The impact of primary school lunch nutrition on childhood obesity : a systematic review

Abstract

Objective: To systematically review the feasibility and effectiveness of recent school lunch interventions in primary schools and whether they instil positive changes to childhood dietary habits and help prevent obesity. Background: Childhood obesity is a growing concern affecting 42 million children (2010) and increasing daily, and may be linked to adult obesity. Lunch contributes 24% of daily energy, making school lunch interventions monumentally important in reducing consumption of high fat and/or sugar foods, and increasing fruit and vegetable (F&V) intake. Methods: A literature search was conducted for studies with interventions in primary school environments that aimed to alter the consumption of fruits, vegetables, and unhealthy foods high in fat or sugar. Studies were only suitable if they utilized randomized controlled trial (RCT) or cluster RCT designs, and included relevant outcome measures for F&V or macronutrient consumption. Relevant studies published between January 1st 2000 and May 31st 2013 were identified through PubMed, ISI Web of Science, and Cochrane Trials, and bibliographies of relevant studies. Results: Nine studies were included in this systematic review from the US or UK, with varied direct and indirect interventions to alter school lunch nutrition either through F&V or improved macronutrient content. Environmental changes to child attitudes towards F&V, such as verbal encouragement, classroom curriculums and audio-visual stimuli, were significantly effective in all 4 studies, whereas 2 studies with changes to F&V availability without involving students had mixed results. Direct reductions to fat content in school lunches produced significant results in 2 of 4 studies, with increased carbohydrate intake compensating for lower fat, resulting in non-significant total energy changes. One of 3 environmental interventions also had similar trends in macronutrient intake. Total energy change was only significant in 1 of 6 studies. Conclusion: Overall interventions for childhood obesity had moderate success, and most were unable to meet primary dietary goals set out by researchers. Ineffectiveness of interventions may be due to parental influences at home, early childhood dietary habits, disproportionately low SES in study samples, among other factors. Further research on targeting calorie intakes, parental involvement, snack food reduction, and related fields is recommended.