Abstract

Background: There have been many studies of health-related behaviours and the mental health of adolescents and young adults. The present article provides an umbrella review of previous systematic reviews. Methods: The search engines PsycINFO, Medline, Web of Science, and Scopus were used to search for articles published between 2010 and 2023. The final search strategy consisted of paired keywords for diet (diet* OR "healthy food*" OR "unhealthy food*" OR "junk food*" OR "junk snack*" OR "processed meat" OR cola OR soda OR "soft drink*" OR beverage* OR "energy drink*" OR coffee OR tea OR caffeine OR "fruit* and vegetable*") AND well-being ("well-being" OR well-being OR stress OR health OR anxiety OR depression) AND adolescence (adolescent* OR adolescence* OR "university student*" or "young adult*" or "early adulthood") AND “systematic review”. Results: Eight systematic reviews of observational studies were found in this umbrella review to identify the most recent data on the relationship between diet, health and well-being outcomes. It was found that most systematic review results were consistent in terms of the influence of junk food, such as fast food, unhealthy snacks, and sweets, which were correlated with an increase in mental health problems and negative well-being and health outcomes. In contrast, healthy food or a good diet was associated with positive affect. At the same time, some studies found no association between diet and well-being, especially between healthy diets such as high fruit and vegetable consumption and positive well-being. Conclusions: The umbrella review suggests that diet may play a role in the mental health of emerging adults, but the evidence base is still limited. It has emphasised the need for further high-quality research to better understand the relationships between diet and mental health outcomes in this age group.