A Positive Causal Relationship between Noodle Intake and Metabolic Syndrome: A Two-Sample Mendelian Randomization Study

Calcium- and Sodium-Rich Food Intake among Koreans with and without Metabolic Syndrome: Cross-Sectional Analysis of the Korean Genome and Epidemiology Study

BACKGROUND

The prevalence of metabolic syndrome (MetS) is increasing. While calcium and sodium are known nutritional factors used for managing MetS, few studies have focused on food-based analyses. This cross-sectional study examined the distribution of calcium- and sodium-rich food intake among Koreans with MetS.

METHODS

This cross-sectional analysis evaluated 130,423 participants from the Health Examinees-Gem cohort study. Foods contributing up to 90% of the calcium and sodium intake were selected from the semi-quantitative food frequency questionnaire, and consumption levels were calculated. MetS was defined as satisfying three or more criteria from the National Cholesterol Education Program Adult Treatment Panel III. The results are presented as odds ratios (OR) with an interquartile range (ORIQR) and 95% confidence interval.

RESULTS

Participants with MetS showed a low calcium intake (ORIQR = 0.95 and 0.92 for men and women, respectively), low consumption of dairy products (ORIQR = 0.92 and 0.89), beverages except for coffee or green tea (ORIQR = 0.97 and 0.96), and bread (ORIQR = 0.96 and 0.94). Men with MetS consumed high total sodium (ORIQR = 1.04), and large amounts of Kimchi (ORIQR = 1.03), fermented paste (ORIQR = 1.04), and noodles (ORIQR = 1.07). Women with MetS consumed more Kimchi than those without MetS (ORIQR = 1.04). The odds ratio for the low calcium and high sodium group compared to the high calcium and low sodium group was 1.26.

CONCLUSION

The MetS group consumed less calcium-rich foods and more sodium-rich foods than those without MetS. Patients with MetS might benefit from precise recommendations of high calcium-rich and low sodium-rich foods.

Use of Mendelian randomization to assess the causal status of modifiable exposures for rheumatic diseases

The explosion in Mendelian randomization (MR) publications is hard to ignore and shows no signs of slowing. Clinician readers, who may not be familiar with jargon-ridden methods, are expected to discern the good from the many low-quality studies that make overconfident claims of causality or stretch the plausibility of what MR can investigate. We aim to equip readers with foundational concepts, contextualized using examples in rheumatology, to appraise the many MR papers that are or will appear in their journals. We highlight the importance of assessing whether exposures are under plausibly specific genetic influence, whether the hypothesized causal pathways make biological sense, and whether results stand up to replication and use of control outcomes. Quality of research can vary substantially using MR as with any design, and all methods have inherent limitations. MR studies have provided and can still contribute valuable insights in the context of evidence triangulation.

Polygenic Variants Linked to Oxidative Stress and the Antioxidant System Are Associated with Type 2 Diabetes Risk and Interact with Lifestyle Factors

Oxidative stress is associated with insulin resistance and secretion, and antioxidant systems are essential for preventing and managing type 2 diabetes (T2DM). This study aimed to explore the polygenic variants linked to oxidative stress and the antioxidant system among those associated with T2DM and the interaction of their polygenic risk scores (PRSs) with lifestyle factors in a large hospital-based cohort (n = 58,701). Genotyping, anthropometric, biochemical, and dietary assessments were conducted for all participants with an average body mass index of 23.9 kg/m². Genetic variants associated with T2DM were searched through genome-wide association studies in participants with T2DM (n = 5383) and without T2DM (n = 53,318). The Gene Ontology database was searched for the antioxidant systems and oxidative stress-related genes among the genetic variants associated with T2DM risk, and the PRS was generated by summing the risk alleles of selected ones. Gene expression according to the genetic variant alleles was determined on the FUMA website. Food components with low binding energy to the GSTA5 protein generated from the wildtype and mutated GSTA5_rs7739421 (missense mutation) genes were selected using in silico analysis. Glutathione metabolism-related genes, including glutathione peroxidase (GPX)1 and GPX3, glutathione disulfide reductase (GSR), peroxiredoxin-6 (PRDX6), glutamate-cysteine ligase catalytic subunit (GCLC), glutathione S-transferase alpha-5 (GSTA5), and gamma-glutamyltransferase-1 (GGT1), were predominantly selected with a relevance score of >7. The PRS related to the antioxidant system was positively associated with T2DM (ORs = 1.423, 95% CI = 1.22-1.66). The active site of the GASTA proteins having valine or leucine at 55 due to the missense mutation (rs7739421) had a low binding energy (<-10 kcal/mol) similarly or differently to some flavonoids and anthocyanins. The PRS interacted with the intake of bioactive components (specifically dietary antioxidants, vitamin C, vitamin D, and coffee) and smoking status (p < 0.05). In conclusion, individuals with a higher PRS related to the antioxidant system may have an increased risk of T2DM, and there is a potential indication that exogenous antioxidant intake may alleviate this risk, providing insights for personalized strategies in T2DM prevention.