Adopting a healthy dietary pattern may be an initial step in combating inflammation-related chronic diseases; however, a comprehensive synthesis evaluating current evidence is lacking. This umbrella review aimed to summarise the current evidence on the effects of dietary patterns on circulating C-reactive protein (CRP) levels in adults. We conducted an exhaustive search of the Pubmed, Scopus and Epistemonikos databases, spanning from their inception to November 2023, to identify systematic reviews and meta-analyses across all study designs. Subsequently, we employed a random-effects model to recompute the pooled mean difference. Methodological quality was assessed using the A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2) checklist, and evidence certainty was categorised as non-significant, weak, suggestive, highly suggestive or convincing (PROSPERO: CRD42023484917). We included twenty-seven articles with thirty meta-analyses of seven dietary patterns, fifteen of which (50 %) exhibited high methodological quality. The summary effects of randomised controlled trials (RCT) found that the Mediterranean diet was the most effective in reducing circulating CRP levels, followed by Vegetarian/Vegan and Energy-restricted diets, though the evidence was of weak quality. In contrast, Intermittent Fasting, Ketogenic, Nordic and Paleolithic diets did not show an inverse correlation with circulating CRP levels. Some results from combined interventional and observational studies, as well as solely observational studies, also agreed with these findings. These dietary patterns show the potential in reducing CRP levels in adults, yet the lack of high-quality evidence suggests future studies may alter the summary estimates. Therefore, further well-conducted studies are warranted.

Posttraumatic stress disorder (PTSD) is one of the most serious and incapacitating mental diseases that can result from trauma exposure. The exact prevalence of this disorder is not known as the literature provides very different results, ranging from 2.5% to 74%. The aim of this umbrella review is to provide an estimation of PTSD prevalence and to clarify whether the prevalence depends on the assessment methods applied (structured interview v. self-report questionnaire) and on the nature of the traumatic event (interpersonal v. not-interpersonal). A systematic search of major databases and additional sources (Google Scholar, EBSCO, Web of Science, PubMed, Galileo Discovery) was conducted. Fifty-nine reviews met the criteria of this umbrella review. Overall PTSD prevalence was 23.95% (95% confidence interval 95% CI 20.74–27.15), with no publication bias or significant small-study effects, but a high level of heterogeneity between meta-analyses. Sensitivities analyses revealed that these results do not change after removing meta-analysis also including data from underage participants (23.03%, 95% CI 18.58–27.48), nor after excluding meta-analysis of low quality (24.26%, 95% CI 20.46–28.06). Regarding the impact of diagnostic instruments on PTSD prevalence, the results revealed a lack of significant differences in PTSD prevalence when structured v. self-report instruments were applied (p = 0.0835). Finally, PTSD prevalence did not differ following event of intentional (25.42%, 95% CI 19.76–31.09) or not intentional (22.48%, 95% CI 17.22–27.73) nature (p = 0.4598). The present umbrella review establishes a robust foundation for future research and provides valuable insights on PTSD prevalence.

Mental disorders are increasing in South Asia (SA), but their epidemiological burden is under-researched. We carried out a systematic umbrella review to estimate the prevalence of mental disorders and intentional self-harm in the region. Multiple databases were searched and systematic reviews reporting the prevalence of at least one mental disorder from countries in SA were included. Review data were narratively synthesised; primary studies of common mental disorders (CMDs) among adults were identified from a selected subset of reviews and pooled. We included 124 reviews. The majority (n = 65) reported on mood disorders, followed by anxiety disorders (n = 45). High prevalence of mental disorders and intentional self-harm was found in general adult and vulnerable populations. Two reviews met our pre-defined criteria for identifying primary studies of CMDs. Meta-analysis of 25 primary studies showed a pooled prevalence of 16.0% (95% CI = 11.0–22.0%, I2 = 99.9%) for depression, 12.0% (5.0–21.0%, I2 = 99.9%) for anxiety, and 14.0% (10.0–19.0, I2 = 99.9%) for both among the general adult population; pooled estimates varied by country and assessment tool used. Overall, reviews suggest high prevalence for mental disorders in SA, but evidence is limited on conditions other than CMDs.

Research on the gut microbiome and mental health among children and adolescents is growing. This umbrella review provides a high-level overview of current evidence syntheses to amalgamate current research and inform future directions. Searches were conducted across seven databases for peer-reviewed pediatric (<18 years) review literature. Studies reporting gut microbiome composition and/or biotic supplementation on depression, bipolar disorder, anxiety, attention deficit hyperactivity disorder, autism spectrum disorder (ASD), or obsessive-compulsive disorder (OCD) were included. Deduplication and screening took place in Covidence. A sensitivity analysis was conducted to assess the degree of primary study overlap. Among the 39 included review studies, 23 (59%) were observational and 16 (41%) were interventional. Most reviews (92%) focused on ASD. Over half (56%) of the observational and interventional reviews scored low or critically low for methodological quality. A higher abundance of Clostridium clusters and a lower abundance of Bifidobacterium were consistently observed in ASD studies. Biotic supplementation was associated with ASD symptom improvement. Gut microbiome-mental health evidence syntheses in child and youth depression, anxiety, bipolar disorder, and OCD are lacking. Preliminary evidence suggests an association between specific microbiota and ASD symptoms, with some evidence supporting a role for probiotic supplementation ASD therapy.

The associations of red/processed meat consumption and cancer-related health outcomes have been well discussed. The umbrella review aimed to summarise the associations of red/processed meat consumption and various non-cancer-related outcomes in humans. We systematically searched the systematic reviews and meta-analyses of associations between red/processed meat intake and health outcomes from PubMed, Embase, Web of Science and the Cochrane Library databases. The umbrella review has been registered in PROSPERO (CRD 42021218568). A total of 40 meta-analyses were included. High consumption of red meat, particularly processed meat, was associated with a higher risk of all-cause mortality, CVD and metabolic outcomes. Dose–response analysis revealed that an additional 100 g/d red meat intake was positively associated with a 17 % increased risk of type 2 diabetes mellitus (T2DM), 15 % increased risk of CHD, 14 % of hypertension and 12 % of stroke. The highest dose–response/50 g increase in processed meat consumption at 95 % confident levels was 1·37, 95 % CI (1·22, 1·55) for T2DM, 1·27, 95 % CI (1·09, 1·49) for CHD, 1·17, 95 % CI (1·02, 1·34) for stroke, 1·15, 95 % CI (1·11, 1·19) for all-cause mortality and 1·08, 95 % CI (1·02, 1·14) for heart failure. In addition, red/processed meat intake was associated with several other health-related outcomes. Red and processed meat consumption seems to be more harmful than beneficial to human health in this umbrella review. It is necessary to take the impacts of red/processed meat consumption on non-cancer-related outcomes into consideration when developing new dietary guidelines, which will be of great public health importance. However, more additional randomised controlled trials are warranted to clarify the causality.

Numerous observational studies have investigated associations between diet indices and health outcomes. Our aim was to systematically synthesise data that was previously summarised separately for each diet index in one umbrella review of all diet indices with sufficient evidence gained in systematic reviews and to assess the quality and strength of evidence for selected health outcomes. The MEDLINE, EMBASE and Scopus databases were systematically searched following the PRISMA guidelines through October 2021 for systematic reviews of observational studies investigating associations between adherence to diet indices and selected health outcomes (all-cause mortality, CVD incidence or mortality, type 2 diabetes mellitus incidence or mortality). Methodological quality and quality of evidence were assessed using the AMSTAR 2 and NutriGrade tools. The inclusion criteria were met by seven systematic reviews, entirely based on prospective cohort studies and reviewing five different diet indices – alternate healthy eating index (AHEI), dietary approaches to stop hypertension (DASH), dietary inflammatory index (DII), healthy eating index (HEI) and Mediterranean diet (MedDiet). All seven included systematic reviews showed that greater adherence to these diet indices reduces the risks of all-cause mortality, CVD incidence and mortality and type 2 diabetes mellitus incidence. Moderate meta-evidence was presented for AHEI and DASH for all outcomes, also for DII for all-cause mortality, CVD mortality and incidence, MedDiet for all-cause mortality and for HEI for CVD incidence and mortality. Our umbrella review provides further evidence for AHEI, DASH, DII and HEI diet indices to be used as predictors of selected health outcomes.

As COVID-19 becomes endemic, identifying vulnerable population groups for severe infection outcomes and defining rapid and effective preventive and therapeutic strategies remains a public health priority. We performed an umbrella review, including comprehensive studies (meta-analyses and systematic reviews) investigating COVID-19 risk for infection, hospitalization, intensive care unit (ICU) admission, and mortality in people with psychiatric disorders, and outlined evidence- and consensus-based recommendations for overcoming potential barriers that psychiatric patients may experience in preventing and managing COVID-19, and defining optimal therapeutic options and current research priorities in psychiatry. We searched Web of Science, PubMed, and Ovid/PsycINFO databases up to 17 January 2022 for the umbrella review. We synthesized evidence, extracting when available pooled odd ratio estimates for the categories “any mental disorder” and “severe mental disorders.” The quality of each study was assessed using the AMSTAR-2 approach and ranking evidence quality. We identified four systematic review/meta-analysis combinations, one meta-analysis, and three systematic reviews, each including up to 28 original studies. Although we rated the quality of studies from moderate to low and the evidence ranged from highly suggestive to non-significant, we found consistent evidence that people with mental illness are at increased risk of COVID-19 infection, hospitalization, and most importantly mortality, but not of ICU admission. The risk and the burden of COVID-19 in people with mental disorders, in particular those with severe mental illness, can no longer be ignored but demands urgent targeted and persistent action. Twenty-two recommendations are proposed to facilitate this process.

ὠφελέειν, ἢ μὴ βλάπτειν (Primum non nocere) – Hιppocrates’ principle should still guide daily medical prescribing. Therefore, assessing evidence of psychopharmacologic agents’ safety and harms is essential. Randomised controlled trials (RCTs) and observational studies may provide complementary information about harms of psychopharmacologic medications from both experimental and real-world settings. It is considered that RCTs provide a better control of confounding variables, while observational studies provide evidence from larger samples, longer follow-ups, in more representative samples, which may be more reflective of real-life clinical scenarios. However, this may not always hold true. Moreover, in observational studies, safety data are poorly or inconsistently reported, precluding reliable quantitative synthesis in meta-analyses. Beyond individual studies, meta-analyses, which represent the highest level of ‘evidence’, can be misleading, redundant and of low methodological quality. Overlapping meta-analyses sometimes even reach different conclusions on the same topic. Meta-analyses should be assessed systematically. Descriptive reviews of reviews can be poorly informative. Conversely, ‘umbrella reviews’ can use a quantitative approach to grade evidence. In this editorial, we present the main factors involved in the assessment of psychopharmacologic agents’ harms from individual studies, meta-analyses and umbrella reviews. Study design features, sample size, number of the events of interest, summary effect sizes, p-values, heterogeneity, 95% prediction intervals, confounding factor adjustment and tests of bias (e.g., small-study effects and excess significance) can be combined with other assessment tools, such as AMSTAR and GRADE to create a framework for assessing the credibility of evidence.