To inform evidence-based practice in health care, guidelines and policies require accurate identification, collation, and integration of all available evidence in a comprehensive, meaningful, and time-efficient manner. Approaches to evidence synthesis such as carefully conducted systematic reviews and metaanalyses are essential tools to summarize specific topics. Unfortunately, not all systematic reviews are truly systematic, and their quality can vary substantially. Since well-conducted evidence synthesis typically involves a complex set of steps, we believe formulating a cohesive, step-by-step guide on how to conduct a systemic review and meta-analysis is essential. While most of the guidelines on systematic reviews focus on how to report or appraise systematic reviews, they lack guidance on how to synthesize evidence efficiently. To facilitate the design and development of evidence syntheses, we provide a clear and concise, 24-step guide on how to perform a systematic review and meta-analysis of observational studies and clinical trials. We describe each step, illustrate it with concrete examples, and provide relevant references for further guidance. The 24-step guide 1) simplifies the methodology of conducting a systematic review, 2) provides healthcare professionals and researchers with methodologically sound tools for conducting systematic reviews and meta-analyses, and 3) it can enhance the quality of existing evidence synthesis efforts. This guide will help its readers to better understand the complexity of the process, appraise the quality of published systematic reviews, and better comprehend (and use) evidence from medical literature.

Akkermansia muciniphila and Faecalibacterium prausnitzii are highly abundant human gut microbes in healthy individuals, and reduced levels are associated with inflammation and alterations of metabolic processes involved in the development of type 2 diabetes. Dietary factors can influence the abundance of A. muciniphila and F. prausnitzii, but the evidence is not clear. We systematically searched PubMed and Embase to identify clinical trials investigating any dietary intervention in relation to A. muciniphila and F. prausnitzii. Overall, 29 unique trials were included, of which five examined A. muciniphila, 19 examined F. prausnitzii, and six examined both, in a total of 1444 participants. A caloric restriction diet and supplementation with pomegranate extract, resveratrol, polydextrose, yeast fermentate, sodium butyrate, and inulin increased the abundance of A. muciniphila, while a diet low in fermentable oligosaccharides, disaccharides, monosaccharides, and polyols decreased the abundance of A. muciniphila. For F. prausnitzii, the main studied intervention was prebiotics (e.g. fructo-oligosaccharides, inulin type fructans, raffinose); seven studies reported an increase after prebiotic intervention, while two studies reported a decrease, and four studies reported no difference. Current evidence suggests that some dietary factors may influence the abundance of A. muciniphila and F. prausnitzii. However, more research is needed to support these microflora strains as targets of microbiome shifts with dietary intervention and their use as medical nutrition therapy in prevention and management of chronic disease.

<b><i>Background:</i></b> Hazardous drinking among students in higher education is a growing concern. The alcohol use disorders identification test (AUDIT) is the gold standard screening instrument for hazardous drinking in the adult population, for which an abbreviated version has been developed: the ­AUDIT-Consumption (AUDIT-C). Currently, there’s no gold standard for identifying hazardous drinking among students in higher education and little evidence regarding the concurrent validity of the AUDIT-C as a screening instrument for this group. This study investigated the concurrent validity of the AUDIT-C in a sample of university students and suggests the most appropriate cutoff points. <b><i>Methods:</i></b> Cross-sectional data of health surveys from 5,401 university and university of applied sciences in the Netherlands were used. Receiver operating characteristic (ROC) curves, sensitivity, specificity, and positive and negative predictive values for different cutoff scores of AUDIT-C were calculated for the total sample and for subgroups stratified by age, gender, and educational level. AUDIT-score ≥11 was used as the criterion of hazardous and harmful drinking. <b><i>Results:</i></b> Twenty percent of students were hazardous and harmful drinkers. The area under the ROC curve was 0.922 (95% CI 0.914–0.930). At an AUDIT-C cutoff score of ≥7, sensitivity and specificity were both &#x3e;80%, while other cutoffs showed less balanced results. A cutoff of ≥8 performed better among males, but for other subgroups ≥7 was most suitable. <b><i>Conclusion:</i></b> AUDIT-C seems valid in identifying hazardous and harmful drinking students, with suggested optimal cutoffs 7 (females) or 8 (males). However, considerations regarding avoiding false-positives versus false-negatives, in relation to the type of intervention following screening, could lead to selecting different cutoffs.