Health effects of high serum calcium levels: Updated phenome-wide Mendelian randomisation investigation and review of Mendelian randomisation studies

Exploring the causal associations of micronutrients on urate levels and the risk of gout: A Mendelian randomization study

BACKGROUND & AIMS

Growing evidence has indicated a potential association between micronutrient levels, urate levels, and the risk of gout. However, the causal association underlying these associations still remains uncertain. Previous observational studies and randomized controlled trials investigating the association between micronutrients, urate levels, and the risk of gout have been limited in their scope and depth. The aim of this study was to utilize Mendelian randomization (MR) to investigate the causal associations between genetically predicted micronutrient levels, urate levels, and the risk of gout.

METHODS

In this study, we conducted a comprehensive examination of 10 specific micronutrients (vitamin B6, vitamin B12, vitamin C, vitamin D, folate, calcium, iron, copper, zinc, and selenium) as potential exposures. Two-sample MR analyses were performed to explore their causal associations with urate levels and the risk of gout. In these analyses, gout data were collected from the Global Biobank Meta-Analysis Initiative (N = 1,069,839, N cases = 30,549) and urate levels data from CKDGen Consortium (N = 288,649) by utilizing publicly available summary statistics from independent cohorts of European ancestry. We performed inverse-variance weighted MR analyses as main analyses, along with a range of sensitivity analyses, such as MR-Egger, weighted median, simple mode, weighted mode, Steiger filtering, MR-PRESSO, and Radial MR analysis, to ensure the robustness of our findings.

RESULTS

The results of our study indicate that there were negative associations between serum vitamin B12 and urate levels, as well as serum folate and the risk of gout. Specifically, we found a negative association between vitamin B12 levels and urate levels, with a β coefficient of -0.324 (95% CI -0.0581 to -0.0066, P = 0.0137) per one standard deviation (SD) increase. Similarly, a negative association was observed between folate levels and gout risk, with an odds ratio of 0.8044 (95% CI 0.6637 to 0.9750, P = 0.0265) per one SD increase. On the other hand, we identified positive associations between serum calcium levels and both urate levels and the risk of gout. Specifically, there was a positive association between serum calcium levels and urate levels (β coefficient: 0.0994, 95% CI 0.0519 to 0.1468, P = 4.11E-05) per one SD increase. Furthermore, a positive association was found between serum calcium levels and the risk of gout, with an odds ratio of 1.1479 (95% CI 1.0460 to 1.2598, P = 0.0036) per one SD increase. These findings were robust in extensive sensitivity analyses. By employing MR-PRESSO and Radial MR to eliminate outliers, the observed associations have been reinforced. No clear associations were found between the other micronutrients and the urate levels, as well as the risk of gout.

CONCLUSION

Our findings provided evidence that there were negative associations between serum vitamin B12 and urate levels, as well as serum folate and the risk of gout, while positive associations existed between the serum calcium levels and urate levels, as well as the risk of gout.

Phenome-wide Mendelian randomization analysis reveals multiple health comorbidities of coeliac disease

BACKGROUND

Coeliac disease (CeD) has been associated with a broad range of diseases in observational data; however, whether these associations are causal remains undetermined. We conducted a phenome-wide Mendelian randomization analysis (MR-PheWAS) to investigate the comorbidities of CeD.

METHODS

Single nucleotide polymorphisms (SNPs) associated with CeD at the genome-wide significance threshold and without linkage disequilibrium (R2 <0.001) were selected from a genome-wide association study including 12,041 CeD cases as the instrumental variables. We first constructed a polygenic risk score for CeD and estimated its associations with 1060 unique clinical outcomes in the UK Biobank study (N = 385,917). We then used two-sample MR analysis to replicate the identified associations using data from the FinnGen study (N = 377,277). We performed a secondary analysis using a genetic instrument without extended MHC gene SNPs.

FINDINGS

Genetic liability to CeD was associated with 68 clinical outcomes in the UK Biobank, and 38 of the associations were replicated in the FinnGen study. Genetic liability to CeD was associated with a higher risk of several autoimmune diseases (type 1 diabetes and its complications, Graves' disease, Sjögren syndrome, chronic hepatitis, systemic and cutaneous lupus erythematosus, and sarcoidosis), non-Hodgkin's lymphoma, and osteoporosis and a lower risk of prostate diseases. The associations for type 1 diabetes and non-Hodgkin's lymphoma attenuated when excluding SNPs in the MHC region, indicating shared genetic aetiology.

INTERPRETATION

This study uncovers multiple clinical outcomes associated with genetic liability to CeD, which suggests the necessity of comorbidity monitoring among this population.

FUNDING

This project was funded by Karolinska Institutet and the Swedish Research Council.

Causal Factors for Osteoarthritis: A Scoping Review of Mendelian Randomization Studies

OBJECTIVE

Mendelian randomization (MR) has increasingly been utilized as a tool for establishing causal relations between modifiable exposures and osteoarthritis (OA). The goal of this review was to summarize available MR studies of OA that evaluate the causal role of modifiable risk factors on OA.

METHODS

This review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) Extension for Scoping Reviews model. We performed a literature search for relevant studies published before December 2021 across multiple databases using the search terms "osteoarthritis" and ("Mendelian randomization" or "polygenic risk score"). We reported the MR estimates of causal associations between exposures and OA and then assessed methodologic quality of abstracted studies according to their efforts to validate the three key MR assumptions.

RESULTS

Our search identified 45 studies reporting on 141 exposure-association analyses. All studies performed a formal instrumental variable analysis to estimate the causal effect of exposure on OA. Causal associations (P < 0.05) were reported in 60 of these analyses representing 36 unique publications, and MR-Egger sensitivity analyses were performed in 45 of these analyses. MR studies provided support for causal associations of OA with increased levels of adiposity, coffee consumption, bone mineral density, and sleep disturbance, and decreased levels of serum calcium and low-density lipoprotein cholesterol.

CONCLUSION

These results highlight the potential benefits of weight reduction and improvement of sleep quality to reduce the risk of OA and call for a better understanding of the relations of coffee consumption and serum calcium to OA risk.

Identifying Potential Causal Effects of Telomere Length on Health Outcomes: A Phenome-Wide Investigation and Mendelian Randomization Study

BACKGROUND

Telomere length has been linked to various health outcomes. To comprehensively investigate the causal effects of telomere length throughout the human disease spectrum, we conducted a phenome-wide Mendelian randomization study (MR-PheWAS) and a systematic review of MR studies.

METHODS

We conducted a PheWAS to screen for associations between telomere length and 1 035 phenotypes in the UK Biobank (n = 408 354). The exposure of interest was the genetic risk score (GRS) of telomere length. Observed associations passing multiple testing corrections were assessed for causality by 2-sample MR analysis. A systematic review of MR studies on telomere length was performed to harmonize the published evidence and complement our findings.

RESULTS

Of the 1 035 phenotypes tested, PheWAS identified 29 and 78 associations of telomere length GRS at a Bonferroni- and false discovery rate-corrected threshold; 24 and 66 distinct health outcomes were causal in the following principal MR analysis. The replication MR using data from the FinnGen study provided evidence of causal effects of genetically instrumented telomere length on 28 out of 66 outcomes, including decreased risks of 5 diseases in respiratory diseases, digestive diseases, and myocardial infarction, and increased risks of 23 diseases, mainly comprised neoplasms, diseases of the genitourinary system, and essential hypertension. A systematic review of 53 MR studies found evidence to support 16 out of the 66 outcomes.

CONCLUSIONS

This large-scale MR-PheWAS identified a wide range of health outcomes that were possibly affected by telomere length, and suggested that susceptibility to telomere length may vary across disease categories.

Lifestyle factors, serum parameters, metabolic comorbidities, and the risk of kidney stones: a Mendelian randomization study

Background and objective

The early identification of modifiable risk factors is important for preventing kidney stones but determining causal associations can be difficult with epidemiological data. We aimed to genetically assess the causality between modifiable factors (lifestyle factors, serum parameters, and metabolic comorbidities) and the risk of kidney stones. Additionally, we aimed to explore the causal impact of education on kidney stones and its potential mediating pathways.

Methods

We conducted a two-sample Mendelian randomization (MR) study to explore the causal association between 44 modifiable risk factors and kidney stones. The FinnGen dataset initially explored the causal relationship of risk factors with kidney stones and the UK Biobank dataset was used as the validation set. Then, a meta-analysis was conducted by combining discovery and validation datasets. We used two-step MR to assess potential mediators and their mediation proportions between education and kidney stones.

Results

The combined results indicated that previous exposures may increase the risk of kidney stones, including sedentary behavior, urinary sodium, the urinary sodium/potassium ratio, the urinary sodium/creatinine ratio, serum calcium, 25-hydroxyvitamin D (25OHD), the estimated creatinine-based glomerular filtration rate (eGFRcrea), GFR estimated by serum cystatin C (eGFRcys), body mass index (BMI), waist circumference, type 2 diabetes mellitus (T2DM), fasting insulin, glycated hemoglobin, and hypertension. Coffee intake, plasma caffeine levels, educational attainment, and the urinary potassium/creatinine ratio may decrease the risk of kidney stones. Ranked by mediation proportion, the effect of education on the risk of kidney stones was mediated by five modifiable risk factors, including sedentary behavior (mediation proportion, 25.7%), smoking initiation (10.2%), BMI (8.2%), T2DM (5.8%), and waist circumference (3.2%).

Conclusion

This study provides MR evidence supporting causal associations of many modifiable risk factors with kidney stones. Sedentary lifestyles, obesity, smoking, and T2DM are mediating factors in the causal relationship between educational attainment and kidney stones. Our results suggest more attention should be paid to these modifiable factors to prevent kidney stones.

Causal effects of modifiable risk factors on kidney stones: a bidirectional mendelian randomization study

BACKGROUND

Increasing epidemiological studies demonstrated that modifiable risk factors affected the risk of kidney stones. We aimed to systemically assess these causal associations using a bidirectional Mendelian randomization study.

METHODS

We obtained instrumental variables related to each exposure at the genome-wide significant threshold (P < 5 × 10^-8). Summary level data for outcomes from the FinnGen consortium and UK Biobank were utilized in the discovery and replication stage. The Inverse-variance weighted (IVW) method was used as the primary analysis, with additional sensitivity analyses and fix-effect meta-analysis to verify the robustness of IVW results.

RESULTS

Among 46 risk factors, five were significantly associated with nephrolithiasis risk in the FinnGen consortium, UK Biobank, and meta-analyses collectively. The odds ratios (ORs) (95% confidence intervals [95%CIs]) of kidney stones were 1.21 (1.13, 1.29) per standard deviation (SD) increase in serum calcium, 1.55 (1.01, 2.36) per SD increase in serum 25(OH)D, 1.14 (1.00, 1.29) per SD increase in total triglycerides, 2.38 (1.34, 4.22) per SD increase in fasting insulin, and 0.28 (0.23, 0.35) per unit increase in log OR of urine pH. In addition, genetically predicted serum phosphorus, urinary sodium, tea consumption, and income affected the risk of kidney stones (false discovery rate [FDR] P < 0.05) based on the outcome data from the FinnGen consortium, and the significant associations of education and waist-to-hip ratio with nephrolithiasis risks were found after FDR correction (FDR P < 0.05) based on the outcome data from UK Biobank.

CONCLUSIONS

Our findings comprehensively provide modifiable risk factors for the prevention of nephrolithiasis. Genome-wide association studies with larger sample sizes are needed to verify these causal associations in the future further.

Association between serum calcium level and type 2 diabetes: An NHANES analysis and Mendelian randomization study

AIMS

This study investigated the association between serum calcium levels and the prevalence of T2D using a cross-sectional study and Mendelian randomization analysis.

METHODS

Cross-sectional data were obtained from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018. Serum calcium levels were divided into three groups (low, medium and high groups) according to the tertiles. Logistic regression was used to estimate the association between serum calcium levels and T2D prevalence. Instrumental variables for serum calcium levels were obtained from the UK Biobank and a two-sample MR analysis was performed to examine the causal relationship between genetically predicted serum calcium levels and the risk of T2D.

RESULTS

A total of 39,645 participants were available for cross-sectional analysis. After adjusting for covariates, participants in the high serum calcium group had significantly higher odds of T2D (OR = 1.18, 95% CI = 1.07, 1.30, p = 0.001) than those in the moderate group. Restricted cubic spline plots showed a J-shaped curve relationship between serum calcium level and prevalence of T2D. Consistently, Mendelian randomization analysis showed that higher genetically predicted serum calcium levels were causally associated with a higher risk of T2D (OR = 1.16, 95% CI: 1.01, 1.33, p = 0.031).

CONCLUSIONS

The results of this study suggest that higher serum calcium levels are causally associated with a higher risk of T2D. Further studies are needed to clarify whether intervening in high serum calcium could reduce the risk of T2D.

Cardiovascular Impact of Calcium and Vitamin D Supplements: A Narrative Review

Calcium and vitamin D play an important role in mineral homeostasis and the maintenance of skeletal health. Calcium and vitamin D supplements have been widely used for fracture prevention in elderly populations. Many trials have studied the effectiveness and cardiovascular safety of calcium and vitamin D supplementation, with disparate results. In this review, we summarize the most important trials and systematic reviews. There is significant heterogeneity in clinical trial design, differences in the nature of trial outcomes (self-reported vs. verified), prior calcium intake, and trial size. Inconsistent results have been reported concerning the effects of calcium and vitamin D supplementation on cardiovascular outcomes. Most current guidelines recommend calcium intake of up to 1,200 mg daily, preferably from the diet, without concern for cardiovascular risk. Recommendations regarding vitamin D supplementation vary widely. There is compelling evidence from well-conducted randomized trials that modest vitamin D supplementation is safe but does not confer cardiovascular benefit or cardiovascular harm.

Prediagnostic serum calcium concentrations and risk of colorectal cancer development in 2 large European prospective cohorts

BACKGROUND

Higher dietary calcium consumption is associated with lower colorectal cancer (CRC) risk. However, little data are available on the association between circulating calcium concentrations and CRC risk.

OBJECTIVES

To explore the association between circulating calcium concentrations and CRC risk using data from 2 large European prospective cohort studies.

METHODS

Conditional logistic regression models were used to calculate multivariable-adjusted ORs and 95% CIs in case-control studies nested within the European Prospective Investigation into Cancer and Nutrition (EPIC; n-cases = 947, n-controls = 947) and the UK Biobank (UK-BB; n-cases = 2759, n-controls = 12,021) cohorts.

RESULTS

In EPIC, nonalbumin-adjusted total serum calcium (a proxy of free calcium) was not associated with CRC (OR: 0.94; 95% CI: 0.85, 1.03; modeled as continuous variable, per 1 mg/dL increase), colon cancer (OR: 0.93; 95% CI: 0.82, 1.05) or rectal cancer (OR: 1.01; 95% CI: 0.84, 1.20) risk in the multivariable adjusted model. In the UK-BB, serum ionized calcium (free calcium, most active form) was inversely associated with the risk of CRC (OR: 0.85; 95% CI: 0.76, 0.95; per 1 mg/dL) and colon cancer (OR: 0.78; 95% CI: 0.68, 0.90), but not rectal cancer (OR: 1.02; 95% CI: 0.83, 1.24) in multivariable adjusted models. Meta-analysis of EPIC and UK-BB CRC risk estimates showed an inverse risk association for CRC in the multivariable adjusted model (OR: 0.90; 95%CI: 0.84, 0.97). In analyses by quintiles, in both cohorts, higher levels of serum calcium were associated with reduced CRC risk (EPIC: ORQ5vs.Q1: 0.69; 95% CI: 0.47, 1.00; P-trend = 0.03; UK-BB: ORQ5vs.Q1: 0.82; 95% CI: 0.72, 0.94; P-trend < 0.01). Analyses by anatomical subsite showed an inverse cancer risk association in the colon (EPIC: ORQ5vs.Q1: 0.63, 95% CI: 0.39, 1.02; P-trend = 0.05; UK-BB: ORQ5vs.Q1: 0.75; 95% CI: 0.64, 0.88; P-trend < 0.01) but not the rectum.

CONCLUSIONS

In UK-BB, higher serum ionized calcium levels were inversely associated with CRC, but the risk was restricted to the colon. Total serum calcium showed a null association in EPIC. Additional prospective studies in other populations are needed to better investigate these associations.

Frontiers and hotspots evolution in anti-inflammatory studies for coronary heart disease: A bibliometric analysis of 1990-2022

Background

Coronary heart disease (CHD) is characterized by forming of arterial plaques composed mainly of lipids, calcium, and inflammatory cells. These plaques narrow the lumen of the coronary artery, leading to episodic or persistent angina. Atherosclerosis is not just a lipid deposition disease but an inflammatory process with a high-specificity cellular and molecular response. Anti-inflammatory treatment for CHD is a promising therapy; several recent clinical studies (CANTOS, COCOLT, and LoDoCo2) provide therapeutic directions. However, bibliometric analysis data on anti-inflammatory conditions in CHD are lacking. This study aims to provide a comprehensive visual perspective on the anti-inflammatory research in CHD and will contribute to further research.

Materials and methods

All the data were collected from the Web of Science Core Collection (WoSCC) database. We used the Web of Science's systematic tool to analyze the year of countries/regions, organizations, publications, authors, and citations. CiteSpace and VOSviewer were used to construct visual bibliometric networks to reveal the current status and emerging hotspot trends for anti-inflammatory intervention in CHD.

Results

5,818 papers published from 1990 to 2022 were included. The number of publications has been on the rise since 2003. Libby Peter is the most prolific author in the field. "Circulation" was ranked first in the number of journals. The United States has contributed the most to the number of publications. The Harvard University System is the most published organization. The top 5 clusters of keywords co-occurrence are inflammation, C-reactive protein, coronary heart disease, nonsteroidal anti-inflammatory, and myocardial infarction. The top 5 literature citation topics are chronic inflammatory diseases, cardiovascular risk; systematic review, statin therapy; high-density lipoprotein. In the past 2 years, the strongest keyword reference burst is "Nlrp3 inflammasome," and the strongest citation burst is "Ridker PM, 2017 (95.12)."

Conclusion

This study analyzes the research hotspots, frontiers, and development trends of anti-inflammatory applications in CHD, which is of great significance for future studies.

Health effects of milk consumption: phenome-wide Mendelian randomization study

BACKGROUND

We performed phenome-wide Mendelian randomization analysis (MR-PheWAS), two-sample MR analysis, and systemic review to comprehensively explore the health effects of milk consumption in the European population.

METHODS

Rs4988235 located upstream of the LCT gene was used as the instrumental variable for milk consumption. MR-PheWAS analysis was conducted to map the association of genetically predicted milk consumption with 1081 phenotypes in the UK Biobank study (n=339,197). The associations identified in MR-PheWAS were examined by two-sample MR analysis using data from the FinnGen study (n=260,405) and international consortia. A systematic review of MR studies on milk consumption was further performed.

RESULTS

PheWAS and two-sample MR analyses found robust evidence in support of inverse associations of genetically predicted milk consumption with risk of cataract (odds ratio (OR) per 50 g/day increase in milk consumption, 0.89, 95% confidence interval (CI), 0.84-0.94; p=3.81×10^-5), hypercholesterolemia (OR, 0.91, 95% CI 0.86-0.96; p=2.97×10^-4), and anal and rectal polyps (OR, 0.85, 95% CI, 0.77-0.94; p=0.001). An inverse association for type 2 diabetes risk (OR, 0.92, 95% CI, 0.86-0.97; p=0.003) was observed in MR analysis based on genetic data with body mass index adjustment but not in the corresponding data without body mass index adjustment. The systematic review additionally found evidence that genetically predicted milk consumption was inversely associated with asthma, hay fever, multiple sclerosis, colorectal cancer, and Alzheimer's disease, and positively associated with Parkinson's disease, renal cell carcinoma, metabolic syndrome, overweight, and obesity.

CONCLUSIONS

This study suggests several health effects of milk consumption in the European population.

Calcium, Its Regulatory Hormones, and Their Causal Role on Blood Pressure: A Two-Sample Mendelian Randomization Study

CONTEXT

Vitamin D (Vit-D), parathyroid hormone (PTH), and fibroblast growth factor 23 (FGF23) are the major calciotropic hormones involved in the regulation of blood calcium levels from the intestine, kidney, and bone through a tight endocrine feedback loop system. Altered levels of calcium itself or through the effect of its regulatory hormones could affect blood pressure (BP), but the exact mechanisms remain unclear.

OBJECTIVE

To evaluate whether a causal relationship exists between serum calcium level and/or the regulatory hormones involved in its homeostasis with BP, we performed a two-sample Mendelian randomization (MR) study.

METHODS

From 4 large genome-wide association studies (GWAS) we obtained independent (r2 < 0.001) single nucleotide polymorphisms (SNPs) associated with serum calcium (119 SNPs), Vit-D (78 SNPs), PTH (5 SNPs), and FGF23 (5 SNPs), to investigate through MR their association with systolic BP (SBP) and diastolic BP (DBP) in a Swedish urban-based study, the Malmö Diet and Cancer study (n = 29 298). Causality was evaluated by the inverse variance weighted method (IVW) and weighted median, while MR Egger and MR-PRESSO were used as sensitivity analyses.

RESULTS

Genetically predicted serum calcium level was found to be associated with DBP (IVW: beta = 0.10, SE = 0.04, P = 0.007) and SBP (IVW: beta = 0.07, SE = 0.04, P = 0.04). Genetically predicted Vit-D and PTH showed no association with the traits, while FGF23 was inversely associated with SBP (IVW: beta = -0.11, SE = 0.04, P = 0.01), although this association lost statistical significance in sensitivity analysis.

CONCLUSION

Our study shows a direct association between genetically predicted calcium level and DBP, and a weaker association with SBP. No such clear association was found for genetically predicted calciotropic hormone levels. It is of interest to detect which target genes involved in calcium homeostasis mediate the effect of calcium on BP, particularly for improving personalized intervention strategies.

Association of famine exposure and the serum calcium level in healthy Chinese adults

OBJECTIVE

Famine exposure and higher serum calcium levels are related with increased risk of many disorders, including Alzheimer's disease, atherosclerosis, diabetes, and osteoporosis. Whether famine exposure has any effect on serum calcium level is unclear. Besides, the normal reference range of serum calcium is variable among different populations. Our aims are 1) determining the reference interval of calcium in Chinese adults; 2) exploring its relationship with famine exposure.

METHODS

Data in this study was from a cross-sectional study of the epidemiologic investigation carried out during March-August 2010 in Jiading district, Shanghai, China. Nine thousand and two hundred eleven participants with estimated glomerular filtration rate (eGFR) ≥60ml/min/1.73m² were involved to calculate reference interval of total calcium from 10569 participants aged 40 years or older. The analysis of famine exposure was conducted in 9315 participants with complete serum biochemical data and birth year information.

RESULTS

After rejecting outliers, the 95% reference interval of total serum calcium was 2.122~2.518 mmol/L. The equation of albumin-adjusted calcium was: Total calcium + 0.019* (49-Albumin), with a 95% reference interval of 2.151~2.500 mmol/L. Compared to the age-balanced control group, there was an increased risk of being at the upper quartile of total serum calcium (OR=1.350, 95%CI=1.199-1.521) and albumin-adjusted calcium (OR=1.381, 95%CI=1.234-1.544) in subjects experienced famine exposure in childhood. Females were more vulnerable to this impact (OR= 1.621, 95%CI= 1.396-1.883 for total serum calcium; OR=1.722, 95%CI= 1.497-1.980 for albumin-adjusted calcium).

CONCLUSIONS

Famine exposure is an important environmental factor associated with the changes in circulating calcium concentrations, the newly established serum calcium normal range and albumin-adjusted calcium equation, together with the history of childhood famine exposure, might be useful in identifying subjects with abnormal calcium homeostasis and related diseases, especially in females.