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Effect of supplementation with probiotics or synbiotics on cardiovascular risk factors in patients with metabolic syndrome: a systematic review and meta-analysis of randomized clinical trials.
Chen, T, Wang, J, Liu, Z, Gao, F
Frontiers in endocrinology. 2023;14:1282699
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Metabolic syndrome (metS) is characterised by insulin resistance, dyslipidaemia, central obesity and/or high blood pressure and is a significant risk factor for cardiovascular disease and type 2 diabetes mellitus. MetS is associated with an imbalanced microbiome and some but not all studies have shown benefits of supplementation with probiotics. The aim of this systematic review and meta-analysis of randomised controlled trials was to evaluate the effects of pro- or synbiotics on cardiovascular risk factors (body mass index, LDL cholesterol, fasting blood glucose and systolic blood pressure) in patients with metS. 11 studies were included in the review of which 7 were judged to have a low risk of bias, whilst risk of bias was unclear in 4 articles. The meta-analysis found that pro- or synbiotics have a positive effect on body mass index, LDL cholesterol and fasting blood glucose but not on systolic blood pressure. Subgroup analysis of pro- and synbiotics separately also found no effects on systolic blood pressure.
Abstract
PURPOSE The effectiveness of probiotics or synbiotics in adults with metabolic syndromes (MetS) remains controversial, this meta-analysis will further analyze the effects of probiotics or synbiotics on cardiovascular factors in adults with MetS. METHODS We searched Web of Science, PubMed, Embase, Cochrane Library and other databases for randomized controlled trials (RCTs) on the effects of probiotics or synbiotics on MetS in adults up to July 2023, and used RevMan 5.4.0 software for statistical analysis. RESULTS This analysis included eleven RCTs (n = 608 participants), and the results showed that compared with the control group, supplementation with probiotics or synbiotics reduced body mass index (weighted mean difference, WMD = -0.83, 95% CI = [-1.21, -0.44], P <0.0001, n = 9), low-density lipoprotein (LDL-c) (standard mean difference, SMD = -0.24, 95% CI = [-0.41, -0.08], P = 0.004, n = 10), fasting blood glucose (FBG)(SMD = -0.17, 95% CI = [-0.33, -0.01], P = 0.03, n = 11), but had no beneficial effect on systolic blood pressure (SBP) (WMD = 1.24, 95% CI = [-2.06, 4.54], P = 0.46, n = 8) in MetS patients. CONCLUSION Supplementation with probiotics or synbiotics can reduce BMI, LDL-c, FBG in patients with MetS, but our findings did not demonstrate a favorable effect on reducing SBP. Future studies with larger samples and longer intervention periods are needed.
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2.
Effects of Omega-3 Fatty Acids Supplementation on Serum Lipid Profile and Blood Pressure in Patients with Metabolic Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Liu, YX, Yu, JH, Sun, JH, Ma, WQ, Wang, JJ, Sun, GJ
Foods (Basel, Switzerland). 2023;12(4)
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Metabolic syndrome (MetS) is a group of disorders that cause disturbed metabolism, including abdominal obesity, insulin resistance, hypertension, and dyslipidaemia. People with MetS may have a higher risk of coronary heart disease and stroke than those without MetS. Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have cardioprotective, anti-inflammatory, and triglyceride-lowering properties, so they may help treat obesity and improve metabolic syndrome. The aim of this study was to explore the effects of n-3 PUFAs on lipid profile and blood pressure in patients with MetS. This study is a meta-analysis of eight studies. One of the studies was a crossover trial, whereas the remaining seven studies were parallel-controlled trials. The mean age of the participants was 45.54 years old. Results show that following supplementation with n-3 PUFAs in patients with metabolic syndrome: - there weren’t significant changes in serum total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol. - there was a significant reduction in serum triglycerides and blood pressure. Authors conclude that n-3 PUFA supplementation may serve as a potential dietary supplement for improving lipids and blood pressure in patients with metabolic syndrome.
Expert Review
Conflicts of interest:
None
Take Home Message:
- Omega 3 PUFA may be beneficial for patients with metabolic syndrome by improving serum lipid profile and blood pressure.
- Omega-3 rich foods include fatty fish, walnuts, flaxseeds and chia seeds.
- While Omega-3 PUFA may be beneficial, they should be considered as part of a comprehensive approach to managing metabolic syndrome that include physical activity and a balanced diet.
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:
Background
This journal article presents a systematic review and meta-analysis of randomised controlled trials (RCTs) investigating the effects of omega-3 fatty acid supplementation on serum lipid profile and blood pressure in patients with metabolic syndrome. Metabolic syndrome is a cluster of conditions that increase the risk of cardiovascular disease and type 2 diabetes.
Methods
This meta-analysis included 8 RCTs with 387 participants with metabolic syndrome. Participants in the intervention group took omega-3 fatty acid supplements and the outcomes included total cholesterol (TC), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), systolic blood pressure (SBP), and diastolic blood pressure (DBP).
Results
- Based on a meta-analysis of data from the included trials, supplementation with omega 3- PUFAs led to no reduction in serum LDL-c level among patients with metabolic syndrome (Standardised Mean Difference (SMD) = 0.18; 95% CI: −0.18 ~ 0.53, I2 = 55%); did not increase serum high-density lipoprotein cholesterol levels (SMD = 0.02; 95% CI: −0.21 ~ 0.25, I2 = 0%); and had no reduction in serum total cholesterol level (SMD = −0.02; 95% CI: −0.22~0.18, I2 = 24%).
- On the other hand, in patients with metabolic syndrome, supplementation with omega 3- PUFAs may decrease serum triglyceride levels (SMD = −0.39; 95% CI: −0.59 ~ −0.18, I2 = 17.2%); systolic blood pressure (SMD = −0.54; 95% CI: −0.86 ~ −0.22, I2 = 48.6%); and diastolic blood pressure (SMD = −0.56; 95% CI: −0.79~ −0.33, I2 = 14.0%).
- Sensitivity analyses indicated that the pooled estimates wererobust for all outcomes.
- The following mechanisms may explain how PUFAs may reduce the risk of metabolic syndrome. First, adequate intake of omega 3 PUFAs may reduce triglyceride and LDL synthesis in the liver. In addition, they may lower blood pressure by reducing angiotensin-converting enzyme levels in the aorta. Finally, PUFAs can increase insulin sensitivity and prevent hyperglycaemia.
Limitations
This study presents some limitations: The literature search may have some omissions. The conclusions may be hindered by the risk of bias of the trials included. No bias test was performed due to the limited number of studies.
Clinical practice applications:
- Improved serum lipid profile: The findings from the paper indicate that omega-3 fatty acid supplementation can have a positive impact on the serum lipid profile in patients with metabolic syndrome.
- Blood pressure management: omega-3 fatty acid supplementation may help reduce blood pressure in patients with metabolic syndrome.
- Nutritional therapists can use this information to consider omega-3 supplementation as part of nutritional therapy
- Complementary approach: Nutritional therapists can utilise the findings as supportive evidence for a holistic approach to managing metabolic syndrome. By incorporating omega-3 fatty acids into personalized nutrition plans, therapists may be able to offer additional dietary or supplemental interventions for individuals with metabolic syndrome, aiming to lower triglyceride levels and manage blood pressure, alongside other lifestyle modifications.
- Patient education: Nutritional therapists can educate their patients with metabolic syndrome about the benefits of omega-3 fatty acids on lipid profile and blood pressure. By explaining the findings from the systematic review and meta-analysis, therapists can empower patients to make informed choices regarding their dietary habits and supplement use, promoting self-management and improved long-term outcomes.
Considerations for future research:
- Future research could focus on determining the optimum dosage of Omega-3 PUFAs for improving lipid profile and BP.
- More investigation is needed to analyse the long term effect of the supplements. The longest RCT was 90 days.
- Comparative studies comparing the effects of omega-3 fatty acids supplementation with other interventions commonly used in metabolic syndrome management, such as pharmacological approaches or diet, would provide a comprehensive understanding of their relative effectiveness.
- Future research could explore potential variations in the effects of omega-3 fatty acids supplementation based on different patient characteristics, such as age, gender, baseline lipid profile, and blood pressure levels.
- Conducting mechanistic studies could shed light on the underlying pathways through which omega-3 fatty acids exert their effects on serum lipid profile and blood pressure.
Abstract
The purpose of this study was to explore the effect of omega-3 polyunsaturated fatty acids (n-3 PUFAs) supplementation on serum lipid profile and blood pressure in patients with metabolic syndrome. We searched PubMed, Web of Science, Embase, and the Cochrane library from database inception to 30 April 2022. This meta-analysis included eight trials with 387 participants. We found that supplementation of n-3 PUFAs has no significant reduction in TC level (SMD = -0.02; 95% CI: -0.22 ~ 0.18, I2 = 23.7%) and LDL-c level in serum (SMD = 0.18; 95% CI: -0.18 ~ 0.53, I2 = 54.9%) of patients with metabolic syndrome. Moreover, we found no significant increase in serum high-density lipoprotein cholesterol level (SMD = 0.02; 95% CI: -0.21 ~ 0.25, I2 = 0%) in patients with metabolic syndrome after consuming n-3 PUFAs. In addition, we found that n-3 PUFAs can significantly decrease serum triglyceride levels (SMD= -0.39; 95% CI: -0.59 ~ -0.18, I2 = 17.2%), systolic blood pressure (SMD = -0.54; 95% CI: -0.86 ~ -0.22, I2 = 48.6%), and diastolic blood pressure (SMD = -0.56; 95% CI: -0.79 ~ 0.33, I2 = 14.0%) in patients with metabolic syndrome. The results from the sensitivity analysis confirmed that our results were robust. These findings suggest that n-3 PUFA supplementation may serve as a potential dietary supplement for improving lipids and blood pressure in metabolic syndrome. Given the quality of the included studies, further studies are still needed to verify our findings.
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Is Extra Virgin Olive Oil the Critical Ingredient Driving the Health Benefits of a Mediterranean Diet? A Narrative Review.
Flynn, MM, Tierney, A, Itsiopoulos, C
Nutrients. 2023;15(13)
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Cardiovascular diseases (CVDs) are the largest contributor to deaths globally, followed by cancers, chronic respiratory diseases and diabetes. It is estimated that 90% of deaths from CVD can be prevented with modifiable risk factors such as diet. The Mediterranean diet, which is rich in extra virgin olive oil (EVOO), is important in the prevention of chronic diseases. There is however very little focus on differentiating healthy fats such as EVOO from other fats and oils in dietary guidelines. This review of 34 studies aims to compare the effect of diets that include EVOO on cardiometabolic risk factors for heart disease, metabolic syndrome, and type 2 diabetes. It looks at the effects on blood pressure (SBP), low- and high-density lipoprotein cholesterol, (HDP-c and LDD-c) fasting blood glucose (FBG) and body weight. It also assesses from published studies the minimum daily amount of EVOO and the shortest time needed to see improvements in the risk factors. There is evidence to support EVOO in improving SBP in patients with high blood pressure, with studies suggesting that specific phenols in the oil may be important compared with a refined olive oil. Compared with other dietary fats or low-fat diets, EVOO can decrease LDL-c and increase HDL-c. Diets including daily EVOO are effective for weight loss. The effect of EVOO on FBG compared with other diets is not yet clear. The authors state that EVOO would be a far superior choice compared with other dietary fats, low-fat diets, or refined olive oil. The daily use of EVOO starting at approximately two tablespoons a day will improve a range of risk factors in as few as three weeks.
Abstract
Most chronic diseases are preventable with a healthy diet, although there is debate about the optimal dietary approach. Increasingly more countries are focusing on food-based guidelines rather than the traditional nutrient-based approach. Although there is good agreement on plant foods, controversy remains about the types and amounts of fats and oils. This narrative review aims to systematically summarize and evaluate the latest evidence on the protective effects of extra virgin olive oil (EVOO) on disease risk factors. A systematic search of the relevant literature using PubMed, Cochrane Library, and Embase databases was conducted for the years 2000 through December 2022. A narrative synthesis was then undertaken. Of 281 retrieved articles, 34 articles fulfilled our inclusion criteria and were included. Compared with other dietary fats and low-fat diets, EVOO is superior in the management of clinical biomarkers including lowering blood pressure and LDL-c, increasing protective HDL-c, improving glycemic control, and weight management. The protective effects of EVOO are likely due to its polyphenol content rather than the monounsaturated fat content. It is therefore important to promote the regular use of EVOO in the context of healthy dietary patterns such as the Mediterranean diet for maximal health benefit.
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Effect of Intermittent Fasting on Reproductive Hormone Levels in Females and Males: A Review of Human Trials.
Cienfuegos, S, Corapi, S, Gabel, K, Ezpeleta, M, Kalam, F, Lin, S, Pavlou, V, Varady, KA
Nutrients. 2022;14(11)
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Intermittent fasting is a term for three different diet regimes. Alternate day fasting involves a feast day where individuals can eat what they want followed by a water only day. The 5:2 diet involves 5 feast days and 2 fast days per week. Time-restricted eating (TRE) involves a short eating window of a specific number of hours per day. Although these are all popular diet regimes for weight loss, animal studies have highlighted concerns with regards to reproductive health. This review paper aimed to summarise the human research on the effects of intermittent fasting on reproductive hormone levels in both men and women. It was found that overall, there were very few studies, however evidence was found on the effect of intermittent fasting on some of the sex hormones. For women, moving calorie intake to earlier in the day may be of benefit to oestrogen, sex hormone binding globulin, and androgen levels in those with polycystic ovary syndrome (PCOS). In addition, a fasting diet may be of benefit to androgen and SHBG levels in women with PCOS. However even though weight loss may be achieved with intermittent fasting, this is insufficient to improve the gonadotrophins. Intermittent fasting was found to be safe in women who were breastfeeding, with no significant change to milk production. In men, TRE was found to negatively affect testosterone levels, but had no effect on SHBG. The effect of intermittent fasting on sex hormones may involve changes in the gut microbiome and circadian rhythms as a direct result of intermittent fasting. It was concluded that the sex hormone levels of women with PCOS may benefit from intermittent fasting, however in men it may be detrimental to sex hormone production. This study could be used by healthcare professionals to understand that recommending an intermittent fasting diet may be of benefit to hormone levels and fertility in women with PCOS, however this may not be the case for men.
Abstract
Intermittent fasting is a popular diet for weight loss, but concerns have been raised regarding the effects of fasting on the reproductive health of women and men. Accordingly, we conducted this literature review to clarify the effects of fasting on reproductive hormone levels in humans. Our results suggest that intermittent fasting decreases androgen markers (i.e., testosterone and the free androgen index (FAI)) while increasing sex hormone-binding globulin (SHBG) levels in premenopausal females with obesity. This effect was more likely to occur when food consumption was confined to earlier in the day (eating all food before 4 pm). In contrast, fasting did not have any effect on estrogen, gonadotropins, or prolactin levels in women. As for men, intermittent fasting reduced testosterone levels in lean, physically active, young males, but it did not affect SHBG concentrations. Interestingly, muscle mass and muscular strength were not negatively affected by these reductions in testosterone. In interpreting these findings, it is important to note that very few studies have been conducted on this topic. Thus, it is difficult to draw solid conclusions at present. From the limited data presented here, it is possible that intermittent fasting may decrease androgen markers in both genders. If this is the case, these results would have varied health implications. On the one hand, fasting may prove to be a valuable tool for treating hyperandrogenism in females with polycystic ovarian syndrome (PCOS) by improving menstruation and fertility. On the other hand, fasting may be shown to decrease androgens among males, which could negatively affect metabolic health and libido. More research is warranted to confirm these preliminary findings.
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Nutritional intervention for diabetes mellitus with Alzheimer's disease.
Li, Z, Li, S, Xiao, Y, Zhong, T, Yu, X, Wang, L
Frontiers in nutrition. 2022;9:1046726
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Diabetes Mellitus (DM) affects more than 463 million people worldwide. Similarly, the number of deaths related to Alzheimer’s disease (AD) has increased by 145%. There are several common risk factors for Type 2 Diabetes and AD, including obesity, insulin resistance, and ageing, as well as common pathological mechanisms, including altered insulin signalling, oxidative stress, neuroinflammation, mitochondrial dysfunction, formation of glycated proteins and metabolic syndrome. This review aims to summarize the therapeutic effects of different nutritional therapy strategies on the reduction of DM and AD risk. Controlling blood sugar levels and reducing calorie intake is crucial to preventing diabetes and Alzheimer's disease. The low-carbohydrate, ketogenic, and Mediterranean diets have been found to improve glucose control in people with Type 2 diabetes (T2D). In addition, MIND (Mediterranean-DASH Diet Intervention for Neurodegenerative Delay) and a ketogenic diet may improve cognition in AD patients. Lactobacillus, Bifidobacterium probiotics, and prebiotics, such as inulin, may inhibit the progression of T2D and AD diseases by suppressing inflammation and modulating gut microbes. In addition, vitamins A, C, D, E, B6, B12, folate, long-chain polyunsaturated fatty acids, zinc, magnesium, and polyphenols may improve cognitive decline, homocysteine levels, and insulin resistance in AD and T2D patients. Healthcare professionals can use the results of this review to understand the beneficial effects of dietary strategies and multi-nutrient supplementation on DM and AD. However, further robust studies are required to investigate the risk factors and underlying mechanisms behind DM-combined AD progression.
Abstract
The combined disease burden of diabetes mellitus (DM) and Alzheimer's disease (AD) is increasing, and the two diseases share some common pathological changes. However, the pharmacotherapeutic approach to this clinical complexity is limited to symptomatic rather than disease-arresting, with the possible exception of metformin. Whether nutritional intervention might extend or synergize with these effects of metformin is of interest. In particular, dietary patterns with an emphasis on dietary diversity shown to affect cognitive function are of growing interest in a range of food cultural settings. This paper presents the association between diabetes and AD. In addition, the cross-cultural nutritional intervention programs with the potential to mitigate both insulin resistance (IR) and hyperglycemia, together with cognitive impairment are also reviewed. Both dietary patterns and nutritional supplementation showed the effects of improving glycemic control and reducing cognitive decline in diabetes associated with AD, but the intervention specificity remained controversial. Multi-nutrient supplements combined with diverse diets may have preventive and therapeutic potential for DM combined with AD, at least as related to the B vitamin group and folate-dependent homocysteine (Hcy). The nutritional intervention has promise in the prevention and management of DM and AD comorbidities, and more clinical studies would be of nutritional scientific merit.
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Amino Acids, B Vitamins, and Choline May Independently and Collaboratively Influence the Incidence and Core Symptoms of Autism Spectrum Disorder.
Jennings, L, Basiri, R
Nutrients. 2022;14(14)
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Autistic disorder, Asperger syndrome, and pervasive developmental disorder can be categorized under autism spectrum disorder (ASD). ASD can result in restrictive, repetitive, and stereotypical behaviour patterns and cause impairments in social interaction and verbal and nonverbal communication. The aim of this study was to examine the effects of nutritional status and supplementation on the incidence and or severity of ASD symptoms using currently available resources. This study is a literature review of fifteen studies. Results show that children with ASD have higher rates of abnormal amino acids and lower blood levels of choline, vitamin B6, vitamin B12, and folate when compared to those without ASD. Furthermore, increasing dietary intake of choline could improve anxious behaviours, receptive language skills, social behaviour, sensory processing, and other symptoms which rely on ion transport in individuals with ASD. Authors conclude that altering nutritional status can be an affordable and effective way to prevent ASD and improve the quality of life for families and individuals impacted by ASD.
Abstract
Autism spectrum disorder (ASD) is a developmental disorder of variable severity, characterized by difficulties in social interaction, communication, and restricted or repetitive patterns of thought and behavior. In 2018, the incidence of ASD was 2.4 times higher than estimated in 2000. Behavior and brain development abnormalities are present in the complex disorder of ASD. Nutritional status plays a key role in the incidence and severity of the core symptoms of ASD. The aim of this study was to review the available peer-reviewed studies that evaluated the relationship between amino acids, choline, B vitamins, and ASD incidence and/or severity of symptoms. Through examining plasma profiles, urine samples, and dietary intake, researchers found that low choline, abnormal amino acid, and low B vitamin levels were present in children with ASD compared to those without ASD. The evidence supports the need for future research that implements simultaneous supplementation of all essential nutrients in individuals with ASD and among prenatal mothers. Future evidence could lead to scientific breakthroughs, ultimately reducing the rates of ASD incidence and severity of symptoms by applying nutritional interventions in at-risk populations.
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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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Effect of Intermittent Fasting Diet on Glucose and Lipid Metabolism and Insulin Resistance in Patients with Impaired Glucose and Lipid Metabolism: A Systematic Review and Meta-Analysis.
Yuan, X, Wang, J, Yang, S, Gao, M, Cao, L, Li, X, Hong, D, Tian, S, Sun, C
International journal of endocrinology. 2022;2022:6999907
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The prevalence of obesity and metabolic syndrome may increase the risk of cardiovascular disease (CVD), diabetes, and neurological conditions. The imbalance in glucose and lipid metabolism and hypertension characterises the development of these chronic diseases. Intermittent fasting (IF) has been considered an effective dietary strategy for reducing the risk of obesity, insulin resistance, dyslipidaemia, diabetes, and CVD. This systematic review and meta-analysis include ten randomised controlled trials to evaluate the effects of IF intervention on glucose and lipid metabolism in people with metabolic syndrome. IF intervention regulated glucose metabolism by improving fasting blood glucose, glycosylated haemoglobin, insulin, and insulin resistance. IF intervention also positively impacted the body mass index and waist circumference. The total cholesterol, low-density lipoprotein levels, and triglyceride levels also improved, followed by the IF, showing the impact on lipid metabolism. Further robust studies are required due to heterogeneity between the included studies in type of IF, duration, the health status of participants, ethnicity, and outcome measurements. However, healthcare professionals can use the results of this systematic review and meta-analysis to understand the therapeutic effect of IF intervention on glycolipid metabolism in people with metabolic syndrome.
Expert Review
Conflicts of interest:
None
Take Home Message:
- IF does not require calorie restriction which may result in greater compliance
- IF does not restrict macronutrients such as CHO and fats, so may avoid the exclusion of key nutrients e.g. healthy fats and wholegrains.
- IF may have fewer adverse effects on daily routines and quality of life, which may mean adherence is easier.
- Improved glucose and lipid metabolism may prevent the development of chronic health conditions such as T2D, CVD and cancer.
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:
Management of glucose and lipid metabolism can be achieved through weight reduction using dietary interventions such as very low calorie or CHO diets, which may be effective but difficult to sustain long term. An alternative approach for weight management, improved insulin resistance and subsequent prevention of comorbitities e.g. Type 2 Diabetes (T2D), Cardiovascular Disease (CVD) and cancer, is Intermittent Fasting (IF). such as time restricted or periodic fasting.
This study summarises the effects of IF dietary interventions lasting less than three months in overweight and obese women with Metabolic Syndrome, defined as the presence of any metabolic dysfunction including obesity, hyperglycaemia, dyslipidaemia or hypertension.
The meta-anlaysis was carried out following PRISMA guidelines. A literature search in PubMed and Medline using the keywords obesity/overweight, IF diet, metabolic syndrome, RCT’s and humans resulted in 10 studies with 12 types of intervention for analysis. The following outcomes were evaluated: glucose and lipid metabolism, insulin resistance, weight loss and blood pressure.
Results were analysed in R software using mean differences and 95% confidence intervals, and either random or fixed effects depending on the Cochrane’s Q and I(2) statistics. Funnel plots were inspected for potential bias and Egger’s regression tests for publication bias.
There were significant differences before and after the interventions for all glucose and lipid metabolism markers as well as body weight and systolic blood pressure :
Glucose metabolism:
- Fasting glucose reduced by 0.15mmol/L
- Insulin plasma reduced by 13.25uUI
- HbA1c reduced by 0.08%
- HOMA-IR (insulin resistance index) reduced by 0.31 on average
Lipid metabolism:
- Total cholesterol reduced by 0.32mmol/L
- LDL reduced by 0.22mmol/L
- Triglyceride reduced by 0.04mmol/L
Weight loss:
- Body weight reduced by 1.87kg
- BMI reduced by 0.8kg/m2
- Waist circumference reduced by 2.08cm
Blood pressure:
- Systolic reduced by 2.58mmHg
- Diastolic reduced by 3.12mmHg
Despite limitations of the meta-analysis, this study demonstrates IF has therapeutic effects on those with disordered lipid and glucose metabolism, and may prove to be an effective and sustainable approach.
Clinical practice applications:
- IF may be an effective alternative to restricted calorie or CHO diets for weight management with the associated benefits of glucose and lipid metabolism.
- IF has been shown to have therapeutic effects on individuals with impaired glucose and lipid metabolism.
- IF may be considered as a sustainable lifestyle choice rather than a ‘weight loss’ programme such as a very low calorie diet, which can result in poor quality of life and subsequent reduced adherence.
- Since it may take time for impaired glucose and lipid metabolism to progress to more serious disease states, establishing IF as an early intervention, may be considered as a prudent form of preventative medicine.
- IF has shown to have other health benefits such as reduced blood pressure and may be considered as adjuvant therapy.
Considerations for future research:
- Compares the effects of IF on different ethnicities, sex and age categories
- Evaluates the effect of IF on other disease states e.g. cancer, auto-immune conditions
- Assesses the response of other biomarkers e.g. inflammatory cytokines
- Compares different types and durations of IF on health biomarkers (eg periodic, time restricted)
Abstract
The question of whether or not intermittent fasting diets improve the clinical indicators of glycolipid metabolism remains unclear. This study systematically reviewed the relevant clinical trials to evaluate the effects of intermittent fasting diet on glucose and lipid metabolism and insulin sensitivity in patients with metabolic syndrome. To evaluate the effect of intermittent fasting diet intervention on patients with disorders of glucose and lipid metabolism, random-effect or fixed-effect meta-analysis models were used to calculate the average difference before and after intermittent fasting diet intervention and the corresponding 95% confidence intervals (CIs). After intermittent fasting diet intervention, in terms of glucose metabolism, fasting blood glucose reduced by 0.15 mmol/L (95% CI: -0.23; -0.06), glycosylated hemoglobin reduced by 0.08 (95% CIs: -0.25; -0.10), insulin plasma levels reduced by 13.25 uUI (95% CIs: -16.69; -9.82), and HOMA-IR decreased by 0.31 on an average (95% CIs: -0.44; -0.19). In addition, BMI decreased by 0.8 kg/m2 (95% CIs: -1.32; -0.28), body weight reduced by 1.87 kg (95% CIs: -2.67; -1.07), and the waist circumference decreased by 2.08 cm (95% CIs: -3.06; -1.10). Analysis of lipid metabolism showed that intermittent fasting diet intervention effectively reduced the total cholesterol level by 0.32 mmol/L (95% CIs: -0.60; -0.05), low-density lipoprotein level by 0.22 mmol/L (95% CIs: -0.37; -0.07), and triglyceride level by 0.04 mmol/L (95% CIs: -0.15; -0.07). Intermittent fasting diets have certain therapeutic effects on blood glucose and lipids in patients with metabolic syndrome and significantly improve insulin resistance. It may be considered as an auxiliary treatment to prevent the occurrence and development of chronic diseases.
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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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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
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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.