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International Journal of Environmental... Mar 2021(1) Background: The purpose of the current meta-analysis was to investigate any positive or negative effects of ketogenic diets in athletes and provide an assessment of... (Meta-Analysis)
Meta-Analysis Review
(1) Background: The purpose of the current meta-analysis was to investigate any positive or negative effects of ketogenic diets in athletes and provide an assessment of the size of these effects. (2) Methods: Databases were used to select relevant studies up to January 2021 regarding the effects of ketogenic diets in athletes. Inclusion criteria were as follows: data before and after ketogenic diet use, being randomized controlled trials and presenting ketogenic diets and assessments of ketone status. Study subjects were required to be professional athletes. Review studies, pilot studies, and studies in which non-athletes were included were excluded from this meta-analysis. The outcome effect sizes in these selected studies were calculated by using the standardized mean difference statistic. (3) Results: Eight studies were selected for this meta-analysis. Athletes who consumed the ketogenic diet had reduced body fat percentages, respiratory exchange rates, and increased total cholesterol compared to athletes who did not consume this diet. However, body mass index, cardiorespiratory fitness, heart rate, HDL cholesterol, glucose level, and insulin level were unaffected by the diet. (4) Conclusions: Ketogenic diets had a beneficial effect by decreasing body fat percentage, but athletes with high total cholesterol level need to be monitored when instituting a ketogenic diet. Our study sample size was limited; therefore, additional studies may be needed to confirm the current findings. Further studies need to be conducted on changes in LDL cholesterol, HDL cholesterol, total cholesterol and ratio of LDL to HDL cholesterol.
Topics: Adipose Tissue; Athletes; Cholesterol, HDL; Diet; Diet, Ketogenic; Humans
PubMed: 33809153
DOI: 10.3390/ijerph18062912 -
Nutrients Nov 2022Caloric restriction and vegan diets have demonstrated protective effects for diabetes, however their role in improving clinically relevant outcomes has not been... (Meta-Analysis)
Meta-Analysis Review
Investigating the Effectiveness of Very Low-Calorie Diets and Low-Fat Vegan Diets on Weight and Glycemic Markers in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis.
Caloric restriction and vegan diets have demonstrated protective effects for diabetes, however their role in improving clinically relevant outcomes has not been summarized. Our aim was to evaluate the evidence for low-calorie diets (VLCD) and vegan diets on weight and glycemic control in the management of patients with Type 2 Diabetes. Database searches were conducted using Cochrane Library, MEDLINE (Ovid) and Embase. Systematic Review Registration: CRD42022310299. Methodological quality of studies was assessed using Cochrane RoB Tool for RCTs, Cochrane ROBINS-I RoB Tool for non-RCTs and NIH Quality Assessment tool for other studies. Sixteen studies with a total of 834 individuals were included and assessed to have a moderate to high risk of bias. Statistically significant changes in weight, BMI, and HbA1c were not observed in vegan diet cohorts. However, LDL cholesterol was significantly decreased by vegan diet. VLCDs significantly improved glycaemic control, with reductions in fasting glucose, pooled mean difference (MD) -1.51 mmol/L (95% CI -2.89, -0.13; = 0.03; 2 studies) and HbA1c, pooled MD -0.66% (95% CI -1.28, -0.03; = 0.04; 3 studies) compared to non-dietary therapy. Both diets suggested a trend towards improved weight loss and anthropometric markers vs. control. VLCD diet intervention is associated with improvement in glycaemia control in patients with Type 2 Diabetes.
Topics: Humans; Diet, Vegan; Diabetes Mellitus, Type 2; Glycated Hemoglobin; Caloric Restriction; Blood Glucose; Diet, Fat-Restricted; Biomarkers
PubMed: 36432557
DOI: 10.3390/nu14224870 -
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 -
JAMA Network Open Aug 2021The 2020 Dietary Guidelines Advisory Committee conducted a systematic review of existing research on diet and health to inform the current Dietary Guidelines for...
IMPORTANCE
The 2020 Dietary Guidelines Advisory Committee conducted a systematic review of existing research on diet and health to inform the current Dietary Guidelines for Americans. The committee answered this public health question: what is the association between dietary patterns consumed and all-cause mortality (ACM)?
OBJECTIVE
To ascertain the association between dietary patterns consumed and ACM.
EVIDENCE REVIEW
Guided by an analytical framework and predefined inclusion and exclusion criteria developed by the committee, the US Department of Agriculture's Nutrition Evidence Systematic Review (NESR) team searched PubMed, the Cochrane Central Register of Controlled Trials, and Embase and dual-screened the results to identify articles that were published between January 1, 2000, and October 4, 2019. These studies evaluated dietary patterns and ACM in participants aged 2 years and older. The NESR team extracted data from and assessed risk of bias in included studies. Committee members synthesized the evidence, developed conclusion statements, and graded the strength of the evidence supporting the conclusion statements.
FINDINGS
A total of 1 randomized clinical trial and 152 observational studies were included in the review. Studies enrolled adults and older adults (aged 17-84 years at baseline) from 28 countries with high or very high Human Development Index; 53 studies originated from the US. Most studies were well designed, used rigorous methods, and had low or moderate risks of bias. Precision, directness, and generalizability were demonstrated across the body of evidence. Results across studies were highly consistent. Evidence suggested that dietary patterns in adults and older adults that involved higher consumption of vegetables, fruits, legumes, nuts, whole grains, unsaturated vegetable oils, fish, and lean meat or poultry (when meat was included) were associated with a decreased risk of ACM. These healthy patterns were also relatively low in red and processed meat, high-fat dairy, and refined carbohydrates or sweets. Some of these dietary patterns also included intake of alcoholic beverages in moderation. Results based on additional analyses with confounding factors generally confirmed the robustness of main findings.
CONCLUSIONS AND RELEVANCE
In this systematic review, consuming a nutrient-dense dietary pattern was associated with reduced risk of death from all causes.
Topics: Cause of Death; Diet; Diet, Healthy; Humans; Nutrition Policy; United States
PubMed: 34463743
DOI: 10.1001/jamanetworkopen.2021.22277 -
Nutrients Feb 2022Limited consumption of dairy foods and use of low-fat products is recommended for cardiovascular (CV) prevention; however, other features besides fat content modulate... (Review)
Review
Limited consumption of dairy foods and use of low-fat products is recommended for cardiovascular (CV) prevention; however, other features besides fat content modulate their metabolic effects. We analyze updated evidence on the relationship of different dairy products (low/full-fat dairy, milk, cheese, yogurt) with CVD by reviewing meta-analyses of cohort studies and individual prospective cohort studies with CV hard endpoints (CVD/CHD incidence/mortality), together with meta-analyses of randomized controlled trials exploring the effect of dairy on major CV risk factors. The analyses provide evidence that moderate dairy consumption (up to 200 g/day, globally) has no detrimental effects on CV health and that their effect depends more on the food type (cheese, yogurt, milk) than on the fat content. These data expand current knowledge and may inform revision of current guidelines for CVD prevention.
Topics: Animals; Cardiovascular Diseases; Dairy Products; Diet; Diet, Fat-Restricted; Humans; Milk; Prospective Studies; Risk Factors
PubMed: 35215479
DOI: 10.3390/nu14040831 -
Distribution of energy intake across the day and weight loss: A systematic review and meta-analysis.Obesity Reviews : An Official Journal... Mar 2023Consuming a greater proportion of total energy intake earlier in the day rather than in the evening is proposed to positively influence weight loss and health,... (Meta-Analysis)
Meta-Analysis Review
Consuming a greater proportion of total energy intake earlier in the day rather than in the evening is proposed to positively influence weight loss and health, potentially due to greater synchronization of human body circadian rhythms. This systematic review provides an update on existing evidence regarding earlier distributed eating patterns in weight loss interventions. Using a robust search strategy in five electronic databases, nine randomized controlled trials investigating the impact of energy intake distribution on weight loss were identified. Following critical appraisal, a random-effects meta-analyses found that, in the context of an energy-reduced diet, distributing energy intake with a focus on earlier intake resulted in significantly greater weight loss (-1.23 kg; 95% CI 2.40, -0.06, p = 0.04). Improvements in HOMA-IR, fasting glucose, and LDL cholesterol were also seen. The current study provides a timely update on the evidence linking distribution of total daily energy intake and health, showing that a focus on earlier intakes can result in greater short-term weight loss compared with later intakes. Future studies are needed to elucidate the impact that earlier intakes may have on weight management and metabolic health.
Topics: Humans; Energy Intake; Diet; Fasting; Feeding Behavior; Weight Loss
PubMed: 36530130
DOI: 10.1111/obr.13537 -
Nutrients Dec 2020Recent observations have shown that lengthening the daily eating period may contribute to the onset of chronic diseases. Time-restricted eating (TRE) is a diet that...
INTRODUCTION
Recent observations have shown that lengthening the daily eating period may contribute to the onset of chronic diseases. Time-restricted eating (TRE) is a diet that especially limits this daily food window. It could represent a dietary approach that is likely to improve health markers. The aim of this study was to review how time-restricted eating affects human health.
METHOD
Five general databases and six nutrition journals were screened to identify all studies published between January 2014 and September 2020 evaluating the effects of TRE on human populations.
RESULTS
Among 494 articles collected, 23 were finally included for analysis. The overall adherence rate to TRE was 80%, with a 20% unintentional reduction in caloric intake. TRE induced an average weight loss of 3% and a loss of fat mass. This fat loss was also observed without any caloric restriction. Interestingly, TRE produced beneficial metabolic effects independently of weight loss, suggesting an intrinsic effect based on the realignment of feeding and the circadian clock.
CONCLUSIONS
TRE is a simple and well-tolerated diet that generates many beneficial health effects based on chrononutrition principles. More rigorous studies are needed, however, to confirm those effects, to understand their mechanisms and to assess their applicability to human health.
Topics: Caloric Restriction; Circadian Rhythm; Databases, Factual; Energy Intake; Fasting; Food; Health; Humans; Nutritional Status; Religion
PubMed: 33302500
DOI: 10.3390/nu12123770 -
Redox Biology Jun 2021Oxidative stress and inflammation are known to play a critical role in ageing and chronic disease development and could therefore represent important targets for...
INTRODUCTION
Oxidative stress and inflammation are known to play a critical role in ageing and chronic disease development and could therefore represent important targets for developing dietary strategies for disease prevention. We aimed to systematically review the results from observational studies and intervention trials published in the last 5 years on the associations between dietary patterns and biomarkers of oxidative stress and inflammation.
METHODS
A systematic search of the PubMed, MEDLINE and Web of Science (January 2015 to October 2020) was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Methodological quality of selected studies was evaluated based on the NUTRIGRADE and BIOCROSS assessment tools.
RESULTS
In total, 29 studies among which 16 observational studies and 13 intervention studies were found eligible for review. Overall, results indicated an inverse association between plant-based diets - the Mediterranean and Dietary Approaches to Stop Hypertension (DASH) diet - and oxidative stress and proinflammatory biomarkers. In observational studies, inverse associations were further revealed for the vegetarian diet, the USDA Healthy Eating Index (HEI) - based diet and the paleolithic diet, whereas a positive association was seen for western and fast food diets. Quality assessment suggested that majority of dietary intervention studies (n = 12) were of low to moderate quality.
CONCLUSIONS
This study provides evidence that the plant-based dietary patterns are associated with lowered levels of oxidative stress and inflammation and may provide valid means for chronic disease prevention. Future large-scale intervention trials using validated biomarkers are warranted to confirm these findings.
Topics: Biomarkers; Diet; Diet, Healthy; Dietary Approaches To Stop Hypertension; Humans; Inflammation; Oxidative Stress
PubMed: 33541846
DOI: 10.1016/j.redox.2021.101869 -
The Cochrane Database of Systematic... Jun 2020Ketogenic diets (KDs) are high in fat and low in carbohydrates and have been suggested to reduce seizure frequency in people with epilepsy. Such diets may be beneficial... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Ketogenic diets (KDs) are high in fat and low in carbohydrates and have been suggested to reduce seizure frequency in people with epilepsy. Such diets may be beneficial for children with drug-resistant epilepsy. This is an update of a review first published in 2003, and last updated in 2018.
OBJECTIVES
To assess the effects of ketogenic diets for people with drug-resistant epilepsy.
SEARCH METHODS
For this update, we searched the Cochrane Register of Studies (CRS Web) and MEDLINE (Ovid, 1946 to 26 April 2019) on 29 April 2019. The Cochrane Register of Studies includes the Cochrane Epilepsy Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), and randomised controlled trials (RCTs) from Embase, ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). We imposed no language restrictions. We checked the reference lists of retrieved studies for additional relevant studies.
SELECTION CRITERIA
RCTs or quasi-RCTs of KDs for people of any age with drug-resistant epilepsy.
DATA COLLECTION AND ANALYSIS
Two review authors independently applied predefined criteria to extract data and evaluated study quality. We assessed the outcomes: seizure freedom, seizure reduction (50% or greater reduction in seizure frequency), adverse effects, cognition and behaviour, quality of life, and attrition rate. We incorporated a meta-analysis. We utilised an intention-to-treat (ITT) population for all primary analyses. We presented the results as risk ratios (RRs) with 95% confidence intervals (CIs).
MAIN RESULTS
We identified 13 studies with 932 participants; 711 children (4 months to 18 years) and 221 adults (16 years and over). We assessed all 13 studies to be at high risk of performance and detection bias, due to lack of blinding. Assessments varied from low to high risk of bias for all other domains. We rated the evidence for all outcomes as low to very low certainty. Ketogenic diets versus usual care for children Seizure freedom (RR 3.16, 95% CI 1.20 to 8.35; P = 0.02; 4 studies, 385 participants; very low-certainty evidence) and seizure reduction (RR 5.80, 95% CI 3.48 to 9.65; P < 0.001; 4 studies, 385 participants; low-certainty evidence) favoured KDs (including: classic KD, medium-chain triglyceride (MCT) KD combined, MCT KD only, simplified modified Atkins diet (MAD) compared to usual care for children. We are not confident that these estimated effects are accurate. The most commonly reported adverse effects were vomiting, constipation and diarrhoea for both the intervention and usual care group, but the true effect could be substantially different (low-certainty evidence). Ketogenic diet versus usual care for adults In adults, no participants experienced seizure freedom. Seizure reduction favoured KDs (MAD only) over usual care but, again, we are not confident that the effect estimated is accurate (RR 5.03, 95% CI 0.26 to 97.68; P = 0.29; 2 studies, 141 participants; very low-certainty evidence). Adults receiving MAD most commonly reported vomiting, constipation and diarrhoea (very low-certainty evidence). One study reported a reduction in body mass index (BMI) plus increased cholesterol in the MAD group. The other reported weight loss. The true effect could be substantially different to that reported. Ketogenic diet versus ketogenic diet for children Up to 55% of children achieved seizure freedom with a classical 4:1 KD after three months whilst up to 85% of children achieved seizure reduction (very low-certainty evidence). One trial reported a greater incidence of seizure reduction with gradual-onset KD, as opposed to fasting-onset KD. Up to 25% of children were seizure free with MAD and up to 60% achieved seizure reduction. Up to 25% of children became seizure free with MAD and up to 60% experienced seizure reduction. One study used a simplified MAD (sMAD) and reported that 15% of children gained seizure freedom rates and 56% achieved seizure reduction. We judged all the evidence described as very low certainty, thus we are very unsure whether the results are accurate. The most commonly reported adverse effects were vomiting, constipation and diarrhoea (5 studies, very low-certainty evidence). Two studies reported weight loss. One stated that weight loss and gastrointestinal disturbances were more frequent, with 4:1 versus 3:1 KD, whilst one reported no difference in weight loss with 20 mg/d versus 10 mg/d carbohydrates. In one study, there was a higher incidence of hypercalcuria amongst children receiving classic KD compared to MAD. All effects described are unlikely to be accurate. Ketogenic diet versus ketogenic diet for adults One study randomised 80 adults (aged 18 years and over) to either MAD plus KetoCal during the first month with MAD alone for the second month, or MAD alone for the first month followed by MAD plus KetoCal for the second month. No adults achieved seizure freedom. More adults achieved seizure reduction at one month with MAD alone (42.5%) compared to MAD plus KetoCal (32.5%), however, by three months only 10% of adults in both groups maintained seizure reduction. The evidence for both outcomes was of very low certainty; we are very uncertain whether the effects are accurate. Constipation was more frequently reported in the MAD plus KetoCal group (17.5%) compared to the MAD only group (5%) (1 study, very low-certainty evidence). Diarrhoea and increase/change in seizure pattern/semiology were also commonly reported (17.5% to 20% of participants). The true effects of the diets could be substantially different to that reported.
AUTHORS' CONCLUSIONS
The evidence suggests that KDs could demonstrate effectiveness in children with drug-resistant epilepsy, however, the evidence for the use of KDs in adults remains uncertain. We identified a limited number of studies which all had small sample sizes. Due to the associated risk of bias and imprecision caused by small study populations, the evidence for the use of KDs was of low to very low certainty. More palatable but related diets, such as the MAD, may have a similar effect on seizure control as the classical KD, but could be associated with fewer adverse effects. This assumption requires more investigation. For people who have drug-resistant epilepsy or who are unsuitable for surgical intervention, KDs remain a valid option. Further research is required, particularly for adults with drug-resistant epilepsy.
Topics: Adolescent; Adult; Age Factors; Aged; Child; Child, Preschool; Diet, Carbohydrate-Restricted; Diet, High-Protein Low-Carbohydrate; Diet, Ketogenic; Dietary Carbohydrates; Dietary Fats; Drug Resistant Epilepsy; Humans; Infant; Intention to Treat Analysis; Middle Aged; Prospective Studies; Quality of Life; Randomized Controlled Trials as Topic; Retrospective Studies; Sample Size; Young Adult
PubMed: 32588435
DOI: 10.1002/14651858.CD001903.pub5 -
Childhood Obesity (Print) Mar 2020Childhood overweight and obesity are recognized as predictors of the risk of obesity in adulthood. The aim of this systematic literature review was to determine the...
Childhood overweight and obesity are recognized as predictors of the risk of obesity in adulthood. The aim of this systematic literature review was to determine the association between dietary pattern and obesity risk among children. Articles were selected from databases (Cochrane Library, Lilacs, Eric, Livivo, and PubMed/Medline), without limitations regarding language or date. Database-specific search terms included the key words "obesity," "diet," "dietary pattern," "childhood," "children," "adolescents," and relevant synonyms. The review included studies that reported the assessment of the dietary pattern in childhood and that correlated eating patterns with the obesity risk through cluster analysis (CA) and/or factor analysis and/or principal component analysis and presented odds ratios (ORs). The methodology of the selected studies was evaluated using the JBI Critical Appraisal Checklist for Analytical Cross-Sectional Studies. Owing to the heterogeneity among the assessments of the association of dietary patterns and obesity, the results are described narratively. Using a selection process in two phases, 16 articles were included. Fifteen studies used a cross-sectional design, and one case-control study. The included studies showed variation in sample size (range = 232 to 10,187 children/adolescents) and age (range = 1-19 years old). The studies reported between two and five dietary patterns each. The OR for the relationship between the dietary pattern and the risk of childhood obesity ranged from OR = 1.02; confidence interval (95% CI) (0.91-1.15) to OR = 3.55; 95% CI (1.80-7.03). In this study, the dietary patterns identified by the studies were given different names. The food intake patterns identified could, in most factor or CA studies, be categorized as (1) potentially obesogenic foods that increased risk of becoming overweight (including fatty cheeses, sugary drinks, processed foods, fast food, candies, snacks, cakes, animal products, whole milk, and refined grains) or (2) food classified as healthy with the weakest association with the risk of becoming overweight or obese (including low levels of sugar and fat and high levels of fruits, vegetables, whole grains, fish, nuts, legumes, and yogurt). Overall, the results indicated from most studies that a diet with a lower percentage of obesogenic foods should be effective in reducing the risk of developing obesity.
Topics: Adolescent; Child; Diet; Feeding Behavior; Humans; Pediatric Obesity; Risk Factors
PubMed: 31742427
DOI: 10.1089/chi.2019.0059