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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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Plum supplementation and lipid profile: a systematic review and meta-analysis of randomised controlled trials.
Askarpour, M, Ghalandari, H, Setayesh, L, Ghaedi, E
Journal of nutritional science. 2023;12:e6
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The rate of nutrition-related non-communicable diseases is increasing worldwide. Lipid profile and its alterations have been used both as indicators of metabolic disorders and methods to evaluate patients’ response to dietary interventions. The aim of this study was to investigate the effectiveness of plums on improving parameters of lipid profile. This study is a systematic review and meta-analysis of nine randomised controlled trials with a total of eleven arms and 592 participants. Results show that plum can be beneficial in reducing triacylglycerols [triglycerides] in the unhealthy and low-density lipoprotein cholesterol in all individuals. However, no significant impact regarding blood triacylglycerols and high-density lipoprotein cholesterol levels, could be detected both in crude and subgroup analyses. Authors conclude that further clinical trials, taking advantage of a standard protocol of plum supplementation, should be conducted to elucidate the possible effect that plum supplementation might exert on lipid profile parameters.
Abstract
Plums are abundant in bioactive compounds which have been associated with numerous health benefits. In the present study, we aimed at examining the impact of plum supplementation on lipid profile of individuals. Electronic bibliographical databases were searched for relevant randomised clinical trials. Articles meeting our eligibility criteria were included for data extraction and final analysis. Weighted mean difference (WMD) was estimated using a random-effect model. Of the total articles retrieved in the initial search, nine articles were found to be eligible to be included in the analysis. Our results show that plum supplementation significantly improves total cholesterols levels in the unhealthy individuals. Moreover, plum supplementation reduces the LDL-c levels in the pooled sample (WMD = -11⋅52 mg/dl; 95 % CI -21⋅93, -1⋅11, P = 0⋅03, I 2 = 98⋅7 %) and also in some of the subgroups of individuals (dried plum, unhealthy subjects, duration more than 8 weeks). Moreover, it had a significant reducing effect on TC levels just in unhealthy subjects. Although plum supplementation did not have any significant impact on serum levels of TG nor HDL-c. Our results show that supplementation with plums is potentially effective in reducing serum total cholesterol and LDL-c.
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Comparative effects of vitamin and mineral supplements in the management of type 2 diabetes in primary care: A systematic review and network meta-analysis of randomized controlled trials.
Xia, J, Yu, J, Xu, H, Zhou, Y, Li, H, Yin, S, Xu, D, Wang, Y, Xia, H, Liao, W, et al
Pharmacological research. 2023;188:106647
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Type 2 diabetes mellitus (T2DM), characterised by sustained hyperglycaemia and insulin resistance, remains a severe driver of chronic metabolic diseases such as cardiovascular diseases. The aim of this study was to investigate and compare the efficacy of vitamin and mineral supplements in the management of glycaemic control and lipid metabolism for type 2 diabetic patients to inform clinical practice. This study is a systematic review and meta-analysis of one hundred and seventy articles with a total of 4223 adults with T2DM. Participants were randomised to either the placebo/no treatment group (n= 6345) or to the treatment group (n= 7878). Results show that: - chromium was the most effective micronutrient for decreasing fasting blood glucose and insulin resistance. - vitamin K was the top-ranked micronutrient in reducing haemoglobin A1C and fasting insulin levels. - vanadium was the top-ranked micronutrient in total cholesterol reductions. - niacin was ranked as the most effective in triglycerides reductions and increasing high-density lipoprotein cholesterol levels. - vitamin E was the top-ranked micronutrient in low-density lipoprotein cholesterol reductions. Authors conclude that micronutrient supplements especially chromium, vitamin E, vitamin K, vanadium, and niacin supplements, may be more effective in the management of T2DM compared with other micronutrients.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Clinicians could consider the adjunctive effect of micronutrients supplements, such as chromium, vitamin E, vitamin K, vanadium, and niacin supplements in a nutrition protocol to manage T2DM and slow or prevent its complications.
- The study authors state that the vitamin and mineral supplements under review had a statistically significant improvement, however they did not reach the study threshold for clinical significance. Therefore they advise caution in utilising micronutrient supplements in the management of glucose and lipid metabolism for T2DM.
Evidence Category:
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A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Objectives
The aim of this systematic review was to evaluate the comparative effects of vitamin and mineral supplements on managing glycemic control and lipid metabolism for type 2 diabetes mellitus (T2DM).
Methodology
This systematic review is registered with PROSPERO and adhered to PRISMA-2020 guidelines for network meta-analysis
The Cochrane Collaboration’s risk-of-bias tool was used to assess eligible randomised trials
8 prespecified markers identified and assessed in this study : 1) HbA1c (%), 2) fasting blood glucose (mmol/L), 3) total cholesterol (mmol/L), 4) triglycerides (mmol/L), 5) fasting insulin (μIU/mL), 6) HOMA-IR, 7) LDL-c (mmol/L), and 8) HDL-c (mmol/L).
Results
- 170 RCT trials of 14223 participants with T2DM treated with vitamin supplements, mineral supplements, or placebo/no treatment were included
- Low to very low certainty evidence established chromium supplements as the most effective in reducing fasting blood glucose levels and homeostasis model assessment of insulin resistance (SUCRAs: 90.4% and 78.3%, respectively)
- Vitamin K supplements ranked best in reducing glycated haemoglobin A1c and fasting insulin levels (SUCRAs: 97.0% and 82.3%, respectively), with moderate to very low certainty evidence
- Vanadium supplements ranked best in lowering total cholesterol levels with very low evidence certainty (SUCRAs:100%)
- Niacin supplements ranked best in triglyceride reductions and increasing high-density lipo-protein cholesterol levels with low to very low evidence certainty (SUCRAs:93.7% and 94.6%, respectively)
- Vitamin E supplements ranked best in reducing low-density lipoprotein cholesterol levels with very low evidence certainty (SUCRAs:80.0%).
Conclusion
- Micronutrient supplements, such as chromium, vitamin E, vitamin K, vanadium, and niacin supplements, may be efficacious in managing T2DM
- It should be noted that the evidence certainty for all was low.
Clinical practice applications:
- Chromium plays an important role in carbohydrate and lipid metabolism and was the most effective micronutrient for decreasing fasting blood glucose, HbA1c, fasting insulin, and HOMA-IR reductions. More pronounced effects were seen for chromium than vitamin E, vitamin C, niacin, selenium, and magnesium supplements
- Vitamin K was the top-ranked micronutrient in reducing HbA1c and fasting insulin levels. The mechanism through which Vitamin K affects glucose metabolism is proposed as activation of the AMP-activated protein kinase/sirtuin 1, that in turn increases phosphocreatine 3-kinase and glucose transporter 2 to decrease insulin resistance and fasting glucose.
- Vanadium was the top-ranked micronutrient in total cholesterol (TC) reductions, where supplementation dosage should be carefully considered, as vanadium compounds can be moderately or highly toxic. Vanadium supplementation is only recommended in cases of vanadium deficiency or diabetes, hyperlipidemia, and hypertension, where the intake of vanadium from food should be enhanced in preference to supplementation
- Niacin was ranked as the most effective in triglyceride (TG) reductions and increasing HDL cholesterol levels. The dose of niacin could not be determined
- Vitamin E was the top-ranked micronutrient in low-density lipo- protein (LDL) cholesterol reductions.
Considerations for future research:
- Considering the clinical importance of these findings, new research is needed to get better insight into the efficacy of micronutrient supplements in managing T2DM
- Selenium homeostasis, selenoprotein, insulin signaling/secretion, and carbohydrate/lipid metabolism are linked in multiple and complex ways but the authors could not explain why chromium supplementation would lower blood glucose more effectively than selenium supplementation, and suggest more research is needed to clarify this
- While vitamin K status could be an emerging treatment target in T2DM prevention and management, it remains to be determined whether vitamin K supplementation has an advantage over other nutrients in terms of hypoglycemic effect, and further research is necessary
- The beneficial effect of vitamin E and niacin supplements regarding lipid metabolism warrant investigation through more rigorous comparative studies.
Abstract
Medical nutrition treatment can manage diabetes and slow or prevent its complications. The comparative effects of micronutrient supplements, however, have not yet been well established. We aimed at evaluating the comparative effects of vitamin and mineral supplements on managing glycemic control and lipid metabolism for type 2 diabetes mellitus (T2DM) to inform clinical practice. Electronic and hand searches for randomized controlled trials (RCTs) were performed until June 1, 2022. We selected RCTs enrolling patients with T2DM who were treated with vitamin supplements, mineral supplements, or placebo/no treatment. Data were pooled via frequentist random-effects network meta-analyses. A total of 170 eligible trials and 14223 participants were included. Low to very low certainty evidence established chromium supplements as the most effective in reducing fasting blood glucose levels and homeostasis model assessment of insulin resistance (SUCRAs: 90.4% and 78.3%, respectively). Vitamin K supplements ranked best in reducing glycated hemoglobin A1c and fasting insulin levels (SUCRAs: 97.0% and 82.3%, respectively), with moderate to very low certainty evidence. Vanadium supplements ranked best in lowering total cholesterol levels with very low evidence certainty (SUCRAs:100%). Niacin supplements ranked best in triglyceride reductions and increasing high-density lipoprotein cholesterol levels with low to very low evidence certainty (SUCRAs:93.7% and 94.6%, respectively). Vitamin E supplements ranked best in reducing low-density lipoprotein cholesterol levels with very low evidence certainty (SUCRAs:80.0%). Our analyses indicated that micronutrient supplements, especially chromium, vitamin E, vitamin K, vanadium, and niacin supplements, may be more efficacious in managing T2DM than other micronutrients. Considering the clinical importance of these findings, new research is needed to get better insight into this issue.
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Effect of omega-3 supplementation on lipid profile in children and adolescents: a systematic review and meta-analysis of randomized clinical trials.
Khorshidi, M, Hazaveh, ZS, Alimohammadi-Kamalabadi, M, Jamshidi, S, Moghaddam, OM, Olang, B, Hatefi, S, Hosseini, A, Jamilian, P, Zarezadeh, M, et al
Nutrition journal. 2023;22(1):9
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Dyslipidaemia is considered as a substantial risk factor for cardiovascular disease (CVD). It is characterised by increased levels of triglyceride and low-density lipoprotein (LDL) and decreased levels of high-density lipoprotein (HDL). Consumption of omega-3 supplements play an important role in reduction of CVD events and its associated mortality by ameliorating lipid profile via lowering triglyceride levels. The aim of this study was to evaluate the effect of omega 3 supplementation on lipid profile in children and adolescents. This study is a systematic review and meta-analysis of fourteen studies. Three trials out of 14 had cross-over design, while others were parallel randomised trials. Results show that omega-3 supplementation may exert therapeutic effects on triglyceride (TG) levels, however, there weren’t any remarkable effects on HDL, LDL, and total cholesterol status. The subgroup analysis showed an improvement in TG levels in studies conducted on participants ≤13 years old and those with hypertriglyceridemia. Furthermore, due to meta-regression results, the omega-3 supplementation improved HDL levels when administered with longer duration. Authors conclude that omega-3 supplementation may have favourable hypolipidemic effects through reduction of TG levels. Additionally, clinical trials with longer duration of intervention and appropriate designs are recommended for younger children and those with hypertriglyceridemia.
Abstract
PURPOSE Dyslipidemia is considered as a known risk factor for cardiovascular disease. Yet various trials with wide ranges of doses and durations have reported contradictory results. We undertook this meta-analysis of randomized controlled trials (RCTs) to determine whether omega-3 supplementation can affect lipid profile in children and adolescents. METHODS Cochrane Library, Embase, PubMed, and Scopus databases were searched up to March 2021. Meta-analysis was performed using random-effect method. Effect size was expressed as weighted mean difference (WMD) and 95% confidence interval (CI). Heterogeneity was assessed using the I2 index. In order to identification of potential sources of heterogeneity, predefined subgroup and meta-regression analysis was conducted. RESULTS A total of 14 RCTs with 15 data sets were included. Based on the combination of effect sizes, there was a significant reduction in TG levels (WMD: -15.71 mg/dl, 95% CI: -25.76 to -5.65, P=0.002), with remarkable heterogeneity (I2=88.3%, P<0.001). However, subgroup analysis revealed that omega-3 supplementation significantly decreased TG only in studies conducted on participants ≤13 years old (WMD=-25.09, 95% CI: -43.29 to -6.90, P=0.007), (I2=84.6%, P<0.001) and those with hypertriglyceridemia (WMD=-28.26, 95% CI: -39.12 to -17.41, P<0.001), (I2=0.0%, P=0.934). Omega-3 supplementation had no significant effect on total cholesterol, HDL, and LDL levels. Also, results of nonlinear analysis showed significant effect of treatment duration on HDL status (Pnon-linearity=0.047). CONCLUSION Omega-3 supplementation may significantly reduce TG levels in younger children and those with hypertriglyceridemia. Also, based on the HDL-related results, clinical trials with longer duration of intervention are recommended in this population.
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Effects of Probiotics on Glycemic Control and Metabolic Parameters in Gestational Diabetes Mellitus: Systematic Review and Meta-Analysis.
Yefet, E, Bar, L, Izhaki, I, Iskander, R, Massalha, M, Younis, JS, Nachum, Z
Nutrients. 2023;15(7)
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The prevalence of gestational diabetes is increasing worldwide. Gestational diabetes mellitus (GDM) increases obesity and future development of type 2 diabetes in mother and child. Previous research has looked at the beneficial effects of probiotics in reducing metabolic diseases, however, these specific benefits on women with GDM are not fully understood yet. This systematic review and meta-analysis of fourteen randomised controlled trials assessed the beneficial effects of probiotics on glycemic control and metabolic parameters in women with GDM. This study separately assessed probiotic bacterial strains such as Lactobacillus acidophilus, Bifidobacterium bifidum, and Lactobacillus casei to understand their beneficial effects on metabolic parameters. This meta-analysis and systematic review suggest that probiotic supplementation could help improve glycemic control, insulin resistance and lipid levels in women diagnosed with GDM. All probiotic strains showed improvements in metabolic parameters when assessed separately. Further robust studies are required to assess the effect of probiotic supplementation on post- and pre-prandial glycemic control in women with GDM. Healthcare professionals can employ the results of this study to understand the therapeutic benefits of probiotics for improving GDM.
Abstract
OBJECTIVES To assess the effects of probiotic supplements on glycemic control and metabolic parameters in women with gestational diabetes mellitus (GDM) by performing a systematic review and meta-analysis of randomized controlled trials. The primary outcome was glycemic control, i.e., serum glucose and insulin levels. Secondary outcomes were maternal weight gain, neonatal birth weight, and lipid parameters. Weighted mean difference (WMD) was used. Cochrane's Q test of heterogeneity and I2 were used to assess heterogeneity. RESULTS Of the 843 papers retrieved, 14 (n = 854 women) met the inclusion criteria and were analyzed. When compared with placebo, women receiving probiotic supplements had significantly lower mean fasting serum glucose, fasting serum insulin, homeostatic model assessment for insulin resistance (HOMA-IR), triglycerides, total cholesterol, and VLDL levels. Decreased neonatal birth weight was witnessed in supplements containing Lactobacillus acidophilus. CONCLUSION Probiotic supplements may improve glycemic control and lipid profile and reduce neonatal birth weight in women with GDM.
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Effects of probiotic administration on overweight or obese children: a meta-analysis and systematic review.
Li, Y, Liu, T, Qin, L, Wu, L
Journal of translational medicine. 2023;21(1):525
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The prevalence of overweight or obesity in children is increasing due to changes in dietary structure and exercise habits, as determined by the body mass index (BMI) calculated from height and weight. Childhood obesity can cause some clinical complications such as hypertension, nonalcoholic fatty liver disease (NAFLD), and cardiovascular disease. The aim of this study was to examine the effects of probiotics on eight factors in children with overweight or obesity. This study was a systematic review and meta-analysis of four studies with a total of 206 overweight or obesity children. Among them, 105 were in the probiotic group, and 101 were in the placebo group. Results showed that probiotics can improve high- and low-density lipoprotein cholesterol, adiponectin, leptin, and TNF-α in overweight or obese children. The systematic review showed that probiotics work mainly by reshaping disturbed intestinal microbiota, regulating lipid metabolism, reducing inflammation and immune response, playing a positive effect of short-chain fatty acids produced, alleviating oxidative stress and endoplasmic reticulum stress, and inhibiting the growth and reproduction of pathogens in the gut. Authors concluded that probiotics could regulate lipid metabolism and immune response to some degree in children with overweight or obesity.
Abstract
BACKGROUND This paper aimed to examine the effects of probiotics on eight factors in overweight or obese children by meta-analysis, namely, body mass index (BMI), total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), adiponectin, leptin and tumor necrosis factor-α (TNF-α) and summarize the mechanisms of action of probiotics based on the existing researches. METHODS Six databases (PubMed, Web of Science, Embase, Cochrane Library, SinoMed and CNKI) were searched until March 2023. Review Manager 5.4 was used for meta-analysis. The data were analysed using weighted mean differences (WMDs) or standardized mean differences (SMDs) under a fixed effect model or random effect model to observe the effects of probiotic administration on the included indicators. RESULTS Four publications with a total of 206 overweight or obesity children were included. According to the meta-analysis, probiotics were able to significantly decrease the levels of HDL-C (MD, 0.06; 95% CI 0.03, 0.09; P = 0.0001), LDL-C (MD, - 0.06; 95% CI - 0.12, - 0.00; P = 0.04), adiponectin (MD, 1.39; 95% CI 1.19, 1.59; P < 0.00001), leptin (MD, - 2.72; 95% CI - 2.9, - 2.54; P < 0.00001) and TNF-α (MD, - 4.91; 95% CI - 7.15, - 2.67; P < 0.0001) compared to those in the placebo group. Still, for BMI, the palcebo group seemed to be better than the probiotic group (MD, 0.85; 95% CI 0.04, 1.66; P = 0.04). TC (MD, - 0.05; 95% CI - 0.12, 0.02; P = 0.14) and TG (MD, - 0.16; 95% CI - 0.36, 0.05; P = 0.14) were not different between two groups. CONCLUSIONS This review drew that probiotics might act as a role in regulating HDL-C, LDL-C, adiponectin, leptin and TNF-α in overweight or obesity children. Additionally, our systematic review yielded that probiotics might regulate lipid metabolism and improve obese associated symptoms by some paths. This meta-analysis has been registered at PROSPERO with ID: CRD42023408359.
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Egg and Dietary Cholesterol Intake and Risk of All-Cause, Cardiovascular, and Cancer Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies.
Darooghegi Mofrad, M, Naghshi, S, Lotfi, K, Beyene, J, Hypponen, E, Pirouzi, A, Sadeghi, O
Frontiers in nutrition. 2022;9:878979
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Eggs are a rich source of vitamins, carotenoids, and dietary cholesterol. However, dietary cholesterol may contribute to an imbalance in blood lipid levels, increasing the risk of developing cardiovascular disease (CVD) and cancer. Therefore, this systematic review and dose-response meta-analysis evaluated the impact of egg and dietary cholesterol on the risk of CVD, cancer, and all-cause mortality. This systematic review and meta-analysis included fifty-five prospective cohort studies. This research showed a positive association between egg and dietary cholesterol consumption with all-cause mortality and cancer mortality. However, daily consumption of up to 1.5 eggs or 450 mg of dietary cholesterol did not affect the mortality risk. Further robust studies are required due to the high heterogeneity between the included studies. Nevertheless, healthcare professionals can use the results of this research to understand the impact of egg and dietary cholesterol consumption on CVD, cancer and all-cause mortality.
Abstract
OBJECTIVE This systematic review and meta-analysis of prospective cohort studies examined the associations between egg and dietary cholesterol intake and the risk of mortality from all causes, including cardiovascular disease (CVD) and cancer. METHODS We searched PubMed, Scopus, ISI Web of Knowledge, and Google Scholar until April 2021, as well as references to the relevant articles retrieved. Random-effects models were used to calculate summary relative risk (RR) and 95% confidence intervals (CIs) for the highest vs. lowest categories of egg and dietary cholesterol intake. Also, linear and non-linear dose-response analyses were conducted to examine the dose-response relationships. RESULTS We included 55 studies, comprising data from 2,772,486 individuals with 228,425, 71,745, and 67,211 cases of all-cause, CVD, and cancer mortality, respectively. Intake of each additional egg per day was associated with a 7% higher risk of all-cause (1.07, 95% CI: 1.02-1.12, I2 = 84.8%) and a 13% higher risk of cancer mortality (1.13, 95% CI: 1.06-1.20, I2 = 54.2%), but was not associated with CVD mortality (1.00, 95% CI: 0.92-1.09, I2 = 81.5%). Non-linear analyses showed increased risks for egg consumption of more than 1.5 and 0.5 eggs/day, respectively. Each 100 mg/day increment in dietary cholesterol intake was associated with a 6% higher risk of all-cause mortality (1.06, 95% CI: 1.03-1.08, I2 = 34.5%) and a 6% higher risk of cancer mortality (1.06, 95% CI: 1.05-1.07, I2 = 0%), but was not associated with CVD mortality (1.04, 95% CI: 0.99-1.10, I2 = 85.9%). Non-linear analyses demonstrated elevated risks of CVD and cancer mortality for intakes more than 450 and 250 mg/day, respectively. CONCLUSIONS AND RELEVANCE High-dietary intake of eggs and cholesterol was associated with all-cause and cancer mortality. Little evidence for elevated risks was seen for intakes below 0.5 egg/day or 250 mg/day of dietary cholesterol. Our findings should be considered with caution because of small risk estimates and moderate between-study heterogeneity. SYSTEMATIC REVIEW REGISTRATION https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=252564, PROSPERO, identifier: CRD42021252564.
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The Effect of Walnut Intake on Lipids: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Alshahrani, SM, Mashat, RM, Almutairi, D, Mathkour, A, Alqahtani, SS, Alasmari, A, Alzahrani, AH, Ayed, R, Asiri, MY, Elsherif, A, et al
Nutrients. 2022;14(21)
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The prevalence of cardiovascular disease increases as the modifiable risk factors increase, such as metabolic syndrome, obesity, type 2 diabetes, dyslipidaemia, and high blood pressure. Walnuts are a rich source of anti-inflammatory polyunsaturated fatty acids and omega-3 fatty acids. Walnuts are also known for their antioxidant properties and have been found to improve dyslipidaemia by reducing total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-c). This systematic review and meta-analysis of thirteen randomised controlled trials evaluated the effects of walnut intake on lipid profile. Most of the included studies used walnut dosage ranging from 15 g to 99 g/day for six to sixteen weeks of intervention. The results of this systematic review and meta-analysis showed significant improvements in TC, LDL-c, and triglyceride (TG) levels. Subgroup analysis revealed greater improvement in TC, LDL-c, and TG in overweight and other comorbidities but had normal levels of TC and LDL-C. Additionally, female participants showed greater improvements in TG levels, followed by the walnut intervention. Intervention duration also affected the beneficial effect of the walnut intervention. Further robust studies are required to determine the effects of walnut intake on cardiovascular disease risk reduction due to the high heterogeneity between the included studies. However, healthcare professionals can use the results of this research to understand the benefits of including walnuts as part of a healthy diet and their impact on reducing dyslipidaemia.
Abstract
Cardiovascular diseases (CVD) are the leading causes of death worldwide. Dyslipidemia is a cardiometabolic risk factor of CVD, yet it can be modifiable. Walnuts have been suggested as a dietary intervention to improve the lipid profile. Therefore, we reviewed the literature to assess the evidence linking walnut intake to the improvement of blood lipids, including total cholesterol (TC), low-density lipoprotein (LDL-C) cholesterol, high-density lipoprotein (HDL-C) cholesterol, and triglycerides (TG). PubMed and Embase databases were searched from 2010 up to March 2022. We limited our search to randomized controlled trials conducted on humans and published in English during the specified period. Cochrane's risk of bias tool for interventional studies was used. A random-effects model was used for the meta-analysis, and weighted mean differences were obtained (WMD) Thirteen trials from the U.S., Europe, and Asia were included. Walnut intake was associated with significant reductions in TC (WMD: -8.58 mg/dL), LDL-C (WMD: -5.68 mg/dL), and TG (WMD: -10.94 mg/dL). Walnut consumption was not associated with HDL-C. Subgroup analysis showed that overweight/obese and those with comorbidities had more lipid improvement. A longer trial duration did result in further improvements. However, our results may be prone to bias due to extraneous confounding factors. Additionally, levels of heterogeneity were considerable for some outcomes of interest. Results from this meta-analysis provide evidence for the health benefits of walnuts on blood lipids. Walnuts possibly reduce the risk of CVD; thus, they can be successfully added to a dietary pattern to enhance health benefits.
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Effect of Peanut Consumption on Cardiovascular Risk Factors: A Randomized Clinical Trial and Meta-Analysis.
Parilli-Moser, I, Hurtado-Barroso, S, Guasch-Ferré, M, Lamuela-Raventós, RM
Frontiers in nutrition. 2022;9:853378
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Peanuts contain bioactive substances that are beneficial for cardiovascular health. This three-arm, parallel-group randomised controlled trial (ARISTOTLE) and meta-analysis evaluated the beneficial effects of high-oleic peanuts and peanut butter in improving cardiometabolic health. Participants in the randomised controlled trial consumed 25 g of skin-roasted peanuts or 32 g of peanut butter, or a control butter made with peanut oil without fibre and polyphenols for six months. The skin-roasted peanuts group showed a reduction in total cholesterol/HDL-cholesterol and LDL-cholesterol/HDL-cholesterol ratios. The meta-analysis was highly heterogeneous in participant ethnicity, health status, peanut intervention dosage and duration. The dosage of peanuts, peanut butter and high oleic peanuts used was between 25 and 200 g/day. The participants were healthy, with metabolic syndrome (MeS), or at risk of MeS. There was a significant increase in body weight among those with or at risk of MeS. In addition, healthy participants showed reduced triglycerides, total cholesterol, and LDL-cholesterol/HDL-cholesterol ratios. Healthcare professionals can use the results of this research to understand the beneficial impact of peanut consumption on the lipid profile. However, further robust studies are required due to the high heterogeneity of the included studies in the meta-analysis.
Abstract
UNLABELLED Although numerous studies have reported the protective effect of nut consumption on cardiovascular risk, evidence for the role of peanuts in maintaining cardiometabolic health is inconclusive. Presented here are the results from the ARISTOTLE study, a parallel randomized controlled trial evaluating the impact of regular peanut intake on anthropometric, biochemical, and clinical measurements. The 63 healthy subjects that completed the study consumed their habitual diet plus either: a) 25 g/day of skin roasted peanuts (SRP, n = 21), b) two tablespoons (32 g)/day of peanut butter (PB, n = 23) or c) two tablespoons (32 g)/day of a control butter based on peanut oil (CB, n = 19) for 6 months. In addition, a meta-analysis of clinical trials, including data from the ARISTOTLE study, was carried out to update the evidence for the effects of consuming peanuts, including high-oleic peanuts, and peanut butter on healthy subjects and those at high cardiometabolic risk. After a systematic search on PubMed, Web of Science, Cochrane Library and Scopus databases up to July 2021, 11 studies were found to meet the eligibility criteria. In the ARISTOTLE study, lower total cholesterol/HDL-cholesterol and LDL-cholesterol/HDL-cholesterol ratios were found in the SRP group compared to the CB group (p = 0.019 and p = 0.008). The meta-analysis of clinical trials revealed that peanut consumption is associated with a decrease in triglycerides (MD: -0.13; 95% CI, -0.20 to -0.07; p < 0.0001) and that healthy consumers had lower total cholesterol and LDL-cholesterol/HDL-cholesterol ratios compared to the control groups (MD: -0.40; 95% CI, -0.71 to -0.09; p = 0.01 and MD: -0.19; 95% CI, -0.36 to -0.01; p = 0.03, respectively). However, individuals at high cardiometabolic risk experienced an increase in body weight after the peanut interventions (MD: 0.97; 95% CI, 0.54 to 1.41; p < 0.0001), although not in body fat or body mass index. According to the dose-response analyses, body weight increased slightly with higher doses of peanuts. In conclusion, a regular consumption of peanuts seems to modulate lipid metabolism, reducing triglyceride blood levels. SYSTEMATIC REVIEW REGISTRATION https://osf.io/jx34y/, identifier: 10.17605/OSF.IO/MK35Y.
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Effects of Oat Beta-Glucan Intake on Lipid Profiles in Hypercholesterolemic Adults: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Yu, J, Xia, J, Yang, C, Pan, D, Xu, D, Sun, G, Xia, H
Nutrients. 2022;14(10)
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Plain language summary
Dyslipidaemia is one of the risk factors associated with cardiovascular disease. Beta-glucan is a viscous soluble fibre found in microalgae, fungi and grains like oats, barley, sorghum etc. This systematic review and meta-analysis included thirteen randomised controlled trials to evaluate the effectiveness of oat beta-glucans on the lipid profiles of patients with hypercholesterolemia. This research showed a significant reduction in total cholesterol and low-density lipoprotein levels in hypercholesterolemic adults after beta-glucan intake. However, beta-glucans did not impact triglyceride and high-density lipoprotein cholesterol. Beta-glucan's effect on lipid profiles depended on the severity of hypercholesterolemia, the duration of the intervention, the source of beta-glucan, and the dosage of beta-glucan. Healthcare professionals can use the results of this study to understand the lipid profile-improving effects of beta-glucans in adults with moderate hypercholesterolemia. However, further robust studies are required to evaluate the effects of beta-glucan on lipid profiles and how the effect is affected by gender differences.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Consumption of oat beta glucans may be beneficial for improving total cholesterol and LDL-c in people with mild and moderate hypercholesterolemia
- The U.S Food and Drug Administration (FDA) recommends 3g or more of oat beta glucans per day to reap the benefits. This could be from 90g of oats (3 x 30g portions) or 1 30g portion of oats, 3 oatcakes and 1-2 tbsp of oat bran.
Evidence Category:
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X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
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B: Systematic reviews including RCTs of limited number
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C: Non-randomized trials, observational studies, narrative reviews
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D: Case-reports, evidence-based clinical findings
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E: Opinion piece, other
Summary Review:
Authors highlight that Hypercholesterolemia is a risk factor for cardiovascular disease and a symptom of Metabolic Syndrome. Hypercholesterolemia commonly includes; elevated levels of total cholesterol and low-density lipoprotein cholesterol (LDL-c) and lower levels of high-density lipoprotein cholesterol (HDL-c).
Conventional medical treatment for hypercholesterolemia is statins, however, statins can have a number of adverse side effects. For this reason, dietary interventions have been investigated including the use of oat beta-glucans for their potential lipid lowering effects.
The aim of this systematic review and meta-analysis was to synthesise and evaluate the evidence for the effects of oat beta-glucans on serum cholesterol and triglyceride (TG) levels in adults with hypercholesterolemia.
Thirteen randomised controlled trials (RCTs) published between 1999 – 2021 met the study inclusion criteria. These studies included a total population of 927 people aged between 38-76 years and from 7 different countries worldwide. The majority of participants were diagnosed with mild hypercholesterolemia.
Participants were randomised into an intervention group receiving dietary sources of oat beta-glucans or food with added oat beta-glucans or a placebo control group consisting of diets without beta-glucans.
Study lengths ranged from 3 to 8 weeks with doses of oat beta-glucans between 1.5g to 6g. The studies were also broken down into sub-groups for high and low doses of oat beta-glucan and mild and moderate hypercholesterolemia.
Baseline and endpoint cholesterol (total cholesterol C, HD-c & LDL-c) and triglycerides were used to assess the effectiveness of the interventions and a weighted mean difference (WMD) calculated with a 95% confidence interval (CI).
Key Findings:
- a reduction in total cholesterol (WMD = -0.24mmol/L; 95% CI)
- a reduction in LDL-c (WMD = -0.27mmol/L; 95% CI )
- Sub-groups found that oat beta-glucans reduced serum TG levels in patients with moderate hypercholesterolemia (WMD = -0.11 mmol/L; 95% CI) but not in cases of mild hypercholesterolemia. (WMD = -0.01 mmol/L; 95% CI)
- Higher daily doses of oat beta glucans had more positive effects on TG levels, however the results were not statistically significant in this meta-analysis
- <3g WMD -0.11 mmol/L; 95% CI: -0.13 to -0.08 mmol/L
- >3g WMD -0.00 mmol/L; 95% CI: -0.16 to -0.16 mmol/L
- Greater reductions in HDL -c were found in patients with moderate hypercholesterolemia (WMD-0.06 mmol/L; 95% CI; -0.07 to -0.05 mmol/L) compared to mild cases (WMD-0.01 mmol/L; 95% CI; -0.08 to -0.10 mmol/L).
Conclusion
Dietary intake of oat beta-glucans may support the reduction of total cholesterol and low density lipoprotein cholesterol, however, no significant changes were found for high density lipoprotein cholesterol or serum triglycerides. Due to the heterogeneity between studies and inconsistencies in results, more trials are needed with larger sample sizes and longer durations.
Notes: The authors reported no conflicts of interest.
Clinical practice applications:
Based on the pooled results of this meta-analysis:
- 1.5g -6g of dietary intake of oat beta-glucans could support a reduction of TC and LDL-c in cases of mild and moderate hypercholesterolemia
- Intake of oat beta glucans >3g may reduce TG levels
- HDl -c may be improved with oat beta glucan intake of between 1.5g to 6g for clients with moderate hypercholesterolemia.
Considerations for future research:
The findings of 8 of the 13 RCTs indicated that when compared to the control group, LDL-c could be lowered by oat beta-glucans whilst the other 5 trials did not. However, the cumulative results of this meta analysis found a reduction in LDL-c.
There were also several limitations to this study:
- Heterogeneity between studies and inconsistent results
- Short study duration
- Small populations and limited sample size
- The results varied for different levels of hypercholesterolemia
- Results may also differ by sex and source of oat beta glucans
Larger and longer trials are therefore needed to confirm the results.
Abstract
(1) Background: hyperlipidemia is one of the cardiovascular diseases which becomes a great threat to the health of people worldwide. Oat beta-glucan is reported to have a beneficial effect on lowering blood lipids. To probe the effect of oat beta-glucan consumption on serum lipid profiles (total cholesterol, total triglyceride, high-density lipoprotein-cholesterol, and low-density lipoprotein-cholesterol), we carried out a systematic search on randomized controlled trials of oat beta-glucan intervention on hypercholesterolemic individuals. (2) Methods: the pieces of literature were obtained from PubMed, Scopus, Cochrane Library, Web of Science, and the Embase from inception to 28 February 2022. The results were presented with the weighted mean difference (WMD) with a 95% CI. The random-effects or fixed-effects model was applied according to the heterogeneity. The subgroup analysis and meta-regression were used to identify the source of heterogeneity. (3) Results: thirteen trials with 927 participants were included in our meta-analysis. Overall, oat beta-glucan supplementation significantly reduced levels of TC (pooled WMD = -0.24 mmol/L; 95%CI: -0.28 to -0.20 mmol/L), LDL-c (pooled WMD = -0.27 mmol/L; 95%CI: -0.35 to -0.20 mmol/L). Furthermore, beta-glucan consumption did not show significant effects on TG (pooled WMD = -0.04 mmol/L; 95%CI: -0.13 to 0.05 mmol/L), HDL-c (pooled WMD = 0.00 mmol/L; 95%CI: -0.05 to 0.05 mmol/L). Subgroup analysis indicated that critical factors, such as disease severity of participants, the daily intervention of oat beta-glucan, source of oat beta-glucan, and duration of intervention had impacts on outcomes. (4) Conclusions: oat beta-glucan intake may significantly decrease the level of TC and LDL-c while no significant changes in TG and HDL-c were observed. This meta-analysis supports the health benefits of oat beta-glucan, especially for its cholesterol-lowering features, although it has some inevitable limitations.