Food literacy programmes in secondary schools: a systematic literature review and narrative synthesis of quantitative and qualitative evidence

Majority of the reviews (n = 14) evaluated multi-component interventions while three reviews evaluated only health education interventions.

“Majority of the reviews (n = 14) evaluated multi-component interventions [30–32, 34–40, 42–45] while three reviews evaluated only health education interventions [29, 33, 41].”

All the reviews included studies based in HICs, and only eight reviews included a few studies based in five LMICs.

“All the reviews included studies based in HICs, and only eight reviews included a few studies based in five LMICs [30, 35–38, 42, 43, 45].”

Fifteen of the reviews used narrative synthesis and two included both meta-analysis and narrative synthesis.

“Fifteen of the reviews used narrative synthesis [29–43] and two included both meta-analysis and narrative synthesis [44, 45].”

These reviews mostly included studies based in HICs; eight reviews among these 14 included primary studies based in five LMICs.

“These reviews mostly included studies based in HICs. Eight reviews among these 14 included primary studies based in five LMICs [30, 35–38, 42, 43, 45].”

According to the JBI critical appraisal tool, 14 reviews scored high, two reviews scored moderate, and only one review scored low in terms of methodological quality.

“According to the JBI critical appraisal tool, 14 reviews scored high [30–32, 34–41, 43–45], two reviews scored moderate [33, 42], and only one review scored low [29] in terms of methodological quality (Table 2).”

The contents of school environment change components involved increased availability of milk and protein and fresh fruits, free or subsidised FV, replacing SSB with healthier alternatives in vending machines, chef and staff consultations on healthy culinary lessons, and healthy eating posters around school.

“The contents involved increased availability of milk and protein [32, 35–38, 45] and fresh fruits [30], free or subsidised FV [35], replacing SSB with healthier alternatives (milk, water, juice) in vending machines [35], chef, staff consultations on healthy culinary lessons [36], and healthy eating posters around school [45].”

These reviews mainly focused on interventions in HICs, with only 11 primary studies from LMICs (Ethiopia, India, Iran, Kenya, and Tunisia).

“These reviews mainly focused on interventions in HICs - only 11 primary studies were from LMICs (Ethiopia, India, Iran, Kenya, and Tunisia) [30, 35–38, 42, 45].”

The contents of healthy eating education components involved lessons on healthy eating, food labelling, healthy cooking, consequences of SSB intake, nutrition, food safety farmers' visits on healthy food cultivation, menu planning, healthy eating goal setting and self-monitoring, healthy food as rewards, and food tasting.

“The contents involved lessons on healthy eating [32, 37, 38, 42, 45], food labelling, healthy cooking [30, 36], consequences of SSB intake [35], nutrition, food safety farmers’ visits on healthy food cultivation [36], menu planning, healthy eating goal setting and self-monitoring, healthy food as rewards, and food tasting [38].”

Seven high-quality and one moderate-quality reviews (including 192 unique studies) reported promising effects of multi-component interventions on healthy eating behaviour.

“There were promising effects of multi-component interventions on healthy eating behaviour reported in seven high-quality [30, 32, 35–38, 45] and one moderate-quality reviews [42] (including 192 unique studies) [30, 32, 35–38, 42, 45].”

The school environment change components at the system level involved FV gardening, school food marketing, canteen modifications, vending machine modifications, postering, workshops with kitchen staff, and loyalty programs.

“The school environment change components at the system level, involved FV gardening [32, 36], school food marketing [38, 45], canteen modifications [30, 36], vending machine modifications [35], postering [45], workshops with kitchen staff [36], and loyalty programs [32].”

The primary outcomes for the reviews reporting promising effects were intake of FV, processed snacks, SSB, fat, protein, fibre and vitamins, frequency of regular meals, recommended calorie intake, healthy eating knowledge, and staying in school for having healthy lunch.

“The primary outcomes for these reviews were intake of FV [30, 32, 36–38, 42, 45], processed snacks [30, 36–38, 45], SSB [30, 35, 37], fat [37, 42], protein, fibre and vitamins [37], frequency of regular meals [30, 37, 38], recommended calorie intake [37, 42], healthy eating knowledge [30, 36], and staying in school for having healthy lunch [38].”

The healthy eating education components at the individual level included lectures, quizzes and games, media shows, plays, electronic messages, rewards, peer-leading activities and training for teachers.

“The healthy eating education components at the individual level, included lectures [30, 32, 36, 38, 42, 45], quizzes and games [30, 36, 38], media shows [37], plays, electronic messages, rewards, peer-leading activities and training for teachers [38].”

The outcomes in the studies were measured by FFQ, 24 h dietary recalls, food diary, KAP survey, cognitive and attitudinal assessments, FV recall, number of days stayed, bought, ate healthy lunch at schools, snack scale, and 7-day recall, or 5-day food recall.

“The outcomes were measured by FFQ [32, 35–38, 42, 45], 24 h dietary recalls [32, 35–38, 45], food diary [38, 42], knowledge attitude practice (KAP) survey [32, 45], cognitive and attitudinal assessments [38], FV recall, number of days stayed, bought, ate healthy lunch at schools, snack scale [38], and 7-day recall [45], or 5-day food recall [42].”

The intervention duration ranged from 15 min to 10 years, and follow-up assessments ranged from immediately to four years after the intervention.

“The intervention duration ranged from 15 min to 10 years [30, 36–38, 42, 45] and time of the follow up assessments ranged from immediately to four years after the intervention [30, 32, 36, 37, 42].”