Meta-analysis of randomized controlled trials on calcium supplements and dairy products for changes in body weight and obesity indices.

This meta-analysis was performed to investigate whether calcium supplements and dairy products change obesity indices including fat mass. Original articles published in English between July 2009 and August 2019 were identified. Ten and 14 randomised controlled trials (RCTs) with ≥ 12 weeks interventions of calcium supplements and dairy products among overweight or obese adults aged ≥18 were critically reviewed. Mean difference (MD) or standardised mean difference (SMD) with 95% confidence interval (CI) were obtained using a random effect meta-analysis. Dairy products significantly changed fat mass (SMD, 95% CI; -0.40 [-0.77, -0.02]) and BMI (MD, 95% CI: -0.46 kg/m2 [-0.67, -0.26]), and calcium supplements also showed changes in fat mass (SMD, 95% CI; -0.15[-0.28, -0.02]). However, in the analysis of RCTs with low risk of bias scores, the significant changes remained only in the dairy-products intervention. Our findings suggest that dairy products without distinction of fat percentage may help reduce fat mass and BMI, but calcium supplements may not.

Dietary Patterns May Be Nonproportional Hazards for the Incidence of Type 2 Diabetes: Evidence from Korean Adult Females.

This study aimed to examine the association between the incidence of type 2 diabetes and various risk factors including dietary patterns based on the rigorous proportional hazards assumption tests. Data for 3335 female subjects aged 40-69 years from the Korea Genome and Epidemiology Study were used. The assumption of proportional hazards was tested using the scaled Schoenfeld test. The stratified Cox regression was used to adjust the nonproportionality of diabetic risk factors, and the regression was adjusted for potential confounding variables, such as age, marital status, physical activity, drinking, smoking, BMI, etc. Metabolic syndrome and meat and fish pattern variables were positively associated with diabetes. However, dietary patterns and metabolic syndrome variables violated the proportional hazards assumption; therefore, the stratified Cox regression with the interaction terms was applied to adjust the nonproportionality and to allow the possible different parameters over each stratum. The highest quartile of meat and fish pattern was associated with diabetes only in subjects aged over 60 years. Moreover, subjects who were obese and had metabolic syndrome had higher risk in bread and snacks (HR: 1.85; 95% CI: 1.00-3.40) and meat and fish pattern (HR: 1.82; 95% CI: 1.01-3.26), respectively. In conclusion, a quantitative proportional hazards assumption test should always be conducted before the use of Cox regression because nonproportionality of risk factors could induce limited effect on diabetes incidence.

Fat Intake and Stress Modify Sleep Duration Effects on Abdominal Obesity.

Though the association between sleep duration and obesity has been generally acknowledged, there is little information about the mechanisms behind this association. The purpose of this study was to examine the effect of the fat intake and stress variables on the association between sleep duration and abdominal obesity. Data for 13,686 subjects aged ≥ 20 years from the 2013-2017 Korea National Health and Nutrition Examination Survey were used, and hierarchical and stratified logistic regression analyses were employed. In the hierarchical logistic regression analyses, fat intake and stress did not change the significance or the size of the sleep effects upon abdominal obesity. These results suggest that sleep duration does not affect abdominal obesity through fat intake or stress variables. In addition, fat intake and stress are not mediators of the sleep duration variable. However, subjects with different levels of fat intake and stress showed different associations between sleep duration and abdominal obesity. Subjects who were in the lowest or highest group of fat intake as well as self-reported stress level showed a weaker relationship between sleep duration and abdominal obesity, compared with the other groups. In conclusion, fat intake and stress modify the effects of sleep duration on abdominal obesity according to the stratified regression results.

An association of urinary sodium-potassium ratio with insulin resistance among Korean adults.

BACKGROUND/OBJECTIVES: This study was conducted to investigate the effects of sodium-potassium ratio on insulin resistance and sensitivity in Korean adults. SUBJECTS/METHODS: Subjects were 3,722 adults (1,632 men and 2,090 women) aged 40-69 years participating in the Korean genome and epidemiology study_Ansan and Ansung study. Insulin resistance was assessed using homeostasis model assessment of insulin resistance (HoMA-IR) and fasting insulin, and insulin sensitivity was assessed by using the quantitative insulin sensitivity check index (QUICKI). The 24-h urinary sodium and potassium excretion were estimated from spot urinary samples using the Tanaka formula. The generalized linear model was applied to determine the association between urinary sodium-potassium ratio and insulin resistance. RESULTS: HoMA-IR (P-value = 0.029, P-trend = 0.008) and fasting insulin (P-value = 0.017, P-trend = 0.005) levels were positively associated with 24-h estimated urinary sodium-potassium ratio in the multivariable model. QUICKI was inversely associated with 24-h estimated urinary sodium-potassium ratio in all models (P-value = 0.0002, P-trend < 0.0001 in the multivariate model). CONCLUSION: The present study suggests that high sodium-potassium ratio is related to high insulin resistance and low insulin sensitivity. Decreasing sodium intake and increasing potassium intake are important for maintaining insulin sensitivity. Further studies are needed to confirm these findings in longitudinal studies.

Association of Genetic Variation in the Epithelial Sodium Channel Gene with Urinary Sodium Excretion and Blood Pressure.

This study was performed to investigate whether genetic variation in the epithelial sodium channel (ENaC) is associated with 24-h urinary sodium excretion and blood pressure. A total of 3345 participants of the KoGES_Ansan and Ansung study were eligible for this study. Genomic DNA samples were isolated from peripheral blood and genotyped on the Affymetrix Genome-Wide Human SNP Array 5.0. Thirty-four single nucleotide polymorphisms (SNPs) were extracted for gene regions (SCNN1A, SCNN1B, and SCNN1G) as additive components by using Plink. Twenty-four-hour sodium excretions were estimated from spot urine samples using the Tanaka formula. The general linear model (GLM) was applied to assess the association between SNPs and urinary sodium excretion or blood pressure. In the SCNN1G gene, six SNPs (rs4073291, rs12934362, rs7404408, rs4494543, rs5735, and rs6497657) were significantly different in 24-h urinary sodium excretion according to gene variants. However, no difference was found in blood pressure among participants with gene variants of ENaC. Our finding indicated that 24-h urinary sodium excretions were different according to variants of the SCNN1G gene in large samples. Further studies to replicate these findings are warranted.

Interaction between Single Nucleotide Polymorphism and Urinary Sodium, Potassium, and Sodium-Potassium Ratio on the Risk of Hypertension in Korean Adults.

Hypertension is a complex disease explained with diverse factors including environmental factors and genetic factors. The objectives of this study were to determine the interaction effects between gene variants and 24 h estimated urinary sodium and potassium excretion and sodium-potassium excretion ratios on the risk of hypertension. A total of 8839 participants were included in the genome-wide association study (GWAS) to find genetic factors associated with hypertension. Tanaka and Kawasaki formulas were applied to estimate 24 h urinary sodium and potassium excretion. A total of 4414 participants were included in interaction analyses to identify the interaction effects of gene variants according to 24 h estimated urinary factors on the risk of hypertension. CSK rs1378942 and CSK-MIR4513 rs3784789 were significantly modified by urinary sodium-potassium excretion ratio. In addition, MKLN rs1643270 with urinary potassium excretion, LOC101929750 rs7554672 with urinary sodium and potassium excretion, and TENM4 rs10466739 with urinary sodium-potassium excretion ratio showed significant interaction effects. The present study results indicated that the mutant alleles of CSK rs1378942 and CSK-MIR4513 rs3784789 had the strongest protective effects against hypertension in the middle group of 24 h estimated urinary sodium-potassium excretion ratio. Further studies are needed to replicate these analyses in other populations.

The Effect of the Sodium to Potassium Ratio on Hypertension Prevalence: A Propensity Score Matching Approach.

This study investigated the effect of the sodium to potassium ratio on hypertension prevalence and blood pressure. The study population was constructed by pooling the Korean National Health and Nutrition Examination Surveys between 2010 and 2014. The study population was divided into quartiles based on the sodium to potassium ratio, and the effect was inferred by the difference in hypertension prevalence across quartiles by six pairwise comparisons using a propensity score matching technique. The quartiles with the higher sodium to potassium ratio had higher hypertension prevalence rates based on the following pairwise comparisons: the first vs. third quartile, the first vs. fourth quartile, the second vs. third quartile, and the second vs. fourth quartile. The prevalence differences were 2.74% point (p < 0.05), 3.44% point (p < 0.01), 2.47% point (p < 0.05), and 2.95% point (p < 0.01), respectively. In addition, statistically significant higher systolic (p < 0.05) and diastolic blood pressure (p < 0.01) was observed in the second quartiles compared to the first quartiles. Because a strong association was also detected between the sodium to potassium ratio and blood pressure even at a low level of sodium to potassium ratio, a lower sodium to potassium ratio diet than a usual diet is recommended to control high blood pressure in Korea.