Female reproductive factors and the risk of dementia: a nationwide cohort study.

BACKGROUND AND PURPOSE: The aim was to investigate whether female reproductive factors are associated with dementia. METHODS: In all, 4 696 633 post-menopausal women without dementia were identified using the Korean National Health Insurance System database. Data on reproductive factors were collected using a self-administered questionnaire. Dementia was determined using dementia diagnosis codes and anti-dementia drug prescription. Cox proportional hazards regression was conducted to assess the hazard ratio (HR) for dementia according to reproductive factors. RESULTS: During a median follow-up of 5.74 years, there were 212 227 new cases of all-cause dementia (4.5%), 162 901 cases of Alzheimer's disease (3.5%) and 24 029 cases of vascular dementia (0.5%). The HR of dementia was 1.15 [95% confidence interval (CI) 1.03-1.16] for menarcheal age ≥17 years compared with menarcheal age 13-14 years, 0.79 (0.77-0.81) for menopausal age ≥55 years compared with menopausal age <40 years, and 0.81 (0.79-0.82) for fertility duration ≥40 years compared with fertility duration <30 years. Whilst being of parity one (HR 0.89, 95% CI 0.85-0.94) and breastfeeding <6 months (HR 0.92, 95% CI 0.88-0.95) was associated with lower risk of dementia, being of parity two or more (HR 1.04, 95% CI 0.99-1.05) and breastfeeding ≥12 months (HR 1.14, 95% CI 1.01-1.07) was associated with a higher risk of dementia than women without parity or breastfeeding history. Use of hormone replacement therapy and oral contraceptives independently reduced the dementia risk by 15% and 10%, respectively. CONCLUSIONS: Female reproductive factors are independent risk factors for dementia incidence, with higher risk associated with shorter lifetime endogenous estrogen exposure.

Lower urinary cotinine level is associated with a trend toward more myopic refractive errors in Korean adolescents.

PurposeTo investigate the association between urinary cotinine levels as an objective biological marker for exposure to nicotine and refractive status.Patients and methodsThis cross-sectional study analyzed data from the Korea National Health and Nutrition Examination Survey between 2008 and 2011. A total of 1139 Korean adolescents aged 12-18 years were enrolled. Urinary cotinine concentrations and other potential risk factors for myopia were examined. Correlation analyses and multivariate regression analysis were performed to investigate the association between urinary cotinine level and refractive error.ResultsSpherical equivalent correlated significantly with urinary cotinine concentration (r=0.104, P=0.011). Lower urinary cotinine level was associated with a trend toward more myopic refractive errors (P for trend=0.003). After adjusting for age, sex, area of residence, physical activity, serum 25-hydroxyvitamin D level, parental income level, and receipt of basic livelihood security, subjects with a low urinary cotinine level had a significantly increased risk of myopia <-0.5 D (odds ratio (OR) 1.95, 95% confidence interval (CI) 1.18-3.21), <-3.0 D (OR 2.03, 95% CI 1.29-3.2), and <-6.0 D (OR 2.2, 95% CI, 1.15-4.23) when compared with subjects with a high urinary cotinine level. As urinary cotinine level decreased, the risks of myopia <-0.5 D, <-3.0 D, and <-6.0 D increased significantly (P for trend <0.05).ConclusionA trend toward less myopic refractive error was observed among Korean adolescents with higher urinary cotinine levels. This result provides the epidemiologic evidence implying nicotine as a potential modulator related with refractive development. Further studies with full consideration for myopia-associated risk factors are required to yield clear answers on the direct effect of smoking to the refractive status.

Effects of low-fat milk consumption on metabolic and atherogenic biomarkers in Korean adults with the metabolic syndrome: a randomised controlled trial.

BACKGROUND: Previous studies of the health effects of low-fat milk or dairy consumption on the metabolic syndrome have yielded inconsistent results. The present study aimed to investigate the effects of low-fat milk consumption on traits associated with the metabolic syndrome, as well as inflammatory and atherogenic biomarkers, in Korean adults with the metabolic syndrome. METHODS: Overweight Koreans with the metabolic syndrome (n = 58) were recruited and randomly assigned to either the low-fat milk or control group. The low-fat milk group was instructed to consume two packs of low-fat milk per day (200 mL twice daily) for 6 weeks, and the control group was instructed to maintain their habitual diet. Clinical investigations were conducted during the screening visit, on study day 0, and after 6 weeks. RESULTS: No significant differences in changes in body mass index, blood pressure, lipid profile and adiponectin levels, as well as levels of inflammatory markers, oxidative stress markers and atherogenic markers, were found between the low-fat milk and control groups. However, compared to the controls, significant favourable decreases in serum soluble vascular adhesion molecule-1 and endothelin-1 levels were found in the 12 subjects with high blood pressure and in the 18 subjects with hypertriglyceridaemia in the low-fat milk group. CONCLUSIONS: The present study did not demonstrate an overall beneficial effect of low-fat milk consumption in subjects with the metabolic syndrome. However, low-fat milk consumption may have a favourable effect on atherogenic markers in subjects with high blood pressure or hypertriglyceridaemia.

Association of lipid parameters and insulin resistance with bone health in South Korean adolescents.

UNLABELLED: This study investigated the association between lipid profiles and insulin resistance and bone mineral content (BMC) in Korean adolescents and found that BMC was inversely associated with triglyceride (TG) and homeostasis model assessment of insulin resistance (HOMA-IR). This association did not differ according to obesity status in either boys or girls. INTRODUCTION: To prevent future osteoporosis, it is important to identify factors that affect bone health in adolescents as well as adults. This study aimed to examine the association between lipid profiles and insulin resistance and BMC in Korean adolescents. METHODS: Data from 706 boys and 621 girls, who participated in the Korea National Health and Nutrition Examination Survey from 2008 to 2011, were analyzed. Lipid profiles were measured, and HOMA-IR was calculated to assess insulin resistance. BMC was measured for the total femur, femur neck, and lumbar spine by using whole-body dual-energy X-ray absorptiometry (DXA). RESULTS: TG level and HOMA-IR were negatively correlated with BMC at all three sites in boys. In girls, TG level showed a negative correlation with BMC at the femur neck and lumbar spine, and HOMA-IR was negatively associated with BMC at the femur neck only. These inverse associations did not differ according to obesity status in either sex. Adjusted means of BMC at the three sites in boys tended to decrease in the higher tertile groups of TG and HOMA-IR, and the adjusted means of BMC for the total femur in girls tended to decrease in the higher tertile groups of TG and HOMA-IR. CONCLUSIONS: BMC was inversely associated with TG and HOMA-IR in Korean adolescents, and this association was more pronounced in boys. This association did not differ according to obesity status in either sex.

Relationship between socioeconomic and lifestyle factors and cataracts in Koreans: the Korea National Health and Nutrition Examination Survey 2008-2011.

PURPOSE: Cataracts are the leading cause of visual impairment and blindness, and therefore early identification and modification of the risk factors for cataracts are meaningful. This study aimed to investigate the relationship between socioeconomic status (SES) and lifestyle factors, and age-related cataracts in South Korea. METHODS: This cross-sectional study was based on data collected in the 2008-2011 Korea National Health and Nutrition Examination Survey. A total of 15 866 subjects, aged ≥40 years, were included. SES was defined using household income and education level. Sociodemographic, lifestyle, and other associated factors were assessed by health interviews and examinations. Cataracts were diagnosed via slit-lamp examination using the Lens Opacities Classification System III. RESULTS: The prevalence of any cataract was 38.9% in men and 42.3% in women (P<0.001). In women, the risk of cataracts increased with decreases in household income (P-value for trend=0.016 and 0.041 in any, and cortical cataract, respectively) and education level (P-value for trend=0.009, 0.027, and 0.016 in any, nuclear, and cortical cataract, respectively) after adjusting for confounding factors. Current smoking was correlated with nuclear cataracts in men (OR 1.21; 95% CI: 1.00, 1.46 in age-adjusted analysis) and cataract surgery in women (OR 2.25; 95% CI: 1.00, 5.04 in multivariate-adjusted analysis). CONCLUSIONS: Socioeconomic disparities in cataract prevalence were observed in women; current smoking increased the risk of nuclear cataracts in men and surgery in women. Public health interventions focusing on gender differences are warranted to prevent and treat cataracts.

Sarcopenia and sarcopenic obesity and their association with dyslipidemia in Korean elderly men: the 2008-2010 Korea National Health and Nutrition Examination Survey.

BACKGROUND: Recently, aging has been shown to be associated with sarcopenic obesity (SO), of which decreased muscle mass and increased fat mass are features. Sarcopenia and obesity alone are known to be associated with abnormal lipid metabolism. However, it remains unclear whether SO has greater adverse effects on dyslipidemia than on sarcopenia or obesity alone. AIM: We aimed to investigate the association between SO and dyslipidemia in elderly Koreans. SUBJECTS AND METHODS: This study was based on data collected during the 2008-2010 Korea National Health and Nutrition Examination Survey. We included 1,466 men and 2,017 women aged 65 years and over. Sarcopenia was indicated in participants with height- or weight-adjusted appendicular skeletal muscle that was 1 standard deviation below the sex-specific mean for the young reference group, and obesity was defined as a body mass index ≥ 25 kg/m(2). Dyslipidemia was defined according to the National Cholesterol Education Program-Adult Treatment Panel III. RESULTS: After adjusting for confounding factors, the SO group had a higher risk for dyslipidemia [odds ratio (OR) 2.82 (95 % confidence interval 1.76-4.51)] than the obese group [2.12 (1.11-4.07)] and sarcopenic group [1.46 (1.01-2.11)] (p < 0.001) only in men. Furthermore, the SO group in men had the highest OR for hypercholesterolemia, hypertriglyceridemia, hypo-high-density lipoprotein cholesterolemia, hyper-low-density lipoprotein cholesterolemia, and a high ratio of triglyceride to high-density lipoprotein cholesterol even after further adjustments. CONCLUSIONS: In Korean elderly men, SO was associated with an increased risk for dyslipidemia compared with sarcopenia or obesity alone.

High intraocular pressure is associated with cardiometabolic risk factors in South Korean men: Korean National Health and Nutrition Examination Survey, 2008-2010.

OBJECTIVE: Elevated intraocular pressure (IOP) contributes to the progression of visual defects such as glaucoma. This study determined whether metabolic syndrome (MetS) and cardiovascular risk factors are associated with IOP in South Korean men. METHODS: We analyzed data on 4875 men who participated in the Korean National Health and Nutrition Examination Survey 2008-2010. We recorded the values for age, weight, height, body mass index (BMI), waist circumference (WC), systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting blood glucose (FBG), insulin, homeostasis model assessment of estimated insulin resistance (HOMA-IR), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglyceride (TG), non-HDL-C (NHDL-C), and TG/HDL-C, as well as sociodemographic factors. IOP was measured using Goldmann applanation tonometry. RESULTS: Weight, BMI, WC, SBP, DBP, FBG, insulin, HOMA-IR, TC, LDL-C, TG, NHDL-C, TG/HDL-C, and the prevalence of MetS differed significantly among the three groups with IOP (P<0.05). Mean IOP was higher in subjects who were obese and had hypertension, diabetes mellitus, MetS, abdominal obesity, high TG, high FBG, or high BP compared with normal subjects (P<0.005). Analysis using Pearson's correlation coefficient showed that all cardiometabolic risk factors were significantly associated with IOP (P<0.005), with the exception of WC and HDL-C. A multivariate linear regression analysis showed that IOP was positively correlated with BMI, SBP, DBP, FBG, HOMA-IR, TC, LDL-C, TG, NHDL-C, and TG/HDL-C after adjusting for all covariates (all P<0.05). CONCLUSIONS: Cardiometabolic risk factors, including the components of MetS, are associated with increased IOP.

Relationship between socioeconomic status and anemia prevalence in adolescent girls based on the fourth and fifth Korea National Health and Nutrition Examination Surveys.

BACKGROUND/OBJECTIVES: We studied the relationship between socioeconomic status (SES), represented by household income, and the prevalence of anemia and iron deficiency anemia (IDA) among adolescent girls in Korea. SUBJECTS/METHODS: The samples were based on the data from a four-year (2008-2011) collection for the Korea National Health and Nutrition Examination Survey (1312 girls, age 10-18 years). The survey included demographic, anthropometric, biochemical and nutritional parameters. A multiple regression analysis after adjusting for age, body mass index (BMI), red blood cell count, white blood cell count and red meat intake was performed. Anemia was defined as hemoglobin level lower than 11.5 g/dl for ages 10-11 years and 12.0 g/dl for ages 12-14 years. Iron deficiency was defined as serum ferritin level below 15 µg/l. RESULTS: The prevalences of anemia and IDA in Korean girls were 5.3 and 4.2%, respectively. Girls with anemia were older, taller, weighed more, had higher BMI, had higher portion of menarche experience and consumed less red meat than girls without anemia. Girls with higher income had lower anemia prevalence and consumed more iron and vitamins. Logistic regression analysis showed a decreasing trend in anemia prevalence as household income increased. Correlation analysis demonstrated that there is a relationship between household income and serum hemoglobin and ferritin levels (P=0.003 and P=0.026, respectively). CONCLUSIONS: Higher SES leads to lower prevalence of anemia and IDA in Korean adolescent girls. This may be due to the fact that higher SES individuals consume more iron and vitamin C.

Eating rate is associated with cardiometabolic risk factors in Korean adults.

BACKGROUND AND AIM: Eating slowly is a crucial concept in behavioural nutrition and is recommended for weight management as it is believed to have an important effect on satiety control. This study aimed to determine whether or not eating rate is associated with cardiometabolic risk factors. METHODS AND RESULTS: This was a cross-sectional study involving 8775 Korean adults, who visited the Center for Health Promotion of Korea University Anam Hospital in Seoul, Korea. In male study participants, weight and body mass index (BMI) were found to depend on eating rate after adjusting for age, alcohol consumption, smoking, exercise and total energy intake. When adjusted for age, alcohol consumption, smoking, exercise and BMI, differences were found between the eating rate groups with respect to high-density lipoprotein (HDL)-cholesterol, alanine aminotransferase (ALT) and alkaline phosphatase (ALP) values, white blood cell (WBC) count and total energy intake. Female participants were found to be different from males in that diastolic blood pressure and low-density lipoprotein (LDL)- and HDL-cholesterol values were significantly different between each eating rate group, while ALT and ALP values, WBC count and total energy intake were not. Compared with the slow eating rate group (>15 min), the fastest eating rate group (<5 min) had significantly increased odds ratios for cardiometabolic risk factors such as high glucose and low HDL-cholesterol levels in males, even after adjusting for BMI. CONCLUSION: Fast eating rates are associated with obesity and other cardiometabolic risk factors, particularly in men. Thus, eating slowly is recommended for weight reduction and to decrease cardiovascular risk factors.