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Coffee Consumption and Risk of Hypertension in Adults: Systematic Review and Meta-Analysis.
Haghighatdoost, F, Hajihashemi, P, de Sousa Romeiro, AM, Mohammadifard, N, Sarrafzadegan, N, de Oliveira, C, Silveira, EA
Nutrients. 2023;15(13)
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High blood pressure (hypertension) is the main risk factor for cardiovascular diseases. Over the past decades the number of people experiencing high blood pressure has steadily increased, making it a serious concern for public health. Many dietary factors influence the development of high blood pressure, either increasing of decreasing the risk. Coffee is a widely consumed beverage. The caffeine in coffee can stimulate stress hormones like adrenaline. Adrenaline increases blood pressure, inflammation and decreases sensitivity to insulin, which are all regarded as risk factors for cardiovascular diseases. At the same time coffee contains many blood pressure lowering nutrients and compounds. Whether coffee contributes or diminishes the risks of developing high blood pressure has remained controversial. Hence, this systematic review and meta-analysis aimed to summarise the current evidence on coffee and hypertension risk. The analysis included 25 observational studies published between 2002 and 2023. The results concluded that coffee consumption was associated with a small reduction in risk for high blood pressure development. An inverse association was found, suggesting that as coffee consumption rose, high blood pressure risk falls. However, upon closer examination this inverse relationship was only found in the USA, but not in Europe and Asia. The authors suggested that geographics, genetics, gender, coffee preparation methods, and differences in lifestyle habits (smoking, salt consumption etc.) may contribute to the discrepancies between outcomes and make it harder to compare studies to form a uniform consensus. Hence, they urged for a cautious interpretation of the findings. In the absence of clear, consistent evidence, coffee consumption and cardiovascular risk may need to be assessed on an individual basis in clinical practice.
Abstract
OBJECTIVES The association between coffee intake and hypertension (HTN) risk is controversial. Therefore, this systematic review and meta-analysis aimed at summarizing the current evidence on the association of coffee with hypertension risk in observational studies. METHODS PubMed/Medline and Web of Science were searched for observational studies up to February 2023. Observational studies which assessed the risk of HTN in the highest category of coffee consumption in comparison with the lowest intake were included in the current meta-analysis (registration number: CRD42022371494). The pooled effect of coffee on HTN was evaluated using a random-effects model. RESULTS Twenty-five studies i.e., thirteen cross-sectional studies and twelve cohorts were identified to be eligible. Combining 13 extracted effect sizes from cohort studies showed that higher coffee consumption was associated with 7% reduction in the risk of HTN (95% CI: 0.88, 0.97; I2: 22.3%), whereas combining 16 effect sizes from cross-sectional studies illustrated a greater reduction in HTN risk (RR = 0.79, 95% CI: 0.72, 0.87; I2 = 63.2%). These results varied by studies characteristics, such as the region of study, participants' sex, study quality, and sample size. CONCLUSIONS An inverse association was found between coffee consumption and hypertension risk in both cross-sectional and cohort studies. However, this association was dependent on studies characteristics. Further studies considering such factors are required to confirm the results of this study.
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Effect of vitamin E on Semen Quality Parameters: A Meta-Analysis of a Randomized Controlled Trial.
Wang, R, Wang, S, Song, Y, Zhou, H, Pan, Y, Liu, L, Niu, S, Liu, X
Urology journal. 2022;19(5):343-351
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The incidence of male infertility is increasing year by year. The mechanism of male infertility is complex. One of the important causes of male infertility is the decline in semen quality. The aim of this study was to evaluate the effectiveness of oral vitamin E in improving semen quality. This study is a meta-analysis of eight articles with a total of 459 patients, including 238 cases in the experimental group and 221 cases in the control group. Results show that oral vitamin E treatment could significantly increase the total sperm count and reduce the volume of semen. It was further found that oral vitamin E treatment for up to 6 months could improve the forward motility of sperm but not for 3 months. Authors conclude that vitamin E could increase the total sperm count and reduce the volume of semen in male infertility patients.
Abstract
PURPOSE To explore the effectiveness of vitamin E in male infertility, a systematic review and meta-analysis was conducted. MATERIALS AND METHODS The retrieval time was from January 1947 to May 2021, without language restriction. Stata 12.0 was used for the meta-analysis. RESULTS A total of 8 randomized controlled trials involving 459 patients were included. The results showed that after vitamin E treatment, semen volume was reduced (95% CI: - 0.55 to - 0.06, SMD = - 0.30, p = 0.015), total sperm count was increased (95% CI: 0.02-0.45, SMD = 0.23, p = 0.035), and the differences were statistically significant. There were no statistically significant differences in increasing sperm concentration (95% CI: -0.21-0.29, SMD = 0.04, p = 0.769), total sperm motility (95% CI: -0.01-0.42, SMD = 0.20, p = 0.061) or sperm forward motility rate (95% CI: -0.06-0.65, SMD = 0.29, p = 0.106). Subgroup analysis showed that vitamin E treatment for six months could improve sperm forward motility (95% CI: 0.46-1.14, SMD = 0.80, p <0.001). CONCLUSION Vitamin E could increase the total sperm count and reduce the volume of semen in male infertility patients, and long-term treatment could improve the forward motility rate of sperm. The decrease of semen volume may be the result of different abstinence time before and after the test.
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Selenium, antioxidants, cardiovascular disease, and all-cause mortality: a systematic review and meta-analysis of randomized controlled trials.
Jenkins, DJA, Kitts, D, Giovannucci, EL, Sahye-Pudaruth, S, Paquette, M, Blanco Mejia, S, Patel, D, Kavanagh, M, Tsirakis, T, Kendall, CWC, et al
The American journal of clinical nutrition. 2020;112(6):1642-1652
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Oxidative damage is a shared characteristic in chronic diseases such as cardiovascular disease (CVD), diabetes, cancer and ageing. Antioxidants mitigate the impact of oxidants and have been widely investigated in ageing and disease. However, the evidence for supplementary antioxidants has been mixed and some authorities have advised against the use of certain single nutrients for the prevention of CVD or cancer. This systematic review and meta-analysis focused on selenium due to its vital role in the antioxidant system and associations of low selenium blood levels with increased risk of CVD, cancers and death. The study included 43 randomised controlled trials (RCTs) evaluating the effect of supplemental selenium and antioxidants with or without selenium and their impact on CVD risk, cancer and all-cause mortality. Overall supplemental selenium or antioxidants alone did not seem to be associated with CVD outcomes, cancer, CVD and cancer mortality, or all-cause mortality. On close examination, a decreased risk was seen for CVD mortality when antioxidants were combined with selenium, whilst antioxidant mixtures without selenium demonstrated an increased risk in all-cause mortality. The findings did not seem to be influenced by dietary selenium intake. The authors suggested that inclusion of selenium as part of an antioxidant mix could be key for an antioxidant associated risk reduction. However, in the absence of further long term studies, a balanced antioxidant-rich diet was advocated as the safest approach. In clinical practice, where antioxidant support beyond diet is warranted, supplemental antioxidant use should be concurrent with adequate selenium supplementation, with dose benefits of 50-200mcg observed.
Abstract
BACKGROUND Antioxidants have been promoted for cardiovascular disease (CVD) risk reduction and for the prevention of cancer. Our preliminary analysis suggested that only when selenium was present were antioxidant mixtures associated with reduced all-cause mortality. OBJECTIVE We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to determine the effect of selenium supplementation alone and of antioxidant mixtures with or without selenium on the risk of CVD, cancer, and mortality. METHODS We identified studies using the Cochrane Library, Medline, and Embase for potential CVD outcomes, cancer, and all-cause mortality following selenium supplementation alone or after antioxidant supplement mixtures with and without selenium up to June 5, 2020. RCTs of ≥24 wk were included and data were analyzed using random-effects models and classified by the Grading of Recommendations, Assessment, Development, and Evaluation approach. RESULTS The meta-analysis identified 9423 studies, of which 43 were used in the final analysis. Overall, no association of selenium alone or antioxidants was seen with CVD and all-cause mortality. However, a decreased risk with antioxidant mixtures was seen for CVD mortality when selenium was part of the mix (RR: 0.77; 95% CI: 0.62, 0.97; P = 0.02), with no association when selenium was absent. Similarly, when selenium was part of the antioxidant mixture, a decreased risk was seen for all-cause mortality (RR: 0.90; 95% CI: 0.82, 0.98; P = 0.02) as opposed to an increased risk when selenium was absent (RR: 1.09; 95% CI: 1.04, 1.13; P = 0.0002). CONCLUSION The addition of selenium should be considered for supplements containing antioxidant mixtures if they are to be associated with CVD and all-cause mortality risk reduction. This trial was registered at https://www.crd.york.ac.uk/PROSPERO/ as CRD42019138268.