Byung Joon Ko

Serum 25-hydroxyvitamin D levels, obesity and the metabolic syndrome among Korean children

BACKGROUND AND AIM Evidence of the relationship between serum vitamin D levels and cardiovascular risk factors in children is limited. We investigated the associations between serum vitamin D levels (25-hydroxyvitamin D [25(OH)D]) and obesity and metabolic syndrome and its components in Korean children. METHODS AND RESULTS We recruited 1660, nine-year-old, Korean children (904 boys and 756 girls) who voluntarily participated in this study while being examined during school-based health examinations. We measured anthropometric variables (height and weight), metabolic parameters (blood pressure, fasting plasma glucose, triglyceride, and HDL cholesterol levels) and serum vitamin D levels. We analyzed the data using multivariate logistic regression models. Mean 25(OH)D levels were lower in children defined as obese or abdominally obese (P <0.001). When serum levels of 25(OH)D were divided into quartiles, BMI, waist circumference, and triglyceride levels were lower, and HDL cholesterol levels were higher, as vitamin D levels increased. Using children from the highest quartile of 25(OH)D levels as a referent, the adjusted ORs (95% CI) for obesity in those in the third, second, and lowest quartiles of 25(OH)D levels were 1.55 (1.01-2.40), 1.87 (1.22-2.85), and 2.59 (1.71-3.90), respectively (P for trend <0.001). For abdominal obesity the ORs (CI) were 2.08 (1.20-3.60), 2.32 (1.36-3.95), and 2.96 (1.75-5.00) (P for trend<0.001), and for metabolic syndrome they were 2.60 (1.08-6.30), 4.00 (1.73-9.26), and 4.25 (1.84-9.85), respectively (P for trend <0.05). CONCLUSIONS We found low vitamin D levels in Korean children to be associated with obesity and metabolic syndrome. Insufficient serum vitamin D levels in children may be a risk factor of obesity and metabolic syndrome.

25-Hydroxyvitamin D insufficiency is associated with cardiometabolic risk in Korean adolescents: the 2008–2009 Korea National Health and Nutrition Examination Survey (KNHANES)

OBJECTIVE Vitamin D insufficiency is known to be related to cardiometabolic disorders; however, the associations among serum 25-hydroxyvitamin D (25(OH)D) concentration and metabolic syndrome and cardiometabolic risk factors in children and adolescents have not yet been clearly delineated. For this reason, we investigated the relationship among serum 25(OH)D concentration and metabolic syndrome and cardiometabolic risk factors among Korean adolescents. DESIGN We performed a cross-sectional analysis and used hierarchical multivariate logistic regression analysis models to adjust for confounding variables. SETTING We used the data gathered during the 2008-2009 Korea National Health and Nutrition Examination Survey (KNHANES). SUBJECTS Our subjects included 1504 Korean adolescents aged 12-18 years who participated in the KNHANES. RESULTS Vitamin D insufficiency, defined as 25(OH)D concentration <50 nmol/l, was found in 75·3% of Korean adolescents and was associated with an increased risk of the prevalence of metabolic syndrome. Waist circumference and BMI were the most closely correlated cardiometabolic components of metabolic syndrome according to serum 25(OH)D status, but no significant relationship was found between serum 25(OH)D concentration and insulin resistance or for the risks for high blood pressure, hyperglycaemia, reduced HDL-cholesterol or hypertriacylglycerolaemia, with or without adjustment for confounding variables. CONCLUSIONS Low serum 25(OH)D concentration appears to be associated with several cardiometabolic risk factors and an increased risk of the prevalence of metabolic syndrome in Korean adolescents.

Estimate of a predictive cut-off value for serum 25-hydroxyvitamin D reflecting abdominal obesity in Korean adolescents ☆

Vitamin D deficiency is a serious global issue. Although the serum 25-hydroxyvitamin D [25(OH)D] test is generally the most accurate way to assess vitamin D levels, the optimal range of 25(OH)D has yet to be established. Moreover, the optimal level may vary according to race, region, and age. Suboptimal vitamin D status is associated with obesity and metabolic syndrome, which are the major risk factors for cardiovascular disorders; however, these relationships in children and adolescents have yet to be clearly determined. Therefore, we identified the best predictive cut-off value for reflecting abdominal obesity and, based on this value, we investigated the relationship between suboptimal 25(OH)D status and the risk for having abdominal obesity, being overweight or obese, and having metabolic syndrome in Korean adolescents. We performed a cross-sectional analysis of 713 Korean adolescents, between 12-19 years of age, and used data collected from the 2008 Korea National Health and Nutrition Examination Survey (KNHANES). Receiver operation characteristic curve analysis was used to identify the cut-off value that reflected abdominal obesity. The cut-off value of serum 25(OH)D that reflected abdominal obesity in Korean adolescents was 17.6 ng/mL. After making adjustments for gender, age, and regular physical exercise, the group that had lower levels of serum 25(OH)D compared to the cut-off value had a significantly higher risk for abdominal obesity, obesity, and metabolic syndrome than the group with 25(OH)D levels higher than the cut-off value. Suboptimal vitamin D status based on this value is associated with increased risk for abdominal obesity, obesity, and metabolic syndrome among Korean adolescents.

Socioeconomic status and dyslipidemia in Korean adults: The 2008-2010 Korea National Health and Nutrition Examination Survey

OBJECTIVE This study investigated the relationship between socioeconomic status (SES) and dyslipidemia and various parameters of dyslipidemia among Korean adults. METHODS Data from the 2008-2010 Korea National Health and Nutrition Examination Survey were used in this study. A total of 19,041 Korean adults greater than 19years old participated in the study. The SES was assessed by monthly household income and education level. The relationship of SES to the risk of dyslipidemia was assessed with multivariate logistic regression analysis after adjusting for potential confounders. RESULTS The prevalence of dyslipidemia was 37.4% among Korean adults. In men, household income level was positively associated with prevalence and risks of several parameters of dyslipidemia, and education level had positive associations with the risks of dyslipidemia and parameters of dyslipidemia. However, low SES was linked to increased prevalence and risks of dyslipidemia (P for trend<0.05) and parameters of dyslipidemia in women. CONCLUSIONS Socioeconomic disparities in dyslipidemia were found in the Korean population. Also, there were gender differences in the relationship between SES and dyslipidemia. These disparities should be considered when performing risk calculations and screening for dyslipidemia, which will ultimately help prevent cardiovascular disease.

Oral health behaviors and metabolic syndrome: the 2008–2010 Korean National Health and Nutrition Examination Survey

ObjectivesThis study examined whether oral health behaviors are associated with metabolic syndrome (MetS) in Korean adults involved in the 2008–2010 Korea National Health and Nutrition Examination Survey (KNHANES).Materials and methodsA total of 18,742 subjects (8,034 men and 10,708 women) were included. MetS was defined according to the criteria of the American Heart Association/National Heart, Lung, and Blood Institute Scientific Statement for Asians. Oral health behavior was assessed using a questionnaire included in the KNHANES.ResultsSubjects with MetS brushed their teeth less frequently and used fewer secondary oral products than subjects without MetS (p < 0.01). As frequency of toothbrushing and number of secondary oral products increased, body mass index, waist circumference, diastolic blood pressure, fasting plasma glucose, triglyceride, and white blood cell count decreased, but high-density lipoprotein–cholesterol increased (all p for trend <0.01). In the multivariable logistic regression models, as frequency of toothbrushing increased, the odds ratios (ORs) for MetS, abdominal obesity, and hyperglycemia are more than one after adjusting for age, gender, education, income, alcohol and tobacco use, physical activity, and the components of MetS. The ORs for MetS, abdominal obesity, and high blood pressure were more than one in subjects who do not use dental floss after adjusting for all covariates.ConclusionMetS is associated with infrequent daily toothbrushing and disuse of dental floss in South Korean.Clinical relevanceDentists may recommend evaluation for MetS in the patients with infrequent daily toothbrushing and disuse of dental floss.

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.

Parathyroid hormone, vitamin D levels and urine albumin excretion in older persons: the 2011 Korea National Health and Nutrition Examination Survey (KNHANES)

Persistent elevation of urinary albumin excretion (UAE), even within normal range, is an independent predictor for cardiovascular disease. Accumulating research suggests that low levels of vitamin D and high levels of parathyroid hormone (PTH) also increase cardiovascular disease risk. This study is intended to investigate the relationship between PTH, vitamin D levels and UAE.

An increase in serum uric acid concentrations is associated with an increase in the Framingham risk score in Korean adults.

Abstract Background: Uric acid is a novel cardiovascular disease (CVD) factor, but its use as an independent risk factor for CVD remains controversial. Here, we examined the correlation between Framingham risk score (FRS) and serum uric acid concentrations in asymptomatic Korean adults. Methods: This cross-sectional study was performed on 8035 Korean adults. Besides FRS, we measured body mass index, fasting blood glucose, homeostasis model assessment of insulin resistance, creatinine, γ-glutamyltransferase, the lipid profile, uric acid, high-sensitive C-reactive protein, and the white blood cell count. All subjects were placed into one of three risk groups according to their FRS. Results: All CVD related factors were significantly different in the three FRS groups. The increments of uric acid in-creased significantly FRS from the 10-year risk 0%–9% group to the >10% group after adjusting for other CVD-related factors using ordinal logistic regression analysis. Analyses of the three age groups showed similar effects. Conclusions: An increased uric acid concentration is associated with an increase in coronary heart disease risk calculated from the FRS, and doctors need to pay attention to this CVD risk in apparently healthy adults with hyperuricemia.

Trends in lipid profiles among South Korean adults: 2005, 2008 and 2010 Korea National Health and Nutrition Examination Survey

BACKGROUND This study aimed to investigate recent trends in the prevalence and parameters of dyslipidemia and rates of lipid-lowering medication use in Korean adults. Trends in lipid profiles in subjects with hypertension, diabetes or obesity were also studied. METHODS Data from the Korea National Health and Nutrition Examination Survey in 2005, 2008 and 2010 were used in this study. A total of 17 009 subjects participated in this study. RESULTS There was a declining trend in the prevalence of dyslipidemia and an increasing trend in the rates of use of lipid-lowering medication among Korean adults. In both men and women, the age-adjusted mean high-density lipoprotein cholesterol level linearly increased. There was a significantly decreasing trend in the age-adjusted mean triglycerides in women and age-adjusted mean lipid-related ratios in both sexes. The age-adjusted mean total cholesterol level showed a slightly increasing trend and the age-adjusted mean low-density lipoprotein cholesterol level was not changed in both sexes. These patterns persisted among subjects not taking lipid-lowering medication. The favorable trends were also observed in subjects with hypertension, diabetes and obesity. CONCLUSIONS Our study showed favorable trends in the prevalence of dyslipidemia and in several lipid profiles among Korean adults.

Dose-related association between urinary cotinine-verified smoking status and dyslipidemia among Korean men: the 2008-2010 Korea National Health and Nutrition Examination Survey.

This cross-sectionally designed study was based on data collected during the 2008–2010 Korea National Health and Nutrition Examination Survey. A total 3231 South Korean men aged more than 19 years were included. Urinary cotinine concentrations were measured. Smoking status was defined using questionnaire responses and urinary cotinine concentrations. Hierarchical multivariate logistic regression analyses were used to assess the association of urinary cotinine concentrations with the prevalence of dyslipidemia and various parameters of dyslipidemia. There is a significant dose-related association between smoking as assessed by urinary cotinine concentration and dyslipidemia and various parameters of dyslipidemia among South Korean men.