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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 -
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 -
Critical Reviews in Food Science and... May 2018Vegetarian diets exclude meat, seafood, and products containing these foods. Although the vegetarian lifestyle could lead to a better health status in adults, it may... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Vegetarian diets exclude meat, seafood, and products containing these foods. Although the vegetarian lifestyle could lead to a better health status in adults, it may also bear risks for certain nutritional deficiencies. Cross-sectional studies and narrative reviews have shown that the iron status of vegetarians is compromised by the absence of highly bioavailable haem-iron in meatless diets and the inhibiting effect of certain components present in plant foods on non-haem iron bioavailability.
METHODS
The databases Pubmed, Scopus, Embase, and Cochrane CentralRegister of Controlled Trials were searched for studies comparing serum ferritin, as the major laboratory parameter for iron status of adult vegetarians with non-vegetarian control groups. A qualitative review was conducted as well as an inverse-variance random-effects meta-analysis to pool available data. In addition the effect of vegetarian diets according to gender was investigated with a subgroup analysis. The results were validated using a sensitivity analysis.
RESULTS
A total of 27 cross-sectional studies and three interventional studies were selected for the systematic review. The meta-analysis which combined data of 24 cross-sectional studies showed that adult vegetarians have significantly lower serum ferritin levels than their non-vegetarian controls (-29.71 µg/L, 95% CI [-39.69, -19.73], p < 0.01). Inclusion of semi-vegetarian diets did not change the results considerably (-23.27 µg/L, 95% CI [-29.77, -16.76], p < 0.01). The effects were more pronounced in men (-61.88 µg/L, 95% CI [-85.59, -38.17], p < 0.01) than in both premenopausal women (-17.70 μg/L, 95% CI [-29.80, -5.60], p < 0.01) and all women (-13.50 μg/L, 95% CI [-22.96, -4.04], p < 0.01), respectively.
CONCLUSIONS
In conclusion our results showed that vegetarians are more likely to have lower iron stores compared with non-vegetarians. However, since high iron stores are also a risk factor for certain non-communicable diseases, such as type 2 diabetes, it is recommended that not only vegetarians but also non-vegetarians should regularly control their iron status and improve their diet regarding the content and bioavailability of iron by consuming more plants and less meat.
Topics: Adult; Diet, Vegetarian; Ferritins; Humans; Iron; Risk Factors
PubMed: 27880062
DOI: 10.1080/10408398.2016.1259210 -
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 -
Critical Reviews in Food Science and... 2023In recent years, plant-based diets have experienced increasing popularity. However, plant-based diets may not always ensure an adequate supply of micronutrients, in... (Meta-Analysis)
Meta-Analysis
In recent years, plant-based diets have experienced increasing popularity. However, plant-based diets may not always ensure an adequate supply of micronutrients, in particular calcium. We performed a systematic review and meta-analysis of calcium intake in vegan and vegetarian diets as compared to omnivorous diets. We searched PubMed and Web of Science and identified 2,009 potentially relevant articles. Mean calcium intake values were pooled and standardized mean differences (SMD) and 95% confidence intervals (CI) were computed.We analyzed 74 studies, including 7,356 vegan, 51,940 vegetarian, and 107,581 omnivorous participants. Of these, dietary calcium intake was examined in 23 studies of vegans, 60 studies of vegetarians and 74 studies of omnivores. Vegans showed a substantially lower calcium intake than vegetarians (SMD = -0.57; 95%CI = -0.83 to -0.32; p = <0.0001) and omnivores (SMD = -0.70; 95%CI = -0.95 to -0.59; p < 0.0001), whereas no statistically significant difference in calcium intake was noted between vegetarians and omnivores (SMD = 0.07; 95%CI = -0.04 to 0.19; p = 0.1976). In conclusion, vegans show a lower calcium intake than vegetarians and omnivores. This finding emphasizes the need for vegans to monitor their calcium status.
Topics: Humans; Vegans; Calcium; Diet, Vegetarian; Diet; Diet, Vegan
PubMed: 38054787
DOI: 10.1080/10408398.2022.2084027 -
The British Journal of Nutrition Nov 2023Vegan and vegetarian diets are widely supported and adopted, but individuals following such diets remain at greater risk of iodine deficiency. This systematic review and... (Meta-Analysis)
Meta-Analysis Review
Vegan and vegetarian diets are widely supported and adopted, but individuals following such diets remain at greater risk of iodine deficiency. This systematic review and meta-analysis was conducted to assess the iodine intake and status in adults following a vegan or vegetarian diet in the modern day. A systematic review and quality assessment were conducted from October 2020 to December 2022 according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Meta-analysis of Observational Studies in Epidemiology (MOOSE) guidance. Studies were identified in Ovid MEDLINE, Web of Science, PubMed, and Scopus. Eleven articles were eligible for review containing 4421 adults (aged ≥ 18 years). Vegan groups had the lowest median urinary iodine concentration (mUIC) (12·2/l). None of the dietary groups had mUIC within the optimal range for iodine status (100-200 µg/l) (WHO). Vegan diets had the poorest iodine intake (17·3 µg/d) and were strongly associated with lower iodine intake ( = < 0·001) compared with omnivorous diets. Lower intake in vegan diets was influenced by sex ( = 0·007), the presence of voluntary or absence of Universal Salt Iodisation (USI) programmes ( = 0·01 & = < 0·001), and living in a country with adequate iodine nutrition ( = < 0·001). Vegetarians and particularly vegans living in countries with no current USI programme continue to have increased risk of low iodine status, iodine deficiency and inadequate iodine intake. Further research into the usefulness of mandatory fortification of vegan appropriate foods is required.
Topics: Adult; Humans; Diet, Vegan; Vegans; Iodine; Diet, Vegetarian; Nutritional Status; Vegetarians
PubMed: 36912094
DOI: 10.1017/S000711452300051X -
Diabetology & Metabolic Syndrome Aug 2022A vegan diet has benefits on weight reduction and on the parameters of glucose and lipid metabolism. This meta-analysis aimed to investigate the efficacy of plant-based...
BACKGROUND
A vegan diet has benefits on weight reduction and on the parameters of glucose and lipid metabolism. This meta-analysis aimed to investigate the efficacy of plant-based diets on insulin resistance and blood lipids in patients with obesity.
METHODS
PubMed, Embase, and the Cochrane Library were searched for available papers published up to March 2021. The primary outcome was insulin resistance which was assessed by Homeostasis Model Assessment Insulin Resistance (HOMA-IR), other metabolic parameters measures including the pre/post-diet changes in triglycerides, HDL-cholesterol, total cholesterol, LDL-cholesterol. All analyses were performed using the random-effects model.
RESULTS
Six studies (seven datasets) were included. Compared with baseline, the plant-based diet improved the HOMA-IR (SMD = 1.64, 95%CI 0.95, 2.33; I = 91.8%, P < 0.001), total cholesterol (SMD = 2.51, 95% CI 0.88, 4.13; I = 98.0%, P < 0.001), HDL-cholesterol (SMD = 1.55, 95% CI 0.66, 2.44; I = 92.0%, P < 0.001), and LDL-cholesterol (SMD = 2.50, 95% CI 1.30, 3.70; I = 94.4%, P < 0.001), but not the triglycerides (SMD = - 0.62, 95% CI - 1.92, 0.68; I = 97.8%, P < 0.001). The sensitivity analyses showed that the results were robust.
CONCLUSIONS
In obese individuals with insulin resistance, a vegan diet improves insulin resistance and dyslipidemia, except for triglycerides.
PubMed: 35964120
DOI: 10.1186/s13098-022-00879-w -
Nutrients Oct 2023Health authorities increasingly recommend sustainable and healthy diets rich in plant foods and with moderate amounts of animal foods. However, there are concerns about... (Review)
Review
Health authorities increasingly recommend sustainable and healthy diets rich in plant foods and with moderate amounts of animal foods. However, there are concerns about whether such diets can meet all nutrient requirements, especially in children and adolescents, who have relatively high nutrient needs for growth and development. Therefore, we aimed to evaluate the nutrient intake and status of children and adolescents (2-18 y) consuming plant-based (i.e., vegetarian and vegan) diets compared to those of meat-eating children following a systematic literature review of studies published between 2000 and 2022. Mean intake and status data of nutrients were calculated across studies and benchmarked to dietary reference values and cut-off values for nutrient deficiencies. A total of 30 studies were included (15 in children 2-5 y, 24 in children 6-12 y, and 11 in adolescents 13-18 y). In all diets, there were risks of inadequate intakes of vitamin D and calcium. Children consuming meat had a risk of inadequate folate and vitamin E intake; and mean fiber, SAFA, and PUFA intakes were not in line with the recommendations. Children consuming plant-based diets risked inadequate vitamin B12, iron, and zinc intakes. In contrast to vegans, vegetarian children may not meet the recommended intakes of fiber, SAFA, and possibly PUFA, but their mean intakes were more favorable than in meat-eating children. Although the data are limited and need further validation, our findings indicate that there are risks of nutritional inadequacies in all diet groups. Therefore, increasing consumption of a variety of plant-based foods, in combination with food fortification and supplementation where needed, is recommended for children and adolescents to have sustainable and nutritionally adequate diets.
Topics: Animals; Humans; Child; Adolescent; Diet; Energy Intake; Meat; Eating; Diet, Vegan; Diet, Vegetarian
PubMed: 37892416
DOI: 10.3390/nu15204341 -
Critical Reviews in Food Science and... 2021To examine the relation between the consumption or avoidance of meat and psychological health and well-being. A systematic search of online databases (PubMed, PsycINFO,...
To examine the relation between the consumption or avoidance of meat and psychological health and well-being. A systematic search of online databases (PubMed, PsycINFO, CINAHL Plus, Medline, and Cochrane Library) was conducted for primary research examining psychological health in meat-consumers and meat-abstainers. Inclusion criteria were the provision of a clear distinction between meat-consumers and meat-abstainers, and data on factors related to psychological health. Studies examining meat consumption as a continuous or multi-level variable were excluded. Summary data were compiled, and qualitative analyses of methodologic rigor were conducted. The main outcome was the disparity in the prevalence of depression, anxiety, and related conditions in meat-consumers versus meat-abstainers. Secondary outcomes included mood and self-harm behaviors. Eighteen studies met the inclusion/exclusion criteria; representing 160,257 participants (85,843 females and 73,232 males) with 149,559 meat-consumers and 8584 meat-abstainers (11 to 96 years) from multiple geographic regions. Analysis of methodologic rigor revealed that the studies ranged from low to severe risk of bias with high to very low confidence in results. Eleven of the 18 studies demonstrated that meat-abstention was associated with poorer psychological health, four studies were equivocal, and three showed that meat-abstainers had better outcomes. The most rigorous studies demonstrated that the prevalence or risk of depression and/or anxiety were significantly greater in participants who avoided meat consumption. Studies examining the relation between the consumption or avoidance of meat and psychological health varied substantially in methodologic rigor, validity of interpretation, and confidence in results. The majority of studies, and especially the higher quality studies, showed that those who avoided meat consumption had significantly higher rates or risk of depression, anxiety, and/or self-harm behaviors. There was mixed evidence for temporal relations, but study designs and a lack of rigor precluded inferences of causal relations. Our study does not support meat avoidance as a strategy to benefit psychological health.
Topics: Anxiety; Depression; Diet, Vegetarian; Female; Humans; Male; Meat; Mental Health
PubMed: 32308009
DOI: 10.1080/10408398.2020.1741505 -
International Journal of Environmental... Apr 2020Creatine monohydrate is a nutritional supplement often consumed by athletes in anaerobic sports. Creatine is naturally found in most meat products; therefore,...
BACKGROUND
Creatine monohydrate is a nutritional supplement often consumed by athletes in anaerobic sports. Creatine is naturally found in most meat products; therefore, vegetarians have reduced creatine stores and may benefit from supplementation.
OBJECTIVE
to determine the effects of creatine supplementation on vegetarians.
DATA SOURCES
PubMed and SPORTDiscus. Eligibility criteria: Randomized controlled trials (parallel group, cross-over studies) or prospective studies.
PARTICIPANTS
Vegetarians.
INTERVENTION
Creatine supplementation. Study appraisal and synthesis: A total of 64 records were identified, and eleven full-text articles (covering nine studies) were included in this systematic review.
RESULTS
Creatine supplementation in vegetarians increased total creatine, creatine, and phosphocreatine concentrations in vastus lateralis and gastrocnemius muscle, plasma, and red blood cells, often to levels greater than omnivores. Creatine supplementation had no effect on brain levels of phosphocreatine. Creatine supplementation increased lean tissue mass, type II fiber area, insulin-like growth factor-1, muscular strength, muscular endurance, Wingate mean power output, and brain function (memory and intelligence) in vegetarian participants. Studies were mixed on whether creatine supplementation improved exercise performance in vegetarians to a greater extent compared to omnivores.
LIMITATIONS
Studies that were reviewed had moderate-high risk of bias.
CONCLUSIONS
Overall, it appears vegetarian athletes are likely to benefit from creatine supplementation.
Topics: Athletes; Cognition; Creatine; Diet, Vegetarian; Dietary Supplements; Humans; Memory; Physical Fitness; Prospective Studies; Vegetarians
PubMed: 32349356
DOI: 10.3390/ijerph17093041