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Effects of Intermittent Energy Restriction Compared with Those of Continuous Energy Restriction on Body Composition and Cardiometabolic Risk Markers - A Systematic Review and Meta-Analysis of Randomized Controlled Trials in Adults.
Schroor, MM, Joris, PJ, Plat, J, Mensink, RP
Advances in nutrition (Bethesda, Md.). 2024;15(1):100130
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Intermittent energy restriction (IER) diets, such as the 5:2 diet, time-restricted eating (TRE), and alternate-day fasting (ADF), are gaining popularity. According to previous research, IER protocols effectively manage obesity and may have many other health benefits, including improving metabolic health. This systematic review and meta-analysis of twenty-eight parallel-design randomised controlled trials looked at the benefits of IER protocols, such as ADF, TRE, and the 5:2 diet, and the effects of continuous energy restriction (CER) on anthropometric and cardiometabolic outcomes. The results of this systematic review and meta-analysis showed that both the IER and CER are equally beneficial. However, IER protocols showed greater but clinically insignificant improvements in fat-free mass and waist circumference in healthy adults. IER and CER protocols were not different in improving the lipid profile, glucose and insulin levels and blood pressure. Different IER diets showed different positive effects on metabolic parameters. Future robust studies are required to assess the effects of these energy-restriction diets on metabolic and anthropometric parameters because of the high variability in the included studies. However, healthcare professionals can use the results of this review to understand the potential clinical utility of various energy-restriction diets.
Abstract
The interest in intermittent energy restriction (IER) diets as a weight-loss approach is increasing. Different IER protocols exist, including time-restricted eating (TRE), alternate-day fasting (ADF), and the 5:2 diet. This meta-analysis compared the effects of these IER diets with continuous energy restriction (CER) on anthropometrics and cardiometabolic risk markers in healthy adults. Twenty-eight trials were identified that studied TRE (k = 7), ADF (k = 10), or the 5:2 diet (k = 11) for 2-52 wk. Energy intakes between intervention groups within a study were comparable (17 trials), lower in IER (5 trials), or not reported (6 trials). Weighted mean differences (WMDs) were calculated using fixed- or random-effects models. Changes in body weight [WMD: -0.42 kg; 95% confidence interval (CI): -0.96 to 0.13; P = 0.132] and fat mass (FM) (WMD: -0.31 kg; 95% CI: -0.98 to 0.36; P = 0.362) were comparable when results of the 3 IER diets were combined and compared with those of CER. All IER diets combined reduced fat-free mass (WMD: -0.20 kg; 95% CI: -0.39 to -0.01; P = 0.044) and waist circumference (WMD: -0.91 cm; 95% CI: -1.76 to -0.06; P = 0.036) more than CER. Effects on body mass index [BMI (kg/m2)], glucose, insulin, homeostatic model assessment for insulin resistance (HOMA-IR), serum lipid and lipoprotein concentrations, and blood pressure did not differ. Further, TRE reduced body weight, FM, and fat-free mass more than CER, whereas ADF improved HOMA-IR more. BMI was reduced less in the 5:2 diet compared with CER. In conclusion, the 3 IER diets combined did not lead to superior improvements in anthropometrics and cardiometabolic risk markers compared with CER diets. Slightly greater reductions were, however, observed in fat-free mass and waist circumference. To what extent differences in energy intakes between groups within studies may have influenced these outcomes should be addressed in future studies.
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Effect of oat supplementation interventions on cardiovascular disease risk markers: a systematic review and meta-analysis of randomized controlled trials.
Llanaj, E, Dejanovic, GM, Valido, E, Bano, A, Gamba, M, Kastrati, L, Minder, B, Stojic, S, Voortman, T, Marques-Vidal, P, et al
European journal of nutrition. 2022;61(4):1749-1778
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Cardiovascular disease (CVD) is one of the leading causes of mortality among adults. Changes in diet can have a beneficial effect on the prevention and management of CVD. Studies have shown that increasing intake of wholegrains, particularly those containing oat components, reduces CVD risk markers including blood cholesterol, blood glucose and body mass index (BMI). The purpose of this systematic review was to look at the effects of oat supplementation interventions (OSI) on CVD risk markers among adults, accounting for different dietary backgrounds or control arms. 74 RCTs were included (4937 subjects). Supplementing the diet with oat cereals improves CVD risk markers in healthy adults and those with mild metabolic disturbances. In particular serum total and LDL cholesterol, BMI and waist circumference. The beneficial effects on total cholesterol and LDL-Cholesterol were independent of the dietary background. The role of OSIs on blood pressure, glucose homeostasis or other markers, could not be established.
Abstract
PURPOSE Oat supplementation interventions (OSIs) may have a beneficial effect on cardiovascular disease (CVD) risk. However, dietary background can modulate such effect. This systematic review assesses the effects of OSIs on CVD risk markers among adults, accounting for different dietary backgrounds or control arms. METHODS We included randomized clinical trials (RCTs) that assessed the effect of oat, oat beta-glucan-rich extracts or avenanthramides on CVD risk markers. RESULTS Seventy-four RCTs, including 4937 predominantly hypercholesterolemic, obese subjects, with mild metabolic disturbances, were included in the systematic review. Of these, 59 RCTs contributed to the meta-analyses. Subjects receiving an OSI, compared to control arms without oats, had improved levels of total cholesterol (TC) [weighted mean difference and (95% CI) - 0.42 mmol/L, (- 0.61; - 0.22)], LDL cholesterol [- 0.29 mmol/L, (- 0.37; - 0.20)], glucose [- 0.25 nmol/L, (- 0.36; - 0.14)], body mass index [- 0.13 kg/m2, (- 0.26; - 0.01)], weight [- 0.94 kg, (- 1.84: - 0.05)], and waist circumference [- 1.06 cm, (- 1.85; - 0.27)]. RCTs on inflammation and/or oxidative stress markers were scarce and with inconsistent findings. RCTs comparing an OSI to heterogeneous interventions (e.g., wheat, eggs, rice, etc.), showed lowered levels of glycated haemoglobin, diastolic blood pressure, HDL cholesterol and apolipoprotein B. The majority of included RCTs (81.1%) had some concerns for risk of bias. CONCLUSION Dietary OSIs resulted in lowered levels of blood lipids and improvements in anthropometric parameters among participants with predominantly mild metabolic disturbances, regardless of dietary background or control. Further high-quality trials are warranted to establish the role of OSIs on blood pressure, glucose homeostasis and inflammation markers.
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Effects of lifestyle interventions on cardiovascular risk factors in South Asians: a systematic review and meta-analysis.
Limbachia, J, Ajmeri, M, Keating, BJ, de Souza, RJ, Anand, SS
BMJ open. 2022;12(12):e059666
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The prevalence of cardiovascular disease (CVD) and associated mortality risk is high in the South Asian population in western countries. Regular physical activity and a healthy diet may modify the risk factors of CVD, such as abdominal fat, high cholesterol, and blood sugar irregularities. This systematic review and meta-analysis included thirty-five randomised controlled trials to evaluate the effectiveness of diet, physical activity interventions or a combination of diet and physical activity interventions on CVD risk factors and compared it against usual care. Combining diet and physical activity interventions reduced CVD risk factors such as systolic and diastolic blood pressure, BMI, weight, waist circumference and fasting plasma glucose (FPG). Dietary interventions reduced diastolic blood pressure, triglycerides, low-density lipoprotein cholesterol, BMI, weight and FPG. Physical activity modifications improved diastolic and systolic blood pressure and high-density lipoprotein cholesterol. Healthcare professionals can use the study results to understand how tailored diet and physical activity modifications improve the CVD risk factors in South Asians. However, further robust studies are required as most of these evidences were of moderate quality and lacked clinical significance.
Abstract
BACKGROUND The cardiovascular disease (CVD) burden among South Asians is high. Lifestyle interventions have been effective in the primary prevention of CVD, but this has not been replicated, through a synthesis of randomised trials, in South Asians. METHODS Four electronic databases (MEDLINE, Embase, CENTRAL and CINAHL), two clinical trial registries and references of included articles were searched through June 2022 (featuring ≥90% South Asian participants). Random-effects pairwise meta-analyses were performed, and heterogeneity was quantified with the I2 statistic. The Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) framework was used to report on the quality of evidence (International Prospective Register of Systematic Reviews registration (PROSPERO). RESULTS Thirty-five studies were included. Twelve tested diet and physical activity interventions; 18 tested diet alone; and 5 tested physical activity alone. All reported effects of the intervention(s) on at least one established risk factor for CVD, including blood pressure (systolic blood pressure (SBP), diastolic blood pressure (DBP) and blood lipids (high-density lipoprotein cholesterol (HDLc), low-density lipoprotein cholesterol (LDLc) or triglycerides). No trials reported clinical CVD. There is moderate-quality evidence that diet and physical activity interventions improve SBP (mean difference (MD) -2.72 mm Hg, 95% CI -4.11 to -1.33) and DBP (MD -1.53 mm Hg, 95% CI -2.57 to -0.48); high-quality to moderate-quality evidence that diet-only interventions improve DBP (MD -2.05 mm Hg, 95% CI -2.93 to -1.16) and blood lipids (triglycerides (MD -0.10 mmol/L, 95% CI -0.14 to -0.06) and LDLc (MD -0.19 mmol/L, 95% CI -0.32 to -0.06)); and moderate-quality evidence that physical activity-only interventions improve SBP (MD -9.7 mm Hg, 95% CI -11.05 to -8.35), DBP (MD -7.29 mm Hg, 95% CI -8.42 to -6.16) and HDLc (MD 0.08 mmol/L, 95% CI 0.04 to 0.11) compared with usual care. CONCLUSIONS Lifestyle interventions improve blood pressure and blood lipid profiles in adult South Asians at risk of CVD. Tailored interventions should be used to modify cardiovascular risk factors in this at-risk group. PROSPERO REGISTRATION NUMBER CRD42018090419.
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Causal relationship between obesity, lifestyle factors and risk of benign prostatic hyperplasia: a univariable and multivariable Mendelian randomization study.
Wang, YB, Yang, L, Deng, YQ, Yan, SY, Luo, LS, Chen, P, Zeng, XT
Journal of translational medicine. 2022;20(1):495
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Benign prostatic hyperplasia (BPH) is a common benign disease in middle-aged and elderly men which is often underestimated and underdiagnosed. If patients are not treated in time, it may lead to serious complications, such as urinary retention, renal insufficiency and renal failure. The aim of this study was to evaluate the possible causal associations of abdominal obesity (measured as waist circumference), overall obesity (measured as body mass index), lifestyle factors (dietary habits, smoking, alcohol drinking, and sedentary behaviour) with risk of BPH. This study is a univariable and multivariable mendelian randomised study. Results show that genetic predisposition to higher waist circumference and sedentary behaviour are independently and causally associated with the risk of BPH. However, there isn’t conclusive evidence that genetic predisposition to relative carbohydrate, fat, protein, and sugar intake, smoking and alcohol drinking are causally associated with the risk of BPH. Authors conclude that further studies are needed to identify comprehensive risk factors on BPH and develop freely accessible prediction models for the BPH. These will help to identify individuals at particular risk and provide decision-making supports for individualised intervention.
Abstract
BACKGROUND Obesity (waist circumference, body mass index (BMI)) and lifestyle factors (dietary habits, smoking, alcohol drinking, Sedentary behavior) have been associated with risk of benign prostatic hyperplasia (BPH) in observational studies, but whether these associations are causal is unclear. METHODS We performed a univariable and multivariable Mendelian randomization study to evaluate these associations. Genetic instruments associated with exposures at the genome-wide significance level (P < 5 × 10-8) were selected from corresponding genome-wide associations studies (n = 216,590 to 1,232,091 individuals). Summary-level data for BPH were obtained from the UK Biobank (14,126 cases and 169,762 non-cases) and FinnGen consortium (13,118 cases and 72,799 non-cases). Results from UK Biobank and FinnGen consortium were combined using fixed-effect meta-analysis. RESULTS The combined odds ratios (ORs) of BPH were 1.24 (95% confidence interval (CI), 1.07-1.43, P = 0.0045), 1.08 (95% CI 1.01-1.17, P = 0.0175), 0.94 (95% CI 0.67-1.30, P = 0.6891), 1.29 (95% CI 0.88-1.89, P = 0.1922), 1.23 (95% CI 0.85-1.78, P = 0.2623), and 1.04 (95% CI 0.76-1.42, P = 0.8165) for one standard deviation (SD) increase in waist circumference, BMI, and relative carbohydrate, fat, protein and sugar intake, 1.05 (95% CI 0.92-1.20, P = 0.4581) for one SD increase in prevalence of smoking initiation, 1.10 (95% CI 0.96-1.26, P = 0.1725) and 0.84 (95% CI 0.69-1.02, P = 0.0741) for one SD increase of log-transformed smoking per day and drinks per week, and 1.31 (95% CI 1.08-1.58, P = 0.0051) for one SD increase in sedentary behavior. Genetically predicted waist circumference (OR = 1.26, 95% CI 1.11-1.43, P = 0.0004) and sedentary behavior (OR = 1.14, 95% CI 1.05-1.23, P = 0.0021) were associated with BPH after the adjustment of BMI. CONCLUSION This study supports independent causal roles of high waist circumference, BMI and sedentary behavior in BPH.
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Astaxanthin Influence on Health Outcomes of Adults at Risk of Metabolic Syndrome: A Systematic Review and Meta-Analysis.
Leung, LY, Chan, SM, Tam, HL, Wong, ES
Nutrients. 2022;14(10)
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Metabolic syndrome is a term used to describe a combination of three or more health issues that can increase the risk of cardiovascular disease by 70%. Risk factors include hypertension, hyperglycaemia, obesity, and dyslipidaemia. Astaxanthin is a powerful antioxidant that can potentially reduce the risk of metabolic syndrome. This systematic review and meta-analysis included seven double-blinded randomised controlled trials that evaluated the beneficial effects of Astaxanthin in reducing the risk factors associated with metabolic syndrome. More than eight weeks of daily ≤6 mg Astaxanthin supplementation significantly reduced systolic blood pressure, total cholesterol, triglycerides, and LDL cholesterol. The therapeutic value of Astaxanthin supplementation requires long-term robust research since studies included in this study are highly heterogeneous in terms of the intervention period, the dosage of the supplements, participant health, and sample size. This study can assist healthcare professionals in understanding the beneficial effects of Astaxanthin supplements on people with metabolic syndrome.
Abstract
The use of medication is effective in managing metabolic syndrome (MetS), but side effects have led to increased attention on using nutraceuticals and supplements. Astaxanthin shows positive effects in reducing the risk of MetS, but results from individual studies are inconclusive. This systematic review summarizes the latest evidence of astaxanthin in adults with risk factors of MetS. A systematic search of English and Chinese randomized controlled trials in 14 electronic databases from inception to 30 June 2021 was performed. Two reviewers independently screened the titles and abstracts, and conducted full-text review, quality appraisal, and extraction of data. Risk of bias was assessed by PEDro. A total of 7 studies met the inclusion criteria with 321 participants. Six studies were rated to have excellent methodological quality, while the remaining one was rated at good. Results show marginal effects of astaxanthin on reduction in total cholesterol and systolic blood pressure, and a significant attenuating effect on low-density lipoprotein cholesterol. Further robust evidence is needed to examine the effects of astaxanthin in adults at risk of MetS.
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Central fatness and risk of all cause mortality: systematic review and dose-response meta-analysis of 72 prospective cohort studies.
Jayedi, A, Soltani, S, Zargar, MS, Khan, TA, Shab-Bidar, S
BMJ (Clinical research ed.). 2020;370:m3324
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Body mass index (BMI) may not be an adequate tool to measure obesity, as it does not describe where fat is located on the body. Distribution of fat around the middle may be related to the risk of death and may be a more accurate measure of obesity. This systematic review of 1950 studies aimed to assess the association of fat around the middle with death. The results showed that every 10cm increase in waist circumference was related to an 11% increased risk of death by any cause. Women with a waist circumference greater than 80cm and 90cm in men had a higher risk of death by any cause. Fat carried around the middle increased the risk of death by any cause, however larger thigh and hip circumferences lowered the risk. This was regardless of BMI. It was concluded that measures of centrally located fat, alongside BMI, could be used to determine the risk of death. This study could be used by healthcare professionals to understand the importance of not solely relying on BMI and measuring where fat is distributed on the body may be an additional measure to determine risk of premature death.
Abstract
OBJECTIVE To quantify the association of indices of central obesity, including waist circumference, hip circumference, thigh circumference, waist-to-hip ratio, waist-to-height ratio, waist-to-thigh ratio, body adiposity index, and A body shape index, with the risk of all cause mortality in the general population, and to clarify the shape of the dose-response relations. DESIGN Systematic review and meta-analysis. DATA SOURCES PubMed and Scopus from inception to July 2019, and the reference lists of all related articles and reviews. ELIGIBILITY CRITERIA FOR SELECTING STUDIES Prospective cohort studies reporting the risk estimates of all cause mortality across at least three categories of indices of central fatness. Studies that reported continuous estimation of the associations were also included. DATA SYNTHESIS A random effects dose-response meta-analysis was conducted to assess linear trend estimations. A one stage linear mixed effects meta-analysis was used for estimating dose-response curves. RESULTS Of 98 745 studies screened, 1950 full texts were fully reviewed for eligibility. The final analyses consisted of 72 prospective cohort studies with 2 528 297 participants. The summary hazard ratios were as follows: waist circumference (10 cm, 3.94 inch increase): 1.11 (95% confidence interval 1.08 to 1.13, I2=88%, n=50); hip circumference (10 cm, 3.94 inch increase): 0.90 (0.81 to 0.99, I2=95%, n=9); thigh circumference (5 cm, 1.97 inch increase): 0.82 (0.75 to 0.89, I2=54%, n=3); waist-to-hip ratio (0.1 unit increase): 1.20 (1.15 to 1.25, I2=90%, n=31); waist-to-height ratio (0.1 unit increase): 1.24 (1.12 to 1.36, I2=94%, n=11); waist-to-thigh ratio (0.1 unit increase): 1.21 (1.03 to 1.39, I2=97%, n=2); body adiposity index (10% increase): 1.17 (1.00 to 1.33, I2=75%, n=4); and A body shape index (0.005 unit increase): 1.15 (1.10 to 1.20, I2=87%, n=9). Positive associations persisted after accounting for body mass index. A nearly J shaped association was found between waist circumference and waist-to-height ratio and the risk of all cause mortality in men and women. A positive monotonic association was observed for waist-to-hip ratio and A body shape index. The association was U shaped for body adiposity index. CONCLUSIONS Indices of central fatness including waist circumference, waist-to-hip ratio, waist-to-height ratio, waist-to-thigh ratio, body adiposity index, and A body shape index, independent of overall adiposity, were positively and significantly associated with a higher all cause mortality risk. Larger hip circumference and thigh circumference were associated with a lower risk. The results suggest that measures of central adiposity could be used with body mass index as a supplementary approach to determine the risk of premature death.
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Body mass index, abdominal fatness, weight gain and the risk of psoriasis: a systematic review and dose-response meta-analysis of prospective studies.
Aune, D, Snekvik, I, Schlesinger, S, Norat, T, Riboli, E, Vatten, LJ
European journal of epidemiology. 2018;33(12):1163-1178
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Psoriasis is an immune-mediated inflammatory skin disease characterised by red, itchy, scaly and flaky skin. Research has shown an association between adiposity and inflammation cytokine release triggered by adipose tissue and increased body mass index and psoriasis. In this meta-analysis, seven prospective studies were included, and the association between BMI, abdominal fat, and psoriasis was examined. According to this meta-analysis, the relative risk of psoriasis increases by 19% for every 5-unit increase in BMI, 24% for a 10 cm increase in waist circumference, 37% for a 0.1-unit increase in waist-to-hip ratio, and 11% for a 5 kg weight gain. The risk of psoriasis was lower for people with a BMI below 20, and it was significantly higher for those with a BMI between 22.5-24. Psoriasis risk was positively associated with waist circumference, waist-to-hip ratio, and weight gain. Psoriasis risk escalates by 2-4 times with an increase in each measure of adiposity. Several potential strategies to reduce the risk of psoriasis are identified in this meta-analysis, including weight loss, dietary factors, and physical activity. To evaluate their effectiveness and develop appropriate strategies, further robust studies are needed. Healthcare professionals can use the results of this study to develop potential therapeutic strategies to reduce the risk of psoriasis by understanding the mechanisms and factors associated with the disease.
Abstract
Greater body mass index (BMI) has been associated with increased risk of psoriasis in case-control and cross-sectional studies, however, the evidence from prospective studies has been limited. We conducted a systematic review and dose-response meta-analysis of different adiposity measures and the risk of psoriasis to provide a more robust summary of the evidence based on data from prospective studies. PubMed and Embase databases were searched for relevant studies up to August 8th 2017. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated using a random effects model. The summary relative risk (RR) for a 5 unit increment in BMI was 1.19 (95% CI 1.10-1.28, I2 = 83%, n = 7). The association appeared to be stronger at higher compared to lower levels of BMI, pnonlinearity < 0.0001, and the lowest risk was observed at a BMI around 20. The summary RR was 1.24 (95% CI 1.17-1.31, I2 = 0%, pheterogeneity = 0.72, n = 3) per 10 cm increase in waist circumference, 1.37 (95% CI 1.23-1.53, I2 = 0%, pheterogeneity = 0.93, n = 3) per 0.1 unit increase in waist-to-hip ratio, and 1.11 (95% CI 1.07-1.16, I2 = 47%, pheterogeneity = 0.15, n = 3) per 5 kg of weight gain. Adiposity as measured by BMI, waist circumference, waist-to-hip ratio, and weight gain is associated with increased risk of psoriasis.