Mental well-being in emerging adulthood (18–29y) can come under severe strain. A healthy diet may support a smooth transition and promote high mental well-being among emerging adults. Several systematic reviews have confirmed that a healthy diet can increase mental health in a general adult population, but so far, no systematic review or meta-analysis has summarized experimental evidence of dietary interventions on mental wellbeing. This study conducted a systematic review and meta-analysis of experimental studies into the effects of dietary interventions on mental wellbeing in emerging adults. Nineteen studies were included in the systematic review, of which thirteen in the meta-analysis. The meta-analysis showed a small but significant effect (g = 0.296, 95% CI 0.110–0.481, p = .002). Review findings show that certain dietary interventions have consistent positive effects on some but not all wellbeing indicators (taking breakfast, Mediterranean diet) whereas others show mixed effects on mental wellbeing (fruit and vegetable consumption). Chocolate consumption showed mixed to very short-lived effects (3 min.) on wellbeing. In sum, a Mediterranean diet and its components (cereal and protein breakfast, fruit and vegetables) may promote mental wellbeing among emerging adults. More experimental studies with larger sample sizes are needed to allow moderator analyses to further understand differences in effects between types of dietary interventions and types of wellbeing outcomes.

Trial Registration This systematic review was registered in the PROSPERO International Prospective Register of Systematic Reviews under the number CRD42020165113.

成年初期（18-29 岁）的心理健康可能会面临严重压力。健康的饮食可以支持新生成年人的平稳过渡并促进良好的心理健康。一些系统评价已经证实，健康饮食可以改善一般成年人的心理健康，但到目前为止，还没有系统评价或荟萃分析总结饮食干预对心理健康的实验证据。本研究对饮食干预对新生成年人心理健康影响的实验研究进行了系统回顾和荟萃分析。系统评价纳入了 19 项研究，其中 13 项进行了荟萃分析。荟萃分析显示影响虽小但显着（g = 0.296，95% CI 0.110–0.481，p = .002）。审查结果表明，某些饮食干预措施对某些但不是所有的健康指标（吃早餐、地中海饮食）具有持续的积极影响，而其他干预措施对心理健康（水果和蔬菜的摄入）则表现出复杂的影响。食用巧克力对健康的影响有好有坏，甚至非常短暂（3 分钟）。总之，地中海饮食及其组成部分（谷物和蛋白质早餐、水果和蔬菜）可以促进新生成年人的心理健康。需要更多更大样本量的实验研究，以便进行调节分析，以进一步了解饮食干预类型和健康结果类型之间的影响差异。

试验注册 该系统评价已在 PROSPERO 国际前瞻性系统评价登记册中注册，注册号为 CRD42020165113。