The food environment in schools and their immediate vicinities associated with excess weight in adolescence: A systematic review and meta-analysis.

AIM: The present study systematically reviewed the characteristics of the food environment in schools and their immediate vicinities associated with excess weight in adolescents. METHODS: We searched for relevant articles in seven databases. No restrictions were applied on language, publication date, and status of publication. The study selection process and data extraction were conducted by two authors independently. For meta-analyses, the random-effects model and the maximum-likelihood method were applied. RESULTS: A total of 9327 publications were identified from the initial search. Of these, 20 studies met the inclusion criteria and were included in the systematic review. The sale of food in school or immediate vicinity was associated with high BMI [Odds ratio (OR)= 1.14, 95% confidence interval (CI) 1.01, 2.06]. The availability of healthy food provided by school significantly decreased the odds of obesity [OR= 0.89, 95%CI 0.82, 0.96]. However, the presence of nutrition policies or programs at school was not associated with obesity (OR= 0.81, 95%CI 0.57, 1.16). CONCLUSIONS: This study highlights the need for improvement in school food environment, including restricting students' exposure to unhealthy foods. The quality of food (healthy vs unhealthy) provided or made available to adolescents in the school food environment influences their weight status. Therefore, promotion of healthy food programs and availability of healthy food at school would limit the prevalence of excess weight in adolescents.

Does the Mediterranean Diet Protect against Stress-Induced Inflammatory Activation in European Adolescents? The HELENA Study.

Stress increases inflammation but whether adherence to Mediterranean diet counteracts this association and how early can these effects be observed is not well known. We tested whether (1) cortisol is associated to inflammation, (2) cortisol is associated to the adolescent Mediterranean diet score (aMDS), (3) aMDS lessens inflammation, (4) aMDS associates with cortisol levels and inflammation. Two hundred and forty-two adolescents (137 females; 12.5⁻17.5 years old) provided salivary cortisol, blood and 2-day 24-h dietary recall from which aMDS was derived. Cortisol levels were associated with increased tumor necrosis factor (TNF-α B = 11.887, p = 0.001) when adjusted for age, gender, parental education and body mass index (BMI). Moreover, cortisol levels were inversely associated to adherence to the Mediterranean Diet (B = -1.023, p = 0.002). Adolescents with higher adherence to aMDS had lower levels of interleukins (IL) IL-1, IL-2, IL-6 and TNF-α, compared to those who did not adhere. The association between cortisol and TNF-α was no longer significant when aMDS was included in the model (B = 6.118, p = 0.139). In addition, comparing lower and higher aMDS groups, the association between cortisol and TNF-α was only observed in those with lower aMDS adherence. Our study suggests that adherence to the Mediterranean Diet may counteract the effect of stress on inflammatory biomarkers which may contribute to decreasing the risk of future mental health.