. In a qualitative study on students, Hess and Trexler⁽⁶⁷⁾ found that students had limited knowledge of conventional agriculture and emphasised experiential learning (e.g. small-scale farming or gardening) to increase students’ understanding of food. Evidence shows that school-based gardening activities positively impact scientific process skills and strengthen interactive, critical, innovative, and creative skills, and all important aspects of FL^(68–70). Indeed, a review of garden-based nutrition education concluded that these interventions improved fruit and vegetable consumption and expanded preference for such foods (functional literacy)⁽⁷¹⁾. Comparable to the studies on garden-based interventions, school-based cooking initiatives improved the cooking skill elements and related components of FL. Food tasting is also a way to get children excited by trying new foods; indeed, senses make individuals innately equipped to make food choices, and the appearance, smell, and taste of food can influence individuals’ food consumption.⁽⁶⁸⁾.

Some research treated gardening, cooking and taste testing as targeted interventions designed to develop cognitive and skill domains of FL in this area^(68,72) . Although these studies demonstrated positive results in nutrition knowledge, changing food preferences, and increased confidence in cooking and gardening skills, more evidence is needed to document the use of these initiatives as a strategy for promoting FL in school settings.

FNLIT encompasses the knowledge and skills that students need to access, understand, interpret, express ideas and opinions, interact (food and nutrition) information with others (peers, family and nutritionists), analyse and evaluate food and nutrition information, and participate in activities related to health and nutrition in and out of schools⁽²⁾. Success in any area requires the use of significant, identifiable, and distinctive FNLIT that is important for learning and representative of the content of that area^(2,62) . Evidence has suggested that a teacher-led intervention to improve students’ knowledge and skills is effective, while, alongside the primary goal to improve students’ outcomes, the impact of professional development activities on teachers’ reactions, learning and teaching behaviour should be considered⁽⁷³⁾.

The collected evidence provides insight into the gaps in intervention to improve children’s interactive and critical skills in future research. It should be noted that all components may not always be present in every individual. Conversely, when a component is missing, the relationship with food and nutrition will be weaker and less likely to respond to change in that area.

To better understand how FL improves in the school context, we must ascertain the environments of food education and the characteristics of instruction that appeal to and encourage all school community members to cooperate⁽⁷⁴⁾.

To our knowledge, this is the first systematic review related to FNLIT interventions in children. This review rigorously applied a comprehensive search strategy and systematic selection process to include the most up-to-date publications according to inclusion criteria. However, our review has some noteworthy limitations despite the rigorous and novel approach. First, a meta-analysis of the effect size of interventions was not possible due to heterogeneous study designs and outcome measures; therefore, a descriptive analysis was performed. Second, we did not find sufficient numbers of studies to estimate the statistical risk of publication bias. However, publication bias might exist, as it is possible that the studies with higher effects are more likely to be published. This review mainly evaluated non-randomised controlled trials with primary schoolchildren (5–12 years old) and school settings. As a result, interventions among adolescents and in different settings (e.g. after school) were not considered. Finally, other limitations were the inclusion of only English papers and the lack of FNLIT as a unique indexing term.

Future research should evaluate pragmatic cluster-randomised controlled trials in a broader variety of settings in children and adolescents.

Conclusion

None of the interventions reviewed included all effective FNLIT components, and there was much emphasis on the functional level of FL. There are considerable gaps in the research evidence reviewed; indeed, there was insufficient data on interactive and critical components. Future interventions should focus holistically on all aspects of FNLIT, especially interactive and critical skills, and use stronger designs, for example, in well-reported, large-sampled randomised controlled trials. However, promising interventions were tailored to the needs and interests of students, incorporated into the existing curriculum, facilitated by teachers, used the profitable strategies including pleasurable hands-on food education, school gardening programme, kitchen classroom, family cooking, eating, and playing together and supporting cultural practices and ethnic foods that led to improvements in functional, and partly interactive and critical skills.