Causal relationship between tea intake and cardiovascular diseases: A Mendelian randomization study

Mediators of the association between nut consumption and cardiovascular diseases: a two-step mendelian randomization study

Previous observational studies have reported inconsistent associations between nut consumption and cardiovascular diseases (CVD). This study aims to identify the causal relationship between different types of nuts consumption and CVD, and to quantify the potential mediating effects of cardiometabolic factors. We utilized Genome-Wide Association Study (GWAS) data to assess the causal effects of nut consumption on CVD using two-sample Mendelian randomization (MR) and a two-step MR analysis. The inverse variance weighted (IVW) method indicated that processed (salted or roasted) peanuts were potentially and positively associated with ischaemic heart disease (IHD) (OR 1.4866; 95%CI 1.0491-2.1065). No causal relationships were found between nuts consumption and other CVD outcomes, including atrial fibrillation, angina, coronary atherosclerosis, coronary heart disease, IHD, myocardial infarction, subarachnoid hemorrhage, intracerebral haemorrhage and stroke. Both MR-Egger and median-based methods yielded similar results to IVW. Furthermore, in the two-step MR analysis, fasting insulin, low-density lipoprotein cholesterol and fasting blood glucose were identified as mediators in the potential causal relationship between processed peanuts and IHD, explaining 16.98%, 6.38% and 4.91% of the mediation, respectively. In total, these mediators accounted for 28.27% of the association between salted or roasted peanuts and IHD.

Navigating the redox landscape: reactive oxygen species in regulation of cell cycle

Objectives: To advance our knowledge of disease mechanisms and therapeutic options, understanding cell cycle regulation is critical. Recent research has highlighted the importance of reactive oxygen species (ROS) in cell cycle regulation. Although excessive ROS levels can lead to age-related pathologies, ROS also play an essential role in normal cellular functions. Many cell cycle regulatory proteins are affected by their redox status, but the precise mechanisms and conditions under which ROS promote or inhibit cell proliferation are not fully understood.Methods: This review presents data from the scientific literature and publicly available databases on changes in redox state during the cell cycle and their effects on key regulatory proteins.Results: We identified redox-sensitive targets within the cell cycle machinery and analysed different effects of ROS (type, concentration, duration of exposure) on cell cycle phases. For example, moderate levels of ROS can promote cell proliferation by activating signalling pathways involved in cell cycle progression, whereas excessive ROS levels can induce DNA damage and trigger cell cycle arrest or cell death.Discussion: Our findings encourage future research focused on identifying redox-sensitive targets in the cell cycle machinery, potentially leading to new treatments for diseases with dysregulated cell proliferation.

Effect of tea consumption on the development of hypertension, diabetes, and obesity: a bidirectional two-sample Mendelian randomization analysis

Background

The effect of tea consumption on conditions such as hypertension, diabetes, and obesity has attracted significant global interest. However, the results of various studies on this topic have been mixed and somewhat contentious. Therefore, we conducted a Mendelian randomization (MR) analysis to investigate the causal relationships between tea consumption and the aforementioned health conditions.

Methods

A bidirectional two-sample MR analysis was used to systematically explores the associations between tea consumption and hypertension, diabetes, and obesity. MR-Egger regression, weighted median, inverse variance weighted, and weighted mode methods were used to evaluate the potential causal associations. Leave-one-out sensitivity test was used to check the robustness of the IVW estimates.

Results

MR analysis indicated that genetically predicted tea consumption is associated with a protective effect against hypertension, with an odds ratio (OR) of 0.78 and a 95% confidence interval (CI) ranging from 0.64 to 0.95. Additionally, tea consumption appeared to have a potential protective effect on type 2 diabetes and obesity related to excessive calorie intake, influenced by specific single nucleotide polymorphisms (SNPs), namely "rs57462170" and "rs17685." No causal link was observed between the consumption of green or herbal tea and hypertension, diabetes, or obesity. However, there was a marginal negative association between type 2 diabetes and tea consumption and (OR = 0.99; 95% CI: 0.97-1.00) and a significant negative correlation between obesity due to excessive calorie intake and green tea consumption (OR = 0.35; 95% CI: 0.16-0.78).

Conclusion

This study demonstrates a protective causal relationship between the consumption of tea (including black and green teas) and reduced risk of hypertension. Furthermore, our results suggest that tea intake may also have a protective effect on type 2 diabetes and obesity. The results recommend further research to verify or refine these findings.

Causal relationship between serum uric acid and cardiovascular disease: A Mendelian randomization study

Background

Observational studies have established an association between serum uric acid and cardiovascular disease (CVD). However, these studies are susceptible to uncontrolled confounders and reverse causality bias. To overcome these challenges, we employed a two-sample Mendelian randomization (MR) approach to investigate the causal link between serum uric acid and CVD.

Methods

We utilized Genome-wide association study (GWAS) data for serum uric acid and six CVD: coronary artery disease (CAD), hypertension, myocardial infarction (MI), heart failure (HF), angina, and coronary heart disease (CHD). MR analyses employed inverse variance weighting (IVW), MR-Egger, weighted median, and weighted model. Sensitivity analyses were conducted to assess result reliability, including Cochrane's Q test, MR-Egger intercept, MR-PRESSO, and the leave-one-out approach.

Results

IVW analysis revealed that a genetic predisposition to elevated serum uric acid levels significantly increases the risk of CVD, with higher odds ratios (ORs) observed for CAD (OR: 1.227; 95 % CI: 1.107-1.360, P = 0.0002), hypertension (OR: 1.318, 95 %CI: 1.184-1.466, P = 2.13E-06), MI (OR: 1.184, 95 %CI: 1.108-1.266, P = 2.13E-06), HF (OR: 1.158, 95 %CI: 1.066-1.258, P = 2.13E-06), angina (OR: 1.150, 95 %CI: 1.074-1.231, P = 0.0002) and CHD (OR: 1.170, 95 %CI: 1.072-1.276, P = 0.0005). Sensitivity analysis research results have robustness.

Conclusion

This MR study robustly demonstrates a significant causal relationship between genetically elevated serum uric acid and various cardiovascular diseases, suggesting that higher levels may enhance the risk of cardiovascular events. Consequently, patients with elevated uric acid levels warrant early and aggressive interventions to mitigate cardiovascular risks.

Unraveling tea and coffee consumption effects on cardiovascular diseases risk factors: A narrative review

Backgrounds and Aims

Daily lifestyle plays a vital role in modifying the risk for cardiovascular diseases (CVDs). Our daily life isn't inseparable from nutrition intake. As such, tea and coffee are often regarded as the most consumed beverages worldwide. There have been a lot of debates on the adverse effects and benefits of consuming these popular beverages. This comprehensive review explores the different types of tea and coffee and their mechanism of action. It delves deeper into their roles in reducing CVD risk, aiding CVD recovery, lowering CVD mortality, and their varying effects across populations and regions.

Methods

An extensive literature search was conducted on PubMed. Relevant articles were identified through cross-referencing and manual searches. Excluded from the study were commentaries, case reports, clinical vignettes, and non-English articles.

Results

Tea and coffee contain varying levels of caffeine and other bioactive compounds with cardioprotective effects against oxidative stress, inflammation, and more. Genetic factors further modulate their effects. Tea flavonoids benefit cholesterol, blood pressure, and endothelial function, while coffee constituents impact oxidative stress, metabolism, insulin sensitivity, and gut flora. Moderate consumption of both beverages may offer cardiovascular benefits, but outcomes vary depending on populations and conditions. Tea and coffee consumption may influence CVD recovery by reducing mortality and improving survival, however, it must be noted that it has the potential to be harmful to some individuals.

Conclusion

Evidence suggests that moderate consumption of these beverages may be linked to reduced cardiovascular mortality, although individual characteristics and pre-existing conditions can influence outcomes. Excessive caffeine consumption, found in both beverages, may pose risks such as arrhythmias, hypertension, and cardiovascular mortality in CVD patients, with a dose-dependent nature. Future research should delve into mechanisms, genetic factors, and diverse cultural impacts of its use. Health care providers should consider individual characteristics when advising on tea and coffee consumption in the context of cardiovascular health.

Genetic liability to human serum metabolites is causally linked to telomere length: insights from genome-wide Mendelian randomization and metabolic pathways analysis

Background

Telomere has been recognized as a biomarker of accelerating aging, and telomere length (TL) shortening is closely related to diverse chronic illnesses. Human serum metabolites have demonstrated close correlations with TL maintenance or shortening in observational studies. Nevertheless, little is known about the underlying pathological mechanisms, and Mendelian randomization (MR) analysis of serum metabolites may provide a more comprehensive understanding of the potential biological process.

Methods

We employed a two-sample MR analysis method to assess the causal links between 486 serum metabolites and TL. We applied the inverse-variance weighted (IVW) approach as our primary analysis, and to assure the stability and robustness of our results, additional analysis methods including the weighted median, MR-Egger, and weighted mode were conducted. MR-Egger intercept test was utilized to detect the pleiotropy. Cochran's Q test was implemented to quantify the extent of heterogeneity. Furthermore, the pathway analysis was conducted to identify potential metabolic pathways.

Results

We identified 11 known blood metabolites associated with TL. Among these metabolites, four were lipid (taurocholate, dodecanedioate, 5,8-tetradecadienoate, and 15-methylpalmitate), one amino acid (levulinate (4-oxovaleate)), one carbohydrate (lactate), one nucleotide (pseudouridine), one energy (phosphate), and three xenobiotics (2-hydroxyacetaminophen sulfate, paraxanthine, and ergothioneine). The known protective metabolites included levulinate (4-oxovaleate), dodecanedioate, 5,8-tetradecadienoate, lactate, phosphate, paraxanthine, and ergothioneine. Multiple metabolic pathways have been identified as being implicated in the maintenance of telomere length.

Conclusion

Our MR analysis provided suggestive evidence supporting the causal relationships between 11 identified blood metabolites and TL, necessitating further exploration to clarify the mechanisms by which these serum metabolites and metabolic pathways may affect the progression of telomeres.

Genetically predicted lipid traits mediate the association between folic acid and atherosclerosis

Atherosclerosis (AS) is one of the most common causes of death from cardiovascular disease, and low folic acid (FA) levels have been reported to be strongly associated with an increased risk of AS. We aimed to obtain causal estimates of the association between FA and AS and to quantify the mediating role of known modifiable risk factors. Based on the largest genome-wide association study (GWAS) from the IEU Open GWAS Project for all human studies, we conducted a two-sample Mendelian randomization (MR) study of genetically predicted FA and AS. A two-step MR design was then used to assess the causal mediating effect of low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG) on the relationship between FA and AS. This MR analysis showed that genetically determined FA levels [IVW: Odds Ratio (OR) = 0.623, 95% CI 0.421-0.924, P = 0.018] were associated with a reduced risk of AS. Inverse variance weighted (IVW) MR analysis also showed that genetically predicted FA was positively correlated with HDL-C levels (OR = 1.358, 95% CI 1.029-1.792, P = 0.031) and negatively correlated with LDL-C (OR = 0.956, 95% CI 0.920-0.994, P = 0.023) and TG levels (OR = 0.929, 95% CI 0.886-0.974, P = 0.003). LDL-C, HDL-C, and TG mediate 3.00%, 6.80%, and 4.40%, respectively, of the total impact of FA on AS. The combined effect of these three factors accounts for 13.04% of the total effect. Sensitivity analysis verifies the stability and reliability of the results. These results support a potential causal protective effect of FA on AS, with considerable mediation through many modifiable risk factors. Thus, interventions on levels of LDL-C, HDL-C, and TG have the potential to substantially reduce the burden of AS caused by low FA.

Assessing the association between tea intake and risk of dental caries and periodontitis: a two-sample Mendelian randomization study

Tea is an indispensable beverage in people's daily life. However, the relationship between tea intake and dental caries and periodontitis is controversial. We extracted datasets for tea intake and oral diseases from genome-wide association studies (GWASs) conducted by the UK Biobank and the Gene Lifestyle Interactions in Dental Endpoints consortium. We selected 38 single-nucleotide polymorphisms (SNPs) significantly associated with tea intake as instrumental variables (IVs) (P < 5.0 × 10-8). Mendelian randomization (MR) was performed to investigate the potential causality between tea intake and caries and periodontitis. Multivariable Mendelian randomization (MVMR) analyses were utilized to estimate causal effects of tea intake on risk of caries and periodontitis after adjusting for smoking, body mass index (BMI), and socioeconomic factors. The results showed that higher tea intake was suggestively associated with fewer natural teeth (β = - 0.203; 95% CI = 0.680 to 0.980; P = 0.029) and higher risk of periodontitis (OR = 1.622; 95% CI = 1.194 to 2.205; P = 0.002). After Bonferroni correction, the causality of tea intake on periodontitis remained significant. The significance of periodontitis disappeared after adjusting for the socioeconomic factors in MVMR (OR = 1.603; 95% CI = 0.964 to 2.666; P = 0.069). Tea intake had no association with risk of caries. Statistical insignificance of the heterogeneity test and pleiotropy test supported the validity of the MR study. Our results provide insight into the potential relationship between tea intake and oral diseases from a dietary lifestyle perspective, which may help prevent oral diseases.

Circulating vitamin levels mediate the causal relationship between gut microbiota and cholecystitis: a two-step bidirectional Mendelian randomization study

Background

The relationship between gut microbiota and the occurrence of cholecystitis remains unclear. Existing research lacks a clear understanding of how circulating vitamin levels modulate this relationship. Therefore, our study aims to investigate whether circulating vitamin levels mediate the causal relationship between gut microbiota and cholecystitis using a two-step bidirectional Mendelian randomization approach.

Methods

In this study, we initially employed Linkage Disequilibrium Score Regression (LDSC) analysis to assess the genetic correlation of five circulating vitamin level genome-wide association study (GWAS) summary datasets, thereby avoiding potential sample overlap. Subsequently, we conducted a two-step analysis to investigate the causal effects between gut microbiota and cholecystitis. In the second step, we explored the causal relationship between circulating vitamin levels and cholecystitis and identified the mediating role of vitamin D. The primary method used for causal analysis was the inverse variance-weighted approach. We performed additional sensitivity analyses to ensure result robustness, including the cML-MA method and reverse Mendelian randomization (MR) analysis.

Results

An increment of one standard deviation in RuminococcaceaeUCG003 was associated with a 25% increased risk of cholecystitis (OR = 1.25, 95%CI = 1.01-1.54, p = 0.04), along with a 3% decrease in 25-hydroxyvitamin D levels (OR = 0.97, 95%CI = 0.944-0.998, p = 0.04). However, following the rigorous Bonferroni correction, every one standard deviation decrease in circulating vitamin D levels was associated with a 33% increased risk of cholecystitis (OR = 0.67, 95%CI = 0.49-0.90, p = 0.008, Padjust = 0.04). Thus, the potential link between gut microbiota and cholecystitis risk might be mediated by circulating vitamin D levels (proportion mediated = 5.5%). Sensitivity analyses provided no evidence of pleiotropy.

Conclusion

Our study results suggest that an elevated abundance of specific gut microbiota is associated with an increased susceptibility to cholecystitis, with the causal relationship being mediated by circulating vitamin D levels. Further large-scale randomized controlled trials are necessary to validate the causal effects of gut microbiota on cholecystitis risk. This study provides novel insights into cholecystitis prevention through the regulation of gut microbiota.

Noncausal effects between tea intake and migraine risk: a Mendelian randomization study

Observational studies have yielded conflicting results regarding the relationship between tea intake and migraine risk. Residual confounders and potential reverse causality are unavoidable in traditional observational studies. To provide evidence for establishing viable disease screening and prevention strategies, a Mendelian randomization study (MR) was conducted to determine the causal inference between tea intake and migraine. We obtained 28 single-nucleotide polymorphisms (SNPs) for any migraine (AM), 25 SNPs for migraine with aura (MA), and 27 SNPs for migraine without aura (MO) associated with tea intake derived from a large genome-wide association study (GWAS) of the UK Biobank (UKBB) (containing 447,485 samples). The largest migraine GWAS performed by the International Headache Genetics Consortium (IHGC), including 29,209 cases and 172,931 controls, provided data on migraines and their subtypes (MA and MO). We used the method of inverse variance weighting (IVW) with fixed effects as the first-string MR selection. Sensitivity analysis and MR-pleiotropy residual sum and outlier (MR-PRESSO) method further assessed the robustness of the findings. Based on the conclusion of IVW in the fixed effects model, we found that tea intake had no causal relationship with AM risk (odds ratio (OR), 0.94; 95% confidence interval (CI), 0.70-1.25; P = 0.65), MA risk (OR, 0.93; 95% CI, 0.51-1.72; P = 0.83), or MO risk (OR, 0.90; 95% CI, 0.52-1.54; P = 0.69). Sensitivity analyses and MR-PRESSO showed no directional pleiotropy or heterogeneity. Our two-sample MR investigation found no causality between tea intake and migraine risk in European populations, implying that attempts to change tea drinking habits may not lead to a reduced risk of migraine.

Causal associations of tea intake with COVID-19 infection and severity

Tea ingredients can effectively inhibit SARS-CoV-2 infection at adequate concentrations. It is not known whether tea intake could impact the susceptibility to COVID-19 or its severity. We aimed to evaluate the causal effects of tea intake on COVID-19 outcomes. We performed Mendelian randomization (MR) analyses to assess the causal associations between tea intake (N = 441,279) and three COVID-19 outcomes, including SARS-CoV-2 infection (122,616 cases and 2,475,240 controls), hospitalized COVID-19 (32,519 cases and 2,062,805 controls), and critical COVID-19 (13,769 cases and 1,072,442 controls). The MR analyses indicated that genetic propensity for tea consumption conferred a negative causal effect on the risk of SARS-CoV-2 infection (OR: 0.87, 95% confidence interval (CI): 0.78-0.97, P = 0.015). No causal effects on hospitalized COVID-19 (0.84, 0.64-1.10, P = 0.201) or critical COVID-19 (0.73, 0.51-1.03, P = 0.074) were detected. Our study revealed that tea intake could decrease the risk of SARS-CoV-2 infection, highlighting the potential preventive effect of tea consumption on COVID-19 transmission.