Effects of Plant-Based Diets on Anthropometric and Cardiometabolic Markers in Adults: An Umbrella Review

A Review of Plant-Based Diets for Obesity Management

OBJECTIVE

Obesity is the most prevalent chronic disease in the United States with over 70% of the American population suffering from overweight/obesity. Recently, the popularity of plant-based diets (PBDs) has grown, with individuals adopting these diets for ethical, health and environmental reasons. Our aim is to evaluate the effect of a PBD on weight loss among patients who are overweight or obese.

METHODS

A literature review of PBDs for the treatment of obesity was conducted using PubMed and Scopus. Our search yielded 27 intervention trials (3361 participants) and 6 metanalyses (9168 participants, 61 trials).

RESULTS

Among the intervention trials evaluated, 75% showed a significant increase in weight loss or decrease in weight in the intervention group, on average -5.0 kg (range -1.8 to -12.1 kg). Other outcomes included energy intake (-420 Kcal/d), systolic blood pressure (-3.78 mmHg), fasting plasma glucose (-2.0 mmol/L), hemoglobin A1c (-0.5%, -3.4 mmol/L), total cholesterol (-0.40 mmol/L), low-density lipoprotein (-0.38 mmol/L), triglyceride levels (+0.13 mmol/L), and fiber intake (+10.8 g/d). The 6 meta-analyses showed weight loss (average -2.9 kg, range -2.02 kg to -4.1 kg), body mass index reduction, and improvements in hemoglobin A1c, low-density lipoprotein, and total cholesterol.

CONCLUSION

PBDs result in significant weight loss and improve metabolic outcomes. PBDs offer a sustainable approach to long-term weight loss maintenance. Health care providers should encourage open discussions with their patients regarding their dietary habits to assist them in setting feasible lifestyle goals and consider shared medical appointments to support patients in transitioning to PBDs.

Plant-based and Early Time-restricted Eating for Prevention and Treatment of Type 2 Diabetes in Adults: A Narrative Review

Type 2 diabetes (T2D) is a significant public health challenge for which effective lifestyle interventions are needed. A growing body of evidence supports the use of both plant-based eating patterns and early time-restricted eating (eTRE) for the prevention and treatment of T2D, but research has not yet explored the potential of these dietary strategies in combination. In this narrative review, we assessed the evidence by which plant-based diets, in conjunction with eTRE, could support T2D care. The electronic databases MEDLINE and the Web of Science were searched for relevant articles published throughout the last decade. Observational research has shown that healthy plant-based eating patterns and eTRE are associated with reductions in T2D risk. Interventional trials demonstrated that plant-based diets promote improvements in glycated hemoglobin, insulin resistance, glycemic management, and cardiometabolic risk factors. These changes may be mediated, in part, by reductions in oxidative stress, dietary acid load, and hepatocellular and intramyocellular lipids. The eTRE strategies were also shown to improve insulin resistance and glycemic management, and mechanisms of action included enhanced regulation of circadian rhythm and increased metabolic flexibility. Integrating these dietary strategies may produce additive benefits, mediated by reduced visceral adiposity and beneficial shifts in gut microbiota composition. However, potential barriers to concurrent implementation of these interventions may exist, including social challenges, scheduling constraints, and tolerance. Prospective trials are needed to examine their acceptability and clinical effects.

The Association Between Overall, Healthy, and Unhealthy Plant-Based Diet Index and Risk of Prediabetes and Type 2 Diabetes Mellitus: A Systematic Review and Dose-Response Meta-Analysis of Prospective Studies

CONTEXT

The global incidence of prediabetes and type 2 diabetes mellitus (T2DM) has increased substantially in recent years. Among the established, modifiable lifestyle factors associated with favorable prediabetes and T2DM risk, healthy dietary patterns have attracted considerable attention.

OBJECTIVE

The association between adherence to plant-based dietary pattern indices (PDIs), including the overall PDI (O-PDI), healthy PDI (H-PDI), and unhealthy PDI (U-PDI), and the risk of prediabetes and T2DM was investigated in this study.

DATA SOURCES

A literature search was conducted of the PubMed/Medline, Scopus, and Web of Sciences databases from their inception to February 2024. A systematic review and meta-analysis were conducted using random effects models and dose-response analyses. The Cochran Q test and the I2 statistic were used to evaluate heterogeneity between studies.

DATA EXTRACTION

A total of 16 publications, with data on a total of 721 012 participants, were identified for the meta-analysis.

DATA ANALYSIS

According to a pooled analysis, compared with the lowest category of O-PDI and H-PDI adherence, the highest category was associated with a 14% and 19% reduction in T2DM risk, respectively, for O-PDI (effect size [ES] = 0.86; 95%CI, 0.82-0.90; I2 = 57.7) and H-PDI (ES = 0.81; 95%CI, 0.75-0.88; I2 = 82.6). Greater adherence to U-PDI was significantly associated with an 10% increase in the risk of T2DM (ES = 1.10; 95%CI, 1.04-1.16). Consistent associations were found within the predetermined subgroups. As well, there was a nonlinear inverse association between O-PDI, H-PDI, and T2DM risk. No significant association was found between adherence to O-PDI (ES = 0.87; 95%CI, 0.75-1.01; I2 = 68%), H-PDI (ES = 0.99; 95%CI, 0.87-1.13; I2 = 0.0%), and U-PDI (ES = 1.09; 95%CI, 0.94-1.21; I2 = 22.9%) and risk of prediabetes.

CONCLUSION

These findings underscore the importance of dietary selections within the framework of a plant-based dietary pattern, particularly when incorporating healthful, plant-based foods, which may have potential benefits in reducing the T2DM risk.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42023459851.

Consumption of Ultra-Processed Food and Drink Products in a Greek Christian Orthodox Church Fasting Population

The positive effects of the Mediterranean diet on healthy living are widely known, while the health effects of religious fasting have received increased attention during the last decade. However, no study has focused on the consumption of ultra-processed foods (UPFs) in such populations. Therefore, our aim was to investigate UPF intake and its association with metabolic syndrome (MetS) in a Christian Orthodox church (COC) religious fasting population in Greece. In this cross-sectional study, 400 individuals who follow the Mediterranean diet were included, stratified as COC fasters and non-fasters. Dietary intake data were collected via three 24 h diet recalls and a monthly food frequency questionnaire (FFQ). The NOVA food classification system was used to identify the level of processing and categorize all food items. Fasters consumed significantly less chicken, turkey, and beef and significantly more seafood, fish, snails, soy products, and fresh fruits, in terms of unprocessed or minimally processed foods, as well as significantly more fried potatoes and olives in terms of processed foods when compared with non-fasters. Regarding UPFs, a significantly lower intake of pork sausages, ketchup, and mustard as well as a significantly higher consumption of margarine and tarama dip were recorded in fasters compared with non-fasters. Fasters with MetS more frequently consumed UPFs (such as cheese pastries, biscuits, and cakes) than fasters without MetS (p < 0.05 for all comparisons). Similarly, non-fasters with MetS had an increased intake of UPFs (such as Cypriot bread and Coco Pops breakfast cereals) than non-fasters without MetS. Future research should focus on UPF consumption and its associations with clinical outcomes in such populations, thus providing further data for the potential health effects of COC fasting.

Association of Vegetarian and Vegan Diets with Cardiovascular Health: An Umbrella Review of Meta-Analysis of Observational Studies and Randomized Trials

BACKGROUND

Cardiovascular diseases (CVDs) are leading global causes of mortality. Unhealthy diets have been linked to an increased risk of CVD, while plant-based diets have shown potential protective effects. This umbrella review summarizes the evidence on the association between vegetarian diets and cardiovascular and cerebrovascular diseases.

METHODS

PubMed, Scopus, Embase, CINAHL, Cochrane, and Web of Science were consulted. Meta-analyses grouped by author and outcome were performed. The heterogeneity was evaluated using I2 statistics.

RESULTS

There was a 41.2% risk reduction for cerebrovascular disease. CVD incidence had a 29% reduced risk. CVD mortality had a 13.8% risk reduction, while IHD incidence had a 24.1% reduction, but with high heterogeneity. IHD mortality showed a significant 32.1% risk reduction. Ischemic stroke had a significant 32.9% risk reduction across six studies. Stroke incidence showed a significant 39.1% risk reduction in a single study. There was a non-significant 11.6% risk reduction for stroke mortality with moderate heterogeneity.

CONCLUSION

Healthier diets are associated with reduced risks of cerebrovascular disease, CVD incidence, IHD mortality, and ischemic stroke. However, evidence quality and consistency vary, emphasizing the need for more research. Policymakers and healthcare professionals should prioritize promoting healthy diets for CVD prevention.