A comprehensive review of healthy effects of vegetarian diets

Impact of diet adherence on weight and lipids among African American participants randomized to vegan or omnivorous diets

Objective

Prior research has found that plant-based diets (PBDs) are rated as acceptable and have similar levels of adherence as compared to other therapeutic dietary approaches; however, previous studies were mostly among white populations. Plant-based diets can produce clinically meaningful weight loss, but outcomes may vary by level of adherence. The goal of this study was to examine the differences in weight and lipids among participants in the Nutritious Eating with Soul study based on adherence to their diet assignment.

Methods

African American adults (n = 159; 79% female) with overweight or obesity (mean BMI 36.9 ± 6.9 kg/m2) were recruited to participate in a 24-month intervention. Participants were randomized to a plant-based vegan (n = 77) or a low-fat omnivorous (n = 82) diet, both emphasizing soul food cuisine. Participants attended nutrition classes and had dietary intake/adherence (three 24-h recalls; adherence score 1-5), body weight, lipids, and other secondary outcomes assessed at baseline, 6-, 12-, and 24 months. Participants who met at least half of the adherence criteria (≥2.5 out of 5) were categorized as adherents.

Results

At 24 months, adherent vegans lost 5% of their body weight, non-adherent vegans lost -0.005%, adherent omnivores lost -0.03%, and non-adherent omnivores lost -0.02%. Adherent vegans lost more weight (kg) than all other participants at both 6- (-3.32 ± 0.92 (-5.14, -1.49), p < 0.001) and 24 months (-3.27 ± 1.49 (-6.23, -0.31), p = 0.03). Adherent vegans also lost more weight than less adherent vegans (-3.74 ± 1.05 (-5.82, -1.65)), adherent omnivores (-4.00 ± 1.27 (-6.51, -1.48)), and less adherent omnivores (-2.22 ± 0.98 (-4.15, -0.28)) at 6 months and lost more weight than less adherent vegans at 24 months (-4.96 ± 1.8 (-8.54, -1.37)) (all p < 0.05). Adherent vegans had greater improvements in cholesterol-to-HDL ratio at 24 months (-0.47 ± 0.22 (-0.92, -0.03), p = 0.04) and greater decreases in insulin (-4.57 ± 2.16 (-8.85, -0.29), p = 0.04) at 6 months than all other participants combined.

Conclusions

The study points to the benefit of the use of a PBD for reducing weight, lipids, and insulin in African American adults, but also highlights the importance of supporting adherence to the PBD.

Clinical TrialsGov ID

Nutritious Eating With Soul (The NEW Soul Study); NCT03354377.

Association between Vegetarian Diet Consumption and Academic Performance, Sleep Quality, and Health-Related Quality of Life among Female Undergraduate College Students

Purpose

This cross-sectional survey study aimed to examine the association between vegetarian diet consumption and sleep quality, academic performance, and health-related quality of life among female undergraduate college students.

Method

A sample of 158 undergraduate female college students was recruited using a convenience sampling approach. Data collection utilized reliable and validated English-language instruments including the Vegetarian Quality of Life Questionnaire (VEGQOL), Pittsburgh Sleep Quality Index (PSQI), and health-related quality of life scale (HRQoL). The data were analyzed using one-way analysis of variance (ANOVA) and appropriate descriptive statistics.

Results

Vegetarians exhibited a significantly lower BMI compared to nonvegetarians (F (1, 156) = [6.09], p=0.015). Those strictly adhering to a vegan diet (48.79 ± 9.41) had the lowest vegetarian quality of life among all participants following various forms of a vegetarian diet (F (3, 68) = [2.78], p=0.04). The majority of female college students reported good to excellent general health (91.7%), with 53.2% perceiving their sleep quality as fairly good. However, the mean PSQI global score of 8.04 (±3.35) indicated poor sleep quality. No significant association was found between diet type (vegetarian vs. nonvegetarian) and academic performance (cGPA) (χ 2 (4, N = 158) = 2.92, p=0.57). There was no significant relationship between diet types and academic performance, HRQoL, and sleep quality.

Conclusion

Despite a significant association between vegetarian diet and lower BMI, surprisingly, no substantial relationships were identified between diet type and academic performance, HRQoL, and sleep quality. These findings contribute to the ongoing discourse on the potential impacts of a vegetarian diet on various facets of female college students' well-being and highlight the need for further exploration in this field.

Health Benefits of Vegetarian Diets: An Insight into the Main Topics

Vegetarian diets are plant-based diets including all the edible foods from the Plant Kingdom, such as grains, legumes, vegetables, fruits, nuts, and seeds. Dairy and eggs can be added in small amounts in the lacto-ovo-vegetarian subtype, or not at all in the vegan subtype. The abundance of non-processed plant foods-typical of all well-planned diets, including vegetarian ones-can provide the body with numerous protective factors (fiber, phytocompounds), while limiting the intake of harmful nutrients like saturated fats, heme-iron, and cholesterol. The beneficial effects on health of this balance have been reported for many main chronic diseases, in both observational and intervention studies. The scientific literature indicates that vegetarians have a lower risk of certain types of cancer, overall cancer, overweight-obesity, type 2 diabetes, dyslipidemia, hypertension, and vascular diseases. Since the trend of following a vegetarian diet is increasing among citizens of developed countries, the knowledge in the field will benefit from further studies confirming the consistency of these findings and clarifying the effects of vegetarian diets on other controversial topics.

Exploring the Association between Mediterranean Diet Adherence and Arterial Stiffness in Healthy Adults: Findings from the EvasCu Study

(1) Background: Previous evidence has indicated a connection between a Mediterranean diet and cardiovascular disease. However, evidence for subclinical markers of cardiovascular disease, such as arterial stiffness, is limited. Therefore, the aim of this study was to assess the associations between adherence to the Mediterranean diet (MD), as assessed by the MEDAS-14 questionnaire, and arterial stiffness, as assessed by aortic pulse wave velocity, in healthy adults and according to sex. (2) A cross-sectional study including 386 healthy participants was performed in the EVasCu study. Adjusted and unadjusted differences in adherence to the MD and arterial stiffness were determined using Student's t test and ANCOVA for the total sample and according to sex. (3) Results: Our results showed that individuals with a high adherence to the MD had a greater arterial stiffness, both in the total sample and in females, although this difference was not significant after adjusting for possible confounding variables, such as age. (4) Conclusions: Our findings indicated that, in the unadjusted analyses, healthy subjects with a high adherence to the MD showed a greater arterial stiffness. When these analyses were adjusted, no significant differences were shown in a-PWv according to the categories of MD adherence.

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.

Effects of Different Nutritional Patterns and Physical Activity on Body Composition: A Gender and Age Group Comparative Study

This cross-sectional study analyses differences in dietary habits, taste preferences, variety of protein sources and body composition (BC) profiles among individuals following omnivorous, flexitarian, lacto-ovo-vegetarian and pescatarian diets. Furthermore, it assesses the correlations between these dietary patterns and various sports, classified by exercise intensity, in relation to BC parameters. The study analysed the eating habits and BC data of 1342 participants aged 18-65 years, classified into four diet groups based on their 7-day food diaries and questionnaire responses. Our analysis revealed gender- and age-related differences in weekly food consumption and protein source variety, with men generally consuming more meat, processed meat and fish than women, especially in younger age groups. Differences in dairy and soy consumption were also noted between age groups, while legume and soy preferences showed no gender disparity across all ages. Among non-sporting individuals, vegetarians exhibited lower fat mass (FM%) compared to other diets, while among athletes, vegetarians and pescatarians in in endurance and strength sports, respectively, displayed lower FM%, with flexitarians and omnivores in endurance sports showing higher FM%. Non-athletic omnivores and vegetarians demonstrated a greater proportion of body protein, while among athletes, those engaged in strength training exhibited a higher body protein content across all dietary groups compared to those in endurance training. Among non-athletic groups, vegetarians exhibited the lowest FM/FFM (fat mass/fat-free mass) ratio, while among athletes, vegetarians in endurance sports and participants in strength training across other diets showed lower FM/FFM ratios. The results emphasise the complex interaction between diet, BC and lifestyle choices, revealing how different combinations of diet and sport are associated with optimised BC.

Differences in carotid to femoral pulse wave velocity and carotid intima media thickness between vegetarian and omnivorous diets in healthy subjects: a systematic review and meta-analysis

Background: Arterial stiffness and atherosclerosis are known risk factors for cardiovascular morbidity and mortality. Vegetarian diets have been associated with cardiovascular benefits, including improvements in metabolic parameters. However, the impact of a vegetarian diet on cardiovascular parameters, specifically arterial stiffness and atherosclerosis, in healthy individuals remains unclear. Thus, this study aims to analyze differences in arterial stiffness and atherosclerosis between vegetarian and omnivorous diets in healthy subjects. Methods: A systematic review and meta-analysis were conducted following established guidelines. PubMed, Scopus, Web of Science, and Cochrane Library databases were searched for studies examining the association between vegetarian and omnivorous diets with arterial stiffness and atherosclerosis. Cross-sectional studies reporting carotid to femoral pulse wave velocity (cf-PWv) as a measure of arterial stiffness and carotid intima media thickness (c-IMT) as a measure of atherosclerosis were included. Data were synthesized using random effects models, and sensitivity analyses, meta-regressions, and assessment of publication bias were performed. Results: Ten studies were included in the systematic review, and seven studies were included in the meta-analysis. The pooled analysis demonstrated that individuals following a vegetarian diet had differences in the levels of arterial stiffness (cf-PWv) compared to those following an omnivorous diet (MD: -0.43 m s-1; 95% CI: -0.63, -0.23). Similarly, atherosclerosis (c-IMT) was found to be different in individuals adhering to a vegetarian dietary pattern (MD = -29.86 mm; 95% CI: -58.41, -1.32). Conclusions: Our findings suggest that a vegetarian diet is associated with improved arterial stiffness and reduced atherosclerosis in healthy individuals. These results support the inclusion of a well-balanced vegetarian dietary pattern in the prevention and management of cardiovascular diseases. However, further research is needed to explore the effects of a vegetarian diet on arterial health in diverse populations and to assess long-term cardiovascular outcomes.