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The synergistic effect of herbal medicine and probiotics in pediatric functional constipation: A systematic review and meta-analysis.
Kim, E, Chang, S, Nam, J, Park, N, Min, SY
Medicine. 2024;103(7):e36899
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Paediatric functional constipation (PFC) is a prevalent gastrointestinal disorder in children. The initial approach to managing PFC involves demystification, education, toilet training, and the use of laxatives. Using laxatives can lead to various adverse effects therefore, patients with functional constipation typically adopt a self-management approach and explore complementary and alternative therapies. The aim of this study was to analyse the synergistic effect of herbal medicine (HM) combined with probiotics in the treatment of PFC, by comparing it to the use of probiotics alone. This study was a systematic review and meta-analysis of twenty-two randomised controlled trials. Results showed that the combination of HM with probiotics may yield significantly greater benefits for total effective rate when compared to probiotics alone. Furthermore, HM combined with probiotics could potentially reduce the recurrence rate by 70% compared to probiotics alone. Authors concluded that HM could potentially offer advantages in enhancing the efficacy rate and Bristol faecal score, influencing gastrointestinal peptide hormones, decreasing inflammation indicators and lowering the recurrence rate among children with functional constipation.
Abstract
BACKGROUND Pediatric functional constipation (PFC) is a prevalent and persistent gastrointestinal disorder, that requires various treatments, including alternative approaches. This review assessed the synergistic efficacy of herbal medicine (HM) and probiotics for PFC. METHODS We conducted a comprehensive search of 11 databases, including English, Chinese, and Korean databases, until June 29, 2023. The inclusion criteria were randomized clinical trials (RCTs) comparing the intervention of HM with probiotics to that of the same probiotics. Statistical analyses included calculation of the mean difference (MD), standardized MD, risk ratio (RR) with a 95% confidence interval (CI), and assessment of risk of bias using Review Manager Version 5.4 software. The Grading of Recommendations Assessment, Development, and Evaluation rating system was used to evaluate evidence quality. Potential publication bias was assessed using funnel plots, Egger test, the fail-safe N test, and Duval and Tweedie trim and fill method. RESULTS A total of 22 RCTs involving 2228 patients were included in the meta-analysis. The HM and probiotics group exhibited superior outcomes compared to the probiotics alone group in various parameters: total effective rate (RR: 1.24, 95% CI: 1.19-1.29, P < .001), Bristol fecal Score (MD: 0.80, 95% CI: 0.71-0.89, P < .001), gastrointestinal peptide hormone (motilin) (MD: 35.37, 95% CI: 24.64-64.10, P < .001), inflammation indicator (nitrous oxide) (MD: -12.45, 95% CI: -15.12 to -9.77, P < .001), minimal sensitive volume of the rectum (MD: -8.7, 95% CI: -10.91 to -6.49, P < .001), and recurrence rate (RR: 0.30, 95% CI: 0.21-0.43, P < .001). CONCLUSION The combination of HM and probiotics may exhibit a synergistic effect on PFC. Nevertheless, it is imperative to undertake rigorously planned RCTs to comprehensively evaluate the synergistic efficacy of HM and probiotics.
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Plum supplementation and lipid profile: a systematic review and meta-analysis of randomised controlled trials.
Askarpour, M, Ghalandari, H, Setayesh, L, Ghaedi, E
Journal of nutritional science. 2023;12:e6
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The rate of nutrition-related non-communicable diseases is increasing worldwide. Lipid profile and its alterations have been used both as indicators of metabolic disorders and methods to evaluate patients’ response to dietary interventions. The aim of this study was to investigate the effectiveness of plums on improving parameters of lipid profile. This study is a systematic review and meta-analysis of nine randomised controlled trials with a total of eleven arms and 592 participants. Results show that plum can be beneficial in reducing triacylglycerols [triglycerides] in the unhealthy and low-density lipoprotein cholesterol in all individuals. However, no significant impact regarding blood triacylglycerols and high-density lipoprotein cholesterol levels, could be detected both in crude and subgroup analyses. Authors conclude that further clinical trials, taking advantage of a standard protocol of plum supplementation, should be conducted to elucidate the possible effect that plum supplementation might exert on lipid profile parameters.
Abstract
Plums are abundant in bioactive compounds which have been associated with numerous health benefits. In the present study, we aimed at examining the impact of plum supplementation on lipid profile of individuals. Electronic bibliographical databases were searched for relevant randomised clinical trials. Articles meeting our eligibility criteria were included for data extraction and final analysis. Weighted mean difference (WMD) was estimated using a random-effect model. Of the total articles retrieved in the initial search, nine articles were found to be eligible to be included in the analysis. Our results show that plum supplementation significantly improves total cholesterols levels in the unhealthy individuals. Moreover, plum supplementation reduces the LDL-c levels in the pooled sample (WMD = -11⋅52 mg/dl; 95 % CI -21⋅93, -1⋅11, P = 0⋅03, I 2 = 98⋅7 %) and also in some of the subgroups of individuals (dried plum, unhealthy subjects, duration more than 8 weeks). Moreover, it had a significant reducing effect on TC levels just in unhealthy subjects. Although plum supplementation did not have any significant impact on serum levels of TG nor HDL-c. Our results show that supplementation with plums is potentially effective in reducing serum total cholesterol and LDL-c.
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Effect of omega-3 supplementation on lipid profile in children and adolescents: a systematic review and meta-analysis of randomized clinical trials.
Khorshidi, M, Hazaveh, ZS, Alimohammadi-Kamalabadi, M, Jamshidi, S, Moghaddam, OM, Olang, B, Hatefi, S, Hosseini, A, Jamilian, P, Zarezadeh, M, et al
Nutrition journal. 2023;22(1):9
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Dyslipidaemia is considered as a substantial risk factor for cardiovascular disease (CVD). It is characterised by increased levels of triglyceride and low-density lipoprotein (LDL) and decreased levels of high-density lipoprotein (HDL). Consumption of omega-3 supplements play an important role in reduction of CVD events and its associated mortality by ameliorating lipid profile via lowering triglyceride levels. The aim of this study was to evaluate the effect of omega 3 supplementation on lipid profile in children and adolescents. This study is a systematic review and meta-analysis of fourteen studies. Three trials out of 14 had cross-over design, while others were parallel randomised trials. Results show that omega-3 supplementation may exert therapeutic effects on triglyceride (TG) levels, however, there weren’t any remarkable effects on HDL, LDL, and total cholesterol status. The subgroup analysis showed an improvement in TG levels in studies conducted on participants ≤13 years old and those with hypertriglyceridemia. Furthermore, due to meta-regression results, the omega-3 supplementation improved HDL levels when administered with longer duration. Authors conclude that omega-3 supplementation may have favourable hypolipidemic effects through reduction of TG levels. Additionally, clinical trials with longer duration of intervention and appropriate designs are recommended for younger children and those with hypertriglyceridemia.
Abstract
PURPOSE Dyslipidemia is considered as a known risk factor for cardiovascular disease. Yet various trials with wide ranges of doses and durations have reported contradictory results. We undertook this meta-analysis of randomized controlled trials (RCTs) to determine whether omega-3 supplementation can affect lipid profile in children and adolescents. METHODS Cochrane Library, Embase, PubMed, and Scopus databases were searched up to March 2021. Meta-analysis was performed using random-effect method. Effect size was expressed as weighted mean difference (WMD) and 95% confidence interval (CI). Heterogeneity was assessed using the I2 index. In order to identification of potential sources of heterogeneity, predefined subgroup and meta-regression analysis was conducted. RESULTS A total of 14 RCTs with 15 data sets were included. Based on the combination of effect sizes, there was a significant reduction in TG levels (WMD: -15.71 mg/dl, 95% CI: -25.76 to -5.65, P=0.002), with remarkable heterogeneity (I2=88.3%, P<0.001). However, subgroup analysis revealed that omega-3 supplementation significantly decreased TG only in studies conducted on participants ≤13 years old (WMD=-25.09, 95% CI: -43.29 to -6.90, P=0.007), (I2=84.6%, P<0.001) and those with hypertriglyceridemia (WMD=-28.26, 95% CI: -39.12 to -17.41, P<0.001), (I2=0.0%, P=0.934). Omega-3 supplementation had no significant effect on total cholesterol, HDL, and LDL levels. Also, results of nonlinear analysis showed significant effect of treatment duration on HDL status (Pnon-linearity=0.047). CONCLUSION Omega-3 supplementation may significantly reduce TG levels in younger children and those with hypertriglyceridemia. Also, based on the HDL-related results, clinical trials with longer duration of intervention are recommended in this population.
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The Influence of Nutritional Intervention in the Treatment of Hashimoto's Thyroiditis-A Systematic Review.
Osowiecka, K, Myszkowska-Ryciak, J
Nutrients. 2023;15(4)
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Hashimoto’s thyroiditis is an autoimmune disorder characterized by the presence of antibodies in the thyroid gland such as thyroid peroxidase (TPO) and thyroglobulin (TG) antibodies. Immune-mediated inflammatory responses eventually lead to the progressive destruction of the gland and impaired thyroid function. The disease has a strong genetic disposition but is also influenced by environmental factors, including diet. Hence diet has been considered a complementary tool to manage thyroid function and disease progression by harnessing the benefits of certain nutrients and anti-inflammatory properties. This systematic review examined the effects of nutrients and dietary interventions on Hashimoto’s disease in current literature. Using antibody levels, thyroid hormone levels and body weight to measure outcomes. The review included 9 studies, all of which compared the intervention group to the control groups. The trials included looked at gluten-free, lactose-free and energy-restricted diets, with or without selected nutrients and foods supplements (ie. Nigella sativa, iodine). The intervention duration ranged from 3 weeks to 12 months. Despite the small number of trials, the data from those studies included in this review showed promising results. Improvements in disease parameters were observed in diets that were energy deficient, eliminated gluten, lactose and goitrogens or added Nigella sativa. Iodine restrictions did not show any improvements. In the discussion section, the authors presented the results in the wider context and the findings from other studies. Ultimately there appears to be a wide variance in outcomes, usually ranging from beneficial to neutral. The authors contributed to such variability due to the complexity of the condition and many influencing factors. Often participants in trials have highly variable thyroid status and function, and differences in regular dietary intakes of nutrients critical to thyroid health can easily distort the results. Hence much more specific research is needed to make firmer conclusions. Whereby no clear conclusions in larger groups could be drawn, potential benefits of dietary interventions in Hashimoto's disease may be much more apparent in clinical settings with personalized approaches that account for such individual variances.
Abstract
Diet can be a complementary treatment for Hashimoto's disease by affecting thyroid function and anti-inflammatory properties. It is still unclear which dietary strategy would be the most beneficial. The aim of this systematic review is to examine all the data currently available in the literature on the effects of nutritional intervention on biochemical parameters (anti-thyroid antibody and thyroid hormones levels) and characteristic symptoms in the course of Hashimoto's thyroiditis. This systematic review was prepared based on PRISMA guidelines. Articles in PubMed and Scopus databases published up to November 2022 were searched. As a result of the selection, out of 1350 publications, 9 were included for further analysis. The nutritional interventions included the following: elimination of gluten (3 articles) or lactose (1 article), energy restriction with or without excluding selected foods (n = 2), consumption of Nigella sativa (n = 2), or dietary iodine restriction (n = 1). The intervention duration ranged from 21 days to 12 months and included individuals with various thyroid function. Of the nine studies, three studies were female only. An improvement was observed during an energy deficit and after the elimination of selected ingredients (e.g., gluten, lactose, or goitrogens), as well as after the intervention of Nigella sativa. These interventions improved antibody levels against peroxidase (anti-TPO), (thyrotropin) TSH, and free thyroxine (fT4). No improvement was seen on the iodine-restricted diet. Varied outcomes of analyzed dietary interventions may be due to the heterogeneous thyroid condition, high variability between patients, and differences in habitual intake of critical nutrients (e.g., iodine, selenium, and iron) in different populations. Therefore, there is a great need for further experimental studies to determine whether any nutritional interventions are beneficial in Hashimoto's disease.
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Therapeutic Properties of Flavonoids in Treatment of Cancer through Autophagic Modulation: A Systematic Review.
de Sousa Silva, GV, Lopes, ALVFG, Viali, IC, Lima, LZM, Bizuti, MR, Haag, FB, Tavares de Resende E Silva, D
Chinese journal of integrative medicine. 2023;29(3):268-279
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Cancer is one of the leading causes of death worldwide. Although there are many different causes for its development, things that can damage the cells such as ultraviolet light and free radicals can be contributors. Protection against cellular damage may be of benefit to the prevention of cancer development and flavonoids, which are natural chemicals found in plants such as fruits and vegetables, have protective properties. This systematic review paper aimed to determine the therapeutic properties of flavonoids in the treatment of cancer. The results showed that all ten studies included in the review were observational studies carried out on human and animal cells. Ten different flavonoids were identified as having a potential role in cancer treatment mainly through promoting cancer cell death; Isolated mimulone-C geranyl flavonoids, baicalein, isoliquiritigenin, wogonin, icariin, fistein, pectolinarigenin, silibinin, sotetsu flavone, and oroxylin A. It was concluded that flavonoids may have a potential therapeutic effect in gall bladder cancer, head and neck squamous cell carcinoma, and oral cancer through it acting on cancer cell death. This study could be used by healthcare professionals to understand that a diet rich in fruits and vegetables may be of benefit to individuals with cancer. However, the results of this study should be interpreted with caution as it was based on animal and human cells and many processes can affect the development of cancer in whole human body systems.
Abstract
Cancers have high morbidity and mortality rates worldwide. Current anticancer therapies have demonstrated specific signaling pathways as a target in the involvement of carcinogenesis. Autophagy is a quality control system for proteins and plays a fundamental role in cancer carcinogenesis, exerting an anticarcinogenic role in normal cells and can inhibit the transformation of malignant cells. Therefore, drugs aimed at autophagy can function as antitumor agents. Flavonoids are a class of polyphenolic secondary metabolites commonly found in plants and, consequently, consumed in diets. In this review, the systematic search strategy was used, which included the search for descriptors "flavonoids" AND "mTOR pathway" AND "cancer" AND "autophagy", in the electronic databases of PubMed, Cochrane Library, Web of Science and Scopus, from January 2011 to January 2021. The current literature demonstrates that flavonoids have anticarcinogenic properties, including inhibition of cell proliferation, induction of apoptosis, autophagy, necrosis, cell cycle arrest, senescence, impaired cell migration, invasion, tumor angiogenesis and reduced resistance to multiple drugs in tumor cells. We demonstrate the available evidence on the roles of flavonoids and autophagy in cancer progression and inhibition. (Registration No. CRD42021243071 at PROSPERO).
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High-protein diets and testosterone.
Whittaker, J
Nutrition and health. 2023;29(2):185-191
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High protein diets have been shown to have several benefits such as weight loss and the promotion of feeling fuller for longer following food. A recent study has however shown that testosterone levels are decreased in men who follow a high protein diet. This study aimed to summarise the data on high protein diets and testosterone. The results showed that diets with more than 3.4g/kg/day protein decreased total testosterone levels possibly due to the body adjusting its biochemistry to ensure that the excess protein in the diet is metabolised. Furthermore, inflammation in response to an increased amount of protein may suppress testosterone production. It was concluded that increased protein intake of more than 3.4g/kg/day drives the decrease in total testosterone in the body of men regardless of what happens to the level of carbohydrate and fat in the body. This study could be used by healthcare professionals to understand that high protein diets may decrease testosterone levels in men.
Abstract
A recent meta-analysis found low-carbohydrate, high-protein diets (> 3.4 g/kg of bodyweight/day) (g/kg/day) decreased men's total testosterone (∼5.23 nmol/L) [Whittaker and Harris (2022) Low-carbohydrate diets and men's cortisol and testosterone: systematic review and meta-analysis. Nutrition and Health. DOI: 10.1177/02601060221083079]. This finding has generated substantial discussion, however, it has often lacked clarity and context, with the term 'high-protein' being used unqualified. Firstly, diets < 3.4 g/kg/day are not associated with a consistent decrease in testosterone. Secondly, the average protein intake is ∼1.3 g/kg/day, conventional 'high-protein' diets are ∼1.8-3 g/kg/day and the vast majority of athletes are < 3.4 g/kg/day; meaning very few individuals will ever surpass 3.4 g/kg/day. To avoid such confusion in the future, the following definitions are proposed: very high (> 3.4 g/kg/day), high (1.9-3.4 g/kg/day), moderate (1.25-1.9 g/kg/day) and low (<1.25 g/kg/day). Using these, very high-protein diets (> 3.4 g/kg/day) appear to decrease testosterone, however high- and moderate-protein diets (1.25-3.4 g/kg/day) do not.
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Lifestyle-, environmental-, and additional health factors associated with an increased sperm DNA fragmentation: a systematic review and meta-analysis.
Szabó, A, Váncsa, S, Hegyi, P, Váradi, A, Forintos, A, Filipov, T, Ács, J, Ács, N, Szarvas, T, Nyirády, P, et al
Reproductive biology and endocrinology : RB&E. 2023;21(1):5
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The World Health Organization defines infertility as regular unprotected sexual intercourse without achieving conception within a year. In recent years, there has been a growing demand for functional, objective parameters reflecting fertility status more clearly than classical parameters. Of these, sperm DNA fragmentation (SDF) and the DNA fragmentation index – denoting the percentage of sperm with damaged DNA – seem to be of utmost importance. The aim of this study was to investigate all risk factors that may potentially be increasing SDF. This study is a systematic review and meta-analysis of one hundred and ninety articles. The earliest studies were published in 2003, and the latest in 2021. Results show that several modifiable risk factors negatively affect SDF, namely; a. health conditions: varicocele [when veins become enlarged inside the pouch of skin that holds the testicles] and impaired glucose tolerance, b. infections: Chlamydia, c. malignancies: testicular tumours, and d. lifestyle factors: smoking, alcohol consumption and body mass index. Authors conclude that several lifestyle-, environmental-, and additional health factors are associated with increased SDF.
Abstract
INTRODUCTION Infertility affects one in every six couples in developed countries, and approximately 50% is of male origin. In 2021, sperm DNA fragmentation (SDF) testing became an evidence-based test for fertility evaluations depicting fertility more clearly than standard semen parameters. Therefore, we aimed to summarize the potential prognostic factors of a higher SDF. METHODS We conducted a systematic search in three medical databases and included studies investigating any risk factors for SDF values. We calculated mean differences (MD) in SDF with 95% confidence interval (CI) for exposed and non-exposed individuals. RESULTS We included 190 studies in our analysis. In the group of associated health conditions, varicocele (MD = 13.62%, CI: 9.39-17.84) and impaired glucose tolerance (MD = 13.75%, CI: 6.99-20.51) had the most significant increase in SDF. Among malignancies, testicular tumors had the highest impact, with a maximum of MD = 11.3% (CI: 7.84-14.76). Among infections, the overall effects of both Chlamydia and HPV were negligible. Of lifestyle factors, smoking had the most disruptive effect on SDF - an increase of 9.19% (CI: 4.33-14.06). Different periods of sexual abstinence did not show significant variations in SDF values. Age seemed to have a more drastic effect on SDF from age 50 onwards, with a mean difference of 12.58% (CI: 7.31-17.86). Pollution also had a detrimental effect - 9.68% (CI: 6.85-12.52). CONCLUSION Of the above risk factors, varicocele, impaired glucose tolerance, testicular tumors, smoking, pollution, and paternal age of over 50 were associated with the highest SDF. TRIAL REGISTRATION CRD42021282533.
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Effects of mild/asymptomatic COVID-19 on semen parameters and sex-related hormone levels in men: a systematic review and meta-analysis.
Che, BW, Chen, P, Yu, Y, Li, W, Huang, T, Zhang, WJ, Xu, SH, He, J, Liu, M, Tang, KF
Asian journal of andrology. 2023;25(3):382-388
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Various studies have shown that coronavirus disease 2019 (COVID-19) can cause more harm and a higher mortality rate to men. However, the literature does not clearly show that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can cause serious and lasting damage to male reproductive function. The aims of this study were to explore the effects of mild/asymptomatic COVID-19 on semen parameters and sex-related hormone levels and to analyse the relationship between semen parameter values and semen collection time after infection, fever, and severity of COVID-19. This study is a systematic review and meta-analysis of thirteen studies of which only five were included in the meta-analysis. Results show that COVID-19 has a certain effect on male reproductive function in the short term especially within about 70 days after infection. Additionally, fever after infection only had a significant effect on sperm concentration. Authors conclude by recommending the avoidance of pregnancy for a short period of time when the male partner has been infected with COVID-19.
Abstract
Coronavirus disease 2019 (COVID-19) has yet to be proven to alter male reproductive function, particularly in the majority of mild/asymptomatic patients. The purpose of this study was to explore whether mild/asymptomatic COVID-19 affects semen quality and sex-related hormone levels. To find suitable comparative studies, a systematic review and meta-analysis was done up to January 22, 2022, by using multiple databases (Web of Science, PubMed, and Embase). Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used to identify and choose the studies. Meta-analysis was used to examine the semen parameters and sex-related hormones of mild/asymptomatic COVID-19 patients before and after infection. The effects of semen collection time, fever, and intensity of verification on semen following infection were also investigated. A total of 13 studies (n = 770) were included in the analysis, including three case-control studies, six pre-post studies, and four single-arm studies. A meta-analysis of five pre-post studies showed that after infection with COVID-19, sperm concentration (I2 = 0; P = 0.003), total sperm count (I2 = 46.3%; P = 0.043), progressive motility (I2 = 50.0%; P < 0.001), total sperm motility (I2 = 76.1%; P = 0.047), and normal sperm morphology (I2 = 0; P = 0.001) decreased. Simultaneously, a systematic review of 13 studies found a significant relationship between semen collection time after infection, inflammation severity, and semen parameter values, with fever having only bearing on semen concentration. Furthermore, there was no significant difference in sex-related hormone levels before and after infection in mild/asymptomatic patients. Mild/asymptomatic COVID-19 infection had a significant effect on semen quality in the short term. It is recommended to avoid initiating a pregnancy during this period of time.
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Evidence of lifestyle interventions in a pregnant population with chronic hypertension and/or pre-existing diabetes: A systematic review and narrative synthesis.
Goddard, L, Patel, R, Astbury, NM, Tucker, K, McManus, RJ
Pregnancy hypertension. 2023;31:60-72
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Chronic hypertension complicates ≤5 % of pregnancies, and those entering pregnancy with a pre-existing diagnosis of diabetes has a global prevalence of between 0.5 % and 2.6 %. The aim of this study was to collate the evidence around lifestyle interventions during pregnancy for women with chronic hypertension and/or pre-existing diabetes (type 1 and type 2). This study is a systematic review and meta-analysis of nine randomised controlled trials. Results show lack of clarity and data on the effect of lifestyle interventions in pregnant women with chronic hypertension and/or pre-existing diabetes, thereby exposing key gaps in the literature. Authors conclude that there is a shortage of primary interventional studies examining the effect of lifestyle interventions in high-risk pregnant populations who enter pregnancy with chronic conditions.
Abstract
BACKGROUND Pregnant people with chronic hypertension, pre-existing diabetes or both are at high risk of developing cardiovascular disease. Lifestyle interventions play an important role in disease management in non-pregnant populations. AIM: To review the existing evidence of randomised controlled trials (RCTs) that examine lifestyle interventions in pregnant people with chronic hypertension and/or pre-existing diabetes. METHODS A systematic review and narrative synthesis was conducted. Five electronic databases were searched from inception to April 2021 for RCTs evaluating antenatal lifestyle interventions in people with chronic hypertension and/or pre-existing diabetes with outcomes to include weight or blood pressure change. RESULTS Nine randomised controlled trials including 7438 pregnant women were eligible. Eight studies were mixed pregnant populations that included women with chronic hypertension and/or pre-existing diabetes. One study included only pregnant women with pre-existing diabetes. Intervention characteristics and procedures varied and targeted diet, physical activity and/or gestational weight. All studies reported weight and one study reported blood pressure change. Outcome data were frequently unavailable for the subset of women of interest, including subgroup data on important pregnancy and birth complications. Eligibility criteria were often ambiguous and baseline data on chronic hypertension was often omitted. CONCLUSION A lack of primary interventional trials examining the effect of lifestyle interventions on weight and blood pressure outcomes in pregnant populations with chronic hypertension and/or pre-existing diabetes was evident. Lifestyle modification has the potential to alter disease progression. Future trials should address the ambiguity and frequent exclusion of these important populations.
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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
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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.