Young Jin Tak

Serum 25-hydroxyvitamin D levels and testosterone deficiency in middle-aged Korean men: a cross-sectional study

Previous studies have demonstrated that male hypogonadism is associated with a low level of vitamin D. However, no reports have investigated the effects of vitamin D on testosterone levels in Korean men. Our aim was to investigate whether testosterone levels are associated with serum vitamin D levels and whether seasonal variation exists. This cross-sectional study analyzed serum 25-hydroxyvitamin D [25(OH)D], total testosterone (TT), and free testosterone (FT) in 652 Korean men over 40 years of age who had undergone a comprehensive medical examination. The average age of the subjects was 56.7 ± 7.9 years, and the mean serum 25(OH)D, TT and FT levels were 21.23 ± 7.9 ng ml−1 , 4.70 ± 1.6 ng ml−1 , and 8.12 ± 3.3 pg ml−1 , respectively. In the multiple linear regression model, 25(OH)D showed positive association with TT (β =0.137, P< 0.001) and FT (β =0.103, P= 0.008). 25(OH)D and FT showed similar seasonal or monthly variation after adjustment for age. A vitamin D deficiency [25(OH)D < 20 ng ml−1 ] was associated with an increased risk of deficiencies of TT (<2.30 ng ml−1 ) (odds ratio [OR]: 2.65; 95% confidence interval [CI]: 1.21-5.78, P= 0.014) and FT (<6.50 pg ml−1 ) (OR: 1.44; 95% CI: 1.01-2.06 P= 0.048) after adjusting for age, season, body mass index, body composition, chronic disease, smoking, and alcohol use. In conclusion, we demonstrated a positive correlation between 25(OH)D and testosterone, which showed similar seasonal variation in Korean men.

25-Hydroxyvitamin D and Its Relationship with Autonomic Dysfunction Using Time- and Frequency-Domain Parameters of Heart Rate Variability in Korean Populations: A Cross-Sectional Study

Previous studies have demonstrated that reduced heart rate variability (HRV) and hypovitaminosis D are associated with cardiovascular disease (CVD). However, few reports have investigated the effects of vitamin D on HRV. This cross-sectional study analyzed serum 25-hydroxyvitamin D (25(OH)D) and HRV indices using 5-min R-R interval recordings with an automatic three-channel electrocardiography in healthy subjects (103 males and 73 females). Standard deviation of N-N interval (SDNN), square root of mean squared differences of successive N-N intervals (RMSSD), total power (TP), very low frequency (VLF), low frequency (LF), and high frequency (HF) were reported. The mean age of subjects was 55.3 ± 11.3 years and the mean 25(OH)D level was 21.2 ± 9.9 ng/mL. In a multiple linear regression model, 25(OH)D was positively correlated with SDNN (β = 0.240, p < 0.002), and LF (β = 0.144, p = 0.044). Vitamin D deficiency (25(OH)D < 15 ng/mL) was associated with decreased SDNN (<30 m/s) (OR, 3.07; 95% confidence interval (CI), 1.32–7.14; p = 0.014) after adjusting for covariates. We found that lower 25(OH)D levels were associated with lower HRV, suggesting a possible explanation for the higher risk of CVD in populations with hypovitaminosis D.

Association between uterine leiomyoma and metabolic syndrome in parous premenopausal women: A case–control study

AbstractPrevious studies have reported that uterine leiomyoma (UL) may share pathogenic features with obesity and hypertension, which are components of metabolic syndrome (MetS). We examined the association between UL and MetS in premenopausal parous women.This 1:1 case–control study was conducted on 615 asymptomatic women with UL and 615 women without UL that were matched for age, reproductive history, and hormonal use, who underwent a comprehensive health examination. UL was diagnosed by a gynecologist based on transvaginal ultrasonography findings. Blood pressure (BP), body composition, fasting plasma glucose, lipid profiles, insulin, and HOMA-IR were checked.Median age of the 1230 study subjects was 44 (40–47) years and 7% had MetS. Women with UL had significantly higher waist circumferences and body fat, BP, and low-density lipoprotein cholesterol (LDL-C) than women without UL. Although nonsignificant, the prevalence of MetS was higher in the UL group than in the non-UL group (9.3% vs 5.7%). In addition, the prevalence of UL increased as the number of abnormal metabolic components increased and was higher than in women without UL. Conditional logistic regression analysis, after adjustment for confounding factors, showed that hyperglycemia was significantly associated with an increased risk of UL (odds ratio = 1.45; 95% confidence interval, 1.10–1.89).Prevalence of abnormal metabolic component was higher in premenopausal women with UL than in normal controls, regardless of age or reproductive history. Furthermore, the study suggests that UL may share pathogenic features with the components of MetS and that women with UL be considered eligible for the early screening of metabolic abnormalities.

Urinary Malondialdehyde Is Associated with Visceral Abdominal Obesity in Middle-Aged Men

The purpose of the present study was to investigate multiple anthropometric parameters used to evaluate obesity, particularly visceral abdominal fat area, and various metabolic parameters including malondialdehyde (MDA) as an oxidative stress marker. We evaluated various measures of obesity, including body mass index (BMI), waist circumference (WC), sagittal abdominal diameter, fat percentages using dual-energy X-ray absorptiometry, visceral fat area (VFA), subcutaneous fat area, multiple biomarkers related to metabolic disease, and urinary MDA, in 73 asymptomatic middle-aged men who were not severely obese. We examined relationships between multiple measures of obesity, metabolic markers, and urinary MDA levels and evaluated associations between VFA and urinary MDA. In the visceral obesity group, γ-glutamyl transferase (GGT), uric acid, and urinary MDA levels were significantly higher than in the nonvisceral obesity group (P = 0.008, P = 0.002, and P = 0.018). Urinary MDA (r = 0.357, P = 0.002) and uric acid (r = 0.263, P = 0.027) levels were only significantly positively correlated with VFA among measures of obesity. Urinary MDA, serum GGT, and serum CRP were significantly positively associated with VFA (P = 0.001, P = 0.046, and P = 0.023, resp.), even after adjusting for BMI and WC.

The Relationship Between the Level of Serum 25-Hydroxyvitamin D and Renal Function in Patients Without Chronic Kidney Disease: A Cross-Sectional Study

OBJECTIVES Low level of vitamin D has been suggested as a risk factor for chronic kidney disease (CKD). However, little is known about the effect of vitamin D on renal function in healthy subjects. Our aim was to investigate the question of whether vitamin D status is associated with renal function in subjects without CKD. METHODS In this cross-sectional study, 1,648 subjects aged older than 20 years were recruited as study participants. Subjects diagnosed with either CKD or other conditions that could influence serum vitamin D were excluded. Estimated glomerular filtration rate (eGFR) from serum creatinine (sCr) was used for the determination of renal function. Vitamin D status was determined by the measurement of serum 25-hydroxyvitamin D [25(OH)D] levels. RESULTS In men, 25(OH)D showed significant positive correlation with age (r = 0.127, P < .001), skeletal muscle mass (r = 0.077, P = .017), sCr (r = 0.128, P < .001), and negative correlation with body fat (r = -0.065, P = .044), eGFR (r = -0.152, P < .001). In women, 25(OH)D showed negative correlation with eGFR (r = -0.085, P = .026), but not with age and body composition. In multiple linear regression analysis, 25(OH)D (β = 0.114, P < .001), total muscle mass (β = 0.202, P = .026), and age (β = 0.117, P = .003) were an independent determinant of sCr in men; in women, 25(OH)D (β = 0.086, P = .023), total muscle mass (β = 0.152, P < .001) were variables showing significant association with sCr. CONCLUSIONS Higher level of 25(OH)D is independently associated with sCr elevation. We suggest that a positive correlation between 25(OH)D and muscle mass could be attributed to sCr. It is thought to be another mechanism of serum 25(OH)D level in renal function in populations without CKD.

Vitamin-Mineral Supplement Use Patterns in Elderly Koreans: Data from the 2007-2008 Korean National Health and Nutrition Examination Survey

Background Vitamin-mineral supplements are the most popular dietary supplements in Korea. However, few studies have assessed the relationship between vitamin-mineral supplementation and associated factors among the Korean elderly. The purpose of this study was to assess the use of vitamin-mineral supplements among elderly in Korea as well as its association with sociodemographic factors, health-related behaviors, medical conditions, and nutrient intake. Methods This study was based on data from the Korean National Health and Nutrition Examination Survey, conducted by the Korean Ministry of Health and Welfare from 2008 to 2009. Data from 3,294 elderly men and women (65 years of age and older) were analyzed. Multivariable-weighted logistic regression model analysis was used to evaluate the association between vitamin-mineral supplement use and sociodemographic factors, health-related habits, and medical conditions. Results Vitamin-mineral supplementation was reported by 16.3% of the participants. The most common reason for using dietary supplements was recommendations from friends and acquaintances. Highly educated person, female participants had a greater likelihood of taking vitamin-mineral supplements. In addition, analysis of nutrient intake from food sources alone revealed a lower proportion of vitamin-mineral supplement users with nutrient intakes below the estimated average requirements for vitamin A, vitamin C, thiamine, riboflavin, niacin, calcium, iron, and phosphorus, compared to nonusers. However, vitamin-mineral supplementation was not associated with health-related behaviors or medical conditions. Conclusion Highly educated person, elderly Korean women had a greater likelihood of using vitamin-mineral supplements. In addition, nutrient intakes from food sources alone were significantly higher among vitamin-mineral supplement users. Finally, vitamin-mineral supplementation may be an indicator of healthier diet in elderly Koreans.

Adjustment of gut hormones release pattern following a fixed mealtime change in human.

BACKGROUND Gut hormones secretion is related to habitual mealtimes. However, how fast gut hormones adjust to that change when people change their fixed mealtime remains unknown. METHODS Seven healthy male volunteers were asked to eat a test breakfast at 0700 am for 2 weeks before the start of the study. Then, their fixed mealtime was intentionally changed from 0700 am to 0900 am for next 2 weeks. Blood samples were drawn every half hour from 0500 am until next 3h after breakfast for determining gut hormone levels every week. RESULTS After a change in fixed mealtime, the release pattern of acylated ghrelin was first adjusted identically according to the change and then total ghrelin was made. The meal-related fluctuations of acylated ghrelin were delayed by 120 min from week 1 after the change, while those of total ghrelin were delayed by 60 min at week 1, by 120 min at week 2. Two weeks was not enough time to adjust completely for PYY(3-36) to the change. CONCLUSION Two weeks is enough time until the pattern release of ghrelin, but not PYY(3-36) , is adjusted fully after a fixed mealtime change in human.

Is Hypovitaminosis D Associated with Stress Perception in the Elderly? A Nationwide Representative Study in Korea

Hypovitaminosis D and stress are common problems among the elderly. The aim of this cross-sectional nationally representative study was to evaluate the association between hypovitaminosis D and stress perception using large-scale nationally representative data from the Korea National Health and Nutrition Examination Survey (2012–2013). In our study, a total of 1393 elders (≥65 years old) were included to evaluate the association between hypovitaminosis D and stress perception. Serum 25-hydroxyvitamin D levels were determined using radioimmunoassay, and perceived stress status was assessed by a self-reporting questionnaire. The association between hypovitaminosis D and stress perception according to sex was examined using logistic regression analysis. After multivariate adjustment for sociodemographic and lifestyle factors and comorbidities, hypovitaminosis D was significantly associated with perceived stress (odds ratio, 2.73; 95% confidence interval, 1.10–6.77; p = 0.029) among women; however, this association was not significant among men. Hypovitaminosis D was a risk factor for higher stress perception in older Korean women. Even though the role of vitamin D in stress perception is still unclear, we suggest screening for hypovitaminosis D among the elderly.

Association of Handgrip Strength with Dietary Intake in the Korean Population: Findings Based on the Seventh Korea National Health and Nutrition Examination Survey (KNHANES VII-1), 2016

To evaluate associations between handgrip strength (HGS) and dietary nutrients, this study of a representative Korean population of 1553 adults aged ≥60 years (706 men and 847 women) analyzed data from the Korea National Health and Nutrition Examination Survey (2016). HGS was measured in both hands three times using a digital grip strength dynamometer. Dietary intake data were collected by the 24-h recall method through computer-assisted personal interviews. The study population had a mean age of 70.1 years, body mass index (BMI) of 24.2 kg/m2, and HGS of 35.7 kg in men, 21.2 kg in women. Total energy (r = 0.411), protein (r = 0.217), polyunsaturated fatty acid (PUFA) (r = 0.269), fiber (r = 0.272), and vitamin C (r = 0.098) were positively correlated with HGS. In multivariable regression analysis, PUFA (β = 0.083) and vitamin C (β = 0.003) were positively associated with HGS among women. Fiber (β = 0.071) and vitamin C (β = 0.006) showed a positive association with HGS among men. Community-dwelling older men and women with higher levels of PUFA, fiber, and vitamin C in their diet were more likely to have greater HGS even after adjusting for age, total calorie intake, BMI, chronic diseases and health-related habits.

Correlations between obesity indices and cardiometabolic risk factors in obese subgroups in women with severe obesity: A multicenter, cross-sectional study.

BACKGROUND To investigate associations between degrees of obesity using correlations between obesity indices and cardiometabolic risk factors in women. METHODS BMI, waist circumference (WC), fasting insulin, fasting glucose, lipids, and visceral adipose tissue (VAT) area using computed tomographic images were measured in 113 women with obesity. Correlations between obesity indices and cardiometabolic risk factors were analyzed in subgroups defined using sequential obesity indices. RESULTS Mean BMI and WC were 29.6kg/m2 and 92.8cm. BMI showed significant correlations with all five cardiometabolic risk factors until the BMI cut-off point reached 29kg/m2, but when it exceeded 30kg/m2, correlations no longer existed. WC was significantly correlated with all five cardiometabolic risk factors up to a value of 85cm, but when WC exceeded 90cm, correlations no longer existed. CONCLUSIONS Our cross-sectional study suggest that significant correlations between obesity indices and cardiometabolic risk factors may disappear, when obesity cut-off points exceed certain limits in women.