The available large prospective studies supporting an inverse association between better adherence to the Mediterranean diet and lower mortality have

Gestational diabetes mellitus (GDM), defined as any degree of glucose intolerance with onset during pregnancy, is increasing worldwide, mostly because obesity among women of reproductive age is continuously escalating. GDM is associated with adverse maternal and fetal outcomes. The aim of this article was to systematically review literature on the effectiveness of nutritional factors before or during pregnancy to prevent GDM. We assessed the primary prevention of GDM through nutritional factors, as diet and supplements. We searched on PubMed, Cochrane Databases and ClinicalTrials.gov from inception to June 2016. Clinical trials and adjusted prospective cohort studies were included. Eight clinical trials and twenty observational studies assessing the association between dietary factors and primary prevention of GDM were included. Furthermore, six clinical trials and two observational studies related to supplements were also added. Only two nutritional interventions were found to significantly reduce the incidence of GDM, besides the supplements. However, the observational studies showed that a higher adherence to a healthier dietary pattern can prevent the incidence of GDM, especially in high risk population before getting pregnant. The results indicate that there may be some benefits of some nutritional factors to prevent GDM. However, better-designed studies are required to generate higher quality evidence. At the moment, no strong conclusions can be drawn with regard to the best intervention for the prevention of GDM.

Waiving parent permission can be an option in some epidemiological and social research with adolescents. However, exemptions have not been uniformly considered or applied. Our aim is to critically assess the different factors that could be taken into account when making decisions about waiving active parental permission in observational research with adolescents.

Objective: To review the evidence on the association between fruit and vegetable (F&V) consumption and risk of chronic disease, and to assess trends in the prevalence of low F&V consumption.Design: Systematic review and cross-sectional analyses of a Mediterranean cohort.Setting: The Seguimiento University of Navarra (SUN) project (Spanish dynamic cohort of graduates).Subjects: A systematic review of prospective studies aimed to assess the relationship between fruit and/or vegetables consumption and chronic disease incidence was conducted. We also assessed 18 457 university graduates (59·4 % women; mean age = 39 (sd12) years) enrolled in a dynamic cohort with permanently open recruitment. Baseline data were collected between 1999 and 2010 using a validated 136-item FFQ. Four definitions for low F&V consumption were used (<400 g/d, <200 g/4184 kJ (1000 kcal) per d, ≤2 servings/d and ≤1 serving/d). Multivariate-adjusted cross-sectional associations between the prevalence of low F&V consumption and the year of recruitment were estimated.Results: The systematic review found that a high F&V consumption is inversely associated with CVD incidence and mortality. This association is not so clear for cancer. Inconsistent findings have been reported for diabetes. In all, 13 % of participants in the SUN cohort did not meet the goal of consuming at least 400 g/d of F&V and 2·1 % of them did not reach >1 serving/d. Between 1999 and 2010 the consumption of F&V significantly increased.Conclusions: Even among health-conscious university graduates, low F&V consumption is fairly prevalent. Although the temporal trends suggest an improvement, preventive strategies addressed to increase F&V consumption are needed.