Research Appraisals
Evidence-based critical appraisals of the latest medical research, systematically evaluated using Oxford CEBM methodology.
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The British journal of general practice : the journal of the Royal College of General Practitioners
Does recommending healthy diets in general practice benefit secondary prevention of cardiovascular disease? A systematic review and meta-analysis.
BACKGROUND: Suboptimal diet is the main preventable risk factor globally for cardiovascular disease (CVD), posing major burden for primary care. However, healthy dietary recommendations' evidence in patients with established CVD is unclear. AIM: Systematically review and meta-analyse dietary patterns' effect on CVD patients' all-cause and CVD mortality, and CVD recurrence. METHOD: Publication databases were searched for randomised controlled trials (RCTs) (≥6 months follow-up) and prospective cohort studies. Random-effects meta-analysis calculated relative-risks (RR) and 95% confidence-intervals (95% CI). Cochrane bias risk tools assessed study quality. RESULTS: Screening 28 291 abstracts identified 41 articles meeting inclusion criteria. Nineteen articles from 14 unique RCTs conducted 1956-2020, enrolling 14 065 CVD patients, compared fat-replacement, Mediterranean, low-fat, low-sodium, and high-fibre diets with minimal/no dietary advice. Pooled results showed no diet intervention significantly impacted mortality/CVD outcomes. However, stratified meta-analysis revealed a Mediterranean-diet significantly reduced CVD mortality (RR: 0.40; 95% CI: 0.19, 0.83). Twenty-two cohort studies, conducted 1976-2017 for 104 386 CVD patients, predominantly assessed a Mediterranean diet (60%), showing greatest healthy dietary pattern adherence significantly reduced all-cause mortality by 29% (0.71; 0.65, 0.78), CVD mortality by 25% (0.75; 0.66, 0.84), and CVD recurrence by 17% (0.83; 0.75, 0.92). Overall, there was considerable between-study heterogeneity (RCTs: I2 = 34-60%, cohorts: I2 = 49-76%) partly explained by disparate geographical locations, and studies were mainly classified as of some concerns (65% RCTs) or high bias risk (52% cohorts). CONCLUSION: GPs providing healthy dietary advice, particularly the Mediterranean diet, likely enhances CVD secondary prevention. However, cogent studies with clearly defined diets are required to bolster the evidence.
16 May 2026
Read appraisal →Philosophical transactions of the Royal Society of London. Series B, Biological sciences
A meta-analysis of gut microbiome research in malnourished African populations: a natural language processing approach
Malnutrition still affects millions of children in Africa. Changes in the gut microbiome have been implicated in malnutrition, but there has been inconsistent nomenclature of microbes. This meta-analysis reviews the microbiome literature using natural language processing (NLP) methods. We searched PubMed for gut microbiome studies of undernourished children living in low- and middle-income countries (LMICs). The primary analysis focused on continental coverage and study characteristics of microbiome research in sub-Saharan Africa (ss-Africa). We also used an NLP tool for normalizing primary data from full-text publications in ss-Africa compared with other LMICs, and between diseased and healthy children. We identified 16 studies. Most studies were conducted in Malawi and characterized the faecal microbiome using 16S rRNA sequencing. For comparison, 18 studies conducted in Bangladesh, India, Pakistan and Peru were included. With this, we identified frequently reported microbes that were distinctly identified in ss-Africa and highlighted possible signatures of an undernourished faecal microbiome across the globe. The consistent associations between elevated Pseudomonadota levels and severe acute malnutrition provide new insights into host-microbiome interactions in African contexts. However, the overlap between taxa associated with healthy and stunting underscores the need for further research to better inform potential targeted interventions in Africa. This article is part of the theme issue 'Biological, biomedical and environmental drivers of stunting'.
15 May 2026
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