Global Magnitude of the Bread Wastes and its Reasons: A Systematic Review andMeta-analysis of Observational Studies

Background and objectives: bread, as a staple food, is a significant part of food waste and a potential threat to foodsecurity. this study aims to systematically investigate and quantify the global extent of bread waste and its reasons.materials and methods: we searched pubmed, embase, web of science and scopus databases from 1990 tofebruary 2024. we selected observational studies that reported the proportion of bread waste. random effects modelswere used to calculate the pooled effect sizes of bread waste.results: 28 observational studies were included in the systematic review and 22 in the meta-analysis, with a sample sizeof 8,408,344 participants. the pooled size (weighted proportion) of bread waste was 18% (95% confidence interval (ci):14–24; i2 = 99.94%, p < 0.002). proportion of bread waste as a consequence of consumers' practices and beliefs estimatedwith pooled effect size 24% (95% ci: 21–28; i2 = 95.2%, p < 0.001) compared with retailers and producers' activitiespooled effect size 14% (95% ci: 10–18; i2 = 98.2%, p < 0.001).conclusions: bread waste prevalence was high, which is due to the behaviors of consumers and retailers. therefore,community food and nutrition education are prescribed.