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Effect of Casein Hydrolysate on Cardiovascular Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.
Zhou, S, Xu, T, Zhang, X, Luo, J, An, P, Luo, Y
Nutrients. 2022;14(19)
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Casein makes up around 80% of the protein in cow’s milk. Hydrolysed casein has been partially broken down, making it easier to digest. It has various biological functions including, anti-inflammatory, antioxidant, and antihypertensive activities which could be beneficial for cardiovascular health. This systematic review and meta-analysis aimed to summarise the effects of casein hydrolysate supplementation on cardiovascular risk factors. 26 randomised control trials (RCTs) were included in the analysis. Casein hydrolysate significantly reduced systolic and diastolic blood pressure compared with control diets, but had no effect on total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides or fasting blood glucose. The authors concluded that their findings support the consumption of casein hydrolysate in the population at risk for the prevention of cardiovascular disease.
Abstract
Casein hydrolysate has various biological functional activities, especially prominent are angiotensin I-converting enzyme inhibitory activities. Increasing evidence has reported the prominent hypotensive effect of casein hydrolysate. However, the effects of casein hydrolysate on cardiovascular risk factors remain unclear and require more comprehensive and detailed studies. Here, we conducted a systematic review and meta-analysis on eligible randomized controlled trials (RCTs) to summarize the effects of casein hydrolysate supplementation on blood pressure, blood lipids, and blood glucose. In the pooled analyses, casein hydrolysate significantly reduced systolic blood pressure by 3.20 mmHg (-4.53 to -1.87 mmHg) and diastolic blood pressure by 1.50 mmHg (-2.31 to -0.69 mmHg). Supplementation of casein hydrolysate displayed no effect on total cholesterol (-0.07 mmol/L; -0.17 to 0.03 mmol/L), low-density lipoprotein cholesterol (-0.04 mmol/L; -0.15 to 0.08 mmol/L), high-density lipoprotein cholesterol (-0.01 mmol/L; -0.06 to 0.03 mmol/L), triglycerides (-0.05 mmol/L, -0.14 to 0.05 mmol/L), or fasting blood glucose (-0.01 mmol/L; -0.10 to 0.09 mmol/L) compared with the placebo diets. Collectively, this study indicated that supplementation of casein hydrolysate displayed decreasing effect on blood pressure without affecting blood lipids or glycemic status.
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The effects of saffron supplementation on cardiovascular risk factors in adults: A systematic review and dose-response meta-analysis.
Zamani, M, Zarei, M, Nikbaf-Shandiz, M, Gholami, F, Hosseini, AM, Nadery, M, Shiraseb, F, Asbaghi, O
Frontiers in nutrition. 2022;9:1055517
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Cardiovascular disease (CVD) is a leading cause of death and disability around the world and presents a significant burden for healthcare systems. CVD has many risk factors, including diet and lifestyle habits. Hence, favourable interventions in those areas can help prevent and manage CVD. This systematic review examined the effects of saffron crocus on cardiovascular risk factors. Saffron is derived from the flowering plant Saffron Crocus (Crocus sativus). It contains many active compounds such as crocetin, crocin, picrocrocin, and safrana, which in various studies demonstrated positive effects on blood glucose levels, insulin resistance and sensitivity and blood fats, besides also having antioxidant and anti-inflammatory qualities. Yet, results were not always consistent, and hence this meta-analysis gathered evidence from 32 randomised controlled trials (RCTs) which included a total of 1674 subjects and investigated the effect of saffron supplements on cardiovascular risk factors such as blood fats, blood glucose control, blood pressure, anthropometric measures, and inflammatory markers. In conclusion, the analysis showed that saffron supplementation aided the reduction of some inflammatory markers (CRP, TNF-α), had favourable effects on antioxidant capacity, reduced blood fats except high-density lipoprotein (HDL), enhanced blood control and insulin sensitivity, reduced blood pressure and was linked to a reduction in waist circumference but with no significant effect on weight itself, BMI or fat mass. The authors discussed how their results relate to previous research and what underlying mechanisms can explain the effects or discrepancies. Given the positive results, saffron presents itself as a promising supplement and adjunct therapy for managing CVD and its risk factors.
Abstract
INTRODUCTION Cardiovascular disease (CVD) is one of the leading causes of death and disability in the world and is estimated to involve more people in the next years. It is said that alternative remedies such as herbs can be used to manage the complications of this disease. For this reason, we aimed to conduct this meta-analysis to systematically assess and summarize the effects of saffron supplementation as an important herb on cardiovascular risk factors in adults. METHODS A systematic search was done in PubMed, Scopus, and Web of Science to find eligible articles up to September 2022. Randomized controlled trials (RCTs) that evaluated the effects of saffron on lipid profiles, glycemic control, blood pressure, anthropometric measures, and inflammatory markers were included. In the meta-analysis, 32 studies were taken into account (n = 1674). RESULTS Consumption of saffron significantly decreased triglyceride (TG) (WMD = -8.81 mg/dl, 95%CI: -14.33, -3.28; P = 0.002), total cholesterol (TC) (WMD = -6.87 mg/dl, 95%CI: -11.19, -2.56; P = 0.002), low density lipoprotein (LDL) (WMD = -6.71 mg/dl, 95%CI: -10.51, -2.91; P = 0.001), (P = 0.660), fasting blood glucose (FBG) level (WMD = -7.59 mg/dl, 95%CI: -11.88, -3.30; P = 0.001), HbA1c (WMD = -0.18%, 95%CI: -0.21, -0.07; P < 0.001), homeostasis model assessment-insulin resistance (HOMA-IR) (WMD = -0.49, 95%CI: -0.89, -0.09; P = 0.016), systolic blood pressure (SBP) (WMD = -3.42 mmHg, 95%CI: -5.80, -1.04; P = 0.005), tumor necrosis factor α (TNF-α) (WMD = -2.54 pg/ml, 95%CI: -4.43, -0.65; P = 0.008), waist circumference (WC) (WMD = -1.50 cm; 95%CI: -2.83, -0.18; P = 0.026), malondialdehyde (MDA) (WMD = -1.50 uM/L, 95%CI: -2.42, -0.57; P = 0.001), and alanine transferase (ALT) (WMD = -2.16 U/L, 95%CI: -4.10, -0.23; P = 0.028). Also, we observed that saffron had an increasing effect on total antioxidant capacity (TAC) (WMD = 0.07 mM/L, 95%CI: 0.01, 0.13; P = 0.032). There was linear regression between FBG and the duration of saffron intake. Additionally, the non-linear dose-response analysis has shown a significant association of saffron intervention with HDL (P = 0.049), HOMA-IR (P = 0.002), weight (P = 0.036), ALP (P = 0.016), FBG (P = 0.011), HbA1c (P = 0.002), and TNF-α (P = 0.042). A non-linear association between the length of the intervention and the level of HDL and DBP was also found. DISCUSSION That seems saffron could effectively improve TG, TC, LDL, FBG, HbA1c, HOMA-IR, SBP, CRP, TNF-α, WC, MDA, TAC, and ALT.
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The effects of berberine supplementation on cardiovascular risk factors in adults: A systematic review and dose-response meta-analysis.
Zamani, M, Zarei, M, Nikbaf-Shandiz, M, Hosseini, S, Shiraseb, F, Asbaghi, O
Frontiers in nutrition. 2022;9:1013055
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Despite advances in medicine, cardiovascular disease (CVD) still remains the primary cause of deaths worldwide. Many of the risk factors of CVD, such as elevated levels of blood fats, high blood pressure, abdominal obesity and poor blood sugar control, can be improved and managed by behaviour, lifestyle and dietary intervention as well as supplements. Berberine (BBR) is a plant-derived compound, available as a supplement, which has gained the attention of researchers due to its ability to modulate cardiovascular risk factors. This dose-response meta-analysis sought to generate a comprehensive overview of the effect of BBR on the risk factors for CVD in adults. The analysis included 49 randomised clinical trials. The results showed BBR significantly reduced blood fats such as total cholesterol, triglycerites and low-density lipoprotein (LDL). It also improved markers of blood sugar control such as fasting blood sugar levels, insulin, HbA1c, HOMA-IR and blood pressure and body weight, whilst enhancing high-density lipoprotein (HDL). The optimal dose of BBR was 1 g/day for triglycerides, total cholesterol, and weight loss. For insulin and HOMA-IR the best effects were seen with 1.8 g/day and for HDL 5 g/day. The most effective timeframe to impact fasting blood sugars seemed to be 40 weeks, and 50 weeks to influence blood pressure and waist circumference. In conclusion, BBR supplementation had beneficial effects on reducing risk factors for CVD, particularly in subgroups with impaired metabolic health. There was no substantial impact on liver enzymes (AST, ALT) or inflammatory markers (CRP, IL-6). Furthermore the supplement was largely ineffective in people with normal body mass index.
Abstract
UNLABELLED Cardiovascular disease (CVD) is a major concern today. Herbal medicine is one helping way to control CVD risks. One conclusive of herbal medicine is Berberine (BBR) and converse about it still exists, to clarify this issue, this meta-analysis was performed. PubMed/Medline, Scopus, and Web of Science were searched for RCTs in adults on the effect of BBR supplementation on CVD risk factors up to July 2022. The pooled results showed BBR significantly reduced triglyceride (WMD = -23.70 mg/dl; 95%CI -30.16, -17.25; P < 0.001), total cholesterol (WMD = -20.64 mg/dl; 95%CI -23.65, -17.63; P < 0.001), low-density lipoprotein WMD = -9.63 mg/dl; 95%CI, -13.87, -5.39; P < 0.001), fasting blood glucose (FBG) (WMD = -7.74 mg/dl; 95%CI -10.79, -4.70; P < 0.001), insulin (WMD = -3.27 mg/dl; 95%CI -4.46,-2.07; P < 0.001), HbA1c (WMD = -0.45%; 95%CI -0.68, -0.23; P < 0.001), HOMA-IR (WMD = -1.04; 95%CI -1.55, -0.52; P < 0.001), systolic blood pressure (WMD = -5.46 mmHg; 95%CI -8.17, -2.76; P < 0.001), weight (WMD = -0.84; 95%CI -1.34,-0.34; P < 0.001), body mass index (WMD = -0.25 kg/m2; 95%CI -0.46, -0.04; P = 0.020), while increased high-density lipoprotein (HDL) (WMD = 1.37 mg/dl; 95%CI 0.41,2.23; P = 0.005). The optimal dose of BBR was 1 g/day for TG, TC, and weight, 1.8 g/day for insulin and HOMA-IR, and 5 g/day for HDL. FBG's most efficient time frame was 40 weeks from the beginning of supplementation, whereas DBP and waist circumference was 50 weeks. In conclusion, the lipid profile, FBG balance, obesity parameters, and SBP were improved with BBR supplementation. SYSTEMATIC REVIEW REGISTRATION CRD42022347004.
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Effects of the Treatment with Flavonoids on Metabolic Syndrome Components in Humans: A Systematic Review Focusing on Mechanisms of Action.
Gouveia, HJCB, Urquiza-Martínez, MV, Manhães-de-Castro, R, Costa-de-Santana, BJR, Villarreal, JP, Mercado-Camargo, R, Torner, L, de Souza Aquino, J, Toscano, AE, Guzmán-Quevedo, O
International journal of molecular sciences. 2022;23(15)
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Metabolic syndrome is a condition characterised by at least three of the five risk factors, such as abdominal obesity, elevated fasting glucose, blood pressure and triglycerides and reduced high-density lipoprotein cholesterol (HDL-c). There is a strong link between metabolic syndrome and the development of cardiovascular disease and Type 2 diabetes. Research suggests that increasing consumption of flavonoid-rich foods can be beneficial in reducing cardiovascular morbidity and mortality. Flavonoids are bioactive compounds that possess antioxidative, anti-inflammatory, anti-cancerous, anti-mutagenic, and enzymatic properties. This systematic review of 29 randomised controlled trials evaluated the beneficial effects of long-term flavonoid supplementation in reducing the risk factors of metabolic syndrome. This review included a variety of flavonoid supplements, such as anthocyanin, hesperidin, quercetin, epigallocatechin gallate (egcg), genistein, theaflavin, catechin, and eriocitrin. Additionally, this research investigated the mechanisms behind the beneficial effects of flavonoid supplementation. Results showed that flavonoid supplementation for at least three weeks improved metabolic parameters and inflammatory markers, with hesperidin showing the greatest improvements in metabolic parameters. Healthcare professionals can use these findings to understand the potential benefits of long-term flavonoid supplementation in improving metabolic parameters. However, more robust studies are needed to determine the therapeutic dosages of different flavonoids.
Abstract
Diets high in bioactive compounds, such as polyphenols, have been used to mitigate metabolic syndrome (MetS). Polyphenols are a large group of naturally occurring bioactive compounds, classified into two main classes: non-flavonoids and flavonoids. Flavonoids are distributed in foods, such as fruits, vegetables, tea, red wine, and cocoa. Studies have already demonstrated the benefits of flavonoids on the cardiovascular and nervous systems, as well as cancer cells. The present review summarizes the results of clinical studies that evaluated the effects of flavonoids on the components of the MetS and associated complications when offered as supplements over the long term. The results show that flavonoids can significantly modulate several metabolic parameters, such as lipid profile, blood pressure, and blood glucose. Only theaflavin and catechin were unable to affect metabolic parameters. Moreover, only body weight and body mass index were unaltered. Thus, the evidence presented in this systematic review offers bases in support of a flavonoid supplementation, held for at least 3 weeks, as a strategy to improve several metabolic parameters and, consequently, reduce the risk of diseases associated with MetS. This fact becomes stronger due to the rare side effects reported with flavonoids.
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Vegetarian and Vegan Diet in Fibromyalgia: A Systematic Review.
Nadal-Nicolás, Y, Miralles-Amorós, L, Martínez-Olcina, M, Sánchez-Ortega, M, Mora, J, Martínez-Rodríguez, A
International journal of environmental research and public health. 2021;18(9)
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Fibromyalgia (FM) is a chronic non-degenerative disease of unknown etiology without effective medical treatment that mostly affects women. The aim of this study was to evaluate the efficacy of mainly plant-based diets in patients with FM compared to omnivorous diets. A secondary aim was to examine the main effects of these diets on patients’ symptoms and the improvement in their quality of life. This study is a systemic review of six studies (n = 4 clinical trials and n = 2 observational cohort studies). The selected studies included 157 FM patients in both the intervention and control groups, and more than 117 were women. Results indicate that a mainly plant-based diet improves biochemical parameters and body inflammation; body weight, sleep quality, quality of life, pain at rest as well as other symptoms of FM and their impact on health. Authors conclude that even though their findings are promising further well-designed clinical trials are needed to consolidate these dietary recommendations in FM patient.
Abstract
Fibromyalgia (FM) is a chronic non-degenerative disease characterized by the presence of multiple symptoms such as chronic pain, which negatively influence the quality of life of sufferers, most of whom are women. Currently, there is no effective treatment to limit the impact of these symptoms. The aim of this research is to review the scientific evidence on the effect of following a vegetarian or vegan diet on fibromyalgia patients. A systematic review included the original articles that answered the research question. These articles were in 2021 in the PubMed, Web of Science and Scopus databases. The research used the PRISMA (preferred reporting items for systematic reviews and meta-analyses) guidelines. No time restriction was applied, and grey literature was not included. The evaluation of the methodological quality of the articles was carried out using the following different scales: STROBE (strengthening the reporting of observational studies in epidemiology), PEDro (Physiotherapy Evidence Database), and MMAT (Mixed Methods Appraisal Tool) scales. A total of 88 studies were analyzed, of which 6 investigations were included in this systematic review (n = 4 clinical trials and n = 2 cohort studies). These investigations show significant improvements in biochemical parameters, quality of life, quality of sleep, pain at rest and general health status when following mainly plant-based dietary patterns. In conclusion, these findings are promising but interpretation of the findings is limited due to the methodological quality of the studies. Well-designed clinical trials are needed to consolidate these dietary recommendations in FM patients.
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Fruit and vegetable consumption and the risk of type 2 diabetes: a systematic review and dose-response meta-analysis of prospective studies.
Halvorsen, RE, Elvestad, M, Molin, M, Aune, D
BMJ nutrition, prevention & health. 2021;4(2):519-531
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Type 2 diabetes is a growing health concern worldwide, with projections estimating it will affect over 700 million people by 2045. Studies have indicated a link between increased consumption of fruits and vegetables and decreased risk of Type 2 diabetes. This systematic review and meta-analysis of twenty-three prospective cohort studies explored this link further, examining the effects of different types of fruits and vegetables on the risk of Type 2 diabetes. The results suggest that a high intake of combined fruits and vegetables and specific varieties, such as apples, pears, blueberries, grapes, and raisins, may slightly reduce the risk of developing Type 2 diabetes. However, consuming cantaloupe, fruit drinks, fruit juice, potatoes, Brussels sprouts, and cabbage may increase the risk of developing Type 2 diabetes. The protective effect of fruit and vegetable consumption on the reduction of type 2 diabetes could be attributed to the dietary fibre, antioxidants, vitamins and minerals and phytochemicals present in fruits and vegetables. While further studies are necessary to confirm these results and explore the impact of specific types of fruits and vegetables on Type 2 diabetes risk, healthcare professionals can use this information to promote the protective benefits of including specific subtypes of fruits and vegetables in the diet to reduce the risk of Type 2 diabetes.
Abstract
BACKGROUND The association between intake of fruit and vegetables and their subtypes, and the risk of type 2 diabetes has been investigated in several studies, but the results have been inconsistent. OBJECTIVE We conducted an updated systematic review and dose-response meta-analysis of prospective studies on intakes of fruit and vegetables and fruit and vegetable subtypes and the risk of type 2 diabetes. DESIGN PubMed and Embase databases were searched up to 20 October 2020. Prospective cohort studies of fruit and vegetable consumption and type 2 diabetes mellitus were included. Summary relative risks (RRs) and 95% CIs were estimated using a random effects model. RESULTS We included 23 cohort studies. The summary RR for high versus low intake and per 200 g/day were 0.93 (95% CI: 0.89 to 0.98, I2=0%, n=10 studies) and 0.98 (95% CI: 0.95 to 1.01, I2=37.8%, n=7) for fruit and vegetables combined, 0.93 (95% CI: 0.90 to 0.97, I2=9.3%, n=20) and 0.96 (95% CI: 0.92 to 1.00, I2=68.4%, n=19) for fruits and 0.95 (95% CI: 0.88 to 1.02, I2=60.4%, n=17) and 0.97 (95% CI: 0.94 to 1.01, I2=39.2%, n=16) for vegetables, respectively. Inverse associations were observed for apples, apples and pears, blueberries, grapefruit and grapes and raisins, while positive associations were observed for intakes of cantaloupe, fruit drinks, fruit juice, brussels sprouts, cauliflower and potatoes, however, most of these associations were based on few studies and need further investigation in additional studies. CONCLUSIONS This meta-analysis found a weak inverse association between fruit and vegetable intake and type 2 diabetes risk. There is indication of both inverse and positive associations between intake of several fruit and vegetables subtypes and type 2 diabetes risk, however, further studies are needed before firm conclusions can be made.
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Systematic review of the prospective association of daily step counts with risk of mortality, cardiovascular disease, and dysglycemia.
Hall, KS, Hyde, ET, Bassett, DR, Carlson, SA, Carnethon, MR, Ekelund, U, Evenson, KR, Galuska, DA, Kraus, WE, Lee, IM, et al
The international journal of behavioral nutrition and physical activity. 2020;17(1):78
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The health benefits of physical activity for people of all ages, fitness levels, and sociodemographic backgrounds are well-documented. The main aim of this study was to provide an updated description of the association between daily step counts and subsequent cardiovascular disease (CVD) morbidity or mortality, dysglycaemia, and all-cause mortality in adults and the patterns of these associations. This study is a systemic review of 17 studies from 13 different cohorts. Participants’ mean age ranged from 49.7 to 78.9 years with samples comprised of 46.9% female participants on average. Results showed that increasing steps per day is beneficial for health: taking more steps per day was associated with lower risk of all-cause mortality, and lower risk of CVD morbidity or mortality. These associations appear to hold across age, gender, and weight status. Authors conclude that this additional evidence will help guide meaningful volume targets that can be used for health care, education, and behavioural interventions, and potentially inform the development of public health guidelines for steps and health.
Abstract
BACKGROUND Daily step counts is an intuitive metric that has demonstrated success in motivating physical activity in adults and may hold potential for future public health physical activity recommendations. This review seeks to clarify the pattern of the associations between daily steps and subsequent all-cause mortality, cardiovascular disease (CVD) morbidity and mortality, and dysglycemia, as well as the number of daily steps needed for health outcomes. METHODS A systematic review was conducted to identify prospective studies assessing daily step count measured by pedometer or accelerometer and their associations with all-cause mortality, CVD morbidity or mortality, and dysglycemia (dysglycemia or diabetes incidence, insulin sensitivity, fasting glucose, HbA1c). The search was performed across the Medline, Embase, CINAHL, and the Cochrane Library databases from inception to August 1, 2019. Eligibility criteria included longitudinal design with health outcomes assessed at baseline and subsequent timepoints; defining steps per day as the exposure; reporting all-cause mortality, CVD morbidity or mortality, and/or dysglycemia outcomes; adults ≥18 years old; and non-patient populations. RESULTS Seventeen prospective studies involving over 30,000 adults were identified. Five studies reported on all-cause mortality (follow-up time 4-10 years), four on cardiovascular risk or events (6 months to 6 years), and eight on dysglycemia outcomes (3 months to 5 years). For each 1000 daily step count increase at baseline, risk reductions in all-cause mortality (6-36%) and CVD (5-21%) at follow-up were estimated across a subsample of included studies. There was no evidence of significant interaction by age, sex, health conditions or behaviors (e.g., alcohol use, smoking status, diet) among studies that tested for interactions. Studies examining dysglycemia outcomes report inconsistent findings, partially due to heterogeneity across studies of glycemia-related biomarker outcomes, analytic approaches, and sample characteristics. CONCLUSIONS Evidence from longitudinal data consistently demonstrated that walking an additional 1000 steps per day can help lower the risk of all-cause mortality, and CVD morbidity and mortality in adults, and that health benefits are present below 10,000 steps per day. However, the shape of the dose-response relation is not yet clear. Data are currently lacking to identify a specific minimum threshold of daily step counts needed to obtain overall health benefit.
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Low-carbohydrate diets for type 1 diabetes mellitus: A systematic review.
Turton, JL, Raab, R, Rooney, KB
PloS one. 2018;13(3):e0194987
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Type 1 diabetes is an autoimmune condition that affects the ability to produce insulin, the hormone that regulates blood sugar levels. Patients with Type 1 diabetes manage their condition with daily insulin injections or patches, and the standard dietary advice is to continue to eat a normal diet, and adjust the insulin dose to keep blood sugar under control. This systematic review of 9 studies of varying types, aimed to examine the effects of low-carbohydrate diets on type 1 diabetes management. 8 of the studies reported a change in HbA1c (the blood marker used to assess long-term blood sugar management); 3 of these reported statistically significant reductions. 2 studies reported statistically significant reductions in daily insulin use whilst following a low-carbohydrate diet. The study authors were unable to conclude an overall effect due to the differences in design and methods used in the 9 studies included. They call for more primary research to be conducted.
Abstract
Type 1 diabetes is an autoimmune condition characterised by pancreatic beta cell destruction and absolute insulin deficiency. The strongest predictor of diabetes complications is glycaemic control and achieving HbA1c ≤ 7.0% is the primary management target. However, standard treatment appears to be lacking and adjunctive strategies require consideration. A systematic review was conducted to examine the effect of low-carbohydrate diets on type 1 diabetes management. Four databases were searched from inception until 28 March 2017: MEDLINE; CINAHL; Cochrane Library; and EMBASE. All primary studies containing a methods section (excluding cross-sectional) were included. Reports had to quantitatively measure the effect(s) of a dietary intervention or observed intake over at least two weeks where carbohydrate is below 45% total energy in adults and/or children with type 1 diabetes. The primary outcome was HbA1c and secondary outcomes were severe hypoglycaemia, total daily insulin, BMI, quality of life and mean daily glucose. Seventy-nine full-text articles were assessed for eligibility and nine were included (two randomised controlled trials, four pre-post interventions, two case-series, one case-report). Eight studies reported a mean change in HbA1c with a low-carbohydrate diet. Of these, four reported a non-significant change (P ≥ 0.05) and three reported statistically significant reductions (P < 0.05). Two studies reported severe hypoglycaemia, five reported total insulin, three reported BMI, and one reported blood glucose. Due to the significant heterogeneity of included studies, an overall effect could not be determined. This review presents all available evidence on low-carbohydrate diets for type 1 diabetes and suggests an urgent need for more primary studies.
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Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies.
Dinu, M, Abbate, R, Gensini, GF, Casini, A, Sofi, F
Critical reviews in food science and nutrition. 2017;57(17):3640-3649
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Vegetarian diet is experiencing a considerable popularity in the general population. The aim of this study was to obtain an estimate of the association between vegetarian, vegan diets, and multiple health outcomes, including risk factors for chronic diseases, risk of all-cause mortality, incidence and mortality from cardio-cerebrovascular diseases, total cancer and specific types of cancer. This study is a comprehensive systematic review with meta-analysis of all cross-sectional and cohort studies. A total of 108 articles were included in the meta-analysis with a total population of over 130,000 vegetarians and 15,000 vegans. Results indicate that: - vegetarians and vegans show significantly lower levels of the most relevant risk factor for chronic disease such as body mass index, lipid variables and fasting glucose, when compared to non-vegetarians and nonvegans. - a significant protection versus ischemic heart disease and cancer is present in vegetarian subjects, however this protection is not significant for overall mortality, cardio and cerebrovascular diseases. - vegan diet seems to be associated with a lower rate of cancer incidence (interpreted with caution due to the small sample size of the study). Authors conclude that their findings may be useful for helping to give correct information to subjects who want to adopt vegetarian or vegan dietary patterns.
Abstract
BACKGROUND Beneficial effects of vegetarian and vegan diets on health outcomes have been supposed in previous studies. OBJECTIVES Aim of this study was to clarify the association between vegetarian, vegan diets, risk factors for chronic diseases, risk of all-cause mortality, incidence, and mortality from cardio-cerebrovascular diseases, total cancer and specific type of cancer (colorectal, breast, prostate and lung), through meta-analysis. METHODS A comprehensive search of Medline, EMBASE, Scopus, The Cochrane Library, and Google Scholar was conducted. RESULTS Eighty-six cross-sectional and 10 cohort prospective studies were included. The overall analysis among cross-sectional studies reported significant reduced levels of body mass index, total cholesterol, LDL-cholesterol, and glucose levels in vegetarians and vegans versus omnivores. With regard to prospective cohort studies, the analysis showed a significant reduced risk of incidence and/or mortality from ischemic heart disease (RR 0.75; 95% CI, 0.68 to 0.82) and incidence of total cancer (RR 0.92; 95% CI 0.87 to 0.98) but not of total cardiovascular and cerebrovascular diseases, all-cause mortality and mortality from cancer. No significant association was evidenced when specific types of cancer were analyzed. The analysis conducted among vegans reported significant association with the risk of incidence from total cancer (RR 0.85; 95% CI, 0.75 to 0.95), despite obtained only in a limited number of studies. CONCLUSIONS This comprehensive meta-analysis reports a significant protective effect of a vegetarian diet versus the incidence and/or mortality from ischemic heart disease (-25%) and incidence from total cancer (-8%). Vegan diet conferred a significant reduced risk (-15%) of incidence from total cancer.