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European Heart Journal Jul 2023Due to growing environmental focus, plant-based diets are increasing steadily in popularity. Uncovering the effect on well-established risk factors for cardiovascular... (Meta-Analysis)
Meta-Analysis
AIMS
Due to growing environmental focus, plant-based diets are increasing steadily in popularity. Uncovering the effect on well-established risk factors for cardiovascular diseases, the leading cause of death worldwide, is thus highly relevant. Therefore, a systematic review and meta-analysis were conducted to estimate the effect of vegetarian and vegan diets on blood levels of total cholesterol, low-density lipoprotein cholesterol, triglycerides, and apolipoprotein B.
METHODS AND RESULTS
Studies published between 1980 and October 2022 were searched for using PubMed, Embase, and references of previous reviews. Included studies were randomized controlled trials that quantified the effect of vegetarian or vegan diets vs. an omnivorous diet on blood lipids and lipoprotein levels in adults over 18 years. Estimates were calculated using a random-effects model. Thirty trials were included in the study. Compared with the omnivorous group, the plant-based diets reduced total cholesterol, low-density lipoprotein cholesterol, and apolipoprotein B levels with mean differences of -0.34 mmol/L (95% confidence interval, -0.44, -0.23; P = 1 × 10-9), -0.30 mmol/L (-0.40, -0.19; P = 4 × 10-8), and -12.92 mg/dL (-22.63, -3.20; P = 0.01), respectively. The effect sizes were similar across age, continent, duration of study, health status, intervention diet, intervention program, and study design. No significant difference was observed for triglyceride levels.
CONCLUSION
Vegetarian and vegan diets were associated with reduced concentrations of total cholesterol, low-density lipoprotein cholesterol, and apolipoprotein B-effects that were consistent across various study and participant characteristics. Plant-based diets have the potential to lessen the atherosclerotic burden from atherogenic lipoproteins and thereby reduce the risk of cardiovascular disease.
Topics: Adult; Humans; Diet, Vegan; Diet, Vegetarian; Randomized Controlled Trials as Topic; Lipids; Vegetarians; Cholesterol, LDL; Lipoproteins; Cardiovascular Diseases; Atherosclerosis; Apolipoproteins
PubMed: 37226630
DOI: 10.1093/eurheartj/ehad211 -
Nutrition, Metabolism, and... Jun 2019The aim of the present review is to examine evidence from published studies on the effectiveness of six or more months of low carbohydrate, macrobiotic, vegan,...
BACKGROUND AND AIM
The aim of the present review is to examine evidence from published studies on the effectiveness of six or more months of low carbohydrate, macrobiotic, vegan, vegetarian, Mediterranean and intermittent fasting (IF) diets compared to low fat diets on diabetes control and management.
METHODS AND RESULTS
In accordance with PRISMA guidelines, Cochrane CENTRAL, PubMed and Scopus databases were systematically searched for relevant studies. Twenty randomised controlled trials (RCTs) > 6 months that investigated the effectiveness of various dietary patterns on type 2 diabetes mellitus (T2DM) were included. Risk of bias was assessed using the Cochrane tool. There were no significant differences in glycemic control, weight and lipids for the majority of low carbohydrate diets (LCDs) compared to low fat diets (LFDs). Four out of fifteen LCD interventions showed better glycemic control while weight loss was greater in one study. The Mediterranean dietary pattern demonstrated greater reduction in body weight and HbA1c levels and delayed requirement for diabetes medications. The vegan and macrobiotic diet demonstrated improved glycemic control, while the vegetarian diet showed greater body weight reduction and insulin sensitivity.
CONCLUSIONS
Although more long-term intervention trials are required, mounting evidence supports the view that vegan, vegetarian and Mediterranean dietary patterns should be implemented in public health strategies, in order to better control glycemic markers in individuals with T2DM.
Topics: Biomarkers; Blood Glucose; Diabetes Mellitus, Type 2; Diet, Diabetic; Diet, Healthy; Diet, Mediterranean; Diet, Vegan; Diet, Vegetarian; Humans; Insulin Resistance; Nutritional Status; Randomized Controlled Trials as Topic; Treatment Outcome; Weight Loss
PubMed: 30952576
DOI: 10.1016/j.numecd.2019.02.004 -
The American Journal of Clinical... Mar 2013There is evidence that reducing blood glucose concentrations, inducing weight loss, and improving the lipid profile reduces cardiovascular risk in people with type 2... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
There is evidence that reducing blood glucose concentrations, inducing weight loss, and improving the lipid profile reduces cardiovascular risk in people with type 2 diabetes.
OBJECTIVE
We assessed the effect of various diets on glycemic control, lipids, and weight loss.
DESIGN
We conducted searches of PubMed, Embase, and Google Scholar to August 2011. We included randomized controlled trials (RCTs) with interventions that lasted ≥6 mo that compared low-carbohydrate, vegetarian, vegan, low-glycemic index (GI), high-fiber, Mediterranean, and high-protein diets with control diets including low-fat, high-GI, American Diabetes Association, European Association for the Study of Diabetes, and low-protein diets.
RESULTS
A total of 20 RCTs were included (n = 3073 included in final analyses across 3460 randomly assigned individuals). The low-carbohydrate, low-GI, Mediterranean, and high-protein diets all led to a greater improvement in glycemic control [glycated hemoglobin reductions of -0.12% (P = 0.04), -0.14% (P = 0.008), -0.47% (P < 0.00001), and -0.28% (P < 0.00001), respectively] compared with their respective control diets, with the largest effect size seen in the Mediterranean diet. Low-carbohydrate and Mediterranean diets led to greater weight loss [-0.69 kg (P = 0.21) and -1.84 kg (P < 0.00001), respectively], with an increase in HDL seen in all diets except the high-protein diet.
CONCLUSION
Low-carbohydrate, low-GI, Mediterranean, and high-protein diets are effective in improving various markers of cardiovascular risk in people with diabetes and should be considered in the overall strategy of diabetes management.
Topics: Blood Glucose; Cardiovascular Diseases; Diabetes Mellitus, Type 2; Diet, Carbohydrate-Restricted; Diet, Fat-Restricted; Diet, Mediterranean; Diet, Protein-Restricted; Diet, Vegetarian; Dietary Carbohydrates; Dietary Fats; Dietary Fiber; Dietary Proteins; Energy Intake; Glycemic Index; Humans; Lipids; Randomized Controlled Trials as Topic; Risk Factors; Weight Loss
PubMed: 23364002
DOI: 10.3945/ajcn.112.042457 -
Nutrients Jul 2023Dietary patterns play a critical role in diabetes management, while the best dietary pattern for Type 2 diabetes (T2DM) patients is still unclear. The aim of this... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Dietary patterns play a critical role in diabetes management, while the best dietary pattern for Type 2 diabetes (T2DM) patients is still unclear. The aim of this network meta-analysis was to compare the impacts of various dietary approaches on the glycemic control of T2DM patients.
METHODS
Relevant studies were retrieved from PubMed, Embase, Web of Knowledge, Cochrane Central Register of Controlled Trials (CENTRAL), and other additional records (1949 to 31 July 2022). Eligible RCTs were those comparing different dietary approaches against each other or a control diet in individuals with T2DM for at least 6 months. We assessed the risk of bias of included studies with the Cochrane risk of bias tool and confidence of estimates with the Grading of Recommendations Assessment, Development, and Evaluation approach for network meta-analyses. In order to determine the pooled effect of each dietary approach relative to each other, we performed a network meta-analysis (NMA) for interventions for both HbA1c and fasting glucose, which enabled us to estimate the relative intervention effects by combing both direct and indirect trial evidence.
RESULTS
Forty-two RCTs comprising 4809 patients with T2DM were included in the NMA, comparing 10 dietary approaches (low-carbohydrate, moderate-carbohydrate, ketogenic, low-fat, high-protein, Mediterranean, Vegetarian/Vegan, low glycemic index, recommended, and control diets). In total, 83.3% of the studies were at a lower risk of bias or had some concerns. Findings of the NMA revealed that the ketogenic, low-carbohydrate, and low-fat diets were significantly effective in reducing HbA1c (viz., -0.73 (-1.19, -0.28), -0.69 (-1.32, -0.06), and -1.82 (-2.93, -0.71)), while moderate-carbohydrate, low glycemic index, Mediterranean, high-protein, and low-fat diets were significantly effective in reducing fasting glucose (viz., -1.30 (-1.92, -0.67), -1.26 (-2.26, -0.27), -0.95 (-1.51, -0.38), -0.89 (-1.60, -0.18) and -0.75 (-1.24, -0.27)) compared to a control diet. The clustered ranking plot for combined outcomes indicated the ketogenic, Mediterranean, moderate-carbohydrate, and low glycemic index diets had promising effects for controlling HbA1c and fasting glucose. The univariate meta-regressions showed that the mean reductions of HbA1c and fasting glucose were only significantly related to the mean weight change of the subjects.
CONCLUSIONS
For glycemic control in T2DM patients, the ketogenic diet, Mediterranean diet, moderate-carbohydrate diet, and low glycemic index diet were effective options. Although this study found the ketogenic diet superior, further high-quality and long-term studies are needed to strengthen its credibility.
Topics: Humans; Diabetes Mellitus, Type 2; Network Meta-Analysis; Glycated Hemoglobin; Blood Glucose; Glycemic Control; Randomized Controlled Trials as Topic; Diet, Mediterranean
PubMed: 37513574
DOI: 10.3390/nu15143156 -
European Journal of Nutrition Aug 2017While the prevalence of children on vegetarian diets is assumed to be on the rise in industrialized countries, there are hardly any representative data available. In... (Review)
Review
PURPOSE
While the prevalence of children on vegetarian diets is assumed to be on the rise in industrialized countries, there are hardly any representative data available. In general, vegetarian diets are presumed to be healthy; nevertheless, there are concerns as to whether the dietary specifications required during infancy, childhood, and adolescence can be met. Therefore, the objective of this systematic review was to evaluate studies on the dietary intake and the nutritional or health status of vegetarian infants, children, and adolescents.
METHODS
The database MEDLINE was used for literature search. In addition, references of reviews and expert opinions were considered. Inclusion criteria were (1) sufficient dietary information to define vegetarian type diet and (2) characteristics of nutritional or health status. Case reports and studies from non-industrialized countries were excluded.
RESULTS
24 publications from 16 studies published from 1988 to 2013 met our criteria. Study samples covered the age range from 0 to 18 years, and median sample size was 35. Five studies did not include a control group. With regard to biomarkers, anthropometry, and dietary or nutritional intake, the outcomes were diverse. Growth and body weight were generally found within the lower reference range. The intakes of folate, vitamin C, and dietary fiber were relatively high compared to reference values and/or control groups. Low status of vitamin B was reported in one study and low status of vitamin D in two studies.
CONCLUSIONS
Due to the study heterogeneity, the small samples, the bias towards upper social classes, and the scarcity of recent studies, the existing data do not allow us to draw firm conclusions on health benefits or risks of present-day vegetarian type diets on the nutritional or health status of children and adolescents in industrialized countries.
Topics: Adolescent; Adolescent Development; Body Weight; Bone Development; Child; Child Development; Child, Preschool; Diet, Vegan; Diet, Vegetarian; Dietary Fiber; Humans; Infant; Infant, Newborn; Micronutrients; Observational Studies as Topic
PubMed: 28299420
DOI: 10.1007/s00394-017-1416-0 -
Nutrition Reviews Mar 2021Vegetarian and vegan diets are increasing in popularity. Although they provide beneficial health effects, they may also lead to nutritional deficiencies. Cognitive... (Meta-Analysis)
Meta-Analysis
CONTEXT
Vegetarian and vegan diets are increasing in popularity. Although they provide beneficial health effects, they may also lead to nutritional deficiencies. Cognitive impairment and mental health disorders have a high economic burden.
OBJECTIVE
A meta-analysis was conducted to examine the relationship between vegan or vegetarian diets and cognitive and mental health.
DATA SOURCES
PubMed, Scopus, ScienceDirect, and Proquest databases were examined from inception to July 2018.
STUDY SELECTION
Original observational or interventional human studies of vegan/vegetarian diets were selected independently by 2 authors.
DATA EXTRACTION
Raw means and standard deviations were used as continuous outcomes, while numbers of events were used as categorical outcomes.
RESULTS
Of 1249 publications identified, 13 were included, with 17 809 individuals in total. No significant association was found between diet and the continuous depression score, stress, well-being, or cognitive impairment. Vegans/vegetarians were at increased risk for depression (odds ratio = 2.142; 95%CI, 1.105-4.148) and had lower anxiety scores (mean difference = -0.847; 95%CI, -1.677 to -0.018). Heterogeneity was large, and thus subgroup analyses showed numerous differences.
CONCLUSIONS
Vegan or vegetarian diets were related to a higher risk of depression and lower anxiety scores, but no differences for other outcomes were found. Subgroup analyses of anxiety showed a higher risk of anxiety, mainly in participants under 26 years of age and in studies with a higher quality. More studies with better overall quality are needed to make clear positive or negative associations.
SYSTEMATIC REVIEW REGISTRATION
PROSPERO registration no. CRD42018097204.
Topics: Anxiety; Cognition; Depression; Diet, Vegan; Diet, Vegetarian; Humans; Mental Health; Vegans; Vegetarians
PubMed: 32483598
DOI: 10.1093/nutrit/nuaa030 -
Nutrition Reviews Mar 2019Vegetarian diets are consistently associated with improved health outcomes, and higher diet quality may contribute to improved health outcomes. This systematic review...
OBJECTIVE
Vegetarian diets are consistently associated with improved health outcomes, and higher diet quality may contribute to improved health outcomes. This systematic review aims to qualitatively compare the a priori diet quality of vegetarian and nonvegetarian diets.
METHODS
Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol, 2 online databases (Web of Science and PubMed) were searched for English language studies comparing diet quality among vegetarian and nonvegetarian adults using an a priori diet quality index. Two reviewers assessed study eligibility. Comparisons were made between total and component (when available) diet quality scores among the 12 studies meeting inclusion criteria.
CONCLUSIONS
Lacto-ovo vegetarians or vegans had higher overall diet quality (4.5-16.4 points higher on the Healthy Eating Index 2010 [HEI-2010]) compared with nonvegetarians in 9 of 12 studies. Higher HEI-2010 scores for vegetarians were driven by closer adherence to recommendations for total fruit, whole grains, seafood and plant protein, and sodium. However, nonvegetarians had closer adherence to recommendations for refined grains and total protein foods. Higher diet quality in vegetarian diets may partially explain improvements in health outcomes compared with nonvegetarians; however, more research controlling for known confounders like health consciousness is needed.
Topics: Adult; Diet; Diet, Vegan; Diet, Vegetarian; Female; Fruit; Humans; Male; Middle Aged; Minerals; Nutritive Value; Young Adult
PubMed: 30624697
DOI: 10.1093/nutrit/nuy067 -
Frontiers in Public Health 2022Diets containing red or processed meat are associated with a growing risk of digestive system cancers. Whether a plant-based diet is protective against cancer needs a... (Meta-Analysis)
Meta-Analysis
BACKGROUND AND OBJECTIVES
Diets containing red or processed meat are associated with a growing risk of digestive system cancers. Whether a plant-based diet is protective against cancer needs a high level of statistical evidence.
METHODS
We performed a meta-analysis of five English databases, including PubMed, Medline, Embase, Web of Science databases, and Scopus, on October 24, 2021 to identify published papers. Cohort studies or case-control studies that reported a relationship between plant-based diets and cancers of the digestive system were included. Summary effect-size estimates are expressed as Risk ratios (RRs) or Odds ratios (ORs) with 95% confidence intervals and were evaluated using random-effect models. The inconsistency index (I) and τ (Tau) index were used to quantify the magnitude of heterogeneity derived from the random-effects Mantel-Haenszel model.
RESULTS
The same results were found in cohort (adjusted RR = 0.82, 95% CI: 0.78-0.86, < 0.001, = 46.4%, Tau = 0.017) and case-control (adjusted OR = 0.70, 95% CI: 0.64-0.77, < 0.001, = 83.8%, Tau = 0.160) studies. The overall analysis concluded that plant-based diets played a protective role in the risk of digestive system neoplasms. Subgroup analyses demonstrated that the plant-based diets reduced the risk of cancers, especially pancreatic (adjusted RR = 0.71, 95% CI: 0.59-0.86, < 0.001, = 55.1%, Tau = 0.028), colorectal (adjusted RR = 0.76, 95% CI: 0.69-0.83, < 0.001, = 53.4%, Tau = 0.023), rectal (adjusted RR = 0.84, 95% CI: 0.78-0.91, < 0.001, = 1.6%, Tau = 0.005) and colon (adjusted RR = 0.88, 95% CI: 0.82-0.95, < 0.001, = 0.0%, Tau = 0.000) cancers, in cohort studies. The correlation between vegan and other plant-based diets was compared using Z-tests, and the results showed no difference.
CONCLUSIONS
Plant-based diets were protective against cancers of the digestive system, with no significant differences between different types of cancer.
SYSTEMATIC REVIEW REGISTRATION
https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022322276, Identifier: CRD42022322276.
Topics: Case-Control Studies; Cohort Studies; Diet; Diet, Vegetarian; Digestive System Neoplasms; Humans
PubMed: 35719615
DOI: 10.3389/fpubh.2022.892153 -
Nutrition Reviews Jan 2019The numbers of vegans and vegetarians have increased in the last decades. However, the impact of these diets on bone health is still under debate. (Meta-Analysis)
Meta-Analysis
CONTEXT
The numbers of vegans and vegetarians have increased in the last decades. However, the impact of these diets on bone health is still under debate.
OBJECTIVE
This systematic review and meta-analysis sought to study the impact of vegetarian and vegan diets on bone mineral density (BMD) and fracture risk.
DATA SOURCES
A systematic search was conducted of PubMed, Scopus, and Science Direct, covering the period from the respective start date of each database to November 2017.
DATA EXTRACTION
Two investigators evaluated 275 studies against the inclusion criteria (original studies in humans, written in English or Spanish and including vegetarian or vegan diets and omnivorous diets as factors with BMD values for the whole body, lumbar spine, or femoral neck and/or the number of fractures as the outcome) and exclusion criteria (articles that did not include imaging or studies that included participants who had suffered a fracture before starting the vegetarian or vegan diet). The quality assessment tool for observational cohort and cross-sectional studies was used to assess the quality of the studies.
RESULTS
Twenty studies including 37 134 participants met the inclusion criteria. Compared with omnivores, vegetarians and vegans had lower BMD at the femoral neck and lumbar spine and vegans also had higher fracture rates.
CONCLUSIONS
Vegetarian and vegan diets should be planned to avoid negative consequences on bone health.
SYSTEMATIC REVIEW REGISTRATION
PROSPERO registration no. CRD42017055508.
Topics: Bone Density; Diet, Vegetarian; Fractures, Bone; Humans; Risk Factors
PubMed: 30376075
DOI: 10.1093/nutrit/nuy045