Associations of meal timing and sleep duration with incidence of obesity: a prospective cohort study.

OBJECTIVES: Late mealtime and short sleep are known to be associated with obesity risk due to a misaligned circadian rhythm. This study aimed to investigate the relationship between obesity and mealtime and sleep duration using the Korean Genome and Epidemiology Study (KoGES) data. DESIGN: Longitudinally prospective cohort study. SETTING: Population-based. PARTICIPANTS: KoGES analysed data from 9,474 Korean adults with an average age of 54- years old at baseline. MEASUREMENTS: Meal timing was defined as the eating occasions of the day reported by the participant eating a 24-h dietary recall method. Sleep duration was categorized as <6, 6-7, 7-8, and ≥8 h. The Cox proportional hazard model was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for incident obesity according to meal timing, sleep duration, and nightly fasting duration. RESULTS: During a mean follow-up of 3.5 years, 826 participants developed obesity. In the multivariable-adjusted analysis, midnight snack eating (HR, 1.20; 95% CI, 1.02-1.41) and higher energy intake from midnight snacks (HR, 1.26; 95% CI, 1.06-1.49) were associated with a higher risk of obesity. Sleeping 8 h or more (HR, 0.67; 95% CI, 0.53-0.85) was associated with a lower risk of obesity. CONCLUSIONS: Our findings highlight the importance of meal and sleep times and suggest that healthy eating habits related to the time of day.

Nutrition survey methods and food composition database update of the Korean Genome and Epidemiology Study.

This study presents the nutrition survey methods and the updated food composition database for the Korean Genome and Epidemiology Study (KoGES). The KoGES, which is the largest and longest cohort study in Korea, aims to identify genetic and environmental factors associated with chronic diseases. This study has collected dietary data using a validated semi-quantitative food frequency questionnaire and/or the 24-hour recall method. However, these dietary survey methods use different food composition databases, and their nutritional values are out of date. Therefore, it became necessary to update the food composition database by revising nutrient analysis values to reflect improvements in the performance of food ingredient analysis equipment, revising international values to analysis values of Korean agricultural products, adjusting nutrient units, and adding newly reported nutrients related to chronic diseases. For this purpose, we integrated the different food composition databases used in each nutrition survey, updated 23 nutrients, and expanded 48 new nutrients for 3,648 food items using the latest reliable food composition databases published by national and international institutions. This revised food composition database may help to clarify the relationship between various nutrients and chronic diseases. It could serve as a valuable resource for nutritional, epidemiological, and genomic research and provide a basis for determining public health policies.

Dietary carbohydrate quality and quantity in relation to the incidence of type 2 diabetes: A prospective cohort study of middle-aged and older Korean adults.

OBJECTIVES: This study aimed to investigate whether dietary glycemic load (GL), glycemic index (GI), and carbohydrate intake were prospectively associated with incident type 2 diabetes mellitus (T2DM) in a middle-aged and older Korean populations. METHODS: Data from the Korean Genome and Epidemiology Study were used. A total of 7294 Korean adults ages 40 y to 69 y and with no previous diagnosis of T2DM or cancer at baseline were followed for 10 y. Dietary GL, GI, and carbohydrate intake were estimated on the basis of participants' responses to a validated, semiquantitative, food-frequency questionnaire at baseline. T2DM was defined according to the World Health Organization and International Diabetes Federation criteria. RESULTS: During 7.7 y (56 377 person-years) of follow-up time, 1259 participants (17.3%) developed T2DM. Grain and its products (particularly refined and whole grains) were the greatest contributors to dietary GL. In the multivariable Cox models, dietary GL was differentially associated with T2DM risk by sex. Men in the highest quintile demonstrated a higher risk of T2DM incidence than did those with the lowest, energy-adjusted, dietary GL (hazard ratio for fifth vs. first quarter = 1.26; 95% confidence interval, 1.05-1.52; P for trend < 0.05) but no association between dietary GL and the risk of T2DM was observed in women. Similar to the findings from the main models, the effect of dietary GL on T2DM incidence according to body mass index, abdominal obesity, and physical activity levels differed substantially by sex. CONCLUSIONS: High GL diets may increase the risk of the development of T2DM in middle-aged and older Korean men but not in women. Nutrition education and emphasis on self-monitoring of dietary carbohydrate quality and quantity of overall diets is necessary in the middle-aged and older Korean populations.

A nonsynonymous SNP in BANK1 is associated with serum LDL cholesterol levels in three Korean populations.

Serum levels of lipids, such as cholesterol and triglycerides, are heritable risk factors for cardiovascular disease and targets for therapeutic intervention. Because previous genome-wide association studies (GWASs) did not target functional genetic variants, we employed an alternate approach using nonsynonymous single-nucleotide polymorphisms (SNPs) to identify functional genetic variants associated with the regulation of serum lipid levels. We selected 3667 healthy individuals from a rural community-based cohort (CAVAS; Cardio Vascular disease Association Study) of the Korean Genome and Epidemiology Study project. We analyzed demographic and lifestyle information, lipid measurements and genotypes using the Illumina-1M SNP chip. For genotyping, we isolated 11 558 nonsynonymous SNPs and conducted a linear regression analysis with four lipid traits (total, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterols and triglycerides). Significantly associated SNPs were validated in two independent Korean populations, Korean Association Resource (KARE) (n=4116) and Health Examinee (HEXA) (n=2178). Of the 11 558 SNPs, one SNP (rs3733197) from the CAVAS was significantly associated with serum LDL cholesterols (beta±s.e.=4.67±0.94, P-value=1.0 × 10(-6 and) Bonferroni corrected P-value=0.012). The replication results of HEXA and KARE were beta±s.e.=2.88±1.12, P-value=0.016 and beta±s.e.=1.26±0.97, P-value=0.196, respectively. An overall meta-analysis of the three data sets revealed beta=2.98±0.57, P-value=6.19 × 10(-7). The rs3733197 is located in the coding region of BANK1 (B-cell scaffold protein with ankyrin repeats 1), and the minor allele (A) resulted in the replacement of the Alanine at position 383 with Threonine.