Department of Primary Care & Public Health, Public Health Policy Evaluation Unit, School of Public Health, Imperial College London, 90 Wood Lane, London, W12 0BZ, UK.
Center for Epidemiological Research in Nutrition and Health, University of São Paulo, São Paulo, 01246-904, Brazil.
Int J Behav Nutr Phys Act. 2024 Nov 1;21(1):124. doi: 10.1186/s12966-024-01656-w.
The Universal Infant Free School Meal (UIFSM) policy was introduced in 2014/15 in England and Scotland for schoolchildren aged 4-7 years, leading to an increase in school meal uptake. UK school meals are known to be healthier and less industrially processed than food brought from home (packed lunches). However, the impact of the UIFSM policy on the quantity of ultra-processed food (UPF) consumed at school during lunchtime is unknown. This study aimed to evaluate the impact of the UIFSM policy on lunchtime intakes of UPF in English and Scottish schoolchildren.
Data from the UK National Diet and Nutrition Survey (2008-2019) were used to conduct a difference-in-difference (DID) natural experiment. Outcomes included school meal uptake and the average intake of UPF (% of total lunch in grams (%g) and % total lunch in Kcal (%Kcal)) during school lunchtime. The change in the outcomes before and after the introduction of UIFSM (September 2014 in England, January 2015 in Scotland) in the intervention group (4-7 years, n = 835) was compared to the change in an unexposed control group (8-11 years, n = 783), using linear regression. Inverse probability weights were used to balance characteristics between intervention and control groups.
Before UIFSM, school meal uptake and consumption of UPFs were similar in the intervention and control groups. The DID model showed that after UIFSM, school meal uptake rose by 25%-points (pp) (95% CI 14.2, 35.9) and consumption of UPFs (%g) decreased by 6.8pp (95% CI -12.5,-1.0). Analyses indicated this was driven by increases in minimally processed dairy and eggs, and starchy foods, and decreases in ultra-processed salty snacks, bread and drinks. The differences were larger in the lowest-income children (-19.3 UPF(%g); 95% CI -30.4,-8.2) compared to middle- and high-income children. Analyses using UPF %Kcal had similar conclusions.
This study builds on previous evidence suggesting that UIFSM had a positive impact on dietary patterns, showing that it reduced consumption of UPFs at school lunchtime, with the greatest impact for children from the lowest-income households. Universal free school meals could be an important policy for long term equitable improvements in children's diet.
2014/15 年，英国和苏格兰为 4-7 岁学童推出了普及免费学校供餐（UIFSM）政策，这导致了学校供餐的摄入量增加。英国学校供餐的健康程度和加工程度均优于从家中带来的食物（即午餐盒）。然而，普及免费学校供餐政策对学童在午餐时间所食用的超加工食品（UPF）数量的影响尚不清楚。本研究旨在评估普及免费学校供餐政策对英国和苏格兰学童在午餐时间摄入 UPF 的影响。
本研究使用来自英国国家饮食与营养调查（2008-2019 年）的数据进行了一项差分法自然实验。研究结果包括学校供餐的摄入量和午餐时间 UPF 的平均摄入量（以总午餐量的克数表示，%g；以总午餐量的千卡数表示，%Kcal）。通过线性回归比较了干预组（4-7 岁，n=835）在普及免费学校供餐政策实施前后（2014 年 9 月在英格兰，2015 年 1 月在苏格兰）的结果变化，与对照组（8-11 岁，n=783）的结果变化。采用逆概率权重法来平衡干预组和对照组之间的特征。
在普及免费学校供餐政策实施之前，干预组和对照组的学校供餐摄入量和 UPF 摄入量相似。差分模型显示，普及免费学校供餐政策实施后，学校供餐摄入量增加了 25 个百分点（95%置信区间 14.2，35.9），UPF 摄入量减少了 6.8 个百分点（95%置信区间-12.5，-1.0）。分析表明，这是由于加工最少的乳制品和蛋类以及淀粉类食物摄入量增加，以及超加工咸零食、面包和饮料摄入量减少所致。最低收入儿童（-19.3 UPF(%g)；95%置信区间-30.4，-8.2）的差异大于中高收入儿童。使用 UPF %Kcal 的分析得出了类似的结论。
本研究进一步证实了先前的研究结果，即普及免费学校供餐对饮食模式产生了积极影响，表明它减少了学童在午餐时间对 UPF 的摄入，对来自低收入家庭的儿童影响最大。普及免费学校供餐可能是改善儿童饮食长期公平的一项重要政策。
