Effect of vegetarian diets on the presentation of metabolic syndrome or its components: A systematic review and meta-analysis

Impact of Prevalent Dietary Pattern on Serum Vitamin B12 Status and Its Association With Inflammation Among Reproductive Age Women

SCOPE

Association between vitamin B12 deficiency (VB12D) and dietary patterns being well documented has bearing on obstetrics and neonatal outcomes. However, relationship between VB12D and serum inflammatory markers (IMs), particularly in vegetarian diet and Polycystic ovary syndrome (PCOS), remains elusive. This cross-sectional study assesses VB12D and IMs among reproductive age women consuming different diets.

METHODS AND RESULTS

Nonvegetarian (PCOS, n = 104; healthy, n = 148) and vegetarian women (PCOS n = 112; healthy, n = 186) are for evaluated clinical, biochemical, hormonal assessment, inflammatory, and four vitamin B 12 (VB12) markers. VB12D is defined by Fedosov's wellness quotient (4cB12). Using 4cB12, prevalence of VB12D is discerned in 54.4% (PCOS: 72.1%; healthy 36.5%) and 93.4% (PCOS: 95.9%; healthy: 91.9%) among nonvegetarians and vegetarians, respectively. Vegetarian PCOS women depict lowest median (interquartile range [IQR]) of serum B12 76.2(72.6) pg mL-1, holotranscobalamine (HTC) 37.9(11.3) and highest homocysteine (HCY) 40.32(6.0) µmol L-1, methylmalonic acid (MMA) 352.26(156.7) nmol L-1 with highest Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) and IMs (Monocyte chemoattractant protein 1 (MCP-1), High sensitivity C-reactive protein (hs-CRP), Tumour Necrosis Factor alpha (TNF-α) and Interleukin 6 (IL-6)). Significant correlation of serum hs-CRP, TNF-α, and IL-6 with VB12 markers is observed.

CONCLUSION

The VB12D is rampant among reproductive age women that gets exacerbated by PCOS or vegetarian diet. It is directly correlated with magnitude of proinflammatory markers. The results carry substantial implications for public health policies aimed at improving preconception maternal VB12 status for better future pregnancy and offspring outcomes.

Cardiovascular health and cancer risk associated with plant based diets: An umbrella review

CONTEXT

Cardiovascular diseases (CVDs) and cancer are the two main leading causes of death and disability worldwide. Suboptimal diet, poor in vegetables, fruits, legumes and whole grain, and rich in processed and red meat, refined grains, and added sugars, is a primary modifiable risk factor. Based on health, economic and ethical concerns, plant-based diets have progressively widespread worldwide.

OBJECTIVE

This umbrella review aims at assessing the impact of animal-free and animal-products-free diets (A/APFDs) on the risk factors associated with the development of cardiometabolic diseases, cancer and their related mortalities.

DATA SOURCES

PubMed and Scopus were searched for reviews, systematic reviews, and meta-analyses published from 1st January 2000 to 31st June 2023, written in English and involving human subjects of all ages. Primary studies and reviews/meta-analyses based on interventional trials which used A/APFDs as a therapy for people with metabolic diseases were excluded.

DATA EXTRACTION

The umbrella review approach was applied for data extraction and analysis. The revised AMSTAR-R 11-item tool was applied to assess the quality of reviews/meta-analyses.

RESULTS

Overall, vegetarian and vegan diets are significantly associated with better lipid profile, glycemic control, body weight/BMI, inflammation, and lower risk of ischemic heart disease and cancer. Vegetarian diet is also associated with lower mortality from CVDs. On the other hand, no difference in the risk of developing gestational diabetes and hypertension were reported in pregnant women following vegetarian diets. Study quality was average. A key limitation is represented by the high heterogeneity of the study population in terms of sample size, demography, geographical origin, dietary patterns, and other lifestyle confounders.

CONCLUSIONS

Plant-based diets appear beneficial in reducing cardiometabolic risk factors, as well as CVDs, cancer risk and mortality. However, caution should be paid before broadly suggesting the adoption of A/AFPDs since the strength-of-evidence of study results is significantly limited by the large study heterogeneity alongside the potential risks associated with potentially restrictive regimens.

Evaluating agreement between evidence from randomised controlled trials and cohort studies in nutrition: a meta-research replication study

This meta-research study aims to evaluate the agreement of effect estimates between bodies of evidence (BoE) from RCTs and cohort studies included in the same nutrition evidence synthesis, to identify factors associated with disagreement, and to replicate the findings of a previous study. We searched Medline, Epistemonikos and the Cochrane Database of Systematic Reviews for nutrition systematic reviews that included both RCTs and cohort studies for the same patient-relevant outcome or intermediate-disease marker. We rated similarity of PI/ECO (population, intervention/exposure, comparison, outcome) between BoE from RCTs and cohort studies. Agreement of effect estimates across BoE was analysed by pooling ratio of risk ratios (RRR) for binary outcomes and difference of standardised mean differences (DSMD) for continuous outcomes. We performed subgroup and sensitivity analyses to explore determinants associated with disagreements. We included 82 BoE-pairs from 51 systematic reviews. For binary outcomes, the RRR was 1.04 (95% confidence interval (CI) 0.99 to 1.10, I2 = 59%, τ2 = 0.02, prediction interval (PI) 0.77 to 1.41). For continuous outcomes, the pooled DSMD was  - 0.09 (95% CI  - 0.26 to 0.09, PI  - 0.55 to 0.38). Subgroup analyses yielded that differences in type of intake/exposure were drivers towards disagreement. We replicated the findings of a previous study, where on average RCTs and cohort studies had similar effect estimates. Disagreement and wide prediction intervals were mainly driven by PI/ECO-dissimilarities. More research is needed to explore other potentially influencing factors (e.g. risk of bias) on the disagreement between effect estimates of both BoE.Trial registration: CRD42021278908.

Dietary polyphenols and the risk of metabolic syndrome: a systematic review and meta-analysis

BACKGROUND

Accumulating evidence has suggested that dietary polyphenols may be protective against metabolic syndrome (MetS); however, the available evidence is contradictory. The aim of this meta-analysis was to assess the association between dietary intake of polyphenols and the odds of MetS.

METHODS

The PubMed and Scopus databases were systematically searched to obtain eligible studies. The risk of MetS for the highest versus the lowest intakes of total, subclasses and individual polyphenols were examined by pooling odds ratios (OR) and 95% confidence intervals (95%CI) using the random effects model.

RESULTS

A total of 14 studies (6 cohort and 8 cross-sectional studies) involving a total of 50,366 participants with 10,879 cases of MetS were included. When various polyphenol compounds were pooled, they were significantly related to a 22% decreased odds of MetS (([5 studies]; OR: 0.78; 95%CI: 0.72-0.85). Higher intakes of total flavonoids (([9 studies]; OR: 0.78; 95%CI: 0.72-0.85), flavan-3-ols (([2 studies]; OR: 0.64; 95%CI: 0.43-0.94), isoflavones (([3 studies]; OR: 0.84; 95%CI: 0.75-0.93), stilbenes (([4 studies]; OR: 0.86; 95%CI: 0.76-0.97), flavones (([2 studies]; OR: 0.79; 95%CI: 0.71-0.89), and quercetin (([2 studies]; OR: 0.63; 95%CI: 0.43-0.93) were also significantly associated with a decreased risk of MetS. The associations were not modified by the age of the participants. No association was found for total polyphenols, phenolic acids, lignans, anthocyanins, and flavonols.

CONCLUSION

The results of this meta-analysis supported that higher polyphenol intake can lower the risk of MetS.

Variation observed in consensus judgments between pairs of reviewers when assessing the risk of bias due to missing evidence in a sample of published meta-analyses of nutrition research

OBJECTIVES

To evaluate the risk of bias due to missing evidence in a sample of published meta-analyses of nutrition research using the Risk Of Bias due to Missing Evidence (ROB-ME) tool and determine inter-rater agreement in assessments.

STUDY DESIGN AND SETTING

We assembled a random sample of 42 meta-analyses of nutrition research. Eight assessors were randomly assigned to one of four pairs. Each pair assessed 21 randomly assigned meta-analyses, and each meta-analysis was assessed by two pairs. We calculated raw percentage agreement and chance corrected agreement using Gwet's Agreement Coefficient (AC) in consensus judgments between pairs.

RESULTS

Across the eight signaling questions in the ROB-ME tool, raw percentage agreement ranged from 52% to 100%, and Gwet's AC ranged from 0.39 to 0.76. For the risk-of-bias judgment, the raw percentage agreement was 76% (95% confidence interval 60% to 92%) and Gwet's AC was 0.47 (95% confidence interval 0.14 to 0.80). In seven (17%) meta-analyses, either one or both pairs judged the risk of bias due to missing evidence as "low risk".

CONCLUSION

Our findings indicated substantial variation in assessments in consensus judgments between pairs for the signaling questions and overall risk-of-bias judgments. More tutorials and training are needed to help researchers apply the ROB-ME tool more consistently.

The association between plant-based diet indices and metabolic syndrome: a systematic review and dose-response meta-analysis

Aim/introduction

The prevalence of metabolic syndrome (MetS) and its components have markedly increased worldwide. Among lifestyle factors introduced to lower the risk of MetS, healthy dietary patterns have gained considerable attention. This study aimed to assess the association between adherence to plant-based diet indices including O-PDI (overall plant-based diet index), H-PDI (healthy plant-based diet index), U-PDI (unhealthy plant-based diet index), and risk of MetS development.

Methods

To find related observational studies which assessed the association between Plant-based Diet indices and risk of MetS development, PubMed/Medline, Scopus, and Web of Science databases were searched from January 2016 to November 2023. A random effects model was used to estimate pooled odds ratios (OR) and 95% confidence intervals (95% CI). To assess the heterogeneity of included studies, the I2 index was used.

Results

Nine studies including 34,953 participants from the initial 288 studies were recognized to include in this meta-analysis study. According to pooled analysis, there was a significant relationship between the adherence to H-PDI and the lower risk of MetS (ES: 0.81; 95% CI: 0.67, 0.97; I2 = 77.2%, p < 0.001), while greater adherence to U-PDI was associated with 27% increases in the risk of MetS (ES: 1.27; 95% CI: 1.05, 1.54; I2 = 76.8%, p < 0.001). According to our analysis of the association between adherence to PDIs and the risk of MetS components, greater adherence to O-PDI and H-PDI was significantly associated with a higher risk of elevated FBS and obesity, respectively. As well, greater adherence to U-PDI was significantly associated with a higher risk of obesity, hypertriglyceridemia, low HDL-C, and elevated FBS.

Conclusion

Our results highlighted the importance of food choices in the context of a plant-based dietary pattern, indicating that adherence to unhealthy plant-based dietary patterns rich in less healthful carbohydrates may induce the risk of MetS development.

Systematic review registration

PROSPERO CRD42023428981.

The Role of Diet in the Prevention of Hypertension and Management of Blood Pressure: An Umbrella Review of Meta-Analyses of Interventional and Observational Studies

High blood pressure (BP) is a major pathological risk factor for the development of several cardiovascular diseases. Diet is a key modifier of BP, but the underlying relationships are not clearly demonstrated. This is an umbrella review of published meta-analyses to critically evaluate the wide range of dietary evidence from bioactive compounds to dietary patterns on BP and risk of hypertension. PubMed, Embase, Web of Science, and Cochrane Central Register of Controlled Trials were searched from inception until October 31, 2021, for relevant meta-analyses of randomized controlled trials or meta-analyses of observational studies. A total of 175 publications reporting 341 meta-analyses of randomized controlled trials (145 publications) and 70 meta-analyses of observational studies (30 publications) were included in the review. The methodological quality of the included publications was assessed using Assessment of Multiple Systematic Reviews 2 and the evidence quality of each selected meta-analysis was assessed using NutriGrade. This umbrella review supports recommended public health guidelines for prevention and control of hypertension. Dietary patterns including the Dietary Approaches to Stop Hypertension and the Mediterranean-type diets that further restrict sodium, and moderate alcohol intake are advised. To produce high-quality evidence and substantiate strong recommendations, future research should address areas where the low quality of evidence was observed (for example, intake of dietary fiber, fish, egg, meat, dairy products, fruit juice, and nuts) and emphasize focus on dietary factors not yet conclusively investigated.

Geographical and sociodemographic disparities in fruit and vegetables consumption among adults in Burkina Faso: baseline results from the 2013 WHO STEPS survey

BACKGROUND

Evidence on sociodemographic determinants and spatial variations in the fruit and/or vegetable (FV) consumption was reported. This study aimed to explore geographical and sociodemographic disparities in the level of FV consumption among adults in Burkina Faso, using the national baseline data.

METHODS

This was a cross-sectional secondary study of primary data obtained by the 2013 (September to October) World Health Organization Stepwise Approach to Surveillance survey conducted in Burkina Faso. The participants were 4402 women and men aged 25-64 years and living in all 13 Burkinabè Regions. Descriptive and analytical analyses were performed using Student's t test, ANOVA, the chi-square test, Fisher's exact test and logistic regressions.

RESULTS

The prevalence of a typical daily consumption of at least three servings was 4.1% (95% CI: 3.6-4.8) for fruits and 6.6% (95% CI: 5.9-7.3) for vegetables. The national prevalence of adequate FV intake was 5.1% (95% CI: 4.4-5.8), and for two Regions ("Centre-Ouest" and "Nord") the pooled prevalence was 22.4%, while in the other eleven Regions its was significantly lower, 2.4% (p = 0.0001). Using quartiles derived from the national level of consumption, each of these two Regions had a higher proportion (about 50%) of their participants in the fourth quartile (the higher level). The associated sociodemographic factors with the adequate intake were being rural residents (aOR = 1.7, p = 0.011) and women (aOR = 1.3; p = 0.03).

CONCLUSION

Except for the Regions of "Centre-Ouest" and "Nord" of Burkina Faso, the prevalence of adequate consumption of FV was very low in its other eleven Regions. Measures to increase consumption in urban people are urgent while women should be the key actor in the family-based approaches implementation and the nutrition education promoting FV consumption.

Vegetarian diets on anthropometric, metabolic and blood pressure outcomes in people with overweight and obesity: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

It is unknown whether vegetarian diets (VDs) may improve outcomes in people with overweight and obesity.

OBJECTIVE

To systematically assess the effects of VDs vs. omnivore diets on anthropometric, metabolic, and blood pressure outcomes in people with overweight and obesity.

METHODS

We searched for randomized controlled trials (RCTs) in EMBASE, PubMed, Web of Science, and Scopus until February 2, 2022. Primary outcomes were anthropometric risk factors (weight, body mass index [BMI], waist circumference [WC], hip circumference [HC], and body fat percentage). Secondary outcomes were metabolic risk factors (fasting serum glucose, HbA1c, insulin levels) and blood pressure (systolic blood pressure [SBP], diastolic blood pressure [DBP]). Random-effects meta-analyses were performed and effects were expressed as mean difference (MD) and their 95% confidence intervals (CI). The quality of evidence was assessed using GRADE methods.

RESULTS

Nine RCTs (n = 1628) were included. VDs decreased weight (MD -3.60 kg, 95%CI -4.75 to -2.46) and glucose (MD -10.64 mg/dL, 95%CI -15.77 to -5.51), but did not decrease WC (MD -3.00 cm, 95%CI -6.20 to 0.20), BMI (MD -0.87 kg/m2, 95%CI -1.80 to 0.06), or HC (MD: -0.86 cm, 95%CI -3.46 to 1.74). VDs did not decrease HbA1c (MD -0.40%, 95%CI -0.89 to 0.10), insulin (MD -3.83 mU/L, 95%CI -8.06 to 0.40), SBP (MD -0.25 mmHg, 95%CI -2.58 to 2.07), or DBP (MD -1.57 mmHg, 95%CI -3.93 to 0.78). Subgroup analyses by type of VD (four RCTs evaluated lacto-ovo-vegetarian diets and five RCTs vegan diets) showed similar results to the main analyses. QoE was very low for most of the outcomes.

CONCLUSIONS

In comparison to an omnivorous diet, VDs may reduce weight and glucose, but not blood pressure or other metabolic or anthropometric outcomes. However, the QoE was mostly very low. Larger RCTs are still needed to evaluate the effects of VD on anthropometric, metabolic factors, and blood pressure in people with overweight and obesity.

Association between Dietary Patterns and Metabolic Syndrome Risk Factors: A Cross-Sectional Study of Christian Orthodox Church Fasters and Non-Fasters in Greece

It is well known that the Mediterranean diet contributes to healthy living, prevention of non-communicable diseases, and longevity. A cross-sectional study was conducted with participants from Greece who follow the Mediterranean diet and were further divided into two categories: (i) Christian Orthodox Church (COC) religious fasters and (ii) non-fasters. Four-hundred individuals underwent anthropometric measurements, whereas information regarding dietary intake was collected via three 24 h diet recalls and a monthly food frequency questionnaire. Principal component analysis was performed to derive dietary patterns, whereas associations between dietary patterns and metabolic syndrome (MetS) risk factors were investigated with the general linear model. Non-fasters (n = 200) were found to consume significantly more beef, chicken, turkey, sausage, broth, fried potatoes, ketchup, and mustard, while consuming less seafood, snails, soya, tarama salads, fresh fruits, margarine, olives, and decaf coffee. Two distinct dietary patterns were identified in fasters: (i) the "Mixed Diet" and (ii) the "Plant-based/Fasting Diet" pattern. Moreover, three patterns were identified in non-fasters, and were identified as follows: (i) the "Western Diet", (ii) the "Mixed Diet", and (iii) the "Mediterranean-like Diet" pattern. No significant association was observed between dietary patterns and the prevalence of MetS in our population. Further epidemiological studies should evaluate the links between dietary patterns and MetS prevalence within the adult Greek population.

Association between plant-based diets and metabolic syndrome in obese adults from Iran: a cross-sectional study

BACKGROUND

Metabolic syndrome (MetS) is a common chronic disease with several complications. Given that, studies on the association of plant-based diet indices (PDIs) with risk of MetS among adults with obesity, are limited, we aimed to examine the association between PDIs (including overall PDI, healthy PDI (hPDI), unhealthy PDI (uPDI)) and MetS in Iranian adults with obesity.

METHODS

In Tabriz, Iran, a total of 347 adults between the ages of 20 and 50 participated in this cross-sectional research study. We created an overall PDI, hPDI, and uPDI from validated semi-quantitative food-frequency questionnaire (FFQ) data. To investigate the association between hPDI, overall PDI, uPDI, and MetS and its components, a binary logistic regression analysis was performed.

RESULTS

The average age was 40.78 ± 9.23 years, and the average body mass index was 32.62 ± 4.80 kg/m². There was no significant association between overall PDI (OR: 0.87; 95% CI: 0.54-1.47), hPDI (OR: 0.82; 95% CI: 0.48-1.40), and uPDI (OR: 0.83; 95% CI: 0.87-2.46) with MetS, even after adjustment for confounders. Moreover, our findings showed that participants with the highest adherence to uPDI had a higher chance of hyperglycemia (OR: 2.50; 95% CI: 1.13-5.52). Also, this association was significant in the first (OR: 2.51; 95% CI: 1.04-6.04) and second (OR: 2.58; 95% CI: 1.05-6.33) models, after controlling for covariates. However, in both adjusted and crude models, we did not find a significant association between hPDI and PDI scores and MetS components such as high triglyceride, high waist circumference, low High-density lipoprotein cholesterol, raised blood pressure, and hyperglycemia. Moreover, those in the top tertile of uPDI had higher fasting blood sugar and insulin levels when compared with those in the first tertile, and subjects in the last tertile of hPDI compared with participants in the first tertile had lower weight, waist-to-hip ratio, and fat-free mass.

CONCLUSION

We found a direct significant association between uPDI and odds of hyperglycemia in the whole population of study. Future large-scale, prospective studies on PDIs and the MetS are necessary to confirm these findings.

Berry Dietary Interventions in Metabolic Syndrome: New Insights

Metabolic Syndrome (MetS) is characterized by a group of dysmetabolic conditions, including abdominal obesity, dyslipidemia, glucose intolerance and/or insulin resistance, and hypertension. Generally, MetS is accompanied by an exacerbation of oxidative stress, inflammation, and vascular dysfunction. Increasing evidence suggests that berries and berry bioactives could play a potential role in the prevention and mitigation of the risk factors associated with MetS. The present systematic review summarizes the more recently available evidence deriving from human intervention studies investigating the effect of berries in subjects with at least three out of five MetS parameters. The PubMed, Scopus, and Embase databases were systematically searched from January 2010 until December 2022. A total of 17 human intervention trials met the inclusion criteria. Most of them were focused on blueberry (n = 6), cranberry (n = 3), and chokeberry (n = 3), while very few or none were available for the other berries. If considering MetS features, the main positive effects were related to lipid profile (low and high-density lipoproteins, cholesterol, and triglycerides) following blueberries and chokeberries, while conflicting results were documented for anthropometric parameters, blood pressure, and fasting blood glucose levels. Other markers analyzed within the studies included vascular function, oxidative stress, and inflammation. Here, the main positive effects were related to inflammation with a reduction in interleukin 6 and tumor necrosis factor-alpha following the intake of different berries. In conclusion, although limited, the evidence seems to support a potential role for berries in the modulation of lipid profile and inflammation in subjects with MetS. Furthermore, high-quality intervention trials are mandatory to demonstrate the role of berries in reducing risk factors for MetS and related conditions. In the future, such a demonstration could bring the adoption of berries as a potential dietary strategy to prevent/counteract MetS and related risk factors.

Association of plant-based dietary patterns with metabolic syndrome: baseline results from the Persian Kavar cohort study (PKCS)

Plant-based diets (PBDs) have gained a positive reputation among experts as a solution to combat the epidemic of MetS. A total of 2225 healthy Iranian individuals aged 35-70 years were considered eligible to be included in this cross-sectional investigation. Various dietary, anthropometric, and biochemical assessments were conducted using standard, valid methods/tools. Relevant PBD scores were calculated using three a posteriori indices, including the overall plant-based diet index (PDI), healthful PDI (hPDI), and unhealthful PDI (uPDI). Our findings showed that women with the highest adherence to hPDI had a lower chance of MetS. Also, participants in the top tertiles of hPDI were more likely to have a lower risk of low serum HDL-c and abnormal glucose homeostasis. Additionally, a significant increasing trend was observed for low serum HDL-c across tertiles of uPDI. Our observations suggest that healthful-rich plant foods may have a protective effect against MetS, especially in women.

Plant-based diets could ameliorate the risk factors of cardiovascular diseases in adults with chronic diseases

Adherence to plant-based diets is recommended to prevent and control chronic diseases. However, not all plant-based foods are healthy for this purpose. This study investigated the relationship between plant-based diets and risk factors for cardiovascular diseases (CVDs) in adults with chronic diseases. This cross-sectional study was performed on 3678 males and females (age range: 40-70 years) with chronic diseases who participated in the Kharameh cohort study. A validated semiquantitative food-frequency questionnaire was used to calculate the plant-based diet index (PDI), healthy plant-based diet index (hPDI), and unhealthy plant-based diet index (uPDI). Lipid profile, fasting blood sugar (FBS), blood pressure, and anthropometric indices were measured. Multivariable-adjusted logistic regression analysis was performed to determine the association between plant-based diets and CVDs risk factors. Higher adherence to the PDI was inversely associated with the level of FBS (odds ratio [OR] = 0.42; 95% confidence interval [CI]: 0.33-0.53; p < .001). A significant decrease was observed for total cholesterol in those with higher adherence to hPDI (OR = 0.80; 95% CI: 0.65-0.98; p = .035). Additionally, the score of uPDI was positively related to FBS (OR = 1.23; 95% CI: 1.00-1.53; p = .01), total cholesterol (OR = 1.23; 95% CI: 1.01-1.49; p = .061), and low-density lipoprotein (OR = 1.39; 95% CI: 1.13-1.71; p = .009). It was concluded that adherence to PDI and hPDI was related to a lower level of FBS and total cholesterol, respectively. Moreover, the findings suggested that regular intake of the uPDI was correlated with some risk factors for CVDs in adults with chronic diseases.

Effects of a vegetarian diet combined with exercise on lipid profiles and blood pressure: A systematic review and meta-analysis

We aimed to evaluate the combined effects of a vegetarian diet (VD) and exercise on total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglyceride (TG), systolic blood pressure (SBP), and diastolic blood pressure (DBP) parameters. A literature search was conducted in electronic databases from build to February 27, 2022. Data were synthesized using random effects model and were expressed as standardized mean difference (SMD)/weighted mean difference (WMD) and 95% confidence interval (CI). Overall, 27 trials with 9,251 participants were included. Pooled results indicated that the combination of a VD and exercise significantly reduced TC (SMD: -0.524; 95% CI: -0.602, -0.446; p < 0.001), LDL-C (SMD: -0.379; 95% CI: -0.471, -0.287; p < 0.001), HDL-C (SMD: -0.213; 95% CI: -0.299, -0.126; p < 0.001), TG (SMD: -0.090; 95% CI: -0.160, -0.020; p = 0.012), SBP (WMD: -7.664 mm Hg; 95% CI: -9.219, -6.109 mm Hg; p < 0.001), and DBP (WMD: -4.347 mm Hg; 95% CI: -5.099, -3.596 mm Hg; p < 0.001). These parameters were reduced more following a low-fat VD, or a mixed high-frequency exercise, especially under strict supervision. Surprisingly, the decreased HDL-C due to VD was observed to recover with the prolongation of exercise.

Retrospective assessment of metabolic syndrome components in early adult life on vegetarian dietary status

Background

Metabolic syndrome (MetS) encompasses several clinical presentations that include truncal obesity and insulin resistance at its core. MetS afflicts 23% of the adult US population, increasing their risk of diabetes and cardiovascular disease. Many studies have indicated the importance of a vegetarian diet in improving overall health and more specifically MetS components. Unfortunately, these findings have been inconsistent and cannot be extended to examine effects on MetS incidence in the younger adult population.

Objective

This study aimed to conduct a retrospective analysis of a vegetarian vs. non-vegetarian dietary status in young adults (age 18-24) based on MetS components in later adulthood (age 20-30). This study focuses on elucidating any relationship between a vegetarian diet and MetS components of central obesity, hypertension, and hyperlipidemia. Methods: Waves 3 and 4 data were acquired from AddHealth. One-to-one propensity score matched vegetarians to non-vegetarians in a cohort of 535 women and 159 men. Logistical regression assessed the relationship between vegetarian status and MetS components, including truncal obesity (cm), hypertension (normal, pre-HT, HT1, and HT2), and hyperlipidemia (high and low). Results MetS components from ages 20 to 30 are not associated with vegetarian dietary status. Truncal obesity [N = 694; M = 92.82 cm; OR 0.999; p = 0.893; 95% CI (0.980, 1.017)]; hypertension [N = 694; OR 0.949; p = 0.638; 95% CI (0.764, 1.179)]; hyperlipidemia [N = 694; OR 0.840; p = 0.581; 95% CI (0.453, 1.559)].

Conclusion

Current study results were consistent with previous findings suggesting that consumption of a vegetarian diet cannot be directly linked to MetS outcomes. However, further investigation should be completed as MetS is a risk factor for several chronic diseases.

Positive association of unhealthy plant-based diets with the incidence of abdominal obesity in Korea: a comparison of baseline, most recent, and cumulative average diets

OBJECTIVES

Different approaches for analyzing repeated dietary measurements may yield differences in the magnitude and interpretation of findings. We aimed to compare 3 dietary measurements (baseline, most recent, and cumulative average) in terms of the association between plant-based diet indices (PDIs) and incident abdominal obesity in Korean adults aged 40-69 years.

METHODS

This study included 6,054 participants (54% women) free of abdominal obesity (defined as waist circumference ≥90 cm for men and ≥85 cm for women) at baseline. As exposures, baseline, most recent, and cumulative average measurements for PDI, healthy-PDI (hPDI), and unhealthy-PDI (uPDI) were created. A Cox proportional-hazard model was used to estimate the hazard ratios (HRs) for abdominal obesity.

RESULTS

During 45,818 person-years of follow-up (median, 9 years), we identified 1,778 incident cases of abdominal obesity. In the multivariable-adjusted analysis, a higher uPDI was associated with a higher risk of abdominal obesity in both total and stratified analyses. The findings were consistent across all approaches (Q5 vs. Q1: HRbaseline=1.70; 95% confidence interval [CI], 1.46 to 1.98; HRmost recent=1.52; 95% CI, 1.30 to 1.78; HRcumulative average=1.76; 95% CI, 1.51 to 2.06 in the total set). PDI showed no meaningful association with abdominal obesity risk in any analyses. hPDIaverage had a suggestive inverse association with abdominal obesity risk in men, and hPDIbaseline had a positive association with abdominal obesity risk in women.

CONCLUSIONS

Greater adherence to unhealthy plant-based diets may increase the risk of developing abdominal obesity in Korean adults. The findings were generally consistent across all approaches.

Evidence of a vegan diet for health benefits and risks - an umbrella review of meta-analyses of observational and clinical studies

To summarize and evaluate the evidence on the health impact of a vegan diet, we conducted an umbrella review of systematic reviews and meta-analyses. PubMed, Cochrane Library, Web of Science and Epistemonikos were searched up to September 2021. Meta-analyses were recalculated by using a random effects model. The certainty of evidence (CoE) was evaluated by the GRADE approach. For the general healthy population, a vegan diet was effective for reducing body weight [MD (95% CI): -2.52 kg (-3.06, -1.98), n = 8 RCTs; moderate CoE] and was associated with further health benefits (with low CoE), including a lower risk of cancer incidence [SRR (95% CI): 0.84 (0.75, 0.95), n = 2] and a trend for lower risk of all-cause mortality [SRR (95% CI): 0.87 (0.75, 1.01), n = 2], as well as lower ApoB levels [MD (95% CI): -0.19 µmol/L (-0.23, -0.15), n = 7 RCTs). The findings suggested adverse associations for a vegan diet with risk of fractures [SRR (95% CI): 1.46 (1.03, 2.07), n = 3; low CoE]. For persons with diabetes or at high CVD risk, a vegan diet reduced measures of adiposity, total cholesterol, LDL and improved glycemic control (CoE moderate to low). A vegan diet may have the potential for the prevention of cardiometabolic health, but it may also impair bone health. More well-conducted primary studies are warranted.

Association Between Ideal Cardiovascular Health and Vegetarian Dietary Patterns Among Community-Dwelling Individuals

Background

Vegetarians have been shown to have better metabolic profiles than non-vegetarians, and vegetarianism has potential beneficial effects on cardiovascular disease. However, there is a lack of studies on vegetarians that examine both metabolic profiles and lifestyle habits, such as physical activity, smoking habits, and dietary patterns, which are equally important in the context of cardiovascular disease. We explored whether a vegetarian diet is associated with both metabolic traits and lifestyle habits by assessing cardiovascular health (CVH) metrics.

Methods

This was a cross-sectional study conducted in a Taiwanese population. Data collected between 2000 and 2016 were extracted from the MJ Health database. Participants aged 40 years and older without cardiovascular disease were included. CVH metrics included smoking habits, blood pressure, total cholesterol, serum glucose, body mass index, physical activity, and healthy diet score. Vegetarian participants were full-time vegetarians who did not consume meat or fish. All the data were assessed from self-report questionnaires, physical examinations, and blood analyses following standard protocol. Multiple logistic regression analysis was used to evaluate the association between vegetarianism and CVH metrics.

Results

Of 46,287 eligible participants, 1,896 (4.1%) were vegetarian. Overall, vegetarians had better CVH metrics (OR = 2.09, 95% CI = 1.84–2.37) but lower healthy diet scores (OR = 0.41, 95% CI = 0.33–0.51) after adjustment. No difference in physical activity (OR = 0.86, 95% CI = 0.73–1.02) was identified between vegetarians and non-vegetarians. Additionally, vegetarians had higher whole grain intake (OR = 2.76, 95% CI = 2.28–3.35) and lower sugar-sweetened beverage consumption (OR = 1.36, 95% CI = 1.18–1.58).

Conclusions

Our results suggested that vegetarians had better overall ideal CVH metrics but lower ideal healthy diet scores than non-vegetarians, which was likely due to the lack of fish consumption in this population group. When assessing CVH metrics and healthy diet scores for vegetarians, metrics and scores chosen should be suitable for use with vegetarian populations.

Evaluation of hypoglycemic therapeutics and nutritional supplementation for type 2 diabetes mellitus management: An insight on molecular approaches

OBJECTIVE

This review aims to summarize the current management of type 2 diabetes principles, including oral hypoglycemic agents, types of insulin administration, diet maintenance, and various molecular approaches.

METHODS

A literature search was conducted in different databases such as Scopus, ScienceDirect, Google Scholar, and Web of Science by using the following keywords: type-2 diabetes mellitus (T2DM), first-line and second-line treatment, oral hypoglycemic agents, insulin administration, diet/nutritional therapy, gene and stem cell therapy, and diabetic complications.

RESULTS

The first-line treatment of T2DM includes administering oral hypoglycemic agents (OHAs) and second-line treatment by insulin therapy and some OHAs like Sulfonylurea's (SU). The oral hypoglycemic or oral antidiabetic drugs have the function of lowering glucose in the blood. Insulin therapy is recommended for people with A1C levels > 7.0, and insulin administration is evolved drastically from the syringe, pump, pen, inhalation, insulin jet, and patch. The use of OHAs and insulin therapy during glycemic control has a severe effect on weight gain and other side effects. Hence, diet maintenance (macro and micronutrients) and nutritional therapy guidelines were also reviewed/recommended for safe T2DM management. Besides, the recent progress in molecular approaches that focuses on identifying new targets for T2DM (i.e.) consisting of gene therapy, stem cell therapy, and the modulation of insulin signaling pathways for the regulation of glucose storage and uptake also discussed.

CONCLUSION

The analysis of all these key factors is necessary to develop a potential agent to cure T2DM and suggest that a combination of therapies will pave the way for advanced management of T2DM.

Assessments of risk of bias in systematic reviews of observational nutritional epidemiologic studies are often not appropriate or comprehensive: a methodological study

BACKGROUND

An essential component of systematic reviews is the assessment of risk of bias. To date, there has been no investigation of how reviews of non-randomised studies of nutritional exposures (called 'nutritional epidemiologic studies') assess risk of bias.

OBJECTIVE

To describe methods for the assessment of risk of bias in reviews of nutritional epidemiologic studies.

METHODS

We searched MEDLINE, EMBASE and the Cochrane Database of Systematic Reviews (Jan 2018-Aug 2019) and sampled 150 systematic reviews of nutritional epidemiologic studies.

RESULTS

Most reviews (n=131/150; 87.3%) attempted to assess risk of bias. Commonly used tools neglected to address all important sources of bias, such as selective reporting (n=25/28; 89.3%), and frequently included constructs unrelated to risk of bias, such as reporting (n=14/28; 50.0%). Most reviews (n=66/101; 65.3%) did not incorporate risk of bias in the synthesis. While more than half of reviews considered biases due to confounding and misclassification of the exposure in their interpretation of findings, other biases, such as selective reporting, were rarely considered (n=1/150; 0.7%).

CONCLUSION

Reviews of nutritional epidemiologic studies have important limitations in their assessment of risk of bias.

Methods used to select results to include in meta-analyses of nutrition research: a meta-research study

OBJECTIVES

To investigate how often review authors encounter multiple results from included studies that are eligible for inclusion in a particular meta-analysis, and how often methods to select results are specified.

METHODS

MEDLINE and Epistemonikos were searched (January 2018 - June 2019) to identify systematic reviews with meta-analysis of the association between food/diet and health-related outcomes. A random sample of these reviews was selected, and for the first presented ('index') meta-analysis, rules used to select effect estimates to include in this meta-analysis were extracted from the reviews and their protocols. All effect estimates from the primary studies that were eligible for inclusion in the index meta-analyses were extracted (e.g. when a study report presented effect estimates for blood pressure at 3 weeks and 6 weeks, both unadjusted and adjusted for covariates, and all were eligible for inclusion in a meta-analysis of the effect of red meat consumption on blood pressure, we extracted all estimates and classified the study as having "multiplicity of results").

RESULTS

Forty-two systematic reviews with 325 studies (104 randomized, 221 non-randomized) were included; 14 reviews had a protocol. In 29% of review protocols and 69% of reviews, authors specified at least one decision rule to select effect estimates when multiple were available. In 68% of studies included in the index meta-analyses, there was at least one type of multiplicity of results.

CONCLUSIONS

Authors of systematic reviews of nutrition studies should anticipate encountering multiplicity of results in the included primary studies. Specification of methods to handle multiplicity when designing reviews is therefore recommended.

Association between Different Types of Plant-Based Diets and Risk of Dyslipidemia: A Prospective Cohort Study

We evaluated the associations among different types of plant-based diet indices, risk of dyslipidemia, and individual lipid disorders in Asian populations with different dietary patterns from Western populations. Participants included 4507 Korean adults aged ≥40 years without dyslipidemia and related chronic diseases at baseline (2001–2002). Dietary intakes were assessed using an average of validated food frequency questionnaires measured twice. We calculated three plant-based diet indices: overall plant-based diet index (PDI), healthful plant-based diet index (hPDI), and unhealthful plant-based diet index (uPDI). During a follow-up of 14 years, 2995 incident dyslipidemia cases occurred. Comparing the highest with lowest quintiles, the multivariable-adjusted hazard ratios (HRs) for incident dyslipidemia were 0.78 (95% CI, 0.69–0.88) for PDI, 0.63 (95% CI, 0.56–0.70) for hPDI, and 1.48 (95% CI, 1.30–1.69) for uPDI (P-trend < 0.0001 for all). Associations between PDI and individual lipid disorders differed by sex. The PDI was inversely associated with risk of developing hypertriglyceridemia in men and with risk of developing low high-density lipoprotein cholesterol in women. The hPDI was inversely associated with risk of all lipid disorders, whereas the uPDI was positively associated with individual lipid disorders. The quality of plant foods is important for prevention of dyslipidemia in a population that consumes diets high in plant foods.

Efficacy of different dietary patterns on lowering of blood pressure level: an umbrella review

BACKGROUND

Many systematic reviews and meta-analyses have assessed the efficacy of dietary patterns on blood pressure (BP) lowering but their findings are largely conflicting.

OBJECTIVE

This umbrella review aims to provide an update on the available evidence for the efficacy of different dietary patterns on BP lowering.

METHODS

PubMed and Scopus databases were searched to identify relevant studies through to June 2020. Systematic reviews with meta-analyses of randomized controlled trials (RCTs) were eligible if they measured the effect of dietary patterns on systolic (SBP) and/or diastolic blood pressure (DBP) levels. The methodological quality of included systematic reviews was assessed by A Measurement Tool to Assess Systematic Review version 2. The efficacy of each dietary pattern was summarized qualitatively. The confidence of the effect estimates for each dietary pattern was graded using the NutriGrade scoring system.

RESULTS

Fifty systematic reviews and meta-analyses of RCTs were eligible for review. Twelve dietary patterns namely the Dietary Approaches to Stop Hypertension (DASH), Mediterranean, Nordic, vegetarian, low-salt, low-carbohydrate, low-fat, high-protein, low glycemic index, portfolio, pulse, and Paleolithic diets were included in this umbrella review. Among these dietary patterns, the DASH diet was associated with the greatest overall reduction in BP with unstandardized mean differences ranging from -3.20 to -7.62 mmHg for SBP and from -2.50 to -4.22 mmHg for DBP. Adherence to Nordic, portfolio, and low-salt diets also significantly decreased SBP and DBP levels. In contrast, evidence for the efficacy of BP lowering using the Mediterranean, vegetarian, Paleolithic, low-carbohydrate, low glycemic index, high-protein, and low-fat diets was inconsistent.

CONCLUSION

Adherence to the DASH, Nordic, and portfolio diets effectively reduced BP. Low-salt diets significantly decreased BP levels in normotensive Afro-Caribbean people and in hypertensive patients of all ethnic origins. This review was registered at PROSPERO as CRD42018104733.

Plant-based diets and incident metabolic syndrome: Results from a South Korean prospective cohort study

BACKGROUND

Prior studies have shown that plant-based diets are associated with lower risk of cardiovascular risk factors and incident cardiovascular disease, but risks differed by quality of plant-based diets. No prospective studies have evaluated the associations between different types of plant-based diets and incident metabolic syndrome (MetS) and components of MetS. Furthermore, limited evidence exists in Asian populations who have habitually consumed a diet rich in plant foods for a long period of time.

METHODS AND FINDINGS

Analyses were based on a community-based cohort of 5,646 men and women (40-69 years of age at baseline) living in Ansan and Ansung, South Korea (2001-2016) without MetS and related chronic diseases at baseline. Dietary intake was assessed using a validated food frequency questionnaire. Using the responses in the questionnaire, we calculated 4 plant-based diet indices (overall plant-based diet index [PDI], healthful plant-based diet index [hPDI], unhealthful plant-based diet index [uPDI], and pro-vegetarian diet index). Higher PDI score represented greater consumption of all types of plant foods regardless of healthiness. Higher hPDI score represented greater consumption of healthy plant foods (whole grains, fruits, vegetables, nuts, legumes, tea and coffee) and lower consumption of less-healthy plant foods (refined grains, potatoes, sugar-sweetened beverages, sweets, salty foods). Higher uPDI represented lower consumption of healthy plant foods and greater consumption of less-healthy plant foods. Similar to PDI, higher pro-vegetarian diet score represented greater consumption of plant foods but included only selected plant foods (grains, fruits, vegetables, nuts, legumes, potatoes). Higher scores in all plant-based diet indices represented lower consumption of animal foods (animal fat, dairy, eggs, fish/seafood, meat). Over a median follow-up of 8 years, 2,583 participants developed incident MetS. Individuals in the highest versus lowest quintile of uPDI had 50% higher risk of developing incident MetS, adjusting for demographic characteristics and lifestyle factors (hazard ratio [HR]: 1.50, 95% CI 1.31-1.71, P-trend < 0.001). When we further adjusted for body mass index (BMI), those in the highest quintile of uPDI had 24%-46% higher risk of 4 out of 5 individual components of MetS (abdominal obesity, hypertriglyceridemia, low high-density lipoprotein [HDL], and elevated blood pressure) (P-trend for all tests ≤ 0.001). Greater adherence to PDI was associated with lower risk of elevated fasting glucose (HR: 0.80, 95% CI 0.70-0.92, P-trend = 0.003). No consistent associations were observed for other plant-based diet indices and MetS. Limitations of the study may include potential measurement error in self-reported dietary intake, inability to classify a few plant foods as healthy and less-healthy, lack of data on vegetable oil intake, and possibility of residual confounding.

CONCLUSIONS

In this study, we observed that greater adherence to diets consisting of a high intake of refined carbohydrates, sugars, and salty foods in the framework of plant-based diets was associated with an elevated risk of MetS. These results suggest that considering the quality of plant foods is important for prevention of MetS in a population that habitually consumes plant foods.

Association between unhealthy plant-based diets and the metabolic syndrome in adult men and women: a population-based study in South Korea

No studies have investigated the associations between established plant-based diet indices and the metabolic syndrome (MetS). We evaluated the associations between an overall plant-based diet index (PDI), healthy PDI (hPDI), unhealthy PDI (uPDI) and the MetS in a nationally representative sample using data from 14 450 Korean adults (≥19 years) in the Korea National Health and Nutrition Examination Survey 2012-2016. Dietary intakes were assessed by a semi-quantitative FFQ. In the PDI, all plant foods received positive scores. In the hPDI, only healthy plant foods received positive scores. In the uPDI, only unhealthy plant foods received positive scores. All indices reverse scored animal food intake. Multivariable logistic regression models were used to examine the associations between three PDI and the MetS by sex, adjusting for potential risk factors. A total of 23·3 % of Korean adults had the MetS. In the overall study population, individuals in the highest quintile of uPDI had greater odds (OR 1·54, 95 % CI 1·28, 1·86, Ptrend < 0·001) of the MetS than those in the lowest quintile. Higher uPDI score was associated with higher odds of hypertriacylglycerolaemia in men and abdominal obesity, high fasting glucose and hypertriacylglycerolaemia in women. No significant associations were observed between PDI, hPDI and the MetS. Greater adherence to unhealthy plant-based diets was associated with greater odds of the MetS and its components suggesting the importance of the quality of plant-based diet in South Korean adults. Sex differences may be considered when recommending plant-based diets for the prevention and management of metabolic diseases.

Effects of Popular Diets on Anthropometric and Cardiometabolic Parameters: An Umbrella Review of Meta-Analyses of Randomized Controlled Trials

The prevalence of overweight, obesity, and their related complications is increasing worldwide. The purpose of this umbrella review was to summarize and critically evaluate the effects of different diets on anthropometric parameters and cardiometabolic risk factors. Medline, Embase, Scopus, Cochrane Database of Systematic Reviews, and Web of Science, from inception to April 2019, were used as data sources to select meta-analyses of randomized controlled trials that examined the effects of different diets on anthropometric parameters and cardiometabolic risk factors. Strength and validity of the evidence were assessed through a set of predefined criteria. Eighty articles reporting 495 unique meta-analyses were examined, covering a wide range of popular diets: low-carbohydrate (n = 21 articles), high-protein (n = 8), low-fat (n = 9), paleolithic (n = 2), low-glycemic-index/load (n = 12), intermittent energy restriction (n = 6), Mediterranean (n = 11), Nordic (n = 2), vegetarian (n = 9), Dietary Approaches to Stop Hypertension (DASH) (n = 6), and portfolio dietary pattern (n = 1). Great variability in terms of definition of the intervention and control diets was observed. The methodological quality of most articles (n = 65; 81%), evaluated using the "A MeaSurement Tool to Assess systematic Reviews-2" questionnaire, was low or critically low. The strength of evidence was generally weak. The most consistent evidence was reported for the Mediterranean diet, with suggestive evidence of an improvement in weight, BMI, total cholesterol, glucose, and blood pressure. Suggestive evidence of an improvement in weight and blood pressure was also reported for the DASH diet. Low-carbohydrate, high-protein, low-fat, and low-glycemic-index/load diets showed suggestive and/or weak evidence of a reduction in weight and BMI, but contrasting evidence for lipid, glycemic, and blood pressure parameters, suggesting potential risks of unfavorable effects. Evidence for paleolithic, intermittent energy restriction, Nordic, vegetarian, and portfolio dietary patterns was graded as weak. Among all the diets evaluated, the Mediterranean diet had the strongest and most consistent evidence of a beneficial effect on both anthropometric parameters and cardiometabolic risk factors. This review protocol was registered at www.crd.york.ac.uk/PROSPERO/ as CRD42019126103.

Combination of Exercise and Vegetarian Diet: Relationship with High Density-Lipoprotein Cholesterol in Taiwanese Adults Based on MTHFR rs1801133 Polymorphism

We examined the association between high-density lipoprotein cholesterol (HDL-C), and exercise and vegetarian diets, in Taiwanese adults, based on the Methylenetetrahydrofolate reductase (MTHFR) rs1801133 polymorphism. Using regression models, we analyzed historical data collected from 9255 Taiwan Biobank (TWB) participants from 2008 through 2015. Exposure to exercise was associated with higher HDL-C (β = 1.0508 and 1.4011 for GG and GA + AA individuals, respectively), whereas a vegetarian diet was associated with lower HDL-C (β = −6.2793 and −4.6359 for those with GG and GA + AA genotype, respectively). We found an interaction between exercise and diet among GG individuals (p = 0.0101). Compared with no exercise/no vegetarian diet, vegetarian diet/no exercise was associated with a 5.1514 mg/dl reduction in HDL-C among those with GG genotype (β = −5.1514, p < 0.0001) and a 4.8426 mg/dl reduction (β = −4.8426, p < 0.0001) among those with GA + AA genotype. Vegetarian diets in combination with exercise predicted a 6.5552 mg/dl reduction in HDL-C among GG individuals (β = −6.5552) and a 2.8668 mg/dl reduction among GA + AA individuals (p < 0.05). These findings demonstrated that vegetarian diet alone was associated with lower HDL-C, no matter the rs1801133 genotype. However, the inclusion of regular exercise predicted much lower levels among GG individuals, whereas levels among GA + AA individuals were relatively higher.

Vegetarian, pescatarian and flexitarian diets: sociodemographic determinants and association with cardiovascular risk factors in a Swiss urban population

Prevalence and trends of different vegetarian diets remain unknown, with estimates varying depending on the source. Evidence suggests that vegetarian diets are associated with a more favourable cardiovascular risk profile. The present study aimed to assess the prevalence and trends of different types of vegetarian diets in a population-based representative sample, sociodemographic characteristics of participants following such diets and the association of these diets with cardiovascular risk factors. Using repeated cross-sectional population-based surveys conducted in Geneva, Switzerland, 10 797 individuals participated in the study between 2005 and 2017. Participants were classified as vegetarians, pescatarians, flexitarians or omnivores using an FFQ. Sociodemographic and cardiovascular risk factors were evaluated through questionnaires, anthropometric measurements and blood tests. Findings show prevalence of vegetarians increased from 0·5 to 1·2 %, pescatarians from 0·3 to 1·1 % and flexitarians remained stable at 15·6 % of the population over the study period. Compared with omnivores, vegetarians were more likely to be young (OR 2·38; 95 % CI 1·01, 5·6), have higher education (OR 1·59; 95 % CI 1·01, 2·49) and lower income (OR 1·83; 95 % CI 1·04, 3·21); pescatarians and flexitarians were more likely to be women (pescatarian: OR 1·81; 95 % CI 1·10, 3·00; vegetarian: OR 1·57; 95 % CI 1·41, 1·75) and flexitarians were also more likely to have a lower income (OR 1·31; 95 % CI 1·13, 1·53). Participants who adhered to any diet excluding/reducing meat intake had lower BMI, total cholesterol and hypertension compared with omnivores. The present study shows an increase in the prevalence of vegetarians over a 13-year period and suggests that the different vegetarian diets assessed are associated with a better cardiovascular risk profile.

Urine Metabolite Profiles and Nutrient Intake Based on 4-Day Weighed Food Diary in Habitual Vegans, Vegetarians, and Omnivores

BACKGROUND

Increasing interest in diets excluding meat and other products of animal origin emphasizes the importance of objective and reliable methods to measure dietary exposure, to evaluate associations and causation between diet and health, and to quantify nutrient intakes in different diets.

OBJECTIVES

This study aimed to investigate if NMR analysis of urine samples can serve as an objective method to discriminate vegan, vegetarian with or without fish, and omnivore diets. A secondary aim was to assess the influence of dietary nutrient intake on the metabolomics results.

METHODS

Healthy individuals (43 men and 75 women, age 19-57 y) complying with habitual vegan (n = 42), vegetarian (n = 25), vegetarian + fish (n = 13), or omnivore (n = 38) diets were enrolled. Data were collected on clinical phenotype and lifestyle including a 4-d weighed food diary. Urine was analyzed for metabolites by NMR spectroscopy and data normalized using probabilistic quotient normalization and Pareto-scaled before multivariate analysis. Before orthogonal projections to latent structures with discriminant analysis, participants were assigned as meat consumers or nonmeat consumers (vegans and vegetarians), vegans or nonvegans (omnivores, vegetarian, and vegetarian + fish).

RESULTS

The main results showed that it was possible to discriminate meat and nonmeat consumers (91% correctly classified), but discrimination between vegans and nonvegans was less rigorous (75% correctly classified). Secondary outcomes showed that reported intake of protein was higher in omnivores, and saturated fat lower and fiber higher in vegans, compared with the other groups. Discriminating metabolites were mainly related to differences in protein intake.

CONCLUSIONS

NMR urine metabolomics appears suitable to objectively identify and predict habitual intake of meat in healthy individuals, but results should be interpreted with caution because not only food groups but also specific foods contribute to the patterns.This trial was registered at clinicaltrials.gov as NCT02039609.

Metabolic Effects of Fasting and Animal Source Food Avoidance in an Ethiopian Adult Cohort

Fasting is a religious practice to which the faithful comply strictly. The longest period of fasting in Orthodox religion is the lent (in Ethiopia known as “Hudade”). According to the doctrine of Ethiopian Orthodox Christianity, fasters should strictly avoid all animal source foods (ASF) and skip breakfast at least up to lunch time. This can be taken as a well-controlled natural experiment to evaluate the effect of breakfast skipping and avoidance of ASF for 55 days. However, there is no study that evaluated the effect of ASF fasting (avoidance of animal source foods  and breakfast skipping) on lipid profiles, fasting blood sugar and body composition in Ethiopian set up. A retrospective cohort study was carried out among 704 employees of Jimma University (253 fasters and 451 non-fasters) from February 2015 to April 2015. Data on socio-demographic, anthropometry, blood pressure and blood samples were collected according to WHO STEPS procedure. Descriptive statistics and multivariable linear regression models were used to compare the effect of fasting on outcome variables. There was a significant difference in the body fat percent (mean ± sd) between non-fasters (32.35 ± 11.12) and fasters (30.59 ± 11.22, P = 0.045). Similarly, the mean ± sd waist circumference was higher among non-fasters (84.96 ± 11.43 cm) compared to fasters (83.04 ± 11.43 cm, P < 0.033). High density lipoprotein was significantly (P = 0.001) high among fasters (68.29 mg/dl) compared to non-fasters (57.24 mg/dl). Total cholesterol (T.chol) was also higher among non- fasters (181.01 mg/dl) than fasters (173.80 mg/dl, P = 0.035). The mean Triglyceride level was significantly (P = 0.035) high among non-fasters (142.76 mg/dl) compared to fasters (129.39 mg/dl). Similarly, fasting blood sugar was high among non-fasters (100.14 mg/dl) compared to fasters (95.11 mg/dl), P = 0.009. On multivariable linear regression analyses after adjusting for different variables, fasters had a significantly high mean HDL and lower mean T.chol, Triglycerides, FBS and LDL levels. Similarly, fasters had a significantly low mean waist circumference and low mean body fat percent (P < 0.05). In conclusion, animal source food avoidanceand breakfast skipping has a significant desirable health effects on lipid profiles, fasting blood sugar and body composition. The findings imply the need for considering such a dietary practice as a basis for public health promotion. Future research should investigate the effect of ASF fasting and breakfast skipping on micronutrient intake and determine the minimum number of days of fasting required to generate clinically significant effects.

Health Biomarkers in Adults Are More Closely Linked to Diet Quality Attributes Than to Plant-Based Diet Categorization

Although plant-based diets are promoted for healthy outcomes, these diets are not synonymous with high-quality diets. Plant-based diets can include highly processed, less healthful foods, including savory snacks, pastries, and sugary fruit drinks. This cross-sectional study examined the diet quality of vegetarian and omnivorous adults, matched for gender, age, and adiposity, and related diet quality to standard health biomarkers. Diet quality was assessed using the Rapid Eating and Activity Assessment for Participants Short Version questionnaire. Participants (17 vegetarians and 16 omnivores; 28.2 ± 8.9 years; 22.5 ± 2.7 kg/m²) were non-smokers and healthy by self-report. The median duration of adherence to the vegetarian diet was 27 months. Physical activity level and diet quality did not differ significantly between diet groups. Moreover, health biomarkers did not differ by diet groups. When participants were regrouped by low versus high diet quality, health biomarkers differed significantly between groups for fasting insulin, HOMA-IR, triglyceride (TG)/HDL ratio, and blood folate, with more favorable levels in the group with high diet quality. These data suggest that health biomarkers more closely align with diet quality attributes than with plant-based diet categorization. Thus, messaging focused on healthy diet attributes may lead to better health outcomes than the simple promotion of plant-based diets.