-
1.
Time of the day of exercise impact on cardiovascular disease risk factors in adults: a systematic review and meta-analysis.
Sevilla-Lorente, R, Carneiro-Barrera, A, Molina-Garcia, P, Ruiz, JR, Amaro-Gahete, FJ
Journal of science and medicine in sport. 2023;26(3):169-179
-
-
-
Free full text
Plain language summary
In humans, shifted sleep patterns seem to interfere with several metabolic pathways. Shift work, short sleep duration, exposure to artificial light, inadequate eating time window, and lack of physical activity, are some characteristics of the modern lifestyle that contributes to the occurrence and worsening of cardiovascular disease (CVD). The aim of this study was to analyse the time of the day of exercise-induced effects on CVD risk factors in adults. This study was a systematic review and meta-analysis of twenty-two studies. Results showed that exercise produces an acute reduction of systolic blood pressure independently of the time of the day at which it is performed. Similarly, exercise produces an acute increase in blood glucose independently of the time of the day. Authors concluded that further research is needed to establish whether there is a diurnal variation of exercise on cardiovascular health and how it is related to health status, sex, or the type of exercise.
Abstract
OBJECTIVES To compare the effect of a single bout of morning vs. evening exercise on cardiovascular risk factors in adults. DESIGN Systematic review and meta-analysis. METHODS A systematic search of studies was conducted using PubMed and Web of Science from inception to June 2022. Selected studies accomplished the following criteria: crossover design, acute effect of exercise, blood pressure, blood glucose, and/or blood lipids as the study's endpoint, a washout period of at least 24 h, and adults. Meta-analysis was performed by analyzing: 1) separated effect of morning and evening exercise (pre vs. post); and 2) comparison between morning and evening exercise. RESULTS A total of 11 studies were included for systolic and diastolic blood pressure and 10 studies for blood glucose. Meta-analysis revealed no significant difference between morning vs. evening exercise for systolic blood pressure (g ∆ = 0.02), diastolic blood pressure (g ∆ = 0.01), or blood glucose (g ∆ = 0.15). Analysis of moderator variables (age, BMI, sex, health status, intensity and duration of exercise, and hour within the morning or evening) showed no significant morning vs. evening effect. CONCLUSIONS Overall, we found no influence of the time of the day on the acute effect of exercise on blood pressure neither on blood glucose.
-
2.
Soluble Fiber Supplementation and Serum Lipid Profile: A Systematic Review and Dose-Response Meta-Analysis of Randomized Controlled Trials.
Ghavami, A, Ziaei, R, Talebi, S, Barghchi, H, Nattagh-Eshtivani, E, Moradi, S, Rahbarinejad, P, Mohammadi, H, Ghasemi-Tehrani, H, Marx, W, et al
Advances in nutrition (Bethesda, Md.). 2023
-
-
-
Free full text
Plain language summary
Dyslipidaemia is considered an important risk factor for cardiovascular disease incidence, characterised by elevated circulating concentrations of blood lipids such as cholesterol and triglycerides (TG). Dietary fibre, particularly water-soluble fibres, has demonstrated efficacy and tolerability in serum lipid management. The aim of this study was to synthesise data from individual investigations and to determine the overall treatment effect of soluble fibre on serum blood lipids. This study is a comprehensive systematic review and a dose-response meta-analysis of 181 studies with 220 treatment arms, including 14,505 participants (7348 cases and 7157 controls). Results show that soluble fibre supplementation improved serum TG, total cholesterol, low-density lipoprotein cholesterol, and apolipoprotein-B concentrations. However, it did not alter serum high-density lipoprotein cholesterol and apolipoprotein-A levels. Furthermore, the meta-analysis showed a significant effect of soluble fibre supplementation on serum TG, total cholesterol, and high-density lipoprotein cholesterol in 15 g/d and low-density lipoprotein cholesterol in 10 g/d. Authors conclude that increasing fibre intake using soluble fibre supplementation could be an effective intervention in the prevention and management of dyslipidaemia, and consequently may contribute to the risk reduction of cardiovascular diseases.
Abstract
To present a comprehensive synthesis of the effect of soluble fiber supplementation on blood lipid parameters in adults, a systematic search was undertaken in PubMed, Scopus, and ISI Web of Science of relevant articles published before November 2021. Randomized controlled trials (RCTs) evaluating the effects of soluble fibers on blood lipids in adults were included. We estimated the change in blood lipids for each 5 g/d increment in soluble fiber supplementation in each trial and then calculated the mean difference (MD) and 95% CI using a random-effects model. We estimated dose-dependent effects using a dose-response meta-analysis of differences in means. The risk of bias and certainty of the evidence was evaluated using the Cochrane risk of bias tool and the Grading Recommendations Assessment, Development, and Evaluation methodology, respectively. A total of 181 RCTs with 220 treatment arms (14,505 participants: 7348 cases and 7157 controls) were included. There was a significant reduction in LDL cholesterol (MD: -8.28 mg/dL, 95% CI: -11.38, -5.18), total cholesterol (TC) (MD: -10.82 mg/dL, 95% CI: -12.98, -8.67), TGs (MD: -5.55 mg/dL, 95% CI: -10.31, -0.79), and apolipoprotein B (Apo-B) (MD: -44.99 mg/L, 95% CI: -62.87, -27.12) after soluble fiber supplementation in the overall analysis. Each 5 g/d increase in soluble fiber supplementation had a significant reduction in TC (MD: -6.11 mg/dL, 95% CI: -7.61, -4.61) and LDL cholesterol (MD: -5.57 mg/dl, 95% CI: -7.44, -3.69). In a large meta-analysis of RCTs, results suggest that soluble fiber supplementation could contribute to the management of dyslipidemia and the reduction of cardiovascular disease risk.
-
3.
Vegetarian and vegan diets and the risk of cardiovascular disease, ischemic heart disease and stroke: a systematic review and meta-analysis of prospective cohort studies.
Dybvik, JS, Svendsen, M, Aune, D
European journal of nutrition. 2023;62(1):51-69
-
-
-
Free full text
-
Plain language summary
Cardiovascular disease (CVD) is mainly due to ischemic heart disease (IHD) and stroke. Plant-based diets are effective for improving CVD risk factors. This is further supported by the favourable cardiometabolic profile seen among vegetarians who predominantly exclude meat, fish and poultry from their diet, when compared to people consuming meat. The aim of this study was to analyse the association between vegetarian or vegan diets and risk of incidence and mortality from CVD, IHD and stroke, both overall and subtypes. This study is a systematic review and meta-analysis of thirteen prospective cohort studies. Results show a 15% and a 21% reduction in the relative risk of CVD and IHD, respectively, for vegetarians compared to nonvegetarians, but there wasn’t a clear association for total stroke or subtypes of stroke. Furthermore, an 18% reduction in the relative risk of IHD was observed among vegans when compared to nonvegetarians but the association lacked precision and no clear association was observed for CVD or stroke; however, there were few studies in the analyses of vegans. Authors conclude that their findings are consistent with existing guidelines recommending plant-based dietary patterns for CVD prevention. However, further studies are required to clarify the association between vegetarian diets and stroke risk, as well as the association between vegan diets and IHD.
Abstract
PURPOSE Vegetarian diets have been associated with reduced risk of ischemic heart disease (IHD). However, results regarding cardiovascular disease (CVD) overall and stroke are less clear. We conducted a systematic review and meta-analysis of prospective cohort studies on CVD, IHD and stroke risk among vegetarians or vegans versus nonvegetarians to clarify these associations. METHODS PubMed and Ovid Embase databases were searched through August 12, 2021. Prospective cohort studies reporting adjusted relative risk (RR) estimates and 95% confidence intervals (CIs) for incidence or mortality from CVD, IHD and stroke, comparing vegetarians and vegans to nonvegetarians were included. Risk of bias (RoB) was assessed using ROBINS-I and the strength of evidence was assessed using World Cancer Research Fund (WCRF) criteria. Summary RRs (95% CIs) were estimated using a random effects model. RESULTS Thirteen cohort studies (844,175 participants, 115,392 CVD, 30,377 IHD, and 14,419 stroke cases) were included. The summary RR for vegetarians vs. nonvegetarians was 0.85 (95% CI: 0.79-0.92, I2 = 68%, n = 8) for CVD, 0.79 (95% CI: 0.71-0.88, I2 = 67%, n = 8) for IHD, 0.90 (95% CI: 0.77-1.05, I2 = 61%, n = 12) for total stroke, and for vegans vs. nonvegetarians was 0.82 (95% CI: 0.68-1.00, I2 = 0%, n = 6) for IHD. RoB was moderate (n = 8) to serious (n = 5). The associations between vegetarian diets and CVD and IHD were considered probably causal using WCRF criteria. CONCLUSIONS Vegetarian diets are associated with reduced risk of CVD and IHD, but not stroke, but further studies are needed on stroke. These findings should be considered in dietary guidelines. REVIEW REGISTRATION No review protocol registered.
-
4.
Distribution of energy intake across the day and weight loss: A systematic review and meta-analysis.
Young, IE, Poobalan, A, Steinbeck, K, O'Connor, HT, Parker, HM
Obesity reviews : an official journal of the International Association for the Study of Obesity. 2023;24(3):e13537
-
-
-
-
Free full text
-
Plain language summary
Obesity increases an individual's risk of metabolic disease, such as diabetes and cardiovascular disease, musculoskeletal disorders such as osteoarthritis, and some cancers. “Chrononutrition” relates to the timing of meals and distribution of total energy intake across the day. Evidence is building chrononutrition as a potential target in both weight loss and metabolic disease interventions. The aim of this study was to examine the impact of earlier versus later distribution of total daily energy intake on weight loss, and to evaluate the potential for utilizing altered energy distribution as a tool in weight loss interventions. This study is a systematic review and meta-analysis of nine clinical studies. Total number of participants was 485 (earlier distributed total energy intakes: n = 244, later distributed total energy intakes; n = 241). Results show that energy intakes with a focus on earlier distribution resulted in significantly greater weight loss when compared with similarly energy-restricted diets with individuals consuming a larger proportion of their total energy intake later in the day and into the evening. Authors conclude that earlier energy intakes may be a promising tool to be used in conjunction with other weight loss strategies such as energy restriction to enhance weight loss. However, further research is required to elucidate the additional positive impacts that earlier distributed total energy intakes may have on weight and metabolic health.
Expert Review
Conflicts of interest:
None
Take Home Message:
Implementing a dietary strategy where a higher proportion of energy is consumed earlier in the day may offer additional benefits to an energy restricted diet for weight loss, blood glucose, improve markers of insulin resistance, increase satiety and improve hunger management. Based on the findings, earlier distribution of energy intake may serve as an effective component of a weight loss protocol.
Evidence Category:
-
X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
-
B: Systematic reviews including RCTs of limited number
-
C: Non-randomized trials, observational studies, narrative reviews
-
D: Case-reports, evidence-based clinical findings
-
E: Opinion piece, other
Summary Review:
Background
Chrononutrition refers to the timing and distribution of total daily energy intake across the day. It has been proposed that consuming a greater proportion of total daily energy intake earlier in the day as opposed to the evening may be beneficial for weight loss and metabolic health.
Aims
This systematic review and meta-analysis aimed to assess the impact of earlier versus later distribution of total daily energy intake on weight loss.
Results
A total of 9 randomised controlled trials involving 485 participants were included in this analysis. The study durations ranged from 5-16 weeks. All of the studies included in this analysis applied energy-restricted diets to both intervention arms. The mean percentages of energy intake in 8 of the 9 studies per meal were:
- Earlier distributed intakes: breakfast: 34% ± 16%, lunch: 38% ± 7%, dinner: 20% ± 6%.
- Later distributed intakes: breakfast: 19% ± 6%, lunch: 30% ± 10%, dinner; 40% ± 11%.
One of the studies advised percentage of energy intakes as either:
- Earlier: 70% for breakfast, morning tea and lunch and 30% for afternoon tea and dinner
- Late: 55% for breakfast, morning tea and lunch and 45% for afternoon tea and dinner.
The earlier distributed energy intake groups demonstrated significantly greater weight loss when compared with later distributed energy intake groups ( Mean Difference (MD) −1.23 kg; 95% CI −2.40, −0.06, p = 0.04;
I2 = 98%).
The earlier energy intake groups also displayed lower fasting and bedtime glucose levels (fasting: −0.83 vs. −0.27 mmol/L, p = 0.001; before sleep: −1.70 vs. −0.28 mmol/L, p = 0.009).
A random-effects model demonstrated that the earlier intake groups displayed greater reductions in LDL (MD: −0.11 mmol/L; 95% CI −0.14, −0.07, p < 0.01), fasting glucose (MD: 0.15 mmol/L, 95% CI −0.23, −0.06, p < 0.001) and HOMA-IR (MD: −0.38; 95% CI −0.64, −0.11, p = 0.005).
One study reported that earlier distribution energy intake also led to a greater reduction in medications following the intervention for type 2 diabetics (31% vs. 0%, P=0.002).
Two of the studies assessed both appetite and hunger and identified that earlier distribution of energy led to improvements in their urge to eat, preoccupation with food and cravings for sweets and fats.
Clinical practice applications:
Earlier distribution of energy intake may be beneficial for:
- Weight loss
- Improve fasting insulin, HOMA-IR, fasting glucose and HbA1c
- Reducing LDL
- Improving satiety and hunger management
- Supporting the reduction of medications for individuals with type 2 diabetes
- Improving regularity of sleep and waking times
Considerations for future research:
As the included studies only ranged from 5-16 weeks, longer duration studies would be useful to identify the effect of earlier distribution of energy intake on body weight, metabolic health and appetite over a longer period of time. There was a high degree of heterogeneity between the studies and a lack of uniformity in the distributions of energy intake across the day. Further studies with more uniformity of energy distribution would be needed to identify the optimal distribution of energy across the day to improve body weight and metabolic health.
Abstract
Consuming a greater proportion of total energy intake earlier in the day rather than in the evening is proposed to positively influence weight loss and health, potentially due to greater synchronization of human body circadian rhythms. This systematic review provides an update on existing evidence regarding earlier distributed eating patterns in weight loss interventions. Using a robust search strategy in five electronic databases, nine randomized controlled trials investigating the impact of energy intake distribution on weight loss were identified. Following critical appraisal, a random-effects meta-analyses found that, in the context of an energy-reduced diet, distributing energy intake with a focus on earlier intake resulted in significantly greater weight loss (-1.23 kg; 95% CI 2.40, -0.06, p = 0.04). Improvements in HOMA-IR, fasting glucose, and LDL cholesterol were also seen. The current study provides a timely update on the evidence linking distribution of total daily energy intake and health, showing that a focus on earlier intakes can result in greater short-term weight loss compared with later intakes. Future studies are needed to elucidate the impact that earlier intakes may have on weight management and metabolic health.
-
5.
The Comparative Effects of Different Types of Oral Vitamin Supplements on Arterial Stiffness: A Network Meta-Analysis.
Saz-Lara, A, Cavero-Redondo, I, Martínez-Vizcaíno, V, Martínez-Ortega, IA, Notario-Pacheco, B, Pascual-Morena, C
Nutrients. 2022;14(5)
-
-
-
Free full text
Plain language summary
Arterial stiffness is related to the onset of vascular aging and could be considered a contributing factor for the development of cardiovascular disease. Inflammation and oxidative stress are possible mechanisms of arterial stiffness. The aim of this study was to assess the effects of different types of oral vitamin supplements on the reduction in arterial stiffness. This study is a network meta-analysis of 22 randomised controlled studies that were published between 2002 and 2017. The sample size of the studies ranged from 9 to 261 healthy or unhealthy adults (aged 21.0 to 72.0 years). Results showed that even though the different types of oral vitamin supplements did not show statistically significant effects, when oral vitamin supplementation was longer than 12 weeks, vitamin D3 showed a significant reduction in central arterial stiffness, compared with placebo and vitamin D2. Authors conclude that oral vitamin D3 supplementation for more than 12 weeks could be an effective approach to reduce central arterial stiffness.
Abstract
Arterial stiffness, a significant prognostic factor of cardiovascular disease, may be affected by dietary factors. Research on the effects of oral vitamin supplements on arterial stiffness and/or endothelial function has produced controversial results. Therefore, the aim of this network meta-analysis was to comparatively assess the effect of different types of oral vitamin supplements on arterial stiffness in the adult population. We searched the PubMed, Embase, Cochrane Library, and Web of Science databases for randomized controlled trials from their inception to 30 September 2021. A network meta-analysis using a frequentist perspective was conducted to assess the effects of different types of oral vitamin supplements on arterial stiffness, as determined by pulse wave velocity. In total, 22 studies were included, with a total of 1318 participants in the intervention group and 1115 participants in the placebo group. The included studies were listed in an ad hoc table describing direct and indirect comparisons of the different types of vitamins. Our findings showed that, in both pairwise comparison and frequentist network meta-analysis, the different types of oral vitamin supplements did not show statistically significant effects on arterial stiffness. However, when oral vitamin supplementation was longer than 12 weeks, vitamin D3 showed a significant reduction in arterial stiffness, compared with the placebo (ES: -0.15; 95% CI: -0.30, -0.00; -60.0% m/s) and vitamin D2 (ES: -0.25; 95% CI: -0.48, -0.02, -52.0% m/s). In summary, our study confirms that oral vitamin D3 supplementation for more than 12 weeks could be an effective approach to reduce arterial stiffness and could be considered a useful approach to improve vascular health in patients at high risk of cardiovascular disease.
-
6.
The effects of olive leaf extract on cardiovascular risk factors in the general adult population: a systematic review and meta-analysis of randomized controlled trials.
Razmpoosh, E, Abdollahi, S, Mousavirad, M, Clark, CCT, Soltani, S
Diabetology & metabolic syndrome. 2022;14(1):151
-
-
-
Free full text
Plain language summary
Modifiable unhealthy behaviours, such as sedentary lifestyle, smoking, and unhealthy food habits, are regarded as important contributors to the widespread prevalence of cardiovascular diseases (CVDs), which occur concurrently in overweight/obesity, hypertension, dyslipidaemia, hyperglycaemia, and inflammation. The aim of this study was to investigate whether olive leaf extract (OLE) could improve the major cardiovascular-related variables, including lipid profile, glucose haemostasis, blood pressure, as well as liver/kidney and inflammatory markers in the general adult population. This study is a systematic review and meta-analysis of twelve randomised controlled studies. Results show that OLE supplementation: - significantly decreased triglycerides and systolic blood pressure levels. - only had short-term positive effects on blood pressure and lipid profiles, which may be attributed to the active constituents in OLE. - had more profitable effects on the improvement of triglycerides, blood pressure, total cholesterol and low-density lipoprotein cholesterol measures among participants with hypertension and individuals with normal body weight. Authors conclude that stronger randomised controlled trial investigations, assessing different doses and durations of OLE, are required to better elucidate the effects of OLE supplementation.
Abstract
BACKGROUND The aim of this systematic review and meta-analysis was to determine the effect of olive leaf extract (OLE) supplementation on cardiovascular-related variables, including lipid, glycemic, inflammatory, liver and renal-related factors, as well as blood pressure. METHODS PubMed, ISI Web of Science, Scopus, and Cochrane library were searched, up to October 2021, for relevant controlled trials. Mean differences and standard deviations were pooled for all outcomes, using a random-effects model. The methodological quality, as well as quality of evidence were assessed using standard tools. RESULTS Twelve studies (n = 819 participants) were included in our analyses. Overall analyses showed that OLE supplementation significantly decreased triglyceride (TG) levels (WMD = - 9.51 mg/dl, 95% CI - 17.83, - 1.18; P = 0.025; I2 = 68.7%; P-heterogeneity = 0.004), and systolic blood pressure (SBP) (WMD = - 3.86 mmHg, 95% CI - 6.44, - 1.28 mmHg; P = 0.003; I2 = 19.9%; P-heterogeneity = 0.28). Subgroup analyses also revealed a significant improvement in SBP (- 4.81 mmHg) and diastolic blood pressure (- 2.45 mmHg), TG (- 14.42 mg/dl), total cholesterol (TC) (- 9.14 mg/dl), and low-density lipoprotein-C (LDL-C) (- 4.6 mg/dl) measurements, in patients with hypertension. Significant reductions were also observed in TC (- 6.69 mg/dl), TG (- 9.21 mg/dl), and SBP (- 7.05 mmHg) in normal-weight individuals. However, no meaningful changes were seen in glucose hemostasis, liver and kidney, or inflammatory markers. CONCLUSION The present study revealed that supplementation with OLE yielded beneficial effects for blood pressure and lipid profile in adults, especially in patients with hypertension. As the quality of evidence for glucose hemostasis variables, liver, kidney, and inflammatory markers, were low-to-very low, higher quality RCTs may impact the overarching results. This study was registered at PROSPERO with the code CRD42022302395.
-
7.
Do B Vitamins Enhance the Effect of Omega-3 Polyunsaturated Fatty Acids on Cardiovascular Diseases? A Systematic Review of Clinical Trials.
Zhu, J, Xun, PC, Kolencik, M, Yang, KF, Fly, AD, Kahe, K
Nutrients. 2022;14(8)
-
-
-
-
Free full text
Plain language summary
Dietary intake of B-vitamins or omega-3 polyunsaturated fatty acids (PUFAs) has been found to be inversely related to cardiovascular disease (CVD). The aim of this study was to examine whether the combined supplementation of B-vitamins and omega-3 PUFAs could provide additional beneficial effects on improving risk factors to prevent CVD beyond the effects of either of them alone. This study is a systematic review of fifteen studies. The sample sizes ranged from 12 to 2501 participants with study duration ranging from 4 weeks to 4.7 years. Results show that the combined supplementation with B-vitamins and omega-3 PUFAs may be promising and more effective at reducing plasma homocysteine, triglycerides and low-density lipoprotein cholesterol than each supplementation alone. Authors conclude that: - there is no solid evidence that the joint supplementation of B-vitamins and omega-3 PUFAs can offer a synergistic effect on preventing CVD and decreasing the relevant morbidity and/or mortality in susceptible populations. - dietetic strategies for preventing CVD need to focus more on the importance of considering effects at the whole food and dietary patterns level. - further well-designed high-quality trials that will use the combined supplementation of B vitamins and omega-3 PUFAs or dietary patterns rich in these two types of nutrients are required.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Combined vitamin B and n3 PUFA supplementation might have favourable health effects
- Combined vitamin B and n3 PUFA supplementation could help in the primary and secondary prevention of cardiovascular disease
- The suggested favourable dose ranges are vitamin B6: 2.5–80 mg/day, vitamin B12: 20–1000 μg/day, folic acid: 150–10000 μg/day, and n3 PUFA 0.2–2) g/day.
Evidence Category:
-
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
-
X
B: Systematic reviews including RCTs of limited number
-
C: Non-randomized trials, observational studies, narrative reviews
-
D: Case-reports, evidence-based clinical findings
-
E: Opinion piece, other
Summary Review:
- The paper reviews whether combined supplementation of vitamin B (B2, B6, B9, and B12) and omega-3 polyunsaturated fatty acids (n3 PUFA) outweighs the individual cardiovascular benefits of each supplement. Registered in PROSPERO under CRD42018085993
- A total of 15 clinical studies including 8,263 individuals published from December 2021, that investigated the combined effects of the supplements met inclusion criteria and were included in the review
- Although the results indicate the beneficial effects of combined supplementation in primary and secondary cardiovascular prevention, firm conclusions cannot be drawn from the existing data, and more studies are needed in this area.
Clinical practice applications:
In comparison with a single supplement alone, the combined administration of vitamin B and n3 PUFA might have:
- Hypolipidemic effects, by reducing triglycerides and LDL-cholesterol. Some of the studies indicate a lowering of LDL-c up to 13% and triglycerides up to 24%
- Anti-inflammatory effects, by reducing homocysteine. Based on some of the studies, the lowering effects might go up to 39%.
Dietary practice might benefit from the following:
- The authors highlighted food-based and healthy dietary pattern-based strategies should include food sources rich in these nutrients such as fish, vegetables, fruit, legumes, nuts, and eggs
- The authors conclude that intake of whole foods and whole diets rich in desirable foods (such as MedDiet) should be encouraged
- The supplementation dose ranges in the studies covered by the review were the following: vitamin B6: 2.5–80 mg/day, vitamin B12: 20–1000 μg/day, folic acid: 150–10000 μg/day and n3 PUFA 0.2–2) g/day
- Limitations of the systematic review include different supplementation regimens, variability of study designs in terms of duration of the intervention, existence of placebo group, dosages and the inability to monitor study subjects’ habitual diet.
Considerations for future research:
- Future studies should be designed regarding the need for a uniform methodological approach in testing the combined effects of vitamin B complex and n3 PUFA supplements
- The studies should investigate supplementation strategies and dietary patterns rich in both nutrients.
Abstract
Studies have suggested that B vitamins or omega-3 polyunsaturated fatty acids (PUFAs) may deter the development of cardiovascular disease (CVD). This systematic review aims to examine whether the combined supplementation of both B vitamins and omega-3 PUFAs could provide additional beneficial effects to prevent CVD beyond the effect of each supplement based on clinical trials published up to December 2021. The overall findings are inconsistent and inconclusive, yet the combined supplementation of these two nutrients may be more effective at reducing plasma homocysteine, triglyceride, and low-density lipoprotein-cholesterol than the individual components. The underlying mechanisms mainly include alleviating endothelial dysfunction, inhibiting atherosclerosis and lesion initiation, reducing oxidative stress, suppressing activation of pro-inflammatory cytokines, regulating endothelial nitric oxide synthase, and interfering with methylation of genes that promote atherogenesis. Although biologically plausible, the existing literature is insufficient to draw any firm conclusion regarding whether B vitamins can further enhance the potential beneficial effects of omega-3 PUFA intake on either primary or secondary prevention of CVD. The inconsistent findings may be largely explained by the methodological challenges. Therefore, well-designed high-quality trials that will use the combined supplementation of B vitamins and omega-3 PUFAs or dietary patterns rich in these two types of nutrients are warranted.
-
8.
Low-carbohydrate diets and men's cortisol and testosterone: Systematic review and meta-analysis.
Whittaker, J, Harris, M
Nutrition and health. 2022;28(4):543-554
-
-
-
-
Free full text
-
Plain language summary
Testosterone is the primary male sex hormone, and vital for reproductive development and function. Moreover, low endogenous testosterone is associated with an increased risk of chronic disease, including type 2 diabetes and cardiovascular disease. The aim of this study was to investigate the effects of low- versus high-carbohydrate diets on mens' testosterone and cortisol. This study is a systematic review and meta-analysis of twenty-seven studies with a total of 309 participants. Twelve of these studies were randomised trials whilst the rest were non-randomised. Results show an increase in resting and post-exercise cortisol on short-term low-carbohydrate diets (<3 weeks). In fact, resting cortisol levels return to baseline after <3 weeks on a LC diet, whilst post-exercise cortisol remains elevated. Furthermore, high-protein diets cause a large decrease in resting total testosterone. Authors conclude that further research is required in order to warrant their findings.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Short-term LC-diets diets cause a moderate increase in resting and post-exercise cortisol however this effect is not seen in LC-diets followed for great than 3 weeks
- HP-LC diets caused a statistically significant decrease in resting TT, suggesting caution in relation to endocrine effects of LC diets
Evidence Category:
-
X
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
-
B: Systematic reviews including RCTs of limited number
-
C: Non-randomized trials, observational studies, narrative reviews
-
D: Case-reports, evidence-based clinical findings
-
E: Opinion piece, other
Summary Review:
Introduction:
A systematic review and network meta-analysis was conducted on the effects of low-carbohydrate (LC) versus high-carbohydrate (HC) diets on men’s testosterone and cortisol.
The review was registered with PROSPERO and reported using PRISMA 2020 checklists.
Methods:
A comprehensive search strategy was used to find intervention studies looking at healthy adult males and LC diets of <35% carbohydrate. Studies were assessed for quality using the Cochrane Risk of Bias tool. Sub-group analyses was conducted for diet duration, protein intake and exercise duration.
Results:
The literature search resulted in 27 studies with a total of 309 healthy adult male participants, age: 27.3 ± 4.7 (to minimise variation in steroid hormone metabolism), body mass: 78.6± 7.1kg and BMI: 24.8 ±1.6. 12 randomised and 15 non-randomised controlled trials were analysed. 21 studies were considered low risk bias, 5 medium and 1 high risk.
- Short-term (<3 weeks) LC diets moderately increased resting cortisol (0.41 [0.16, 0.66], p < 0.01) when compared to HC diets.
- Long-term (≥3 weeks) LC diets had no consistent effect on resting cortisol
- LC diets resulted in higher post-exercise cortisol, after long-duration exercise (≥20 min): 0 h (0.78 [0.47, 1.1], p < 0.01), 1 h (0.81 [0.31, 1.31], p < 0.01), and 2 h (0.82 [0.33, 1.3], p < 0.01).
- The overall results for resting total testosterone (TT) showed a significant decrease on LC versus HC diets (SMD = −0.48, p = 0.01. However, subgroup analyses revealed this effect to be limited to high-protein (HP) LC diets, which yielded a very large decrease in TT (SMD = −1.08, p < 0.01; ∼5.23 nmol/L), albeit in a small sample (n = 26).
- Moderate protein (MP) (<35%), low-carbohydrate diets had no consistent effect on resting total testosterone, however high-protein (≥35%), low-carbohydrate diets greatly decreased resting (−1.08 [−1.67, −0.48], p < 0.01) and post-exercise total testosterone (−1.01 [−2, −0.01] p = 0.05).
- There was no overall effect of LC versus HC diets on 0 h post-exercise TT (SMD = −0.03, p = 0.95). However, subgroup analysis showed 0 h post-exercise was non-significantly higher on long-term LC versus HC diets (SMD = 0.44, p = 0.18), and much lower on short-term LC versus HC diets (SMD = −1.01, p = 0.05)
Conclusion:
This systematic review and metanalysis found an increase in resting and post-exercise cortisol on short-term LC diets. Cortisol does return to baseline in the first 3 weeks of a low-carbohydrate (LC) diet. The same response is, however, not seen in post-exercise cortisol, which remains elevated. In addition, the review showed that compared to moderate-protein diets, HP diets were found to cause a large decrease in resting and post-exercise TT (∼5.23 nmol/L).
Clinical practice applications:
The results of this review suggest that exercising whilst following a LC diet can increase cortisol in the short term, but not long-term. This suggests a period of diet adaptation. The effects of long-term LC diets on cardiovascular disease risk is uncertain and healthcare practitioners should monitor client responses and keep up-to-date with new research in this area
Since HP-LC diets were found to significantly decrease resting testosterone it highlights the need to ensure that protein intake does not exceed the urea cycle’s capacity due to potential adverse endocrine effects.
For clients where there is a desire to increase strength, power and hypertrophy, a MP-LC diet could be of benefit, as it showed potential to signal an increased anabolic state post exercise..
NB: Since the review only included a low number of studies and saw within these some heterogeneity that could not be explained, more research is needed before the paper’s findings can be conclusive. The above potential practice applications should therefore be seen as something to be mindful of when working with clients where cortisol and testosterone levels are relevant to their protocol.
Considerations for future research:
Future research should consider:
- Since LC diets have been shown to have a positive effect on health – decreased triglycerides, increased high density lipoprotein cholesterol and weight loss - future studies would benefit from including these markers so any positive and negative impacts can be monitored directly.
- Despite extensive analysis including sensitivity analysis to reduce bias and heterogeneity of the results, the paper highlights a need for further research to ensure consistency in key parameters e.g., exercise duration and intensity, carbohydrate supplements inclusion and period of dietary intervention. Since it was identified that HP-LP diets impact post exercise and resting TT, follow up studies would benefit from consistency in participants diets. This would help to reduce any potential confounding results.
Abstract
Background: Low-carbohydrate diets may have endocrine effects, although individual studies are conflicting. Therefore, a review was conducted on the effects of low- versus high-carbohydrate diets on men's testosterone and cortisol. Methods: The review was registered on PROSPERO (CRD42021255957). The inclusion criteria were: intervention study, healthy adult males, and low-carbohydrate diet: ≤35% carbohydrate. Eight databases were searched from conception to May 2021. Cochrane's risk of bias tool was used for quality assessment. Random-effects, meta-analyses using standardized mean differences and 95% confidence intervals, were performed with Review Manager. Subgroup analyses were conducted for diet duration, protein intake, and exercise duration. Results: Twenty-seven studies were included, with a total of 309 participants. Short-term (<3 weeks), low- versus high-carbohydrate diets moderately increased resting cortisol (0.41 [0.16, 0.66], p < 0.01). Whereas, long-term (≥3 weeks), low-carbohydrate diets had no consistent effect on resting cortisol. Low- versus high-carbohydrate diets resulted in much higher post-exercise cortisol, after long-duration exercise (≥20 min): 0 h (0.78 [0.47, 1.1], p < 0.01), 1 h (0.81 [0.31, 1.31], p < 0.01), and 2 h (0.82 [0.33, 1.3], p < 0.01). Moderate-protein (<35%), low-carbohydrate diets had no consistent effect on resting total testosterone, however high-protein (≥35%), low-carbohydrate diets greatly decreased resting (-1.08 [-1.67, -0.48], p < 0.01) and post-exercise total testosterone (-1.01 [-2, -0.01] p = 0.05). Conclusions: Resting and post-exercise cortisol increase during the first 3 weeks of a low-carbohydrate diet. Afterwards, resting cortisol appears to return to baseline, whilst post-exercise cortisol remains elevated. High-protein diets cause a large decrease in resting total testosterone (∼5.23 nmol/L).
-
9.
Cinnamon as a Complementary Therapeutic Approach for Dysglycemia and Dyslipidemia Control in Type 2 Diabetes Mellitus and Its Molecular Mechanism of Action: A Review.
Silva, ML, Bernardo, MA, Singh, J, de Mesquita, MF
Nutrients. 2022;14(13)
-
-
-
Free full text
Plain language summary
Diabetes is a metabolic disorder resulting from defects in insulin secretion and/or action, leading to chronic hyperglycaemia, which has an adverse impact on health. The aim of this study was to provide an overview of the beneficial effects of cinnamon in exerting dysglycemia and dyslipidaemia control in type 2 diabetic patients and a summary of its mechanisms of action. This study is a narrative review of twenty-three articles. Results showed that: - in diabetic patients with dyslipidaemia, the lipid profile could be modulated with cinnamon supplementation as it seems to decrease serum triglycerides, total cholesterol and low-density lipoprotein levels. - cinnamon seems to exert beneficial and protective anti-inflammatory and antioxidant effects. - cinnamon seems to be effective as an antihyperlipidemic agent – through the regulation of lipid metabolism in enterocyte [a cell of the intestinal lining]. Authors conclude that targeted cinnamon-based therapy can provide an opportunity to modulate glucose and lipid dysregulation to avoid the progression of T2DM. Thus, future research studies should investigate the effect of cinnamon by employing a larger number of standardized randomized clinical trials to provide a comprehensive impact of cinnamon on diabetic patients.
Abstract
The scientific evidence that cinnamon may exert beneficial effects on type 2 diabetes mellitus due to the biological activity of its bioactive compounds has been increasing in recent years. This review provides an overview of the effects of cinnamon on clinical parameters of diabetes and summarizes the molecular mechanisms of action of cinnamon on glucose and lipid metabolism. Search criteria include an electronic search using PubMed, Medline, and Cochrane Library databases. English literature references from 2000 up to 2022 were included. Following title and abstract review, full articles that met the inclusion criteria were included. The results from the available evidence revealed that cinnamon improved glycemic and lipidemic indicators. Clinical trials clarified that cinnamon also possesses an anti-inflammatory effect, which may act beneficially in diabetes. Based on in vitro and in vivo studies, cinnamon seems to elicit the regulation of glucose metabolism in tissues by insulin-mimetic effect and enzyme activity improvement. Furthermore, cinnamon seems to decrease cholesterol and fatty acid absorption in the gut. The current literature search showed a considerable number of studies on diabetic subjects. Some limitations in comparing published data should be highlighted, including variability in doses, extracts and species of cinnamon, administration forms, and antidiabetic therapy.
-
10.
The Therapeutic Roles of Cinnamaldehyde against Cardiovascular Diseases.
Lu, L, Xiong, Y, Zhou, J, Wang, G, Mi, B, Liu, G
Oxidative medicine and cellular longevity. 2022;2022:9177108
-
-
-
Free full text
Plain language summary
Cardiovascular disease (CVD) is still a growing concern around the world. Current treatments for the prevention of CVD are inadequate due to limited efficacy and the occurrence of side effects and so there is a need for new therapies. Cinnamaldehyde (CA), which is an active constituent of cinnamon has been reported to have protective effects against certain diseases and evidence is growing for its use against the initiation and development of CVD. This review study aimed to evaluate the cardioprotective effects of CA. The review reported that CA is a compound that is relatively safe but is not easily absorbed by the body, however it can be encapsulated into capsules that enable it to be more easily absorbed. CA was reported to have anti-inflammatory, antioxidant, antithrombotic, blood cell dilatory and blood sugar lowering properties. In addition, CA was shown to prevent the death of cells of the heart and modulate the gut microbiota all of which may be cardioprotective. It was concluded that CA can benefit the heart in several ways. This study could be used by healthcare professionals to understand that cinnamon may be of benefit to heart health, however as studies in humans were not reviewed, further research is warranted before recommendations are made.
Abstract
Evidence from epidemiological studies has demonstrated that the incidence and mortality of cardiovascular diseases (CVDs) increase year by year, which pose a great threat on social economy and human health worldwide. Due to limited therapeutic benefits and associated adverse effects of current medications, there is an urgent need to uncover novel agents with favorable safety and efficacy. Cinnamaldehyde (CA) is a bioactive phytochemical isolated from the stem bark of Chinese herbal medicine Cinnamon and has been suggested to possess curative roles against the development of CVDs. This integrated review intends to summarize the physicochemical and pharmacokinetic features of CA and discuss the recent advances in underlying mechanisms and potential targets responsible for anti-CVD properties of CA. The CA-related cardiovascular protective mechanisms could be attributed to the inhibition of inflammation and oxidative stress, improvement of lipid and glucose metabolism, regulation of cell proliferation and apoptosis, suppression of cardiac fibrosis, and platelet aggregation and promotion of vasodilation and angiogenesis. Furthermore, CA is likely to inhibit CVD progression via affecting other possible processes including autophagy and ER stress regulation, gut microbiota and immune homeostasis, ion metabolism, ncRNA expression, and TRPA1 activation. Collectively, experiments reported previously highlight the therapeutic effects of CA and clinical trials are advocated to offer scientific basis for the compound future applied in clinical practice for CVD prophylaxis and treatment.