Short sleep duration is associated with inadequate hydration: cross-cultural evidence from US and Chinese adults.

Study Objectives: Short and long sleep durations are linked to reduced kidney function, but little research has examined how sleep is associated with hydration status. Our aim was to assess the relationship between sleep duration and urinary hydration biomarkers among adults in a cross-cultural context. Methods: Three samples of adults aged ≥20 years were analyzed: 2007-2008 National Health and Nutrition Examination Survey (NHANES; n = 4680), 2009-2012 NHANES (n = 9559), and 2012 cross-sectional wave of the Chinese Kailuan Study (n = 11903), excluding pregnant women and adults with failing kidneys. We estimated multiple linear regression models between self-reported usual night-time sleep duration (<6, 6, 7, 8 (reference), and ≥9 hr/day) and urine specific gravity (Usg) and urine osmolality (Uosm) as continuous variables and logistic regression models dichotomized as inadequate hydration (>1.020 g/mL; >831 mOsm/kg). In primary analyses, we estimated models excluding diabetes and diuretic medications for healthier subpopulations (NHANES, n = 11353; Kailuan, n = 8766). Results: In the healthier NHANES subset, 6 hr was associated with significantly higher Usg and odds of inadequate hydration (adjusted OR: 1.59, 95% CI: 1.25, 2.03) compared with 8 hr. Regression results were mixed using Uosm, but in the same direction as Usg. Among Chinese adults, short sleep duration (<6 and 6 hr) was associated with Usg and higher likelihood of inadequate hydration (6 hr adjusted OR: 1.42, 95% CI: 1.26, 1.60). No consistent association was found with sleeping ≥9 hr. Conclusions: Short sleep duration was associated with higher odds of inadequate hydration in US and Chinese adults relative to sleeping 8 hr.

Tea Consumption and Longitudinal Change in High-Density Lipoprotein Cholesterol Concentration in Chinese Adults.

BACKGROUND: The relation between tea consumption and age-related changes in high-density lipoprotein cholesterol (HDL-C) concentrations remains unclear, and longitudinal human data are limited. The aim of current study was to examine the relation between tea intake and longitudinal change in HDL-C concentrations. METHODS AND RESULTS: Baseline (2006) tea consumption was assessed via a questionnaire, and plasma HDL-C concentrations were measured in 2006, 2008, 2010, and 2012 among 80 182 individuals (49±12 years of age) who did not have cardiovascular diseases or cancer, or did not use cholesterol-lowering agents both at baseline (2006) and during the follow-up period (2006-2012). The associations between baseline tea consumption and rate of change in HDL-C concentrations were examined using generalized estimating equation models. Tea consumption was inversely associated with a decreased rate of HDL-C concentrations (P-trend <0.0001) in the fully adjusted model. The adjusted mean difference in the HDL-C decreased rate was 0.010 (95% confidence interval, 0.008, 0.012) mmol/L per year for tea consumers versus nonconsumers (never or less than once/month group). Interactions between tea consumption and age, sex, lifestyle scores, and metabolic syndrome (all P-interaction <0.0001) were identified. The associations between greater tea consumption and slower decrease in HDL-C concentrations were more pronounced in men, individuals aged 60 or older, individuals with a lower lifestyle score, and individuals with metabolic syndrome (all P-trend <0.0001). CONCLUSIONS: Tea consumption was associated with slower age-related decreases in HDL-C concentrations during 6 years of follow-up. CLINICAL TRIAL REGISTRATION: URL: www.chictr.org. Unique identifier: ChiCTR-TNRC-11001489.

Longitudinal study of alcohol consumption and HDL concentrations: a community-based study.

Background: In cross-sectional studies and short-term clinical trials, it has been suggested that there is a positive dose-response relation between alcohol consumption and HDL concentrations. However, prospective data have been limited.Objective: We sought to determine the association between total alcohol intake, the type of alcohol-containing beverage, and the 6-y (2006-2012) longitudinal change in HDL-cholesterol concentrations in a community-based cohort.Design: A total of 71,379 Chinese adults (mean age: 50 y) who were free of cardiovascular diseases and cancer and did not use cholesterol-lowering agents during follow-up were included in the study. Alcohol intake was assessed via a questionnaire in 2006 (baseline), and participants were classified into the following categories of alcohol consumption: never, past, light (women: 0-0.4 servings/d; men: 0-0.9 servings/d), moderate (women: 0.5-1.0 servings/d; men: 1-2 servings/d), and heavy (women: >1.0 servings/d; men: >2 servings/d). HDL-cholesterol concentrations were measured in 2006, 2008, 2010, and 2012. We used generalized estimating equation models to examine the associations between baseline alcohol intake and the change in HDL-cholesterol concentrations with adjustment for age, sex, smoking, physical activity, obesity, hypertension, diabetes, liver function, and C-reactive protein concentrations.Results: An umbrella-shaped association was observed between total alcohol consumption and changes in HDL-cholesterol concentrations. Compared with never drinkers, past, light, moderate, and heavy drinkers experienced slower decreases in HDL cholesterol of 0.012 mmol · L-1 · y-1 (95% CI: 0.008, 0.016 mmol · L-1 · y-1), 0.013 mmol · L-1 · y-1 (95% CI: 0.010, 0.016 mmol · L-1 · y-1), 0.017 mmol · L-1 · y-1 (95% CI: 0.009, 0.025 mmol · L-1 · y-1), and 0.008 mmol · L-1 · y-1 (95% CI: 0.005, 0.011 mmol · L-1 · y-1), respectively (P < 0.0001 for all), after adjustment for potential confounders. Moderate alcohol consumption was associated with the slowest increase in total-cholesterol:HDL-cholesterol and triglyceride:HDL-cholesterol ratios. We observed a similar association between hard-liquor consumption and the HDL-cholesterol change. In contrast, greater beer consumption was associated with slower HDL-cholesterol decreases in a dose-response manner.Conclusion: Moderate alcohol consumption was associated with slower HDL-cholesterol decreases; however, the type of alcoholic beverage had differential effects on the change in the HDL-cholesterol concentration.