The effects of consuming a Mediterranean style diet on associated COVID-19 severity biomarkers in obese/overweight adults: A systematic review.

Background: COVID-19 severity is strongly associated with high Body Mass Index (BMI) (≥25kg/m2) amongst adults and elevated inflammatory markers have enabled prediction of disease progression. The composition of a Mediterranean diet provides favourable outcomes on weight reduction and inflammatory markers. Aim: This systematic review aimed to investigate the effects of consuming a Mediterranean diet on BMI and inflammatory markers of obese/overweight adults (≥18 years) at risk of developing severe COVID-19 outcomes. Methods: PubMed Central, Cochrane Library and MEDLINE databases were searched to identify randomised controlled trials published between January 2010 to August 2021 evaluating the impact of Mediterranean diet on BMI and inflammatory markers in overweight/obese adults. The review followed the PRISMA checklist, used Cochrane Collaboration search strategies, and is PROSPERO registered (CRD42021277070). Two authors independently screened and evaluated studies for methodological quality. Papers were extracted and included based eligibility, despite risk of bias scores. Results: Of 65 extracted records, six studies met the eligibility criteria and were included. Reductions in BMI, TNF-α, IL-6 and hs-CRP were reported amongst most findings, the majority of which were significant. Conclusion: The main findings indicate a hypocaloric, fibre dense Mediterranean diet is a short-term (<4 months) mitigation strategy to significantly reduce BMI and inflammatory markers amongst overweight/obese adults at risk of developing severe COVID-19 outcomes. Further research is now needed to examine the role of Mediterranean diet in COVID-19 prevalence, severity, morbidity and mortality.

A systematic review and meta-analysis of randomized controlled trials to evaluate plant-based omega-3 polyunsaturated fatty acids in nonalcoholic fatty liver disease patient biomarkers and parameters.

CONTEXT: Nonalcoholic fatty liver disease (NAFLD) is prevalent in 25-30% of British and European populations, representing a potential global public health crisis. Marine omega-3 (n-3) polyunsaturated fatty acids offer well-evidenced benefits to NAFLD biomarkers; however, the effect of plant-based n-3 has not been evaluated with a systematic review and meta-analysis. OBJECTIVE: The review aimed to systematically evaluate the effect of plant-based n-3 supplementation on NAFLD surrogate biomarkers and parameters. DATA SOURCES: Medline (EBSCO), PubMed, CINAHL (EBSCO), Cochrane Central Register of Controlled Trials, the International Clinical Trials Registry Platform, and Google Scholar databases were searched to identify randomized controlled trials published between January 1970 and March 2022 evaluating the impact of plant-based n-3 interventions on diagnosed NAFLD. The review followed the PRISMA checklist and is PROSPERO registered (CRD42021251980). DATA EXTRACTION: A random-effects model and generic inverse variance methods synthesized quantitative data, followed by a leave-one-out method for sensitivity analysis. We identified 986 articles; after the application of selection criteria, six studies remained with 362 patients with NAFLD. RESULTS: The meta-analysis showed that plant-based n-3 fatty acid supplementation significantly reduced alanine aminotransferase (ALT) (mean difference: 8.04 IU/L; 95% confidence interval: 14.70, 1.38; I2 = 48.61%) and plasma/serum triglycerides (44.51 mg/dL; 95% confidence interval: -76.93, -12.08; I2 = 69.93%), alongside body-composition markers in patients with NAFLD (P < 0.05). CONCLUSION: Plant-based n-3 fatty acid supplementation improves ALT enzyme biomarkers, triglycerides, body mass index, waist circumference, and weight loss when combined with lifestyle interventions to increase physical activity and a calorie-controlled diet. Further research is needed to identify the most effective plant-based n-3 sources in larger numbers of patients with NAFLD over longer study durations. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42021251980.

Effects of Single Low-Carbohydrate, High-Fat Meal Consumption on Postprandial Lipemia and Markers of Endothelial Dysfunction: A Systematic Review of Current Evidence.

CONTEXT: Postprandial lipemia (PPL) is associated with increased risk of endothelial dysfunction (ED), a precursor of atherosclerotic cardiovascular disease (ASCVD). The effects of low-carbohydrate, high-fat (LCHF) diets on ASCVD risk are uncertain; therefore, gaining a greater understanding of LCHF meals on PPL may provide valuable insights. OBJECTIVE: The current systematic review investigated the effects of single LCHF meal consumption on PPL and markers of ED. DATA SOURCES: CINAHL Plus, PubMed, Web of Science, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for key terms related to endothelial function, cardiovascular disease, glycemia, lipemia, and the postprandial state with no restriction on date. DATA EXTRACTION: Full-text articles were independently screened by 2 reviewers, of which 16 studies were eligible to be included in the current review. All trials reported a minimum analysis of postprandial triglycerides (PPTG) following consumption of an LCHF meal (<26% of energy as carbohydrate). Results were reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. DATA ANALYSIS: Single-meal macronutrient composition was found to play a key role in determining postprandial lipid and lipoprotein responses up to 8 hours post-meal. Consumption of LCHF meals increased PPTG and may contribute to ED via reduced flow-mediated dilation and increased oxidative stress; however, energy and macronutrient composition varied considerably between studies. CONCLUSION: Consumption of an LCHF meal had a negative impact on PPL based on some, but not all, single-meal studies; therefore, the contribution of LCHF meals to cardiometabolic health outcomes remains unclear. Further research is needed on specific categories of LCHF diets to establish a causal relationship between postprandial modulation of lipids/lipoproteins and impaired vascular endothelial function. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD 42023398774.