Dairy consumption, systolic blood pressure, and risk of hypertension: Mendelian randomization study

The association of smoking on the increased risk of osteoporotic fracture: Results from a cross-sectional study and two-sample Mendelian randomization

INTRODUCTION

We conducted analyses of the association between smoking and osteoporosis and osteoporotic fractures using a secondary dataset analysis of the National Health and Nutrition Examination Survey (NHANES) database and the two-sample Mendelian randomization (MR) method.

METHODS

The associations between smoking and osteoporosis or osteoporotic fractures were analyzed using weighted logistic regression models for both univariate and multivariable analyses using pooled 1999-2018 NHANES data. The summary-level data of genome-wide association studies (GWAS) of smoking and osteoporosis were extracted from the IEU Open GWAS project. The inverse variance weighted method was used as the main method for the two-sample MR analysis.

RESULTS

We obtained the following main findings based on the NHANES data: smoking was associated with osteoporosis according to the analyses of 30856 participants (OR=1.21; 95% CI: 1.06-1.39, p=0.004); smoking was associated with hip osteoporotic fracture according to the analyses of 30928 participants (OR=1.47; 95% CI: 1.14-1.90, p=0.004); smoking was associated with wrist osteoporotic fracture according to the analyses of 30923 participants (OR=1.33; 95% CI: 1.18-1.49, p<0.001); and smoking was associated with spine osteoporotic fracture according to the analyses of 30910 participants (OR=1.43, 95% CI: 1.18-1.73, p<0.001). In addition, we confirmed the potential causal effect of smoking on the risk of osteoporotic fracture (OR=24.5; 95% CI: 1.11-539, p=0.043) by conducting two-sample MR analyses.

CONCLUSIONS

Smoking was associated with increased risks of both osteoporosis and osteoporotic fracture. Smoking showed a potential causal effect on the risk of osteoporotic fracture.

Evaluating agreement between evidence from randomised controlled trials and cohort studies in nutrition: a meta-research replication study

This meta-research study aims to evaluate the agreement of effect estimates between bodies of evidence (BoE) from RCTs and cohort studies included in the same nutrition evidence synthesis, to identify factors associated with disagreement, and to replicate the findings of a previous study. We searched Medline, Epistemonikos and the Cochrane Database of Systematic Reviews for nutrition systematic reviews that included both RCTs and cohort studies for the same patient-relevant outcome or intermediate-disease marker. We rated similarity of PI/ECO (population, intervention/exposure, comparison, outcome) between BoE from RCTs and cohort studies. Agreement of effect estimates across BoE was analysed by pooling ratio of risk ratios (RRR) for binary outcomes and difference of standardised mean differences (DSMD) for continuous outcomes. We performed subgroup and sensitivity analyses to explore determinants associated with disagreements. We included 82 BoE-pairs from 51 systematic reviews. For binary outcomes, the RRR was 1.04 (95% confidence interval (CI) 0.99 to 1.10, I2 = 59%, τ2 = 0.02, prediction interval (PI) 0.77 to 1.41). For continuous outcomes, the pooled DSMD was  - 0.09 (95% CI  - 0.26 to 0.09, PI  - 0.55 to 0.38). Subgroup analyses yielded that differences in type of intake/exposure were drivers towards disagreement. We replicated the findings of a previous study, where on average RCTs and cohort studies had similar effect estimates. Disagreement and wide prediction intervals were mainly driven by PI/ECO-dissimilarities. More research is needed to explore other potentially influencing factors (e.g. risk of bias) on the disagreement between effect estimates of both BoE.Trial registration: CRD42021278908.

Associations between obesity and hyperuricemia combing mendelian randomization with network pharmacology

Objective

Obesity has become a global health issue and a risk factor for hyperuricemia. However, the associations between obesity and hyperuricemia are sometimes confounding. In the present study, we performed mendelian randomization (MR) analysis to study their relationship and investigate the underlying mechanism by network pharmacology.

Method

Body mass index (BMI) and uric acid related to single nucleotide polymorphism were selected as instrumental variables for MR analysis. Three robust analytical methods are used for bidirectional MR analysis such as inverse-variance weighting, weighted median and MR-Egger regression. Then, we further performed sensitivity analysis to evaluate the horizontal pleiotropy, heterogeneities, and stability. The targets related to obesity and hyperuricemia were collected, screened and further conducted for Kyoto Encyclopedia of Genes and Genomes pathway enrichment to explore the mechanism of obesity and hyperuricemia using network pharmacology.

Results

The positive causality was indicated between BMI and hyperuricemia based on inverse variance-weighted analysis [odds ratio:1.23, 95% confidence interval: 1.11 to 1.30 for each standard deviation increase in BMI (4.6 kg/m2)]. Conversely, hyperuricemia did not influence BMI. 235 intersected targets from obesity and hyperuricemia were collected. Insulin resistance were the top 1 key target. The mechanism between obesity and hyperuricemia are associated with important pathways including adipocytokine signaling pathway, insulin resistance and cholesterol metabolism et al.

Conclusions

Our MR analysis supported the causal association between obesity and hyperuricemia based on availablegenome-wide association analysis summary statistics. Obesity leads to hyperuricemia via insulin resistance, which is a key link in the huge network pathways using network pharmacology.

Association of consumption of sugar-sweetened beverages with elevated blood pressure among college students in Yunnan Province, China

OBJECTIVE

Although some studies have examined the association between eating behaviour and elevated blood pressure (EBP) in adolescents, current data on the association between sugar-sweetened beverages (SSB) and EBP in adolescents in Yunnan Province, China, are lacking.

SETTING

Cluster sampling was used to survey freshmen at a college in Kunming, Yunnan Province, from November to December. Data on SSB consumption were collected using an FFQ measuring height, weight and blood pressure. A logistic regression model was used to analyse the association between SSB consumption and EBP, encompassing prehypertension and hypertension with sex-specific analyses.

PARTICIPANTS

The analysis included 4781 college students.

RESULTS

Elevated systolic blood pressure (SBP) and diastolic blood pressure (DBP) were detected in 35·10 % (1678/4781) and 39·34 % (1881/4781) of patients, respectively. After adjusting for confounding variables, tea beverage consumption was associated with elevated SBP (OR = 1·24, 95 % CI: 1·03, 1·49, P = 0·024), and carbonated beverage (OR = 1·23, 95 % CI: 1·04, 1·45, P = 0·019) and milk beverage (OR = 0·81, 95 % CI: 0·69, 0·95, P = 0·010) consumption was associated with elevated DBP in college students. Moreover, fruit beverage (OR = 1·32, 95 % CI: 1·00, 1·75, P = 0·048) and milk beverage consumption (OR = 0·69, 95 % CI: 0·52, 0·93, P = 0·014) was associated with elevated DBP in males.

CONCLUSION

Our findings indicated that fruit and milk beverage consumption was associated with elevated DBP in males, and no association was observed with EBP in females.

Different types of milk consumption and the risk of dementia: Analysis from a large-scale cohort study

BACKGROUND & AIMS

Previous studies have investigated whether milk consumption has a role in preventing the development of cognitive impairment, but the results were inconsistent. Importantly, most of them have disregarded the role of different types of milk. This study aimed to examine the associations between different types of milk consumption and the risk of dementia.

METHODS

In this large-scale cohort study, participants without cognitive impairment at baseline were included from the UK Biobank. The type of milk mainly used was self-reported at baseline, including full-cream milk, skimmed-milk, soy milk, other milk, and no milk. The primary outcome was all-cause dementia. Secondary outcomes included Alzheimer's disease and vascular dementia.

RESULTS

Of the 307,271 participants included in the study (mean age 56.3 [SD 8.1] years), 3789 (1.2%) incident all-cause dementia cases were observed over a median follow-up of 12.3 years. After adjustment for potential confounders, only soy milk consumers had a statistically significantly lower risk of all-cause dementia compared with no milk consumers (hazard ratio [HR], 0.69; 95% confidence interval [CI], 0.54 to 0.90). When compared with soy milk non-consumers consisting of full-cream milk, skimmed-milk, and other milk consumers, soy milk consumers still showed a lower risk of all-cause dementia (HR, 0.76; 95% CI, 0.63 to 0.92), and there was no significant interaction with genetic risk for dementia (P for interaction = 0.15). Soy milk consumers showed a lower risk of Alzheimer's disease (HR, 0.70; 95% CI, 0.51 to 0.94; P = 0.02), while the association was not significant for vascular dementia (HR, 0.72; 95% CI, 0.47 to 1.12; P = 0.14).

CONCLUSIONS

The main consumption of soy milk was associated with a lower risk of dementia, particularly non-vascular dementia. Additional studies are needed to investigate how this association varies with the dose or frequency of the consumption of soy milk and to examine the generalizability of these findings in different populations.

The relationship between the intake of fruits, vegetables, and dairy products with hypertension: findings from the STEPS study

BACKGROUND

The current research aimed to evaluate the relationship between fruit, vegetable (FV), and dairy consumption with the odds of developing hypertension based on nationwide Stepwise approach to surveillance (STEPS) data in Iran.

METHODS

This cross-sectional study was accomplished by the research center of non-communicable diseases (NCDs) in Tehran. In total, 29,378 individuals' data were analyzed. Participants were classified into normal, elevated BP, stage I, and stage II hypertension according to systolic blood pressure (SBP) and diastolic blood pressure (DBP) examinations. Based on the STEPS questionnaire, the consumption of FVs and dairy products was evaluated. Multinomial logistic regression was applied to assess the relationship between the consumption of FVs and dairy products with hypertension.

RESULTS

The findings revealed that only fruit consumption (≥ 2 servings/day) was negatively related to stage I hypertension (odds ratio (OR) = 0.81; 95% confidence interval (CI): 0.69-0.95) in two servings per day and OR = 0.81; 95% CI: 0.68-0.96 in > two servings per day) in the adjusted model. There was no significant relationship between consuming vegetables and dairy products with elevated BP and hypertension.

CONCLUSION

Our study showed that increasing fruit consumption was related to reducing hypertension odds. Regarding the consumption of dairy products and vegetables, no significant relationship was found with the odds of hypertension. More studies, especially cohorts, are needed to evaluate the impacts of FV and dairy products on the risk of hypertension.

A Retrospective Cohort Study of the Association Between Calcium Serum Level and Hypertension in Older Adults

INTRODUCTION

 One of the major global risk factors for cardiovascular morbidity and death is hypertension. Earlier research has been conducted on the connection between calcium consumption and blood pressure.

OBJECTIVE

This study aims to investigate the association between calcium serum levels and hypertension in older hypertensive adults.

METHODS

 A retrospective cohort study of 121 of hypertension patients was conducted in Prince Faisal Bin Khalid Cardiac Center. The data of all patients were collected by records, including lab, pathology, and medical review, in order to determine the effects on patients, providers, and institutions. Statistical analyses were performed using SPSS Statistics version 26.0. A p-value of <0.05 was considered statistically significant.

RESULTS

 The study included 121 adult hypertensive patients with a mean of age 60.29 ± 13.92. The majority of included patients were male (81%). More than one-third of patients were obese (39.7%), about one-third (33.9%) were overweight, and 26.4% of patients were in normal weight. The majority of patients had co-morbidities (68.3%); about one-half of them had diabetes mellitus (52.1%). The calcium level mean was 5.07 ± 1.26. The creatine kinase (CK) (initial day) mean ± SD was 813.22 ± 1146.37 became 221.4 ± 330.67 on the last day. The CK-myocardial band (CK-MB) (initial day) was 65.43 ± 118.9 and became 24.38 ± 23.26 on the last day. Additionally, the troponin (initial day) mean was 23.49 ± 104.26 and became 1.65 ± 2.66 on the last day. The most common discharge medications were anti-platelets (95%), beta-blockers (78.5%), statins (70.2%), and proton-pump inhibitors (PPI) (64.5%). The hospital stay days ranged from 1 to 20 days with a mean of 4.83 ± 3.38. The ICU stay days ranged from 1 to 15 days with a mean of 3.57 ± 2.72. Most of the patients (90.9%) improved.

CONCLUSION

There is no significant correlation between calcium levels in hypertensive patients and the demographic characteristics of patients, home or current medications, ECHO findings, or procedures done. However, there is a significant correlation between the calcium level and CK level among patients with hypertension. Further investigations are required to verify the relationship between CK and calcium levels in hypertensive patients.

Effects of dairy intake on markers of cardio-metabolic health in adults - a systematic review with network meta-analysis

Health effects of dairy products are still a matter of scientific debate due to inconsistent findings across trials. Therefore, this systematic review and network meta-analysis (NMA) aimed to compare the effects of different dairy products on markers of cardio-metabolic health. A systematic search was conducted in three electronic databases (MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science, search date: 23/09/2022). Randomized controlled trials (RCTs) were included with ≥12 week intervention comparing any two of the eligible interventions (e.g., high dairy [≥3 servings/day or equal amount in g/day], full-fat dairy, low-fat dairy, naturally fermented milk products, low dairy/control [0-2 servings/day or usual diet]). We performed pairwise meta-analysis and NMA using random-effects model in the frequentist framework for ten outcomes (body weight, BMI, fat mass, waist circumference, LDL-cholesterol, HDL-cholesterol, triglycerides, fasting glucose, glycosylated hemoglobin, systolic blood pressure). Continuous outcome data were pooled using mean difference (MD) and dairy interventions were ranked using the surface under the cumulative ranking curve (SUCRA). Nineteen RCTs with 1427 participants were included. High dairy intake (irrespective of fat content) showed no detrimental effects on anthropometric outcomes, blood lipids, and blood pressure. Both low-fat and full-fat dairy improved systolic blood pressure (MD: -5.22 to -7.60 mmHg; low certainty), but, concomitantly, may impair glycemic control (fasting glucose [MD: 0.31 to 0.43 mmol/L] and glycosylated hemoglobin [MD: 0.37 to 0.47%]). Full-fat dairy may increase HDL-cholesterol compared to a control diet (MD: 0.26 mmol/L, 95% confidence interval (CI): 0.03, 0.49). Yogurt improved waist circumference (MD: -3.47 cm, 95%CI: -6.92, -0.02; low certainty), triglycerides (-0.38 mmol/L, 95%CI: -0.73, -0.03; low certainty), and HDL-cholesterol (MD: 0.19 mmol/L, 95%CI: 0.00, 0.38) compared to milk. In conclusion, our findings indicate that there is little robust evidence that a higher dairy intake has detrimental effects on markers of cardio-metabolic health. (PROSPERO: CRD42022303198).

Evaluating the association between the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet, mental health, and cardio-metabolic risk factors among individuals with obesity

BACKGROUND

Several previous investigations have examined the brain-protective role of the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet. However, more knowledge is needed about the MIND diet's other favorable impacts. The purpose of this study was to examine the relationship between the MIND diet, mental health, and metabolic markers in individuals with obesity.

METHODS

In this cross-sectional study, we included 339 individuals with obesity (BMI ≥ 30 kg/m²) aged 20-50 years. We utilized a semi-quantitative Food Frequency Questionnaire (FFQ), we assessed dietary intake, including 168 food items, and calculated the value of MIND. Metabolic syndrome (MetS) was defined according to the National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III) guidelines. We assessed biochemical parameters using Enzymatic methods. Blood pressure and body composition were also determined.

RESULTS

Higher tertiles of the MIND diet score were associated with significantly higher energy intake, macronutrients, and brain-healthy food intakes (P < 0.001). Among the brain-unhealthy foods, only the intake of sweets and pastries was significantly lower in the highest versus lowest MIND tertiles. We also observed lower odds of stress (P < 0.05) and higher insulin sensitivity (P < 0.05) in the highest versus lowest MIND diet tertiles. We witnessed no significant changes in other parameters.

CONCLUSION

Lower stress levels and higher insulin sensitivity independent of some confounders like age, BMI, sex, and physical activity were associated with the highest tertile of MIND diet score.

Milk intake, lactase persistence genotype, plasma proteins and risks of cardiovascular events in the Swedish general population

To investigate the associations of milk intake (non-fermented and fermented milk), lactase persistence (LCT-13910 C/T) genotype (a proxy for long-term non-fermented milk intake), and gene-milk interaction with risks of cardiovascular disease (CVD) and CVD mortality. Also, to identify the CVD-related plasma proteins and lipoprotein subfractions associated with milk intake and LCT-13910 C/T genotype. The prospective cohort study included 20,499 participants who were followed up for a mean of 21 years. Dietary intake was assessed using a modified diet history method. Cox proportional hazards regression models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs). After adjusting for sociodemographic and lifestyle factors, higher non-fermented milk intake was significantly associated with higher risks of coronary heart disease (CHD) and CVD mortality, whereas higher fermented milk intake was significantly associated with lower risks of CVD and CVD mortality. The genotype associated with higher milk (mainly non-fermented) intake was positively associated with CHD (CT/TT vs. CC HR = 1.27; 95% CI: 1.03, 1.55) and CVD (HR = 1.22; 95% CI: 1.05, 1.42). The association between rs4988235 genotype and CVD mortality was stronger in participants with higher milk intake than among participants with lower intake (P for interaction < 0.05). Furthermore, leptin, HDL, and large HDL were associated with non-fermented milk intake, while no plasma proteins or lipoprotein subfractions associated with fermented milk intake and LCT-13910 C/T genotype were identified. In conclusion, non-fermented milk intake was associated with higher risks of CHD and CVD mortality, as well as leptin and HDL, whereas fermented milk intake was associated with lower risks of CVD and CVD mortality.

Consumption of Dairy Products and the Risk of Overweight or Obesity, Hypertension, and Type 2 Diabetes Mellitus: A Dose-Response Meta-Analysis and Systematic Review of Cohort Studies

Dairy products have been suggested to be related to the prevention of overweight or obesity, hypertension, and type 2 diabetes mellitus (T2DM). These associations are currently controversial, however, and a systematic quantitative meta-analysis is lacking. In this study, we examined the associations between dairy products and the risk of overweight or obesity, hypertension, and T2DM and tested for dose-response relations. We comprehensively searched PubMed, Embase, and Web of Science up to April 2021. Cohort studies were included if dairy food consumption was reported at a minimum of 3 levels or as continuous variables, and the associations were assessed with overweight or obesity, hypertension, and T2DM. Summary RRs and 95% CIs were estimated for the dose-response association. Restricted cubic splines were used to evaluate the linear or nonlinear relations. Among the 9887 articles retrieved, 42 articles were included. For overweight or obesity, a linear association was observed for total dairy, milk, and yogurt. The risk decreased by 25%, 7%, and 12% per 200-g/d increase for total dairy, high-fat dairy, and milk, respectively, and by 13% per 50-g/d increment of yogurt. For hypertension, a nonlinear association was observed with total dairy, whereas significant inverse associations were found for low-fat dairy (RR: 0.94; 95% CI: 0.90, 0.98) and milk (RR: 0.94; 95% CI: 0.92, 0.97) per 200-g/d intake increase. For T2DM, all types of dairy food consumption except for milk and low-fat dairy products showed nonlinear associations, with total dairy and yogurt intake associated with 3% and 7% lower risk per 200-g/d and 50-g/d intake increase, respectively. In conclusion, our study suggests that total dairy is associated with a low risk of overweight or obesity, hypertension, and T2DM, especially milk and yogurt for overweight or obesity, low-fat dairy and milk for hypertension, and yogurt for T2DM.

Milk intake and incident stroke and CHD in populations of European descent: a Mendelian randomisation study

Higher milk intake has been associated with a lower stroke risk, but not with risk of CHD. Residual confounding or reverse causation cannot be excluded. Therefore, we estimated the causal association of milk consumption with stroke and CHD risk through instrumental variable (IV) and gene-outcome analyses. IV analysis included 29 328 participants (4611 stroke; 9828 CHD) of the European Prospective Investigation into Cancer and Nutrition (EPIC)-CVD (eight European countries) and European Prospective Investigation into Cancer and Nutrition-Netherlands (EPIC-NL) case-cohort studies. rs4988235, a lactase persistence (LP) SNP which enables digestion of lactose in adulthood was used as genetic instrument. Intake of milk was first regressed on rs4988235 in a linear regression model. Next, associations of genetically predicted milk consumption with stroke and CHD were estimated using Prentice-weighted Cox regression. Gene-outcome analysis included 777 024 participants (50 804 cases) from MEGASTROKE (including EPIC-CVD), UK Biobank and EPIC-NL for stroke, and 483 966 participants (61 612 cases) from CARDIoGRAM, UK Biobank, EPIC-CVD and EPIC-NL for CHD. In IV analyses, each additional LP allele was associated with a higher intake of milk in EPIC-CVD (β = 13·7 g/d; 95 % CI 8·4, 19·1) and EPIC-NL (36·8 g/d; 95 % CI 20·0, 53·5). Genetically predicted milk intake was not associated with stroke (HR per 25 g/d 1·05; 95 % CI 0·94, 1·16) or CHD (1·02; 95 % CI 0·96, 1·08). In gene-outcome analyses, there was no association of rs4988235 with risk of stroke (OR 1·02; 95 % CI 0·99, 1·05) or CHD (OR 0·99; 95 % CI 0·95, 1·03). Current Mendelian randomisation analysis does not provide evidence for a causal inverse relationship between milk consumption and stroke or CHD risk.

An empirical evaluation of the impact scenario of pooling bodies of evidence from randomized controlled trials and cohort studies in medical research

BACKGROUND

Randomized controlled trials (RCTs) and cohort studies are the most common study design types used to assess treatment effects of medical interventions. We aimed to hypothetically pool bodies of evidence (BoE) from RCTs with matched BoE from cohort studies included in the same systematic review.

METHODS

BoE derived from systematic reviews of RCTs and cohort studies published in the 13 medical journals with the highest impact factor were considered. We re-analyzed effect estimates of the included systematic reviews by pooling BoE from RCTs with BoE from cohort studies using random and common effects models. We evaluated statistical heterogeneity, 95% prediction intervals, weight of BoE from RCTs to the pooled estimate, and whether integration of BoE from cohort studies modified the conclusion from BoE of RCTs.

RESULTS

Overall, 118 BoE-pairs based on 653 RCTs and 804 cohort studies were pooled. By pooling BoE from RCTs and cohort studies with a random effects model, for 61 (51.7%) out of 118 BoE-pairs, the 95% confidence interval (CI) excludes no effect. By pooling BoE from RCTs and cohort studies, the median I² was 48%, and the median contributed percentage weight of RCTs to the pooled estimates was 40%. The direction of effect between BoE from RCTs and pooled effect estimates was mainly concordant (79.7%). The integration of BoE from cohort studies modified the conclusion (by examining the 95% CI) from BoE of RCTs in 32 (27%) of the 118 BoE-pairs, but the direction of effect was mainly concordant (88%).

CONCLUSIONS

Our findings provide insights for the potential impact of pooling both BoE in systematic reviews. In medical research, it is often important to rely on both evidence of RCTs and cohort studies to get a whole picture of an investigated intervention-disease association. A decision for or against pooling different study designs should also always take into account, for example, PI/ECO similarity, risk of bias, coherence of effect estimates, and also the trustworthiness of the evidence. Overall, there is a need for more research on the influence of those issues on potential pooling.

Phenome-Wide Association Analysis Reveals Novel Links Between Genetically Determined Levels of Liver Enzymes and Disease Phenotypes

Serum liver enzymes (alanine aminotransferase [ALT], aspartate aminotransferase [AST], λ-glutamyl transferase [GGT] and alkaline phosphatase [ALP]) are the leading biomarkers to measure liver injury, and they have been reported to be associated with several intrahepatic and extrahepatic diseases in observational studies. We conducted a phenome-wide association study (PheWAS) to identify disease phenotypes associated with genetically predicted liver enzymes based on the UK Biobank cohort. Univariable and multivariable Mendelian randomization (MR) analyses were performed to obtain the causal estimates of associations that detected in PheWAS. Our PheWAS identified 40 out of 1,376 pairs (16, 17, three and four pairs for ALT, AST, GGT and ALP, respectively) of genotype-phenotype associations reaching statistical significance at the 5% false discovery rate threshold. A total of 34 links were further validated in Mendelian randomization analyses. Most of the disease phenotypes that associated with genetically determined ALT level were liver-related, including primary liver cancer and alcoholic liver damage. The disease outcomes associated with genetically determined AST involved a wide range of phenotypic categories including endocrine/metabolic diseases, digestive diseases, and neurological disorder. Genetically predicted GGT level was associated with the risk of other chronic non-alcoholic liver disease, abnormal results of function study of liver, and cholelithiasis. Genetically determined ALP level was associated with pulmonary heart disease, phlebitis and thrombophlebitis of lower extremities, and hypercholesterolemia. Our findings reveal novel links between liver enzymes and disease phenotypes providing insights into the full understanding of the biological roles of liver enzymes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s43657-021-00033-y.

Evaluating agreement between bodies of evidence from randomized controlled trials and cohort studies in medical research: a meta-epidemiological study

BACKGROUND

Randomized controlled trials (RCTs) and cohort studies are the most common study design types used to assess the treatment effects of medical interventions. To evaluate the agreement of effect estimates between bodies of evidence (BoE) from randomized controlled trials (RCTs) and cohort studies and to identify factors associated with disagreement.

METHODS

Systematic reviews were published in the 13 medical journals with the highest impact factor identified through a MEDLINE search. BoE-pairs from RCTs and cohort studies with the same medical research question were included. We rated the similarity of PI/ECO (Population, Intervention/Exposure, Comparison, Outcome) between BoE from RCTs and cohort studies. The agreement of effect estimates across BoE was analyzed by pooling ratio of ratios (RoR) for binary outcomes and difference of mean differences for continuous outcomes. We performed subgroup analyses to explore factors associated with disagreements.

RESULTS

One hundred twenty-nine BoE pairs from 64 systematic reviews were included. PI/ECO-similarity degree was moderate: two BoE pairs were rated as "more or less identical"; 90 were rated as "similar but not identical" and 37 as only "broadly similar". For binary outcomes, the pooled RoR was 1.04 (95% CI 0.97-1.11) with considerable statistical heterogeneity. For continuous outcomes, differences were small. In subgroup analyses, degree of PI/ECO-similarity, type of intervention, and type of outcome, the pooled RoR indicated that on average, differences between both BoE were small. Subgroup analysis by degree of PI/ECO-similarity revealed high statistical heterogeneity and wide prediction intervals across PI/ECO-dissimilar BoE pairs.

CONCLUSIONS

On average, the pooled effect estimates between RCTs and cohort studies did not differ. Statistical heterogeneity and wide prediction intervals were mainly driven by PI/ECO-dissimilarities (i.e., clinical heterogeneity) and cohort studies. The potential influence of risk of bias and certainty of the evidence on differences of effect estimates between RCTs and cohort studies needs to be explored in upcoming meta-epidemiological studies.

Mendelian randomization study of circulating lipids and biliary tract cancer among East Asians

BACKGROUND

Associations of High-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, total cholesterol (CHL), and triglyceride (TRG) concentrations with risk of biliary tract cancer (BtC) were conflicting in observational studies. We aim to investigate the causal link between circulating lipids and BtC using genetic information.

METHODS

Single nucleotide polymorphisms of the four circulating lipids (n = 34,421) and BtC (418 cases and 159,201 controls) were retrieved from two independent GWAS studies performed in East Asian populations. Two-sample univariate and multivariate Mendelian Randomization (MR) analyses were conducted to determine the causal link between circulating lipids and BtC.

RESULTS

No significant horizontal pleiotropy was detected for all circulating lipids according to the MR-PRESSO global test (P = 0.458, 0.368, 0.522, and 0.587 for HDL, LDL, CHL, and TRG, respectively). No significant evidence of heterogeneity and directional pleiotropy was detected by the Cochran's Q test and MR-Egger regression. Univariate MR estimates from inverse variance weighting method suggested that one standard deviation (1-SD) increase of inverse-normal transformed HDL (OR = 1.38, 95% CI 0.98-1.94), LDL (OR = 1.46, 95% CI 0.96-2.23), and CHL (OR = 1.34, 95% CI 0.83-2.16) were not significantly associated with BtC risk. Whereas 1-SD increase of inverse-normal transformed TRG showed a significantly negative association with BtC risk (OR = 0.48, 95% CI 0.31-0.74). In multivariate MR analyses including all the four lipid traits, we found that 1-SD increase of LDL and TRG was significantly associated with elevated (OR = 1.32, 95% CI 1.04-2.01) and decreased (OR = 0.54, 95% CI 0.42-0.68) risk of BtC, respectively.

CONCLUSION

Circulating lipids, particularly LDL and TRG, may have roles in the development of BtC. However, the results of this study should be replicated in MR with larger GWAS sample sizes for BtC.

Assessment of bidirectional relationships between 98 genera of the human gut microbiota and amyotrophic lateral sclerosis: a 2-sample Mendelian randomization study

BACKGROUND

Growing evidence suggests a mutual interaction between gut microbiome alterations and ALS pathogenesis. However, previous studies were susceptible to potential confounding factors and reverse causation bias, likely leading to inconsistent and biased results.

OBJECTIVES

To decipher the potentially mutual relationship between gut microbiota and ALS, we used a bidirectional two-sample MR approach to examine the associations between the gut microbiome and ALS.

RESULTS

Using the inverse variance-weighted method, OTU10032 unclassified Enterobacteriaceae species-level OTU and unclassified Acidaminococcaceae were associated with a higher risk of ALS (per relative abundance: OR, 1.04; 95% CI, 1.01-1.07; P = 0.011 and OR, 1.02; 95% CI, 1.01-1.04; P = 0.009, respectively). Importantly, Gamma-Glu-Phe was showed potential deleterious effects on the risk of ALS (genetically predicted per a 1-standard deviation increase in the level of Gamma-Glu-Phe: OR, 1.96; 95% CI, 1.50-2.55; P = 0.012). Sensitivity analysis of the two candidate genera and metabolites using the MR-Egger and weighted-median methods produced similar estimates, and no horizontal pleiotropy or outliers were observed. Intriguingly, genetically predicted ALS was associated with an increase in the relative abundance of OTU4607_Sutterella (per 1-unit higher log odds: β, 2.23; 95% CI, 1.27-3.18; P = 0.020) and Lactobacillales_ORDER (per 1-unit higher log odds: β, 0.51; 95% CI, 0.09-0.94; P = 0.019).

CONCLUSIONS

Our findings provide novel evidence supporting the bidirectional relationship between the gut microbiota and ALS. These results may contribute to designing microbiome- and microbiome-dependent metabolite interventions in future ALS clinical trials.

Dairy Consumption, Lactase Persistence, and Mortality Risk in a Cohort From Southern Sweden

Background: Whether high dairy consumption is related to longevity is still unclear, and additional studies of prospective cohorts with high-quality dietary data from populations with wide consumption ranges are needed.

Objective: To examine the association between dairy consumption and mortality in a Swedish cohort.

Design: Among 26,190 participants (62% females, 45–73 years old) without diabetes and cardiovascular disease from the population-based Malmö Diet and Cancer cohort, 7,156 individuals died during a mean follow-up time of 19 years. Data on intake of dairy (non-fermented milk, fermented milk, cheese, cream and butter) were collected from 7 day food records and food questionnaires. A genetic marker (rs4988235) associated with lactase persistence was detected among 22,234 individuals born in Sweden.

Results: Higher intakes up to 1,000 g/day of non-fermented milk were associated with only marginal higher mortality rates after adjusting for potential confounders. However, intakes above 1,000 g/day (1.5% of the population) were associated with 34% (95% CI: 14, 59%, p-trend=0.002) higher mortality compared to that with < 200 g/day. Fermented milk and cheese intake were inversely associated with mortality. Cream showed a protective association only among men. Butter was not associated with mortality. CT/TT genotype carriers (i.e., individuals with lactase persistence) had a 27% higher reported consumption of non-fermented milk, and non-significant higher mortality risk (HR = 1.08; 95% CI = 0.96, 1.23; p = 0.20) than CC genotype carriers.

Conclusions: Higher mortality rates were mainly observed among participants consuming more than 1,000 g of non-fermented milk per day. In contrast, fermented milk and cheese were associated with lower mortality. Because dairy products differ in composition, it is important to examine them separately in their relation to health and disease. The use of a genetic variant as an objective marker of lactose-containing milk intake should be examined in relation to mortality in a larger population.

Dairy Product Consumption and Cardiovascular Health: a Systematic Review and Meta-Analysis of Prospective Cohort Studies

The association between dairy product consumption and cardiovascular health remains highly debated. We quantitatively synthesized prospective cohort evidence on the associations between dairy consumption and risk of hypertension (HTN), coronary heart disease (CHD) and stroke. We systematically searched PubMed, Embase, and Web of Science through August 1st, 2020 to retrieve prospective cohort studies that reported on dairy consumption and risk of HTN, CHD or stroke. We used random-effects models to calculate the pooled relative risk (RR) and 95% confidence interval (CI) for the highest vs the lowest category of intake and for 1 serving/day increase in consumption. We rated the quality of evidence using NutriGrade. Fifty-five studies were included. Total dairy consumption was associated with a lower risk of HTN (RR for highest vs lowest level of intake: 0.91, 95% CI: 0.86-0.95, I2 = 73.5%; RR for 1 serving/day increase: 0.96, 95% CI: 0.94-0.97, I2 = 66.5%), CHD (highest vs lowest level of intake: 0.96, 95% CI: 0.92-1.00, I2 = 46.6%; 1 serving/day increase: 0.98, 95% CI: 0.95-1.00, I2 = 56.7%), and stroke (highest vs lowest level of intake: 0.90, 95% CI: 0.85-0.96, I2 = 60.8%; 1 serving/day increase: 0.96, 95% CI: 0.93-0.99, I2 = 74.7%). Despite moderate to considerable heterogeneity, these associations remained consistent across multiple subgroups. Evidence on the relationship between total dairy and risk of HTN and CHD were of moderate quality and of low quality for stroke. Low-fat dairy consumption was associated with lower risk of HTN and stroke, and high-fat dairy with a lower risk of stroke. Milk, cheese, or yogurt consumption showed inconsistent associations with the cardiovascular outcomes in high vs. low intake and dose-response meta-analyses. Total dairy consumption was associated with a modestly lower risk of hypertension, CHD and stroke. Moderate to considerable heterogeneity was observed in the estimates and the overall quality of the evidence was low to moderate.

Dietary patterns and cardiometabolic risks in diverse less-developed ethnic minority regions: results from the China Multi-Ethnic Cohort (CMEC) Study

Background In Western developed countries, food-based dietary patterns have been associated with the risk of cardiometabolic diseases, but little is known about such associations in less developed ethnic minority regions (LEMRs), where the cardiometabolic disease burden is growing rapidly and food patterns differ substantially.

Methods Between May 2018 and September 2019, we recruited 99556 participants aged 30-79 years from the China Multi-Ethnic Cohort (CMEC) Study. We measured habitual dietary intake with validated food frequency questionnaire (FFQ) and then calculated dietary pattern scores for two of the most studied a priori dietary patterns, i.e., Dietary Approaches to Stop Hypertension (DASH) and alternative Mediterranean (aMED) style diets, and three a posteriori dietary patterns. Four cardiometabolic risks, including hypertension, diabetes, dyslipidaemia and metabolic syndrome (MetS), were newly diagnosed by medical examination and blood tests. We estimated adjusted odds ratios (OR) relating various dietary pattern scores to cardiometabolic risks using marginal structural models under the guidance of directed acyclic graphs. For the above associations, we further calculated the proportion mediated by overweight (PM) using regression-based mediation analysis for better public health implications.

Findings The final study sample consisted of 68834 participants. Among them, we newly diagnosed 12803 hypertension, 3527 diabetes, 16342 hyperlipidaemia, and 8198 MetS cases. Overall, all 5 dietary patterns showed considerable associations with risks of hypertension and MetS. Comparing the highest with the lowest quintiles, the DASH score showed the strongest inverse associations with risks of hypertension (OR=0.74, 95% CI:0.70-0.79; PM=10%) and MetS (OR=0.79, 95% CI:0.74-0.85; PM=35%); conversely, scores of the localized a posteriori Yunnan-Guizhou plateau dietary pattern in LEMRs showed the strongest positive associations with risks of hypertension (OR=1.44, 95% CI:1.35-1.52; PM=10%) and MetS (OR=1.35, 95% CI:1.26-1.46; PM=33%), with all P values for trend <0.001. These associations were consistent in various subgroups defined by sex, age, smoking and physical activity, but with magnitudes that differed substantially across different ethnic regions and urbanicity. By investigating the single-component effects of dietary patterns, the dairy intake component contributed a major proportion to the beneficial effects of DASH (41.9% for hypertension and 100.5% for MetS).

Interpretation Substantial socioeconomic status and ethnic disparities in diet quality and related cardiometabolic risks were seen in LEMRs, with hypertension being the top diet-related cardiometabolic risk. Our findings support that DASH provides superior dietary guidance compared to aMED for reducing cardiometabolic risks in LEMRs. In particular, the dairy intake encouraged by DASH may produce considerable beneficial effects.

Funding This study was funded by the National Key R&D Program of China; full funding sources listed in the acknowledgements.

Association of heart rate and diabetes among 0.5 million adults in the China Kadoorie biobank: Results from observational and Mendelian randomization analyses

BACKGROUND AND AIMS

Observational studies have associated resting heart rate with incident diabetes. Whether the associations are causal remains unclear. We aimed to examine the shape and strength of the associations and assessed the causal relevance of such associations in Chinese adults.

METHODS AND RESULTS

The China Kadoorie Biobank enrolled 512,891 adults in China. Cox proportional hazard regression models was conducted to estimate hazard ratios (HRs) for the associations of resting heart rate with type 2 diabetes and total diabetes. Among 92,724 participants, 36 single-nucleotide polymorphisms (SNPs) related to resting heart rate were used to construct genetic risk score. We used Mendelian randomization analyses to make the causal inferences. During a median follow-up of 9 years, 7872 incident type 2 diabetes and 13,349 incident total diabetes were documented. After regression dilution bias adjustment, each 10 bpm higher heart rate was associated with about a 26% higher risk of type 2 diabetes (HR, 1.26 [95% CI, 1.23, 1.29]) and 23% higher risk of total diabetes (HR, 1.23 [95% CI, 1.20, 1.26]). Instrumental variable analyses showed participants at top quintile compared with those at bottom quintile had 30% higher risk for type 2 diabetes (HR, 1.30 [95% CI, 1.17, 1.43]), and 10% higher risk for total diabetes (HR, 1.10 [95% CI, 1.02, 1.20]).

CONCLUSIONS

This study provides evidence that resting heart rate is an important risk factor for diabetes risk. The results suggest that novel treatment approaches targeting reduction of high heart rate for incidence of diabetes may be worth further investigation.

Dairy products consumption and the risk of hypertension in adults: An updated systematic review and dose-response meta-analysis of prospective cohort studies

AIMS

With an increase in the number of published prospective cohort studies, we sought to summarize the relationship between dairy products consumption and the risk of hypertension (HTN).

DATA SYNTHESIS

We searched PubMed, Web of Science, Embase, Science direct, and Scopus. Pooled RRs and 95% CIs were calculated using a random effects model. The certainty of the evidence was assessed by Grading of Recommendations Assessment, Development and Evaluation (GRADE). Sixteen studies were included in the current meta-analysis. We found an inverse association between total dairy products (RR = 0.90; 95% CI: 0.87, 0.94; n = 16), low-fat dairy products (RR = 0.86; 95% CI: 0.77, 0.96; n = 8), milk (RR = 0.94; 95% CI: 0.90, 0.99; n = 11), and fermented dairy (RR = 0.95; 95% CI: 0.91, 0.99; n = 8) consumption and the risk of HTN. However, in subgroup analysis, despite a significant association for total dairy products in women, Americans, longer and larger studies, and self-reported HTN, no associations were found in males, Europeans, or Asians, and studies which followed participants for <10 years or had <3000 participants or measured HTN. Dose-response analysis revealed a non-linear association between total dairy products and milk consumption and the risk of HTN, but a linear association for low-fat dairy products.

CONCLUSIONS

Higher dairy products consumption was associated with reduced risk of HTN. This association was dependent on sex, geographical region of study, and the stage of HTN. However, the certainty of the evidence was graded either as low or very low.

Evaluating marginal genetic correlation of associated loci for complex diseases and traits between European and East Asian populations

Genome-wide association studies (GWASs) have successfully identified a large amount of single-nucleotide polymorphisms associated with many complex phenotypes in diverse populations. However, a comprehensive understanding of the genetic correlation of associated loci of phenotypes across populations remains lacking and the extent to which associations discovered in one population can be generalized to other populations or can be utilized for trans-ethnic genetic prediction is also unclear. By leveraging summary statistics, we proposed MAGIC to evaluate the trans-ethnic marginal genetic correlation (r_m) of per-allele effect sizes for associated SNPs (P < 5E-8) under the framework of measurement error models. We confirmed the methodological advantage of MAGIC over general approaches through simulations and demonstrated its utility by analyzing 34 GWAS summary statistics of phenotypes from the East Asian (N_max = 254,373) and European (N_max = 1,220,901) populations. Among these phenotypes, r_m was estimated to range from 0.584 (se = 0.140) for breast cancer to 0.949 (se = 0.035) for age of menarche, with an average of 0.835 (se = 0.045). We also uncovered that the trans-ethnic genetic prediction accuracy for phenotypes in the target population would substantially become low when using associated SNPs identified in non-target populations, indicating that associations discovered in the one population cannot be simply generalized to another population and that the accuracy of trans-ethnic phenotype prediction is generally dissatisfactory. Overall, our study provides in-depth insight into trans-ethnic genetic correlation and prediction for complex phenotypes across diverse populations.

Mendelian randomization as a tool for causal inference in human nutrition and metabolism

PURPOSE OF REVIEW

The current review describes the fundamentals of the Mendelian randomization framework and its current application for causal inference in human nutrition and metabolism.

RECENT FINDINGS

In the Mendelian randomization framework, genetic variants that are strongly associated with the potential risk factor are used as instrumental variables to determine whether the risk factor is a cause of the disease. Mendelian randomization studies are less susceptible to confounding and reverse causality compared with traditional observational studies. The Mendelian randomization study design has been increasingly used in recent years to appraise the causal associations of various nutritional factors, such as milk and alcohol intake, circulating levels of micronutrients and metabolites, and obesity with risk of different health outcomes. Mendelian randomization studies have confirmed some but challenged other nutrition-disease associations recognized by traditional observational studies. Yet, the causal role of many nutritional factors and intermediate metabolic changes for health and disease remains unresolved.

SUMMARY

Mendelian randomization can be used as a tool to improve causal inference in observational studies assessing the role of nutritional factors and metabolites in health and disease. There is a need for more large-scale genome-wide association studies to identify more genetic variants for nutritional factors that can be utilized for Mendelian randomization analyses.

An Academic Clinician's Road Map to Hypertension Genomics: Recent Advances and Future Directions MMXX

At the dawn of the new decade, it is judicious to reflect on the boom of knowledge about polygenic risk for essential hypertension supplied by the wealth of genome-wide association studies. Hypertension continues to account for significant cardiovascular morbidity and mortality, with increasing prevalence anticipated. Here, we overview recent advances in the use of big data to understand polygenic hypertension, as well as opportunities for future innovation to translate this windfall of knowledge into clinical benefit.

Evidence for a causal association between milk intake and cardiometabolic disease outcomes using a two-sample Mendelian Randomization analysis in up to 1,904,220 individuals

BACKGROUND

High milk intake has been associated with cardio-metabolic risk. We conducted a Mendelian Randomization (MR) study to obtain evidence for the causal relationship between milk consumption and cardio-metabolic traits using the lactase persistence (LCT-13910 C > T, rs4988235) variant as an instrumental variable.

METHODS

We tested the association of LCT genotype with milk consumption (for validation) and with cardio-metabolic traits (for a possible causal association) in a meta-analysis of the data from three large-scale population-based studies (1958 British Birth Cohort, Health and Retirement study, and UK Biobank) with up to 417,236 participants and using summary statistics from consortia meta-analyses on intermediate traits (N = 123,665-697,307) and extended to cover disease endpoints (N = 86,995-149,821).

RESULTS

In the UK Biobank, carriers of 'T' allele of LCT variant were more likely to consume milk (P = 7.02 × 10^-14). In meta-analysis including UK Biobank, the 1958BC, the HRS, and consortia-based studies, under an additive model, 'T' allele was associated with higher body mass index (BMI) (P_{meta-analysis} = 4.68 × 10^-12) and lower total cholesterol (TC) (P = 2.40 × 10^-36), low-density lipoprotein cholesterol (LDL-C) (P = 2.08 × 10^-26) and high-density lipoprotein cholesterol (HDL-C) (P = 9.40 × 10^-13). In consortia meta-analyses, 'T' allele was associated with a lower risk of coronary artery disease (OR:0.86, 95% CI:0.75-0.99) but not with type 2 diabetes (OR:1.06, 95% CI:0.97-1.16). Furthermore, the two-sample MR analysis showed a causal association between genetically instrumented milk intake and higher BMI (P = 3.60 × 10^-5) and body fat (total body fat, leg fat, arm fat and trunk fat; P < 1.37 × 10^-6) and lower LDL-C (P = 3.60 × 10^-6), TC (P = 1.90 × 10^-6) and HDL-C (P = 3.00 × 10^-5).

CONCLUSIONS

Our large-scale MR study provides genetic evidence for the association of milk consumption with higher BMI but lower serum cholesterol levels. These data suggest no need to limit milk intakes with respect to cardiovascular disease risk, with the suggested benefits requiring confirmation in further studies.

A Novel Promising Frontier for Human Health: The Beneficial Effects of Nutraceuticals in Cardiovascular Diseases

Cardiovascular diseases (CVDs) such as hypertension, atherosclerosis, myocardial infarction, and diabetes are a significant public health problem worldwide. Although several novel pharmacological treatments to reduce the progression of CVDs have been discovered during the last 20 years, the better way to contain the onset of CVDs remains prevention. In this regard, nutraceuticals seem to own a great potential in maintaining human health, exerting important protective cardiovascular effects. In the last years, there has been increased focus on identifying natural compounds with cardiovascular health-promoting effects and also to characterize the molecular mechanisms involved. Although many review articles have focused on the individual natural compound impact on cardiovascular diseases, the aim of this manuscript was to examine the role of the most studied nutraceuticals, such as resveratrol, cocoa, quercetin, curcumin, brassica, berberine and Spirulina platensis, on different CVDs.

Causal relationships between gut metabolites and Alzheimer's disease: a bidirectional Mendelian randomization study

Observational studies have shown that gut microbiota-dependent metabolites are associated with the risk of Alzheimer's disease (AD). However, whether such association reflects a causality remains unclear. We conducted a bidirectional Mendelian randomization analysis to examine the causal relationships between gut microbiota-dependent metabolites trimethylamine N-oxide (TMAO) or its predecessors and AD. We observed that genetically predicted TMAO (odds ratio: 0.99, 95% confidence interval: 0.89 to 1.09 per 10 units, p = 0.775) or its predecessors including betaine (1.06, 1.00 to 1.12 per 10 units, p = 0.056), carnitine (1.05, 0.98 to 1.12 per 10 units, p = 0.178), and choline (1.01, 0.92 to 1.10 per 10 units, p = 0.905) were not associated with the risk of AD. Our Mendelian randomization estimates from AD to metabolites showed that genetically predicted higher risk of AD was also not causally associated with TMAO, betaine, carnitine, and choline levels. Our findings support that gut microbiota-dependent metabolites TMAO or its predecessors do not play causal roles in the development of AD.

Milk Consumption for the Prevention of Fragility Fractures

Results indicating that a high milk intake is associated with both higher and lower risks of fragility fractures, or that indicate no association, can all be presented in the same meta-analysis, depending on how it is performed. In this narrative review, we discuss the available studies examining milk intake in relation to fragility fractures, highlight potential problems with meta-analyses of such studies, and discuss potential mechanisms and biases underlying the different results. We conclude that studies examining milk and dairy intakes in relation to fragility fracture risk need to study the different milk products separately. Meta-analyses should consider the doses in the individual studies. Additional studies in populations with a large range of intake of fermented milk are warranted.

Education, intelligence, and amyotrophic lateral sclerosis: A Mendelian randomization study

OBJECTIVE

To systematically investigate causal relationships between educational attainment, cognitive-related phenotypes, and amyotrophic lateral sclerosis (ALS).

METHODS

Summary statistics from genome-wide association studies for educational attainment, math ability, highest math class taken, cognitive performance, intelligence, and ALS were used. A two-sample Mendelian randomization (MR) design was applied to explore the potential causal associations between them.

RESULTS

Genetically predisposition to longer educational attainment and harder math class taken were associated with significantly lower statistical odds ratio of ALS. For per year increase in education completed there was a 21% lower (95% confidence interval [CI] = 27-14%) in risk for ALS. For per 1-SD increase in the highest math class taken obtained there was a 19% lower (95% CI = 9-28%) in risk for ALS. Genetically predisposition to math ability, cognitive performance, and intelligence did not decrease the risk of ALS.

INTERPRETATION

This study provides genetic support for a causal association between higher educational attainment and a lower risk of ALS. The genes related to these phenotypes are involved in almost all aspects of neuron-to-neuron communication. ALS patients are occasionally accompanied by varying degrees of cognitive impairment. People with greater cognitive reserve may be better able to offset damages of degenerative brain changes associated with dementia or other brain diseases, such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, or ALS.

Association of physical activity, sedentary behaviours and sleep duration with cardiovascular diseases and lipid profiles: a Mendelian randomization analysis

Background

Observational studies have shown that moderate-to-vigorous physical activity (MVPA), vigorous physical activity (VPA), sedentary behaviours, and sleep duration were associated with cardiovascular diseases (CVDs) and lipid levels. However, whether such observations reflect causality remain largely unknown. We aimed to investigate the causal associations of physical activity, sedentary behaviours, and sleep duration with coronary artery disease (CAD), myocardial infarction (MI), stroke and lipid levels.

Methods

We conducted a Mendelian randomization (MR) study using genetic variants as instruments which are associated with physical activity, sedentary behaviours, and sleep duration to examine the causal effects on CVDs and lipid levels. This study included analyses of 4 potentially modifiable factors and 7 outcomes. Thus, the threshold of statistical significance is P = 1.8 × 10^− 3 (0.05/4 × 7) after Bonferroni correction.

Results

In the present study, there was suggestive evidence for associations of genetically predicted VPA with CAD (odds ratio, 0.65; 95% confidence intervals, 0.47–0.90; P = 0.009) and MI (0.74; 0.59–0.93; P = 0.010). However, genetically predicted VPA, MVPA, sleep duration and sedentary behaviours did not show significant associations with stroke and any lipid levels.

Conclusions

Our findings from the MR approach provided suggestive evidence that vigorous exercise decreased risk of CAD and MI, but not stroke. However, there was no evidence to support causal associations of MVPA,sleep duration or sedentary behaviours with cardiovascular risk and lipid levels.

Translational perspective

The findings of this study did not point out specific recommendations on increasing physical activity required to deliver significant health benefits. Nevertheless, the findings allowed clinicians and public health practitioners to provide advice about increasing the total amount of excising time by demonstrating that such advice can be effective. Reliable assessment of the association of physical activity levels with different subtypes of CVDs is needed to provide the basis for a comprehensive clinical approach on CVDs prevention, which can be achieved through lifestyle interventions in addition to drug therapy.

Objectives, design and main findings until 2020 from the Rotterdam Study

The Rotterdam Study is an ongoing prospective cohort study that started in 1990 in the city of Rotterdam, The Netherlands. The study aims to unravel etiology, preclinical course, natural history and potential targets for intervention for chronic diseases in mid-life and late-life. The study focuses on cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, otolaryngological, locomotor, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. Since 2016, the cohort is being expanded by persons aged 40 years and over. The findings of the Rotterdam Study have been presented in over 1700 research articles and reports. This article provides an update on the rationale and design of the study. It also presents a summary of the major findings from the preceding 3 years and outlines developments for the coming period.

Association of dairy consumption with metabolic syndrome, hypertension and diabetes in 147 812 individuals from 21 countries

OBJECTIVE

Our aims were to assess the association of dairy intake with prevalence of metabolic syndrome (MetS) (cross-sectionally) and with incident hypertension and incident diabetes (prospectively) in a large multinational cohort study.

METHODS

The Prospective Urban Rural Epidemiology (PURE) study is a prospective epidemiological study of individuals aged 35 and 70 years from 21 countries on five continents, with a median follow-up of 9.1 years. In the cross-sectional analyses, we assessed the association of dairy intake with prevalent MetS and its components among individuals with information on the five MetS components (n=112 922). For the prospective analyses, we examined the association of dairy with incident hypertension (in 57 547 individuals free of hypertension) and diabetes (in 131 481 individuals free of diabetes).

RESULTS

In cross-sectional analysis, higher intake of total dairy (at least two servings/day compared with zero intake; OR 0.76, 95% CI 0.71 to 0.80, p-trend<0.0001) was associated with a lower prevalence of MetS after multivariable adjustment. Higher intakes of whole fat dairy consumed alone (OR 0.72, 95% CI 0.66 to 0.78, p-trend<0.0001), or consumed jointly with low fat dairy (OR 0.89, 95% CI 0.80 to 0.98, p-trend=0.0005), were associated with a lower MetS prevalence. Low fat dairy consumed alone was not associated with MetS (OR 1.03, 95% CI 0.77 to 1.38, p-trend=0.13). In prospective analysis, 13 640 people with incident hypertension and 5351 people with incident diabetes were recorded. Higher intake of total dairy (at least two servings/day vs zero serving/day) was associated with a lower incidence of hypertension (HR 0.89, 95% CI 0.82 to 0.97, p-trend=0.02) and diabetes (HR 0.88, 95% CI 0.76 to 1.02, p-trend=0.01). Directionally similar associations were found for whole fat dairy versus each outcome.

CONCLUSIONS

Higher intake of whole fat (but not low fat) dairy was associated with a lower prevalence of MetS and most of its component factors, and with a lower incidence of hypertension and diabetes. Our findings should be evaluated in large randomized trials of the effects of whole fat dairy on the risks of MetS, hypertension, and diabetes.

Science dialogue mapping of knowledge and knowledge gaps related to the effects of dairy intake on human cardiovascular health and disease

Dairy has been described as everything from a superfood to a poison; yet, arguments, assumptions, and data justifying these labels are not always clear. We used an issue-based information system, "dialogue mapping™," to summarize scientific points of a live panel discussion on the putative effects of dairy on cardiovascular diseases (CVD) from a day-long session among experts in nutrition and CVD. Dialogue mapping captures relations among ideas to explicitly, logically, and visually connect issues/questions, ideas, pro/con arguments, and agreements, even if discussed at different times. Experts discussed two propositions: for CVD risk, consumption of full-fat dairy products 1) should be minimized, in part because of their saturated fat content, or 2) need not be minimized, despite their saturated fat content. The panel discussed the dairy-CVD relation through blood lipids, diabetes, obesity, energy balance, blood pressure, dairy bioactives, biobehavioral components, and other putative causal pathways. Associations and effects reported in the literature have varied by fat content of dairy elements considered, study design, intake methods, and biomarker versus disease outcomes. Two conceptual topics emerged from the discussion: 1) individual variability: whether recommendations should be targeted only to those at high CVD risk; 2) quality of evidence: whether data on dairy-CVD relations are strong enough for reliable conclusions-positive, negative, or null. Future procedural improvements for science dialog mapping include using singular rather than competing propositions for discussion.

Dairy product consumption and hypertension risk in a prospective French cohort of women

BACKGROUND

Among potentially modifiable factors, dairy product consumption has been inconsistently associated with hypertension risk. The objective of this study was to investigate the relation between dairy product consumption and the risk of hypertension among middle-aged women.

METHODS

In a prospective cohort of 40,526 French women, there were 9340 new cases of hypertension after an average 12.2 years of follow up. Consumptions of milk, yogurt, and types of cheese were assessed at baseline using a validated dietary questionnaire. Hazard ratios (HRs) and 95% confidence intervals (95% CI) for hypertension were estimated with multivariate Cox models with age as the time scale.

RESULTS

The mean dairy consumption was 2.2 + 1.2 servings/day, as cottage cheese (0.2 + 0.2 servings/day), yogurt (0.6 + 0.5 servings/day), milk (0.4 + 0.7 servings/day), and cheese (1.1 + 0.8 servings/day). There was no association between risk of hypertension and total dairy consumption (multivariate HR for the fifth vs. first quintile HR_5vs.1 = 0.97 [0.91; 1.04]). There was no association with any specific type of dairy, except for a positive association between processed cheese consumption and hypertension (multivariate HR_{4vs.1 =} 1.12 [1.06; 1.18]; p trend = < 0.003).

CONCLUSIONS

In this large prospective cohort of French women, overall consumption of dairy products was not associated with the risk of hypertension. Results regarding processed cheese must be further confirmed.

A Randomized Study of the Effect of Replacing Sugar-Sweetened Soda by Reduced Fat Milk on Cardiometabolic Health in Male Adolescent Soda Drinkers

Soda consumption in adolescents has been linked to poorer metabolic outcomes. We tested whether replacing soda with reduced fat milk would improve features of atherogenic dyslipidemia and other cardiometabolic risk factors. Thirty overweight and obese adolescent boys who were habitual consumers of sugar-sweetened beverages were randomly assigned to consume 24 oz/day of sugar-sweetened soda or an energy equivalent of reduced fat (2%) milk for 3 weeks with crossover to the alternate beverage after a ≥ 2 weeks washout. Plasma lipids and lipoproteins and other laboratory measures were assessed after each beverage period. Lipid and lipoprotein measurements, C-reactive protein, and serum transaminases did not differ significantly between the soda and milk phases of the study. Systolic blood pressure z-score and uric acid concentration were significantly lower after consuming milk compared to soda. Milk consumption also significantly decreased plasma glucosyl ceramide (d18:1/C16:0) and lactosylceramides (d18:1/C16:0 and d18:1/C18:0). While no effects of replacing soda with milk on lipid and lipoprotein measurements were observed in these normolipidemic weight-stable adolescent boys, decreases in systolic blood pressure, uric acid, and glycosphingolipids suggest that an overall favorable effect on cardiometabolic risk can be achieved following a short-term dietary intervention.

Negative Effects of Age at Menarche on Risk of Cardiometabolic Diseases in Adulthood: A Mendelian Randomization Study

CONTEXT

Observational studies have demonstrated that early menarche is associated with cardiometabolic diseases, but confounding factors make it difficult to infer causality.

OBJECTIVE

We used Mendelian randomization (MR) to examine whether age at menarche (AAM) is causally associated with type 2 diabetes (T2D), coronary artery disease (CAD) and cardiometabolic traits.

DESIGN AND METHODS

A 2-sample MR analysis was conducted using genome-wide association study (GWAS) summary statistics from the Diabetes Genetics Replication and Meta-analysis (DIAGRAM) consortium (n = 159 208) for T2D and the Coronary Artery Disease Genome-wide Replication and Meta-analysis plus the Coronary Artery Disease Genetics (CARDIoGRAMplusC4D) consortium (n = 184 305) for CAD. We used 122 instrumental variables (IVs) extracted from a published GWAS meta-analysis incorporating 182 416 women to determine the causal effect of AAM on cardiometabolic diseases, treating childhood and adult body mass index (BMI) as the confounders. Sensitivity analyses were also performed to detect the pleiotropy of the IVs.

RESULTS

Employing the MR approach, we found that later AAM was associated with decreased risk of CAD (OR, 0.92 [95% CI, 0.88-0.96]; P = 2.06 × 10-4) in adults, as well as lower blood levels of log fasting insulin, log homeostatic model assessment of insulin resistance (HOMA-IR), log HOMA of β-cell function (HOMA-B), triglycerides, and diastolic blood pressure, but higher blood level of high-density lipoprotein. However, the associations were substantially attenuated after excluding BMI-related variants. MR analyses provide little evidence on the causal effect between AAM and T2D.

CONCLUSIONS

Our findings showed that AAM did not appear to have a causal effect on the risk of cardiometabolic diseases in adult life, as their associations observed in epidemiological studies might be largely mediated through excessive adiposity. We propose adiposity might be a primary target in future intervention strategy.

Life Course Adiposity and Amyotrophic Lateral Sclerosis: A Mendelian Randomization Study

OBJECTIVE

Observational studies have indicated that life course adiposity is associated with amyotrophic lateral sclerosis (ALS). However, whether such an association reflects causality remains unclear. We aimed to determine whether life course adiposity such as birth weight (BW), childhood body mass index (BMI), adult BMI, body fat percentage (BF%), and waist-to-hip ratio (WHR) have causal effects on ALS.

METHODS

Single nucleotide polymorphisms (SNPs) significantly associated with life course adiposity were used as instrumental variables to estimate the causal effects on ALS. We used summary-level data from a cohort of 20,806 cases and 59,804 controls in a Mendelian randomization (MR) framework.

RESULTS

Genetically predicted one standard deviation (1-SD) increase in BF% was associated with lower risk of ALS (odds ratio [OR] = 0.67, 95% confidence interval [CI] = 0.54-0.83, p = 3.25E-04) after Bonferroni correction (p < 0.05/5). Genetically predicted 1-SD higher childhood BMI was suggestively associated with lower risk of ALS (OR = 0.88, 95% CI = 0.78-0.99, p = 0.031). The weighted median method indicated a suggestive association between BMI and ALS (OR = 0.86, 95% CI = 0.69-0.96, p = 0.016). Neither a genetically predicted 1-SD increase in BW (inverse variance weighted [IVW]: OR = 1.01, 95% CI = 0.87-1.17, p = 0.939) nor WHR adjusted for BMI (IVW: OR = 0.90, 95% CI = 0.76-1.05, p = 0.178) was associated with ALS.

INTERPRETATION

Our findings provide novel evidence supporting a causal role of higher adiposity, taken as a whole, on lower risk of ALS. A deeper understanding of the energy metabolism of ALS is more likely to identify feasible nutritional interventions and even novel therapeutic targets that might improve the survival of ALS patients. Ann Neurol 2020;87:434-441.

The Eurasian lactase persistence variant LCT-13910 C/T is associated with vitamin D levels in individuals living at high latitude, more so than exposure to sunlight

Rapid selection of a genetic variant that confers continuous life-long lactase production in Europeans (LCT-13910 C/T) has been attributed to the advantages of acquiring nutrients from consuming milk without the disadvantages of lactose malabsorption. Individuals with this genetic lactase persistence (LP) variant generally consume more milk and have been shown to have higher levels of serum vitamin D. Vitamin D is the principal regulator of Ca absorption and its synthesis in skin is dependent on UVB exposure. The primary aim of the present study was to compare serum vitamin D concentrations with LP variant and to control for UVB exposure. Data from over 100 000 individuals living in Norway, a country with low UVB exposure, was retrospectively retrieved for comparison of genetic LP variant, serum 25-hydroxyvitamin D (25(OH)D) concentration and the time of year when serum samples were taken. For comparison, a similar analysis was performed with a natural dairy micronutrient, namely vitamin B₁₂. It was found that individuals with the genetic LP variant had considerably higher levels of serum 25(OH)D (P < 2 × 10^-16, Cohen's d = 0·73) but lower levels of vitamin B₁₂ (P < 2 × 10^-16, Cohen's d = 0·11), compared with genetic lactase non-persistent individuals, even when controlled for seasonality, age and sex. The difference in serum 25(OH)D levels did not diminish in summer months, showing the role of vitamin D in LP variant selection in areas of low UVB irradiation. LP variant selection advantage through acquiring another dairy micronutrient, vitamin B₁₂, was not observed.

Dairy Consumption in Relation to Hypertension Among a Large Population of University Students: The MEPHASOUS Study

BACKGROUND

Hypertension is a chronic condition that its prevalence is increasing at an alarming rate. Findings on the association between dairy consumption and hypertension are conflicting and few data are available in the Middle East.

AIM

To assess the association between dairy consumption and hypertension among a large population of university students.

MATERIALS AND METHODS

The current study was performed in the framework of the Mental and Physical Health Assessment of University Student (MEPHASOUS) project. Overall, 67,011 university students with complete information were included in the statistical analysis. To assess dairy consumption, a self-administered dietary habits questionnaire was employed. Blood pressure was measured using a standard protocol. The systolic/diastolic blood pressure of ≥140/90 mmHg was considered hypertension.

RESULTS

Hypertension was prevalent among 6.9% of students. A significant inverse association was found between dairy consumption and the odds of hypertension; such that after taking potential confounders into account, individuals in the highest levels of dairy consumption had 85% lower odds for having hypertension compared with those in the lowest levels (odds ratio (OR): 0.15, 95% confidence interval (CI): 0.13-0.18). Such an inverse association was also seen among males (OR: 0.14, 95% CI: 0.11-0.18) and females (OR: 0.16, 95% CI: 0.12-0.21), normal-weight students (OR: 0.15, 95% CI: 0.12-0.18) and those with overweight or obesity (OR: 0.15, 95% CI: 0.11-0.21), and individuals with (OR: 0.13, 95% CI: 0.11-0.16) and without (OR: 0.24, 95% CI: 0.17-0.35) family history of hypertension.

CONCLUSION

Our results support the previous findings on the inverse association between dairy consumption and hypertension among university students.

Effects of regular-fat and low-fat dairy consumption on daytime ambulatory blood pressure and other cardiometabolic risk factors: a randomized controlled feeding trial

BACKGROUND

The extent to which dairy products and their fat content influence cardiovascular health remains uncertain.

OBJECTIVE

This study aimed to assess how consumption of low-fat milk and regular-fat cheese enriched in γ-aminobutyric acid (GABA) influences daytime ambulatory blood pressure (BP) and other cardiometabolic risk factors.

METHODS

In this crossover controlled feeding study, 55 healthy men and women with high-normal daytime BP were randomly assigned to sequences of three 6-wk isoenergetic diets, each comprising 1) no dairy (control diet), 2) 3 daily servings of 1% fat milk, and 3) 1 daily serving of 31% fat cheddar cheese naturally enriched in GABA. Total proteins, carbohydrates, and fats were matched across all 3 diets. The additional 2% of energy from SFAs in the cheese diet was replaced by n-6 PUFAs in the other diets.

RESULTS

Comparison of postdiet ambulatory systolic BP revealed no difference (P = 0.34), which was also the case for ambulatory diastolic BP (P = 0.45). The cheese diet increased serum LDL-cholesterol concentrations compared with the control and milk diets (+5.8%, P = 0.006 and +7.0%, P = 0.0008, respectively) and increased LDL particle size compared with the milk diet (P = 0.02). HDL-cholesterol concentrations after the milk diet were lower than after the control diet (-4.1%; P = 0.009). The milk and cheese diets increased triglycerides compared with the control diet (+9.9%, P = 0.01 and +10.5%, P = 0.007, respectively). There was no significant difference between all diets for C-reactive protein concentrations and markers of glucose/insulin homeostasis.

CONCLUSIONS

These results suggest that short-term consumption of dairy products, whether low or regular in fat, has no overall effect on daytime ambulatory BP compared with a dairy-free diet. Other cardiometabolic risk factors may be differently modified according to the fat content of the dairy product. This trial was registered at clinicaltrials.gov as NCT02763930.

Important Food Sources of Fructose-Containing Sugars and Incident Hypertension: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies

Background Sugar-sweetened beverages are associated with hypertension. We assessed the relation of important food sources of fructose-containing sugars with incident hypertension using a systematic review and meta-analysis of prospective cohort studies. Methods and Results We searched MEDLINE, EMBASE, and Cochrane (through December week 2, 2018) for eligible studies. For each food source, natural log-transformed risk ratios (RRs) for incident hypertension were pooled using pair-wise meta-analysis and linear and nonlinear dose-response meta-analyses. Certainty in our evidence was assessed using Grading of Recommendations Assessment, Development and Evaluation. We identified 26 reports, including 15 prospective cohorts (930 677 participants; 363 459 cases). Sugar-sweetened beverages showed harmful (RRper-355-mL, 1.10 [95% CI, 1.08, 1.12]) whereas fruit (RRper-240-g, 0.94 [95% CI, 0.96, 0.99]) and yogurt showed protective associations (RRper-125-g, 0.95 [95% CI, 0.94, 0.97]) with incident hypertension throughout the dose range. One hundred percent fruit juice showed a protective association only at moderate doses (RRat-100-mL, 0.97 [95% CI, 0.94, 0.99]). The pair-wise protective association of dairy desserts was not supported by linear dose-response analysis. Fruit drinks or sweet snacks were not associated with hypertension. Certainty of the evidence was "low" for sugar-sweetened beverages, 100% fruit juice, fruit, and yogurt and "very low" for fruit drinks, sweet snacks, and dairy desserts. Conclusions The harmful association between sugar-sweetened beverages and hypertension does not extend to other important food sources of fructose-containing sugars. Further research is needed to improve our estimates and better understand the dose-response relationship between food sources of fructose-containing sugars and hypertension. Registration URL: https://www.clinicaltrials.gov/. Unique identifier: NCT02702375.

Associations of dairy intake with risk of mortality in women and men: three prospective cohort studies

OBJECTIVE

To examine the association of consumption of dairy foods with risk of total and cause specific mortality in women and men.

DESIGN

Three prospective cohort studies with repeated measures of diet and lifestyle factors.

SETTING

Nurses' Health Study, Nurses' Health Study II, and the Health Professionals Follow-up Study, in the United States.

PARTICIPANTS

168 153 women and 49 602 men without cardiovascular disease or cancer at baseline.

MAIN OUTCOME MEASURE

Death confirmed by state vital records, the national death index, or reported by families and the postal system. During up to 32 years of follow-up, 51 438 deaths were documented, including 12 143 cardiovascular deaths and 15 120 cancer deaths. Multivariable analysis further adjusted for family history of cardiovascular disease and cancer, physical activity, overall dietary pattern (alternate healthy eating index 2010), total energy intake, smoking status, alcohol consumption, menopausal status (women only), and postmenopausal hormone use (women only).

RESULTS

Compared to the lowest category of total dairy consumption (average 0.8 servings/day), the multivariate pooled hazard ratio for total mortality was 0.98 (95% confidence interval 0.96 to 1.01) for the second category of dairy consumption (average 1.5 servings/day), 1.00 (0.97 to 1.03) for the third (average 2.0 servings/day), 1.02 (0.99 to 1.05) for the fourth (average 2.8 servings/day), and 1.07 (1.04 to 1.10) for highest category (average 4.2 servings/day; P for trend <0.001). For the highest compared to the lowest category of total dairy consumption, the hazard ratio was 1.02 (0.95 to 1.08) for cardiovascular mortality and 1.05 (0.99 to 1.11) for cancer mortality. For subtypes of dairy products, whole milk intake was significantly associated with higher risks of total mortality (hazard ratio per 0.5 additional serving/day 1.11, 1.09 to 1.14), cardiovascular mortality (1.09, 1.03 to 1.15), and cancer mortality (1.11, 1.06 to 1.17). In food substitution analyses, consumption of nuts, legumes, or whole grains instead of dairy foods was associated with a lower mortality, whereas consumption of red and processed meat instead of dairy foods was associated with higher mortality.

CONCLUSION

These data from large cohorts do not support an inverse association between high amount of total dairy consumption and risk of mortality. The health effects of dairy could depend on the comparison foods used to replace dairy. Slightly higher cancer mortality was non-significantly associated with dairy consumption, but warrants further investigation.

Association of Birth Weight With Type 2 Diabetes and Glycemic Traits: A Mendelian Randomization Study

IMPORTANCE

Observational studies have shown associations of birth weight with type 2 diabetes (T2D) and glycemic traits, but it remains unclear whether these associations represent causal associations.

OBJECTIVE

To test the association of birth weight with T2D and glycemic traits using a mendelian randomization analysis.

DESIGN, SETTING, AND PARTICIPANTS

This mendelian randomization study used a genetic risk score for birth weight that was constructed with 7 genome-wide significant single-nucleotide polymorphisms. The associations of this score with birth weight and T2D were tested in a mendelian randomization analysis using study-level data. The association of birth weight with T2D was tested using both study-level data (7 single-nucleotide polymorphisms were used as an instrumental variable) and summary-level data from the consortia (43 single-nucleotide polymorphisms were used as an instrumental variable). Data from 180 056 participants from 49 studies were included.

MAIN OUTCOMES AND MEASURES

Type 2 diabetes and glycemic traits.

RESULTS

This mendelian randomization analysis included 49 studies with 41 155 patients with T2D and 80 008 control participants from study-level data and 34 840 patients with T2D and 114 981 control participants from summary-level data. Study-level data showed that a 1-SD decrease in birth weight due to the genetic risk score was associated with higher risk of T2D among all participants (odds ratio [OR], 2.10; 95% CI, 1.69-2.61; P = 4.03 × 10-5), among European participants (OR, 1.96; 95% CI, 1.42-2.71; P = .04), and among East Asian participants (OR, 1.39; 95% CI, 1.18-1.62; P = .04). Similar results were observed from summary-level analyses. In addition, each 1-SD lower birth weight was associated with 0.189 SD higher fasting glucose concentration (β = 0.189; SE = 0.060; P = .002), but not with fasting insulin, 2-hour glucose, or hemoglobin A1c concentration.

CONCLUSIONS AND RELEVANCE

In this study, a genetic predisposition to lower birth weight was associated with increased risk of T2D and higher fasting glucose concentration, suggesting genetic effects on retarded fetal growth and increased diabetes risk that either are independent of each other or operate through alterations of integrated biological mechanisms.

Assessment of Causal Direction Between Gut Microbiota-Dependent Metabolites and Cardiometabolic Health: A Bidirectional Mendelian Randomization Analysis

We examined the causal direction between gut microbiota-dependent metabolite trimethylamine N-oxide (TMAO) or its predecessors and cardiometabolic diseases, such as risk of type 2 diabetes mellitus (T2DM), coronary artery disease (CAD), myocardial infarction (MI), stroke, atrial fibrillation (AF), and chronic kidney disease (CKD). We used genetic variants as instruments to test the causal associations. Genetically predicted higher TMAO and carnitine were not associated with higher odds of T2DM, AF, CAD, MI, stroke, and CKD after Bonferroni correction (P ≤ 0.0005). However, we observed that genetically increased choline showed a suggestive association with higher risk of T2DM (odds ratio 1.84 [95% CI 1.00-3.42] per 10 units, P = 0.05). In contrast, genetically predicted higher betaine (0.68 [0.48-0.95] per 10 units, P = 0.023) was suggestively associated with a lower risk of T2DM. We observed a suggestive association of genetically increased choline with a lower level of body fat percentage (β ± SE -0.28 ± 0.11, P = 0.013) but a higher estimated glomerular filtration rate (0.10 ± 0.05, P = 0.034). We further found that T2DM (0.130 ± 0.036, P < 0.0001) and CKD (0.483 ± 0.168, P = 0.004) were causally associated with higher TMAO levels. Our Mendelian randomization findings support that T2DM and kidney disease increase TMAO levels and that observational evidence for cardiovascular diseases may be due to confounding or reverse causality.

Vitamin D and cause-specific vascular disease and mortality: a Mendelian randomisation study involving 99,012 Chinese and 106,911 European adults

BACKGROUND

Randomised control trials and genetic analyses have demonstrated that vitamin D or 25-hydroxyvitamin D (25[OH]D) levels may not play a causal role in the development of cardiovascular disease. However, it is unclear if 25(OH)D is causally associated with cause-specific vascular disease and lipids. Therefore, we examined the causal association of 25(OH)D with myocardial infarction, stroke, ischaemic heart disease, ischaemic stroke, subarachnoid haemorrhage, intracerebral haemorrhage, and lipid levels among both Chinese and Europeans.

METHODS

We used a Mendelian randomisation (MR) design in the China Kadoorie Biobank, the Copenhagen City Heart Study, and the Copenhagen General Population Study. The 25(OH)D-related genetic variants in the CYP2R1 and DCHR7 genes were genotyped in 99,012 Chinese adults and 106,911 Danish adults.

RESULTS

In Chinese adults, plasma 25(OH)D levels were not significantly associated with cause-specific vascular disease or mortality, with the exception of intracerebral haemorrhage (HR, 1.09 [95% CI, 1.01,1.18] per 25 nmol/L higher plasma 25(OH)D). In Europeans, plasma 25(OH)D levels were inversely associated with all types of vascular diseases and mortality. However, MR analysis did not demonstrate causal associations of genetically increased 25(OH)D levels with cause-specific vascular diseases, or mortality in both Chinese and European adults. In addition, each 25 nmol/L higher 25(OH)D was observationally associated with lower total cholesterol and low-density lipoprotein cholesterol levels, but higher high-density lipoprotein cholesterol levels. Likewise, MR analysis showed that 25(OH)D levels were not causally associated with lipids in both Chinese and European adults after Bonferroni correction.

CONCLUSIONS

We found no evidence to support that genetically increased 25(OH)D was associated with a lower risk of ischaemic stroke, intracerebral haemorrhage, subarachnoid haemorrhage, and lipid levels in both Chinese and European adults. These results suggest that the inverse associations of vitamin D with vascular disease could be the result of confounding.