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Research indicates that green tea extract (GTE) supplementation is beneficial for a range of conditions, including several forms of cancer, cardiovascular, and liver diseases; nevertheless, the existing evidence addressing its effects on body composition, oxidative stress, and obesity-related hormones is inconclusive. This systematic review and meta-analysis aimed to investigate the effects of GTE supplementation on body composition (body mass [BM], body fat percentage [BFP], fat mass [FM], body mass index [BMI], waist circumference [WC]), obesity-related hormones (leptin, adiponectin, and ghrelin) and oxidative stress (malondialdehyde [MDA], and total antioxidant capacity [TAC]) markers. We searched proper databases, including PubMed/Medline, Scopus, and Web of Science, up to July 2022 to recognize published randomized controlled trials (RCTs) that investigated the effects of GTE supplementation on the markers mentioned above. A random-effects model was used to carry out a meta-analysis. The heterogeneity among the studies was assessed using the I2 index. Among the initial 11286 studies identified from an electronic database search, 59 studies involving 3802 participants were eligible to be included in this meta-analysis. Pooled effect sizes indicated that BM, BFP, BMI, and MDA significantly reduced following GTE supplementation. In addition, GTE supplementation increased adiponectin and TAC, with no effects on FM, leptin, and ghrelin. Certainty of evidence across outcomes ranged from low to high. Our results suggest that GTE supplementation can attenuate oxidative stress, BM, BMI, and BFP, which are thought to negatively affect human health. Moreover, GTE as a nutraceutical dietary supplement can increase TAC and adiponectin.
Prior meta-analytic investigations over a decade ago rather inconclusively indicated that conjugated linoleic acid (CLA) supplementation could improve anthropometric and body composition indices in the general adult population. More recent investigations have emerged, and an up-to-date systematic review and meta-analysis on this topic must be improved. Therefore, this investigation provides a comprehensive systematic review and meta-analysis of randomised controlled trials (RCT) on the impact of CLA supplementation on anthropometric and body composition (body mass (BM), BMI, waist circumference (WC), fat mass (FM), body fat percentage (BFP) and fat-free mass (FFM)) markers in adults. Online databases search, including PubMed, Scopus, the Cochrane Library and Web of Science up to March 2022, were utilised to retrieve RCT examining the effect of CLA supplementation on anthropometric and body composition markers in adults. Meta-analysis was carried out using a random-effects model. The I2 index was used as an index of statistical heterogeneity of RCT. Among the initial 8351 studies identified from electronic databases search, seventy RCT with ninety-six effect sizes involving 4159 participants were included for data analyses. The results of random-effects modelling demonstrated that CLA supplementation significantly reduced BM (weighted mean difference (WMD): −0·35, 95 % CI (−0·54, −0·15), P < 0·001), BMI (WMD: −0·15, 95 % CI (−0·24, −0·06), P = 0·001), WC (WMD: −0·62, 95% CI (−1·04, −0·20), P = 0·004), FM (WMD: −0·44, 95 % CI (−0·66, −0·23), P < 0·001), BFP (WMD: −0·77 %, 95 % CI (−1·09, −0·45), P < 0·001) and increased FFM (WMD: 0·27, 95 % CI (0·09, 0·45), P = 0·003). The high-quality subgroup showed that CLA supplementation fails to change FM and BFP. However, according to high-quality studies, CLA intake resulted in small but significant increases in FFM and decreases in BM and BMI. This meta-analysis study suggests that CLA supplementation may result in a small but significant improvement in anthropometric and body composition markers in an adult population. However, data from high-quality studies failed to show CLA’s body fat-lowering properties. Moreover, it should be noted that the weight-loss properties of CLA were small and may not reach clinical importance.
This systematic review and meta-analysis aimed to investigate the effects of beetroot (BR) or nitrate supplements on body composition indices. A systematic search was conducted for randomised controlled trials (RCT) published up to August 2022 among online databases including Scopus, PubMed/Medline, Web of Science and Embase. Meta-analyses were carried out using a random-effects model. The I2 index was used to assess the heterogeneity of RCT. A total of twelve RCT met the inclusion criteria for this meta-analysis. The pooled effect size of included studies indicated that BR or nitrate supplementation did not change body weight (weighted mean differences (WMD): –0·14 kg, 95 % CI –1·22, 1·51; P = 0·836; I2 = 0 %), BMI (WMD: −0·07 kg/m2, 95 % CI −0·19,0·03; P = 0·174, I2 = 0 %), fat mass (WMD: –0·26 kg, 95 % CI –1·51, 0·98; P = 0·677, I2 = 0 %), waist circumference (WMD: –0·28 cm, 95 % CI –2·30, 1·74; P = 0·786, I2 = 0 %), body fat percentage (WMD: 0·18 %, 95 % CI –0·62, 0·99; P = 0·651, I2 = 0 %), fat-free mass (WMD: 0·31 kg, 95 % CI –0·31, 1·94; P = 0·703, I2 = 0 %) and waist-to-hip ratio (WMD: 0, 95 % CI –0·01, 0·02; P = 0·676, I2 = 0 %). Subgroup analyses based on trial duration, BR or nitrate dose, study design, baseline BMI and athletic status (athlete v. non-athlete) demonstrated similar results. Certainty of evidence across outcomes ranged from low to moderate. This meta-analysis study suggests that BR or nitrate supplements cannot efficiently ameliorate body composition indices regardless of supplement dosage, trial duration and athletic status.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the novel global coronavirus disease 2019 (COVID-19) disease outbreak. Its pathogenesis is mostly located in the respiratory tract. However, other organs are also affected. Hence, realising how such a complex disturbance affects patients after recovery is crucial. Regarding the significance of control of COVID-19-related complications after recovery, the current study was designed to review the cellular and molecular mechanisms linking COVID-19 to significant long-term signs including renal and cardiac complications, cutaneous and neurological manifestations, as well as blood coagulation disorders. This virus can directly influence on the cells through Angiotensin converting enzyme 2 (ACE-2) to induce cytokine storm. Acute release of Interleukin-1 (IL1), IL6 and plasminogen activator inhibitor 1 (PAI-1) have been related to elevating risk of heart failure. Also, inflammatory cytokines like IL-8 and Tumour necrosis factor-α cause the secretion of von Willebrand factor (VWF) from human endothelial cells and then VWF binds to Neutrophil extracellular traps to induce thrombosis. On the other hand, the virus can damage the blood–brain barrier by increasing its permeability and subsequently enters into the central nervous system and the systemic circulation. Furthermore, SARS-induced ACE2-deficiency decreases [des-Arg9]-bradykinin (desArg9-BK) degradation in kidneys to induce inflammation, thrombotic problems, fibrosis and necrosis. Notably, the angiotensin II-angiotensin II type 1 receptor binding causes an increase in aldosterone and mineralocorticoid receptors on the surface of dendritic cells cells, leading to recalling macrophage and monocyte into inflammatory sites of skin. In conclusions, all the pathways play a key role in the pathogenesis of these disturbances. Nevertheless, more investigations are necessary to determine more pathogenetic mechanisms of the virus.
Recent meta-analytic work indicated that guar gum supplementation might improve lipid profile markers in different populations. However, critical methodological limitations such as the use of some unreliable data and the lack of inclusion of several relevant studies, and the scarcity in assessments of regression and dose-specific effects make it difficult to draw meaningful conclusions from the meta-analysis. Therefore, current evidence regarding the effects of guar gum supplementation on lipid profile remains unclear. The present systematic review, meta-regression and dose–response meta-analysis aimed to examine the effects of guar gum supplementation on lipid profile (total cholesterol (TC), LDL, TAG and HDL) in adults. Relevant studies were obtained by searching the PubMed, SCOPUS, Embase and Web of Science databases (from inception to September 2021). Weighted mean differences (WMD) and 95 % CI were estimated via a random-effects model. Heterogeneity, sensitivity analysis and publication bias were reported using standard methods. Pooled analysis of nineteen randomised controlled trials (RCT) revealed that guar gum supplementation led to significant reductions in TC (WMD: −19·34 mg/dl, 95 % CI −26·18, −12·49, P < 0·001) and LDL (WMD: −16·19 mg/dl, 95 % CI −25·54, −6·83, P = 0·001). However, there was no effect on TAG and HDL among adults in comparison with control group. Our outcomes suggest that guar gum supplementation lowers TC and LDL in adults. Future large RCT on various populations are needed to show further beneficial effects of guar gum supplementation on lipid profile and establish guidelines for clinical practice.
Previous studies evaluating the effects of betaine supplementation on body composition offer contradictory findings. This systematic review and meta-analysis assessed the effects of betaine supplementation on body composition indices (body mass (BM), BMI, body fat percentage (BFP), fat mass (FM), fat-free mass (FFM)), and dietary intakes. Studies examining the effects of betaine supplementation on body composition and dietary intakes published up to August 2021 were identified through PubMed, the Cochrane Library, Web of Science, Embase, SCOPUS and Ovid databases. Betaine supplementation failed to significantly affect BM ((weighted mean difference (WMD): −0·40 kg, 95 % CI −1·46, 0·64), P = 0·447), BMI ((WMD: −0·05 kg/m2, 95 % CI −0·36, 0·25), P = 0·719), BFP ((WMD: 0·26 %, 95 % CI −0·82, 1·36), P = 0·663), FM ((WMD: −0·57 kg, 95 % CI −2·14, 0·99), P = 0·473) and FFM ((WMD: 0·61 kg, 95 % CI −1·27, 2·49), P = 0·527). Subgroup analyses based on participant’s age (< 40 and > 40 years), sex, BMI, trial duration (< 8 and ≥ 8 weeks), betaine supplementation dosage (< 4 and ≥ 4 g) and health status (healthy or unhealthy) demonstrated similar results. Other than a potential negligible increase in protein intake (WMD: 3·56 g, 95 % CI 0·24, 6·88, P = 0·035), no changes in dietary intakes were observed following betaine supplementation compared with control. The present systematic review and meta-analysis does not show any beneficial effects of betaine supplementation on body composition indices (BM, BMI, FM and FFM).
Obesity remains a serious relevant public health concern throughout the world despite related countermeasures being well understood (i.e. mainly physical activity and an adjusted diet). Among different nutritional approaches, there is a growing interest in ketogenic diets (KD) to manipulate body mass (BM) and to enhance fat mass loss. KD reduce the daily amount of carbohydrate intake drastically. This results in increased fatty acid utilisation, leading to an increase in blood ketone bodies (acetoacetate, 3-β-hydroxybutyrate and acetone) and therefore metabolic ketosis. For many years, nutritional intervention studies have focused on reducing dietary fat with little or conflicting positive results over the long term. Moreover, current nutritional guidelines for athletes propose carbohydrate-based diets to augment muscular adaptations. This review discusses the physiological basis of KD and their effects on BM reduction and body composition improvements in sedentary individuals combined with different types of exercise (resistance training or endurance training) in individuals with obesity and athletes. Ultimately, we discuss the strengths and the weaknesses of these nutritional interventions together with precautionary measures that should be observed in both individuals with obesity and athletic populations. A literature search from 1921 to April 2021 using Medline, Google Scholar, PubMed, Web of Science, Scopus and Sportdiscus Databases was used to identify relevant studies. In summary, based on the current evidence, KD are an efficient method to reduce BM and body fat in both individuals with obesity and athletes. However, these positive impacts are mainly because of the appetite suppressive effects of KD, which can decrease daily energy intake. Therefore, KD do not have any superior benefits to non-KD in BM and body fat loss in individuals with obesity and athletic populations in an isoenergetic situation. In sedentary individuals with obesity, it seems that fat-free mass (FFM) changes appear to be as great, if not greater, than decreases following a low-fat diet. In terms of lean mass, it seems that following a KD can cause FFM loss in resistance-trained individuals. In contrast, the FFM-preserving effects of KD are more efficient in endurance-trained compared with resistance-trained individuals.
Due to the important roles of resistance training and protein consumption in the prevention and treatment of sarcopenia, we assessed the efficacy of post-exercise Icelandic yogurt consumption on lean mass, strength and skeletal muscle regulatory factors in healthy untrained older males. Thirty healthy untrained older males (age = 68 ± 4 years) were randomly assigned to Icelandic yogurt (IR; n 15, 18 g of protein) or an iso-energetic placebo (PR; n 15, 0 g protein) immediately following resistance training (3×/week) for 8 weeks. Before and after training, lean mass, strength and skeletal muscle regulatory factors (insulin-like growth factor-1 (IGF-1), transforming growth factor-beta 1 (TGF-β1), growth differentiation factor 15 (GDF15), Activin A, myostatin (MST) and follistatin (FST)) were assessed. There were group × time interactions (P < 0·05) for body mass (IR: Δ 1, PR: Δ 0·7 kg), BMI (IR: Δ 0·3, PR: Δ 0·2 kg/m2), lean mass (IR: Δ 1·3, PR: Δ 0·6 kg), bench press (IR: Δ 4, PR: 2·3 kg), leg press (IR: Δ 4·2, PR: Δ 2·5 kg), IGF-1 (IR: Δ 0·5, Δ PR: 0·1 ng/ml), TGF-β (IR: Δ − 0·2, PR: Δ − 0·1 ng/ml), GDF15 (IR: Δ − 10·3, PR: Δ − 4·8 pg/ml), Activin A (IR: Δ − 9·8, PR: Δ − 2·9 pg/ml), MST (IR: Δ − 0·1, PR: Δ − 0·04 ng/ml) and FST (IR: Δ 0·09, PR: Δ 0·03 ng/ml), with Icelandic yogurt consumption resulting in greater changes compared with placebo. The addition of Icelandic yogurt consumption to a resistance training programme improved lean mass, strength and altered skeletal muscle regulatory factors in healthy untrained older males compared with placebo. Therefore, Icelandic yogurt as a nutrient-dense source and cost-effective supplement enhances muscular gains mediated by resistance training and consequently may be used as a strategy for the prevention of sarcopenia.
We aimed to assess the effects of spirulina supplementation during gradual weight loss on serum concentrations of follistatin (FST), myostatin (MST), insulin-like growth factor 1 (IGF-1), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and body composition in competitive wrestlers. Forty competitive wrestlers (age: 22 (sem 2) years) were randomly assigned to one of two groups: gradual weight loss + spirulina (SP; n 20) or gradual weight loss + placebo (PL; n 20). Subjects in both groups lost weight according to a designed diet over 12 d and were required to reduce baseline body mass (BM) by 4%. Subjects in the SP group received two tablets of spirulina, while subjects in the PL received two tablets of placebo before each meal. Concentrations of mentioned serum markers and body composition were measured before and after the interventions. BM (SP = −3·1 kg and PL = −2·9 kg), body fat percentage (BFP) (SP = −2·1 % and PL = −0·6 %), fat mass (FM) (SP = −2·2 kg and PL = −0·9 kg) and skeletal muscle mass (SP = −1·4 kg and PL = −1·5 kg) significantly decreased in both groups (P < 0·05). The changes in BFP and FM were significantly greater in SP compared with the PL group (P < 0·001). Additionally, MST (SP = −0·1 ng/ml), AST (SP = −2·1 u/l) and ALT (SP = −2·7 u/l) concentrations significantly diminished in SP group (P = 0·005), while FST (PL = −0·1 ng/ml) and IGF-1 (PL = −2·6 ng/ml) concentrations significantly decreased in PL group (P < 0·05). Spirulina supplementation during gradual weight loss is beneficial in reducing BFP, FM, MST and liver enzymes while maintaining IGF-1 and FST concentrations in competitive wrestlers.
Eggs are considered a high-quality protein source for their complete amino acid profile and digestibility. Therefore, this study aimed to compare the effects of whole egg (WE) v. egg white (EW) ingestion during 12 weeks of resistance training (RT) on the skeletal muscle regulatory markers and body composition in resistance-trained men. Thirty resistance-trained men (mean age 24·6 (sd 2·7) years) were randomly assigned into the WE + RT (WER, n 15) or EW + RT (EWR, n 15) group. The WER group ingested three WE, while the EWR group ingested an isonitrogenous quantity of six EW per d immediately after the RT session. Serum concentrations of regulatory markers and body composition were measured at baseline and after 12 weeks. Significant main effects of time were observed for body weight (WER 1·7, EWR 1·8 kg), skeletal muscle mass (WER 2·9, EWR 2·7 kg), fibroblast growth factor-2 (WER 116·1, EWR 83·2 pg/ml) and follistatin (WER 0·05, EWR 0·04 ng/ml), which significantly increased (P < 0·05), and for fat mass (WER –1·9, EWR –1·1 kg), transforming growth factor-β1 (WER –0·5, EWR −0·1 ng/ml), activin A (WER –6·2, EWR –4·5 pg/ml) and myostatin (WER –0·1, EWR –0·06 ng/ml), which significantly decreased (P < 0·05) in both WER and EWR groups. The consumption of eggs absent of yolk during chronic RT resulted in similar body composition and functional outcomes as WE of equal protein value. EW or WE may be used interchangeably for the dietary support of RT-induced muscular hypertrophy when protein intake is maintained.
This systematic review and meta-analysis compared the effects of different rates of weight loss (WL), but equivalent total WL, on body composition and RMR. Studies examining gradual v. rapid WL on body composition and RMR in participants with overweight/obesity published up to October 2019 were identified through PubMed, the Cochrane Library, Web of Science, Embase, Scopus and Ovid databases. Meta-analysis was carried out using a fixed or random effects model as appropriate. Although the magnitude of WL was similar (mean difference 0·03 kg, 95 % CI –0·65, 0·71), gradual WL promoted greater reductions in fat mass (FM) (–1 kg, 95 % CI –1·70, –0·29) and body fat percentage (BFP) (–0·83 %, 95 % CI –1·49, –0·17). Gradual WL significantly preserved RMR compared with rapid WL (407·48 kJ, 95 % CI 76·76, 118·01). However, there was no significant difference in waist and hip circumferences, waist:hip ratio and fat-free mass (FFM) between gradual and rapid WL. The present systematic review and meta-analysis indicates beneficial effects of gradual WL, as compared with rapid WL, on FM, BFP and RMR in individuals with overweight/obesity. However, FFM changes and anthropometric indices did not significantly differ following different rates of WL.
Normal-weight obesity (NWO) syndrome is associated with metabolic diseases. The present study aimed to investigate the effects of 12 weeks of a high-protein (HP) v. a standard protein (SP) diet on appetite, anthropometry and body composition in NWO women. In this clinical trial, fifty NWO women were randomly allocated to HP (n 25) or SP (n 25) diet groups. Women in the HP and SP groups consumed 25 and 15 % of their total energy intake from protein for 12 weeks. Weight, fat mass (FM), lean body mass (LBM), waist circumference (WC) and appetite were evaluated at baseline and following their 3-month intervention. After 12 weeks, the LBM was higher in HP compared with no significant changes in the SP group (mean between-group difference = 1·5 kg; 95 % CI 3·1, 0·01; effect size (d) = 0·4). Furthermore, the HP group had lower FM (mean between-group difference –1·1 kg; 95 % CI 1, –3·3; d = –0·2), body fat percentage (BFP) (mean between-group difference –2 %; 95 % CI 0·7, –5·2; d = –0·3) and WC (mean between-group difference –1·4 cm; 95 % CI 0·6, –3·6; d = –0·2) at the end of the study in comparison with the SP group. In both groups, weight and appetite were unchanged over time without significant differences between groups. Twelve weeks of euenergetic diets with different dietary protein contents resulted in no significant weight loss in women with NWO. However, an HP diet significantly improved body composition (LBM, FM, BFP and WC) in this population.
Vitamin D deficiency is now a recognised problem affecting multiple physiological functions. The aim of the present study was to evaluate the effect of a single dose of vitamin D3 injection on the inflammatory, muscular damage, metabolic and cardiovascular responses to an acute bout of resistance exercise (RE) in vitamin D-deficient resistance-trained males. Blood samples from fourteen vitamin D-deficient resistance-trained males were obtained during two separate trials: lower vitamin D (LVD) and higher vitamin D (HVD, after vitamin D3 injection). Metabolic, inflammatory, muscle damage and cardiovascular markers were evaluated at baseline, immediately and 1 h after RE. There were significant trial-by-time interactions for insulin and homeostatic model assessment of insulin resistance (HOMA-IR) which significantly (P < 0·05) declined for 1 h after RE in the HVD trial compared with the LVD trial. Homeostasis model assessment of β-cell function (HOMA-β) declines at 1 h post-RE in the HVD trial. There was also a time effect for blood sugar which significantly (P < 0·05) decreased and for creatine kinase, lactate dehydrogenase and IL-6 which increased significantly 1 h post-RE in both trials. There were no significant changes in other inflammatory and cardiovascular markers following both trials. A single injection of vitamin D3 improved insulin resistance and β-cell function following RE in previously vitamin D-deficient resistance-trained males. Conversely, the injection did not change muscle damage and the inflammatory response to acute RE. Intramuscular vitamin D replacement may have key implications for the promotion of glucose metabolism and lowering the risk of diabetes in vitamin D-deficient individuals.
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