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Nutrients Nov 2022Caloric restriction and vegan diets have demonstrated protective effects for diabetes, however their role in improving clinically relevant outcomes has not been... (Meta-Analysis)
Meta-Analysis Review
Investigating the Effectiveness of Very Low-Calorie Diets and Low-Fat Vegan Diets on Weight and Glycemic Markers in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis.
Caloric restriction and vegan diets have demonstrated protective effects for diabetes, however their role in improving clinically relevant outcomes has not been summarized. Our aim was to evaluate the evidence for low-calorie diets (VLCD) and vegan diets on weight and glycemic control in the management of patients with Type 2 Diabetes. Database searches were conducted using Cochrane Library, MEDLINE (Ovid) and Embase. Systematic Review Registration: CRD42022310299. Methodological quality of studies was assessed using Cochrane RoB Tool for RCTs, Cochrane ROBINS-I RoB Tool for non-RCTs and NIH Quality Assessment tool for other studies. Sixteen studies with a total of 834 individuals were included and assessed to have a moderate to high risk of bias. Statistically significant changes in weight, BMI, and HbA1c were not observed in vegan diet cohorts. However, LDL cholesterol was significantly decreased by vegan diet. VLCDs significantly improved glycaemic control, with reductions in fasting glucose, pooled mean difference (MD) -1.51 mmol/L (95% CI -2.89, -0.13; = 0.03; 2 studies) and HbA1c, pooled MD -0.66% (95% CI -1.28, -0.03; = 0.04; 3 studies) compared to non-dietary therapy. Both diets suggested a trend towards improved weight loss and anthropometric markers vs. control. VLCD diet intervention is associated with improvement in glycaemia control in patients with Type 2 Diabetes.
Topics: Humans; Diet, Vegan; Diabetes Mellitus, Type 2; Glycated Hemoglobin; Caloric Restriction; Blood Glucose; Diet, Fat-Restricted; Biomarkers
PubMed: 36432557
DOI: 10.3390/nu14224870 -
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 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 -
The British Journal of Nutrition Mar 2024Plant-based diets have emerged as athletic performance enhancers for various types of exercise. Therefore, the present study evaluated the effectiveness of plant-based... (Meta-Analysis)
Meta-Analysis Review
Plant-based diets have emerged as athletic performance enhancers for various types of exercise. Therefore, the present study evaluated the effectiveness of plant-based diets on aerobic and strength/power performances, as well as on BMI of physically active individuals. This systematic review and meta-analysis was conducted and reported according to the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement. A systematic search of electronic databases, including PubMed, Web of Science and SPORTDiscus, was performed. On the basis of the search and inclusion criteria, four and six studies evaluating the effects of plant-based diets on aerobic and strength/power performances in humans were, respectively, included in the systematic review and meta-analysis. Plant-based diets had a moderate but positive effect on aerobic performance (0·55; 95 % CI 0·29, 0·81) and no effect on strength/power performance (-0·30; 95 % CI -0·67, 0·07). The altogether analyses of both aerobic and strength/power exercises revealed that athletic performance was unchanged (0·01; 95 % CI -0·21, 0·22) in athletes who adopted plant-based diets. However, a small negative effect on BMI (-0·27; 95 % CI -0·40, -0·15) was induced by these diets. The results indicate that plant-based diets have the potential to exclusively assist aerobic performance. On the other hand, these diets do not jeopardise strength/power performance. Overall, the predicted effects of plant-based diets on physical performance are impactless, even though the BMI of their adherents is reduced.
Topics: Humans; Diet, Plant-Based; Athletic Performance; Diet; Exercise; Exercise Therapy; Muscle Strength
PubMed: 37869973
DOI: 10.1017/S0007114523002258 -
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 -
Nutrients Jul 2021The human gut microbiota are the microorganisms (generally bacteria and archaea) that live in the digestive tracts of humans. Due to their numerous functions, the gut...
The human gut microbiota are the microorganisms (generally bacteria and archaea) that live in the digestive tracts of humans. Due to their numerous functions, the gut microbiota can be considered a virtual organ of the body, playing a pivotal role in health maintenance. Dietary habits contribute to gut microbiota composition, and evidence from observational and intervention studies suggest that vegan diets may promote health, potentially through affecting the diverse ecosystem of beneficial bacteria in the gut. A systematic literature search was conducted on PubMed and Scopus to identify studies investigating the microbiota composition in vegans. Vegans are defined as people excluding food products that are derived from animals from their diet. Nine observational studies were identified. The main outcome of the systematic review was an increase in Bacteroidetes on the phylum level and a higher abundance of on the genus level. In conclusion, the present systematic literature review highlighted some benefits of a vegan diet but also demonstrated the complexity of evaluating results from gut microbiota research. The available evidence only consisted of cross-sectional studies, therefore suggesting the need for well-designed randomised controlled trials. Furthermore, the quality assessment of the studies included in the review suggested a lack of standardised and validated methods for participant selection as well as for faecal sampling and faecal analysis.
Topics: Adult; Bacteria; Diet, Healthy; Diet, Vegan; Dysbiosis; Feces; Female; Gastrointestinal Microbiome; Humans; Intestines; Male; Middle Aged; Nutritive Value
PubMed: 34371912
DOI: 10.3390/nu13072402 -
Translational Psychiatry Sep 2019Western societies notice an increasing interest in plant-based eating patterns such as vegetarian and vegan, yet potential effects on the body and brain are a matter of...
Western societies notice an increasing interest in plant-based eating patterns such as vegetarian and vegan, yet potential effects on the body and brain are a matter of debate. Therefore, we systematically reviewed existing human interventional studies on putative effects of a plant-based diet on the metabolism and cognition, and what is known about the underlying mechanisms. Using the search terms "plant-based OR vegan OR vegetarian AND diet AND intervention" in PubMed filtered for clinical trials in humans retrieved 205 studies out of which 27, plus an additional search extending the selection to another five studies, were eligible for inclusion based on three independent ratings. We found robust evidence for short- to moderate-term beneficial effects of plant-based diets versus conventional diets (duration ≤ 24 months) on weight status, energy metabolism and systemic inflammation in healthy participants, obese and type-2 diabetes patients. Initial experimental studies proposed novel microbiome-related pathways, by which plant-based diets modulate the gut microbiome towards a favorable diversity of bacteria species, yet a functional "bottom up" signaling of plant-based diet-induced microbial changes remains highly speculative. In addition, little is known, based on interventional studies about cognitive effects linked to plant-based diets. Thus, a causal impact of plant-based diets on cognitive functions, mental and neurological health and respective underlying mechanisms has yet to be demonstrated. In sum, the increasing interest for plant-based diets raises the opportunity for developing novel preventive and therapeutic strategies against obesity, eating disorders and related comorbidities. Still, putative effects of plant-based diets on brain health and cognitive functions as well as the underlying mechanisms remain largely unexplored and new studies need to address these questions.
Topics: Brain; Cognition; Diet, Vegan; Diet, Vegetarian; Humans
PubMed: 31515473
DOI: 10.1038/s41398-019-0552-0 -
Nutrition Reviews Jul 2023The popularity of plant-based diets, characterized by a partial or complete exclusion of animal products, has increased significantly over the last 10 years. The... (Meta-Analysis)
Meta-Analysis
CONTEXT
The popularity of plant-based diets, characterized by a partial or complete exclusion of animal products, has increased significantly over the last 10 years. The exclusion of animal products removes the most common sources of vitamin B12, which can lead to vitamin B12 deficiency and result in irreversible damage, such as growth stunting.
OBJECTIVE
This aim of this systematic review and meta-analysis was to qualitatively evaluate all studies on this subject and to quantify the potential difference in vitamin B12 levels in healthy children and adolescents aged 5 to 18 years.
DATA SOURCES
PubMed and Embase databases were searched for relevant studies investigating vitamin B12 levels in healthy children and adolescents aged 5 to 18 years on plant-based diets.
DATA EXTRACTION
Studies were assessed qualitatively with the AXIS tool and quantitatively with Stata 16.0 software.
DATA ANALYSIS
Overall, children and adolescents on plant-based diets had a significantly lower vitamin B12 level than omnivorous children and adolescents (-97 pmol/L; 95%CI, -187 to -7; I2 = 98.5%), a difference that remained statistically significant after adjusting for methodological confounders. After subgroup analyses, this effect was not statistically significant for children and adolescents on vegetarian diets but remained significant in children and adolescents on vegan or macrobiotic diets. Moreover, total vitamin B12 intake nullified the mean difference in vitamin B12 levels.
CONCLUSION
Despite high heterogeneity across studies, these results indicate that children and adolescents on plant-based diets, especially those on vegan and macrobiotic diets, may be at risk of developing vitamin B12 deficiency.
Topics: Child; Humans; Diet; Diet, Vegetarian; Nutritional Status; Vitamin B 12; Vitamin B 12 Deficiency
PubMed: 36413044
DOI: 10.1093/nutrit/nuac096 -
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