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Gut Microbiota-Derived Metabolites and Cardiovascular Disease Risk: A Systematic Review of Prospective Cohort Studies.
Sanchez-Gimenez, R, Ahmed-Khodja, W, Molina, Y, Peiró, OM, Bonet, G, Carrasquer, A, Fragkiadakis, GA, Bulló, M, Bardaji, A, Papandreou, C
Nutrients. 2022;14(13)
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Cardiovascular disease (CVD) remains a major public health issue. Identification of circulating biomarkers with prognostic value may help to both identify pathophysiological processes relevant to CVD development and improve preventive cardiovascular risk reduction efforts. The aim of this study was to identify the association of circulating levels of microbial metabolites with CVD incidence. This study is a systematic review of twenty-one studies of which 19 were prospective cohort studies, one study included one nested case-control study and one study included two nested case–control studies. Results show that: - associations of trimethylamine N-oxide (TMAO) [molecular metabolite derived from the gut flora] and subsequent risk of CV outcomes were supported by some but not all prospective studies. - inconsistent results were also obtained for secondary bile acids in relation to CVD and related outcomes, and CVD/all-cause mortality. - with regards to branched-chain amino acids (BCAAs), their associations with CV outcomes were robust amongst most of the studies. Authors conclude that their findings show inconsistent results for TMAO and bile acids but robust ones for the relationships between BCAAs and CVD. Thus, further studies are needed to investigate whether circulating microbial metabolites could be an intervention target for CVD.
Abstract
Gut microbiota-derived metabolites have recently attracted considerable attention due to their role in host-microbial crosstalk and their link with cardiovascular health. The MEDLINE-PubMed and Elsevier's Scopus databases were searched up to June 2022 for studies evaluating the association of baseline circulating levels of trimethylamine N-oxide (TMAO), secondary bile acids, short-chain fatty acids (SCFAs), branched-chain amino acids (BCAAs), tryptophan and indole derivatives, with risk of cardiovascular disease (CVD). A total of twenty-one studies were included in the systematic review after evaluating 1210 non-duplicate records. There were nineteen of the twenty-one studies that were cohort studies and two studies had a nested case-control design. All of the included studies were of high quality according to the "Newcastle-Ottawa Scale". TMAO was positively associated with adverse cardiovascular events and CVD/all-cause mortality in some, but not all of the included studies. Bile acids were associated with atrial fibrillation and CVD/all-cause mortality, but not with CVD. Positive associations were found between BCAAs and CVD, and between indole derivatives and major adverse cardiovascular events, while a negative association was reported between tryptophan and all-cause mortality. No studies examining the relationship between SCFAs and CVD risk were identified. Evidence from prospective studies included in the systematic review supports a role of microbial metabolites in CVD.
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A systematic review and meta-analysis of school-based interventions with health education to reduce body mass index in adolescents aged 10 to 19 years.
Jacob, CM, Hardy-Johnson, PL, Inskip, HM, Morris, T, Parsons, CM, Barrett, M, Hanson, M, Woods-Townsend, K, Baird, J
The international journal of behavioral nutrition and physical activity. 2021;18(1):1
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Obesity in childhood and adolescence is associated with an increased risk of non-communicable diseases such as Type 2 diabetes, cardiovascular disease, chronic obstructive lung disease and some forms of cancer. The aim of this study was to investigate the effectiveness of health education interventions delivered in school settings to prevent overweight and obesity and/ or reduce BMI in adolescents, and to explore the key features of effectiveness. This study is a systematic review and meta-analysis of 39 publications based on 33 studies. Six studies recruited adolescent girls only, one adolescent boys only and one study included parent-student dyad. Results show that: - Most of the effective interventions were delivered by teachers who were trained prior to the intervention. - School-based interventions are often delivered through school-staff, however, appropriate training/ CPD prior to the intervention could be a crucial component to support the provision and uptake of the intervention. - Many of the effective interventions included parental involvement and modifications to the school environment. - Interventions should target the biological, psychosocial, environmental, and behavioural influences on diet and physical activity. Authors conclude that school-based health education interventions could potentially help in improving BMI outcomes in the adolescent age group.
Abstract
BACKGROUND Adolescents are increasingly susceptible to obesity, and thus at risk of later non-communicable diseases, due to changes in food choices, physical activity levels and exposure to an obesogenic environment. This review aimed to synthesize the literature investigating the effectiveness of health education interventions delivered in school settings to prevent overweight and obesity and/ or reduce BMI in adolescents, and to explore the key features of effectiveness. METHODS A systematic search of electronic databases including MEDLINE, CINAHL, PsychINFO and ERIC for papers published from Jan 2006 was carried out in 2020, following PRISMA guidelines. Studies that evaluated health education interventions in 10-19-year-olds delivered in schools in high-income countries, with a control group and reported BMI/BMI z-score were selected. Three researchers screened titles and abstracts, conducted data extraction and assessed quality of the full text publications. A third of the papers from each set were cross-checked by another reviewer. A meta-analysis of a sub-set of studies was conducted for BMI z-score. RESULTS Thirty-three interventions based on 39 publications were included in the review. Most studies evaluated multi-component interventions using health education to improve behaviours related to diet, physical activity and body composition measures. Fourteen interventions were associated with reduced BMI/BMI z-score. Most interventions (n = 22) were delivered by teachers in classroom settings, 19 of which trained teachers before the intervention. The multi-component interventions (n = 26) included strategies such as environment modifications (n = 10), digital interventions (n = 15) and parent involvement (n = 16). Fourteen studies had a low risk of bias, followed by 10 with medium and nine with a high risk of bias. Fourteen studies were included in a random-effects meta-analysis for BMI z-score. The pooled estimate of this meta-analysis showed a small difference between intervention and control in change in BMI z-score (- 0.06 [95% CI -0.10, - 0.03]). A funnel plot indicated that some degree of publication bias was operating, and hence the effect size might be inflated. CONCLUSIONS Findings from our review suggest that school-based health education interventions have the public health potential to lower BMI towards a healthier range in adolescents. Multi-component interventions involving key stakeholders such as teachers and parents and digital components are a promising strategy.
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Association between plant-based diets and plasma lipids: a systematic review and meta-analysis.
Yokoyama, Y, Levin, SM, Barnard, ND
Nutrition reviews. 2017;75(9):683-698
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Plasma lipids play a prominent role in heart disease and modifiable factors such as diet and lifestyle can facilitate in preventing or developing hyperlipidemia. Previous research has suggested that vegetarian diets are associated with lower plasma lipid concentrations, however long-term impacts of consuming a plant-based diet (PBD) has not been studied. The aim of this research was to conduct a systematic review and meta-analysis for studies that have examined the relationship between PBDs and plasma lipids. Thirty observational studies and 19 clinical trials were included in this analysis and showed consumption of a PBD was significantly associated with lower total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C), but not in triglyceride concentrations. Based on these results, the authors conclude PBDs could offer individuals and healthcare professionals an effective option for reducing heart disease. They also add that while dietary changes may not be as powerful as pharmaceutical drugs in reducing plasma lipids, dietary and pharmacologic interventions can work together.
Abstract
CONTEXT Although a recent meta-analysis of randomized controlled trials showed that adoption of a vegetarian diet reduces plasma lipids, the association between vegetarian diets and long-term effects on plasma lipids has not been subjected to meta-analysis. OBJECTIVE The aim was to conduct a systematic review and meta-analysis of observational studies and clinical trials that have examined associations between plant-based diets and plasma lipids. DATA SOURCES MEDLINE, Web of Science, and the Cochrane Central Register of Controlled Trials were searched for articles published in English until June 2015. STUDY SELECTION The literature was searched for controlled trials and observational studies that investigated the effects of at least 4 weeks of a vegetarian diet on plasma lipids. DATA EXTRACTION Two reviewers independently extracted the study methodology and sample size, the baseline characteristics of the study population, and the concentrations and variance measures of plasma lipids. Mean differences in concentrations of plasma lipids between vegetarian and comparison diet groups were calculated. Data were pooled using a random-effects model. RESULTS Of the 8385 studies identified, 30 observational studies and 19 clinical trials met the inclusion criteria (N = 1484; mean age, 48.6 years). Consumption of vegetarian diets was associated with lower mean concentrations of total cholesterol (-29.2 and -12.5 mg/dL, P < 0.001), low-density lipoprotein cholesterol (-22.9 and -12.2 mg/dL, P < 0.001), and high-density lipoprotein cholesterol (-3.6 and -3.4 mg/dL, P < 0.001), compared with consumption of omnivorous diets in observational studies and clinical trials, respectively. Triglyceride differences were -6.5 (P = 0.092) in observational studies and 5.8 mg/dL (P = 0.090) in intervention trials. CONCLUSIONS Plant-based diets are associated with decreased total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol, but not with decreased triglycerides. SYSTEMATIC REVIEW REGISTRATION PROSPERO number CRD42015023783. Available at: https://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42015023783.