Serum 25-hydroxyvitamin D and metabolic syndrome in a Japanese working population: The Furukawa Nutrition and Health Study

Low serum 25-Hydroxy-Vitamin D Levels are associated with Metabolic Syndrome in a representative community population from Macau, China

Asians, especially Chinese have an increasingly high prevalence of vitamin D deficiency and insufficiency (serum 25-hydroxy-vitamin D (25OHD) <30 nmol/L and <50 nmol/L, respectively). This population group also has a high prevalence of cardiometabolic risk factors such as Myocardial Infarction (MI), Metabolic Syndrome (MetS) and low blood levels of high-density lipoproteins (HDL) and high blood levels of triglycerides (TG). The aim of this analysis was to investigate these associations in a population from Macau, China. Blood, anthropometric, and physical data were collected from 1410 randomly selected residents of Macau. In this population, (55% female, 19-89 years) 54% were vitamin D insufficient. Results from categorical multivariate regression analyses (adjusted for age, sex, and hours per day of physical activity, sitting and sunlight exposure) indicated significant two-fold associations between vitamin D insufficiency and prevalence of MI, MetS and low HDL and high TG levels. These associations became stronger when investigated with vitamin D deficiency (25OHD < 30 nmol/L). The association between cardiometabolic factors and vitamin D deficiency in those older (≥60yrs) increased markedly to OR MI=9.48 (2.62-34.32), OR MetS=7.82 (3.31-18.46) and OR low HDL=8.68 (1.56-21.16) and OR high TG=2.37 (1.07-5.25). These interesting observational findings suggest high vulnerability to lower 25OHD levels with related health disparities affecting older Asians. Integration of public health measures to detect vitamin D deficiency and insufficiency in Macau is important, and we suggest that routine health screening including serum 25OHD, HDL and TG in China may be protective for those at higher risk for related cardiometabolic conditions.

Seasonal Serum 25(OH) Vitamin D Level and Reproductive or Immune Markers in Reproductive-Aged Women with Infertility: A Cross-Sectional Observational Study in East Japan

Several studies have reported that vitamin D may modify human reproductive functions; however, the results are conflicting. We aimed to comprehensively evaluate serum vitamin D levels and examine the relationship between serum vitamin D levels and ovarian reserve markers, and immune markers of implantation, in reproductive-aged Japanese women with infertility.in reproductive-aged women with infertility. This cross-sectional, single-center study included reproductive-aged women who underwent preconception screening for fertility. Serum vitamin D levels and reproductive and immune markers were measured. Standard and advanced statistical techniques were used. We observed a statistically significant difference in the seasonal and monthly 25(OH) vitamin D levels; the 25(OH) vitamin D level during winter was the lowest among all seasons. However, there was no linear correlation between 25(OH) vitamin D levels and ovarian reserve markers, such as follicle-stimulating hormone and anti-Müllerian hormone, or the Th1/Th2 cell ratio, which is used as an implantation-related immunological marker. In this large-scale study, we evaluated the serum 25(OH) vitamin D concentration in reproductive-aged women with infertility in Japan; however, there was no association between reproductive function and vitamin D levels.

The Association between Atherosclerotic Disease Risk Factors and Serum 25-Hydroxyvitamin D Concentration in Japanese Subjects

Recent studies have described that vitamin D deficiency/insufficiency is associated with hypertension, insulin resistance, and dyslipidemia, which are major components of metabolic syndrome causing atherosclerosis. Therefore, we investigated the relationship between serum 25-hydroxyvitamin D [25(OH)D] concentration and atherosclerotic disease risk factors in healthy Japanese adults. In the present cross-sectional study, 1,177 subjects (348 males and 829 females) aged 20-72 y living in Japan (34.7-35.0ºN) were evaluated for vitamin D status by measuring serum 25(OH)D concentration. Atherosclerotic disease risk factors were defined as the presence of two or more of the following three risk factors: high blood pressure, dyslipidemia, and hyperglycemia. The percentages of vitamin D deficient and insufficient subjects were 33% and 46% in males and 59% and 32% in females, respectively. Subjects with atherosclerotic disease risk factors were significantly older and had higher BMI than those without it in both sexes. Male subjects with atherosclerotic disease risk factors had significantly lower physical activity and serum 25(OH)D concentration than those without it. In a logistic regression analysis adjusted for confounding factors, serum 25(OH)D concentration showed a significant inverse association with risk factors of atherosclerotic disease in males (OR=0.951, 95%CI: 0.906-0.998), but not in females. A covariance structure analysis also suggested that serum 25(OH)D level has a direct association with risk factors of atherosclerotic disease. In conclusion, we have demonstrated that low serum 25(OH)D level is a significant factor for increased atherosclerotic disease risk factors in males.

Usefulness of Vitamin D Deficiency Questionnaire for Japanese (VDDQ-J) for Screening of Vitamin D Deficiency and Low Muscle Mass in Relatively Healthy Japanese Anti-Aging Health Checkup Examinees

The Vitamin D Deficiency Questionnaire for Japanese (VDDQ-J) has been developed as an alternative indicator of the vitamin D nutritional status when serum 25(OH)D measurement is unavailable. In the present study, we compared the usefulness of the VDDQ-J with that of serum 25(OH)D concentration and examined the relationship among vitamin D, DXA-based body composition, and muscle strength in 163 anti-aging health check examinees. The median age, 25(OH)D concentration and VDDQ-J score were 62.0 y, 20.1 ng/mL and 22.0 points, respectively. In total, 47.9% of the subjects had serum 25(OH)D concentrations of <20 ng/mL. The VDDQ-J score was significantly negatively correlated with the serum 25(OH)D concentration, and the positive predictive value for vitamin D deficiency was 86.3%. The prevalence of sarcopenia was 6.1%. Low 25(OH)D levels and high VDDQ-J scores were significantly associated with low muscle mass in both univariate analysis and multiple linear regression analysis. The serum 25(OH)D level showed a significant negative correlation with body fat mass. The VDDQ-J score was selected as a significant determinant of low skeletal muscle mass index (<7.0 kg/m2 for men and <5.4 kg/m2 for women) by a multiple logistic regression analysis. In conclusion, the present study showed that a low vitamin D nutritional status as indicated by both low 25(OH)D levels, and high VDDQ-J scores was associated with low muscle mass and the VDDQ-J is considered useful not only for the detection of vitamin D deficiency but also in the screening of individuals with low muscle mass and a high risk of sarcopenia.

Serum 25-hydroxyvitamin D levels and dyslipidemia: a systematic review and dose-response meta-analysis of epidemiologic studies

CONTEXT

Findings of previous observational studies that examined the association between circulating vitamin D levels and lipid profiles have been inconsistent.

OBJECTIVE

A dose-response meta-analysis of epidemiologic studies was conducted to investigate the relationship between serum 25-hydroxyvitamin D levels and dyslipidemia in adults.

DATA SOURCES

Electronic databases were searched systematically for articles published up to June 2021.

DATA EXTRACTION

Fifty-seven observational studies and 2 cohort studies that reported odds ratios (ORs) or relative risks (RRs) with 95%CIs for dyslipidemia in relation to serum 25-hydroxyvitamin D levels in adults were included.

DATA ANALYSIS

A high level, vs a low level, of serum 25-hydroxyvitamin D was related to a significant 19% decrease in the odds of hypertriglyceridemia (OR 0.81; 95%CI, 0.74-0.89), an 18% reduction in low high-density lipoprotein cholesterol (HDL-C) (OR 0.82; 95%CI, 0.76-0.89), and an 18% reduction in dyslipidemia (OR 0.82; 95%CI, 0.75-0.91). No significant association was found between a high vs a low level of serum 25-hydroxyvitamin D and risk of high low-density lipoprotein cholesterol (LDL-C) levels (OR 0.86; 95%CI, 0.62-1.19) or hypercholesterolemia (OR 1.03; 95%CI, 0.93-1.15). Dose-response analyses demonstrated that each 10 ng/mL increase in the serum 25-hydroxyvitamin D level was linked, respectively, to a 7% (OR 0.93;95%CI, 0.85-1.02), a 3% (OR 0.97; 95%CI, 0.90-1.05), and a 4% (OR 0.96; 95%CI, 0.92-1.00) marginally significant decrease in the odds of hypertriglyceridemia, low HDL-C, and dyslipidemia.

CONCLUSION

Higher serum 25-hydroxyvitamin D levels are associated with significant reductions in the odds of hypertriglyceridemia, low HDL-C, and dyslipidemia in a dose-response trend.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021219484.

Vitamin D status and prevalence of metabolic syndrome by race and Hispanic origin in US adults: findings from the 2007-2014 NHANES

BACKGROUND

Vitamin D status has been found to be inversely associated with metabolic syndrome (MetS) in some studies. Vitamin D status varies by race and ethnicity, and the association of MetS with vitamin D status in US adults and by race and Hispanic origin has not been evaluated extensively.

OBJECTIVES

We aimed to examine the associations between vitamin D status and MetS overall, and across race and Hispanic origin groups, in a nationally representative sample of US adults who participated in the NHANES from 2007 to 2014.

METHODS

The total sample included 8639 adults, ≥20 y of age. Serum vitamin D was measured using a standardized LC-tandem MS method and was categorized using data-driven tertiles. MetS was defined using measured waist circumference, triglycerides, HDL cholesterol, blood pressure, and fasting glucose. Multivariable logistic regression models were fitted [accounting for sociodemographic and lifestyle factors, dietary supplement use, and BMI (in kg/m2)] to examine the associations of serum vitamin D with MetS among adults overall, and by race and Hispanic origin.

RESULTS

Serum vitamin D in the lowest tertile (≤56 nmol/L) was significantly associated with increased odds of MetS compared with the highest tertile (>77.9 nmol/L) (fully adjusted model OR: 1.85; 95% CI: 1.51, 2.27). Inverse associations were noted for all race-Hispanic origin groups: non-Hispanic white (NHW) (OR: 2.24; 95% CI: 1.67, 3.01), non-Hispanic black (OR: 1.56; 95% CI: 1.06, 2.29), and Hispanic (OR: 1.48; 95% CI: 1.03, 2.14) adults.

CONCLUSIONS

Lower vitamin D status was significantly associated with MetS among US adults after adjusting for sociodemographic and lifestyle factors, dietary supplement use, and BMI. This finding was noted across all race and Hispanic origin groups, although the strength of the association varied, being strongest for NHW adults.

Association of Serum 25(OH)D with Metabolic Syndrome in Chinese Women of Childbearing Age

Objective: To analyze the associations between serum 25(OH)D levels and the risk of metabolic syndrome (MetS) and its components, and the related genetic and non-genetic factors in non-diabetic women of childbearing age in China. Methods: Subjects were randomly selected from the 2015 Chinese Adult Chronic Disease and Nutrition Surveillance. The data of sociodemographic characteristics and lifestyle factors were obtained through questionnaire survey. Anthropometry was measured by trained interviewers, and fasting blood was collected to test 25-hydroxyvitamin D [25(OH)D], total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), fasting blood glucose (FBG), and other related parameters. Generalized linear mode and multivariate logistic analysis were performed to analyze the associations between serum 25(OH)D and MetS and its components, adjusting for the possible confounders. Results: Body mass index (BMI), serum alanine aminotransferase (ALT), hypersensitive C-reactive protein (hs-CRP), 25(OH)D, phosphorus (P), and parathyroid hormone (PTH) levels were associated with the number of MetS’s components. G allele carriers of GC rs2282679 had higher diastolic blood pressure (DBP) and FBG levels compared with the TT genotypes, while higher genetic risk score (GRS) seemed to be associated with reduced HDL-C level. The odds ratio (OR) for MetS in lowest group of 25(OH)D was 1.533 (0.980−2.399) after adjusting for season, district, area type, latitude, age, BMI, PTH, P, ALT, CRE, interleukin-6 (IL-6), and hs-CRP, compared with the median group, but the association was not significant. An insufficient 25(OH)D concentration (<14.22 ng/mL) was significantly related to the risk of elevated waist circumference (WC) (OR = 1.612 (1.014−2.561)) and TG (OR = 2.210 (1.318−3.706)), and reduced HDL-C (OR = 1.639 (1.206−2.229)) after adjusting for the confounders among these women. Moreover, these relationships were not affected by vitamin D metabolism-related gene polymorphisms. Conclusion: After comprehensively considering various influencing factors, significant associations between insufficient serum 25(OH)D and MetS‘s components, including elevated WC, TG, and reduced HDL-C, were observed. However, MetS, hypertension, and hyperglycemia were not found independently associated with 25(OH)D levels.

Serum Vitamin D Levels in Relation to Hypertension and Pre-hypertension in Adults: A Systematic Review and Dose–Response Meta-Analysis of Epidemiologic Studies

Background

Findings of observational studies that evaluated the association of serum vitamin D status and high blood pressure were contradictory. This meta-analysis of epidemiologic studies assessed the relation of serum vitamin D levels to hypertension (HTN) and pre-hypertension in adults.

Methods

We conducted a systematic search of all published articles up to March 2021, in four electronic databases (MEDLINE (PubMed), Web of Science (ISI), Embase and Scopus), and Google scholar. Seventy epidemiologic studies (10 prospective cohort, one nested case–control, and 59 cross-sectional investigations) that reported relative risks (RRs), odds ratios (ORs), hazard ratios, or prevalence ratios with 95% CIs for HTN or pre-hypertension in relation to serum vitamin D concentrations in adults were included in the analysis.

Results

In prospective studies, a 16% decrease in risk of hypertension was observed in participants with high levels of serum vitamin D compared to low levels (RR: 0.84; 95%CI: 0.73, 0.96; 12 effect sizes). Dose–response analysis in prospective studies revealed that each 25 nmol/L increase in serum vitamin D concentrations resulted in 5% reduced risk of HTN (RR: 0.95; 95% CI: 0.90, 1.00). Also, a significant nonlinear relationship between serum vitamin D levels and HTN was found (P_nonlinearity < 0.001). In cross-sectional investigations, highest vs. lowest level of serum vitamin D was related to reduced odds of HTN (OR: 0.84; 95%CI: 0.79, 0.90; 66 effect sizes) and pre-hypertension (OR: 0.75; 0.95%CI: 0.68, 0.83; 9 effect sizes). Dose–response analysis in these studies showed that each 25 nmol/L increase in serum vitamin D levels was related to a significant 6% reduction in odds of hypertension in all populations (RR: 0.94; 95%CI: 0.90, 0.99) and 3% in studies with representative populations (RR: 0.97; 95%CI: 0.95, 0.99).

Conclusion

This meta-analysis of epidemiologic studies disclosed that serum vitamin D concentrations were inversely related to the risk of HTN in adults, in a dose–response manner in both prospective cohort and cross-sectional studies.

Systematic Review Registration:http://www.crd.york.ac.uk/Prospero, identifier: CRD42021251513.

Development of a predictive model for vitamin D deficiency based on the vitamin D status in young Japanese women: A study protocol

Background

Vitamin D deficiency (VDD) is associated with an increased risk for lifestyle-related diseases. In Japan, VDD is quite prevalent in all age groups, with its high risk in young women. Furthermore, its association during pregnancy with gestational hypertension and low birth weight has also been reported. VDD can be diagnosed by serum 25-hydroxyvitamin D [25(OH)D] levels, which, however, is not suited for screening. Therefore, we will create a predictive model for serum 25(OH)D concentration and prevalence of VDD based on such data as region, sun exposure habit, and vitamin D intake in young women.

Methods

From 2020 to 2022, we conduct a cross-sectional study of 600 young women in four regions of Japan, identify the indices associated with serum 25(OH)D concentrations such as sun exposure habits, habitual vitamin D intake, ultraviolet-B irradiation, seasons (summer and winter) and latitude, and construct prediction models for serum 25(OH)D concentrations and VDD risk. This study has been registered with UMIN-CTR (ID: UMIN000041527).

Results

One hundred and fifteen subjects have been collected from 6 institutions in winter as of May 2021. When data from more than 200 subjects have become available, we will conduct the interim analysis, summarize the data by region and facility, review the inclusion criteria for analysis, and check for missing values and outliers. Prediction models for serum 25(OH)D concentration and VDD will be determined in the final analysis when all cases have been collected.

Conclusions

A screening tool for VDD risk to be developed in our study based on the predictive model would help the public and medical professionals prevent lifestyle-related diseases through improving VDD. Additionally, the results may serve as the scientific basis for determining the appropriate vitamin D intake and sun exposure standards.

Global differences in vitamin D status and dietary intake: a review of the data

BACKGROUND

Internationally, concern has been repeatedly raised about the little notable progress in the collection, analysis and use of population micronutrient status and deficiency data globally. The need for representative status and intake data for vitamin D has been highlighted as a research priority for well over a decade.

AIM AND METHODS

A narrative review which aims to provide a summary and assessment of vitamin D nutritional status data globally. This review divides the world into the Food and Agriculture Organisation's (FAO) major regions: the Americas, Europe, Oceania, Africa and Asia. Emphasis was placed on published data on the prevalence of serum 25-hydroxyvitamin D (25(OH)D) < 25/30 and <50 nmol/L (reflecting vitamin D deficiency and inadequacy, respectively) as well as vitamin D intake, where possible from nationally representative surveys.

RESULTS

Collating data from the limited number of available representative surveys from individual countries might suggest a relatively low overall prevalence of vitamin D deficiency in South America, Oceania and North America, whereas there is more moderate prevalence in Europe and Asia, and possibly Africa. Overall, the prevalence of serum 25(OH)D < 25/30 and <50 nmol/L ranges from ~5 to 18% and 24 to 49%, respectively, depending on FAO world region. Usual intakes of vitamin D can also vary by FAO world region, but in general, with a few exceptions, there are very high levels of inadequacy of vitamin D intake.

CONCLUSIONS

While the burden of vitamin D deficiency and inadequacy varies by world regions and not just by UVB availability, the global burden overall translates into enormous numbers of individuals at risk.

Metabolic Syndrome and Sarcopenia

Skeletal muscle is a major organ of insulin-induced glucose metabolism. In addition, loss of muscle mass is closely linked to insulin resistance (IR) and metabolic syndrome (Met-S). Skeletal muscle loss and accumulation of intramuscular fat are associated with a variety of pathologies through a combination of factors, including oxidative stress, inflammatory cytokines, mitochondrial dysfunction, IR, and inactivity. Sarcopenia, defined by a loss of muscle mass and a decline in muscle quality and muscle function, is common in the elderly and is also often seen in patients with acute or chronic muscle-wasting diseases. The relationship between Met-S and sarcopenia has been attracting a great deal of attention these days. Persistent inflammation, fat deposition, and IR are thought to play a complex role in the association between Met-S and sarcopenia. Met-S and sarcopenia adversely affect QOL and contribute to increased frailty, weakness, dependence, and morbidity and mortality. Patients with Met-S and sarcopenia at the same time have a higher risk of several adverse health events than those with either Met-S or sarcopenia. Met-S can also be associated with sarcopenic obesity. In this review, the relationship between Met-S and sarcopenia will be outlined from the viewpoints of molecular mechanism and clinical impact.

Serum vitamin D levels in relation to metabolic syndrome: A systematic review and dose-response meta-analysis of epidemiologic studies

Several epidemiological studies examined the association of serum vitamin D with metabolic syndrome (MetS), but the findings were inconsistent. We conducted a systematic review and dose-response meta-analysis to quantify the association between blood vitamin D levels and MetS in adults. A systematic search up to December 2020 was conducted in MEDLINE (PubMed), ISI (Web of Science), Scopus, and Google Scholar databases for epidemiological studies that assessed the relation of serum 25-hydroxyvitamin D (as the exposure) and MetS (as the outcome) in adults. Eligible cross-sectional studies were restricted to those with representative populations. Finally, 43 studies were included in the analysis (38 cross-sectional, one nested case-control, and four cohorts studies). Combining 41 effect sizes from 38 cross-sectional studies included 298,187 general adult population revealed that the highest level of serum vitamin D, compared with the lowest level, was significantly related to a 43% decreased odds of MetS in developed countries (odds ratio [OR]: 0.57; 95% confidence interval [CI]: 0.49-0.65) and 40% in developing countries (OR: 0.60; 95% CI: 0.52-0.70). Linear dose-response analysis (including 222,175 healthy individuals and 39,308 MetS patients) revealed that each 25 nmol/L increase in serum vitamin D level was significantly associated with a 15% decreased odds of MetS (OR: 0.85; 95% CI: 0.80-0.91); however, we found no significant nonlinear association. Meta-analysis of five prospective studies with 11,019 participants revealed no significant relation (relative risk [RR]: 0.70; 95% CI: 0.37-1.32). This meta-analysis indicated an inverse association between serum vitamin D concentrations and risk of MetS in general adult populations in cross-sectional studies in a dose-response manner. However, no significant association was found in a small number of cohorts. More prospective studies are needed to confirm the causality of this relationship.

The Association between Vitamin D and Nonalcoholic Fatty Liver Disease Assessed by Controlled Attenuation Parameter

BACKGROUND

An association between nonalcoholic fatty liver disease (NAFLD) and low vitamin D levels has been suggested. We investigated the relationship between vitamin D and NAFLD assessed by controlled attenuation parameter (CAP).

METHODS

We conducted a retrospective cohort study of apparently healthy subjects who underwent Fibroscan during health screening tests. NAFLD was diagnosed using CAP values.

RESULTS

Among the 1202 subjects (mean age 57.2 years, 60.6% male), 630 (52.4%) subjects had NAFLD with CAP ≥ 248 dB/m. Multivariable analysis was conducted after adjusting for metabolic risk factors including diabetes, hypertension, hypercholesterolemia, body mass index, high-density lipoprotein cholesterol, triglyceride and smoking. Higher vitamin D levels showed a lower risk of NAFLD compared to the lowest quartile of vitamin D in a dose-dependent manner (OR 0.68, 95% CI 0.47-1.00 in Q2 vs. Q1; OR 0.65, 95% CI 0.44-0.94 in Q3 vs. Q1; and OR 0.64, 95% CI 0.44-0.94 in Q4 vs. Q1). The highest quartile of vitamin D showed a decreased risk of a severe grade of steatosis (CAP ≥ 302 dB/m) compared to the lowest quartile (OR 0.52, 95% CI 0.31-0.87 in Q4 vs. Q1).

CONCLUSIONS

Higher levels of serum vitamin D were associated with a decreased risk of CAP-defined NAFLD, compared to low levels of serum vitamin D. The association between NAFLD and vitamin D suggests that vitamin D may exert a protective role against NAFLD.

Dose-response relationship between serum 25-hydroxyvitamin D and the risk of metabolic syndrome

BACKGROUND & AIMS

There are conflicting results for the association of 25-hydroxyvitamin D [25(OH)D] with metabolic syndrome (MetS). The aim of this study was to investigate the relationship between serum 25(OH)D concentration and MetS and its components in a Chinese adult population.

METHODS

A cross-sectional study of 25,691 men and 22,146 women from China was performed in 2017. MetS was defined according to National Cholesterol Education Program Adult Treatment Panel Ш. Logistic and restricted cubic spline regression analyses were used to assess the association between 25(OH)D and MetS.

RESULTS

Of the 43,837 participants aged 18-96 years, the prevalence of MetS was 21.0%. The adjusted odds ratios (ORs) for MetS decreased gradually with increasing 25(OH)D concentrations (P for trend < 0.001). Compared with the lowest 25(OH)D quartile, the adjusted ORs (95% CIs) for MetS from second to the highest quartile were 0.95 (0.88-1.02), 0.82 (0.76-0.88), and 0.70 (0.65-0.75), respectively. We observed a linear dose-response relationship between 25(OH)D concentrations and MetS risk (P for nonlinear trend = 0.35); the risk of MetS decreased by 20% (OR = 0.80, 95%CI: 0.77-0.82) for each 10 ng/ml increment in 25(OH)D concentration. The inverse association was more evident in men and participants with eGFR <60 ml/min/1.73 m² or AST ≥40 U/L (all P for interaction < 0.05). Moreover, significant inverse relationships were observed between 25(OH)D and elevated triglycerides, reduced high-density lipoprotein cholesterol and elevated blood pressure.

CONCLUSIONS

These findings suggested that higher 25(OH)D concentrations were independently associated with a dose-response decreased risk of MetS among Chinese adults.

Serum vitamin D levels in relation to abdominal obesity: A systematic review and dose-response meta-analysis of epidemiologic studies

Although several observational studies have investigated the relationship between vitamin D deficiency and risk of central obesity, the results were inconsistent. We performed a dose-response meta-analysis on epidemiologic studies that evaluated the association of vitamin D status and abdominal obesity in adults. A systematic search was carried out of all published articles, up to May 2020, in five electronic databases, including MEDLINE (Pubmed), EMBASE, Institute for Scientific Information (ISI) (Web of science), Scopus and Google scholar. Forty-one observational studies reported odds ratios (ORs) or relative risks (RRs) with 95% confidence intervals (CIs) for abdominal obesity in relation to serum vitamin D levels in adults were included in the analysis. Using a random effects model, the overall effect size was calculated. Combining 44 effect sizes from 36 cross-sectional studies with 257,699 participants revealed that the highest versus the lowest serum vitamin D level was significantly associated with a 23% decreased odds of abdominal obesity (OR: 0.77; 95% CI [0.71, 0.83]). This inverse association was significant in almost all subgroups based on different covariates. Dose-response analysis showed that each 25 nmol/L increase in serum vitamin D was related to 8% reduced risk of abdominal obesity (OR: 0.92; 95% CI [0.85, 0.99]). When we confined the analysis to 23 effect sizes from 17 studies with representative population (242,135 participants), the same results were obtained (OR: 0.79; 95% CI [0.71, 0.87]). Dose-response analysis indicated that each 25 nmol/L increase in blood vitamin D levels was linked to 10% decreased central adiposity risk in representative populations (OR: 0.90; 95% CI [0.82, 0.99]). This meta-analysis of epidemiologic studies revealed that serum vitamin D level was inversely associated with risk of abdominal obesity in adults, in a dose-response manner. The same findings were obtained in representative populations. Further prospective studies are required to examine the causal association between serum vitamin D levels and abdominal obesity.

Serum vitamin D status and metabolic syndrome: a systematic review and dose-response meta-analysis

BACKGROUD/OBJECTIVES

Evidence has suggested an association between serum vitamin D and metabolic syndrome (MetS), but prospective studies are very limited. The objective was to assess the dose-response association between serum vitamin D concentration and MetS risk using a systematic review and meta-analysis of updated observational studies.

MATERIALS/METHODS

Using MEDLINE, PubMed, and Embase, a systematic literature search was conducted through February 2020 and the references of relevant articles were reviewed. A random-effects model was used to estimate the summary odds ratio/relative risk and 95% confidence interval (CI). Heterogeneity among studies was evaluated with I² statistic. In total, 23 observational studies (19 cross-sectional studies, and four cohort studies) were included in the meta-analysis.

RESULTS

The pooled estimates (95% CI) for MetS per 25-nmol/L increment in serum vitamin D concentration were 0.80 (95% CI, 0.76–0.84; I² = 53.5) in cross-sectional studies, and 0.85 (95% CI, 0.72–0.98; I² = 85.8) in cohort studies. Similar results were observed, irrespectively of age of study population, study location, MetS criteria, and adjustment factors. There was no publication bias for the dose-response meta-analysis of serum vitamin D concentrations and MetS.

CONCLUSIONS

Dose-response meta-analysis demonstrated that a 25-nmol/L increment in the serum vitamin D concentration was associated with 20% and 15% lower risks of MetS in cross-sectional studies and cohort studies, respectively.

Effects of vitamin D supplements in patients with chronic hepatitis C: a randomized, multi-center, open label study

BACKGROUND/AIMS

We aimed to assess the role of vitamin D supplementation in the response to pegylated interferon-α (PEG-IFN-α) plus ribavirin (RBV) treatment in patients with chronic hepatitis C (CHC).

METHODS

Our study was a multi-center, randomized controlled trial in 11 hospitals. CHC patients were randomly assigned (1:1) to two groups namely, PEGIFN-α plus RBV (control group) or PEG-IFN-α plus RBV + vitamin D (800 IU daily) (vitamin D group). The primary end-point was the rate of sustained virologic response (SVR).

RESULTS

One hundred forty eight CHC patients were randomly assigned to two groups. Seventy-one patients received the PEG-IFN-α plus RBV and 77 patients received the PEG-IFN-α plus RBV + vitamin D. A total of 105 patients completed the study (control group, 47 vs. vitamin D group, 58). Baseline characteristics were mostly similar in both the groups. There was a modest but non-significant increase in SVR in the vitamin D group compared to the control group with the intention to treat analysis (64.0% vs. 49.3 %, p = 0.071) as well as in the per protocol analysis (control group vs. vitamin D group: 74.5% vs. 84.5%, p = 0.202). Fifty-two patients (73.2%) in the control group and 63 patients (81.8%) in the vitamin D group experienced at least one adverse event. The drop-out rate due to adverse effects was not different between both groups (control group vs. vitamin D group: 19.7% vs. 10.4%, p = 0.111).

CONCLUSION

Vitamin D supplement did not increase SVR in treatment naïve patients with CHC irrespective of genotype.

Vitamin D Status and Correlation with Glucose and Lipid Metabolism in Gansu Province, China

OBJECTIVE

To investigate the relationship between serum 25-hydroxyvitamin D [25(OH)D] levels and blood glucose and lipid levels in people over 18 years of age in Gansu, China.

SUBJECTS AND METHODS

A total of 1928 volunteers (958 males and 970 females) were selected. The prevalence of abnormal glucose metabolism and lipid metabolism in the vitamin D deficiency group (<20 ng/mL) and the non-vitamin D deficiency group (≥20 ng/mL) were compared. The correlations between serum 25(OH)D and blood glucose and lipid were analyzed.

RESULTS

A total of 1681 patients had 25(OH)D deficiency, with an overall prevalence of 87.2% (82.9% in males and 91.4% in females). The levels of 25(OH)D in the diabetic group and the IGT/IFG group were significantly lower than that in the normal group. The level of 25(OH)D was significantly lower in the dyslipidemia group than that in the normal group, and was significantly lower in the fasting plasma glucose (FPG) ≥5.6 mmol/L group than that in the FPG <5.6 mmol/L group (p=0.002). The 25(OH)D level in the serum triglyceride (TG) ≥1.7 mmol/L group was significantly lower than that of the TG <1.7 mmol/L group (p=0.0274). The age, heart rate, TG, TC, FPG and H₂PG levels in the vitamin D deficiency group were significantly higher than those in the non-vitamin D deficiency group (p<0.05). The prevalence of FPG ≥5.6 mmol/L in the vitamin D deficiency group was higher than that in the non-vitamin D deficiency group (23.5% vs 16.6%, p=0.016). Multiple linear regression analysis suggested that serum 25(OH)D levels were independently correlated with gender, age, FPG, TG and heart rate (β=-0.218, -0.129, -0.075, β=-0.103, -0.058, all p<0.05).

CONCLUSION

The incidences of dyslipidemia and dysglycemia were higher in the vitamin D deficiency group. The vitamin D level was independently and negatively correlated with FPG and TC, but not with waist circumference, BMI and blood pressure.

Vitamin D, menopause, and aging: quo vadis?

Menopause and aging are associated with changes in circulating gonadal steroid hormones, insulin sensitivity, body composition, and also lifestyle and social coordinates. Vitamin D status influences different metabolic adjustments, aside from calcium-phosphorus and bone metabolism. The main blood marker used to measure endogenous vitamin D status is 25-hydroxyvitamin D. Aging is associated with increases in serum parathyroid hormone and alkaline phosphatase, and a decrease of serum calcium, phosphorus, and vitamin D metabolites. 25-Hydroxyvitamin D status is also influenced by the circannual rhythm of sun irradiation. Results of clinical association studies have not correlated with intervention trials, experimental studies, and/or meta-analyses regarding the role of vitamin D on different outcomes in women during their second half of life and the vitamin D supplementation dose needed to improve clinical endpoints. Discordant results have been related to the method used to measure vitamin D, the studied population (i.e., sociodemographics and ethnicity), study designs, and biases of analyses. Vitamin D supplementation with cholecalciferol or calcifediol may improve some metabolic variables and clinical outcomes in young postmenopausal and older women. Studies seem to suggest that calcifediol may have some advantages over other forms of vitamin D supplementation. Further studies are needed to define interventions with supplements and effective food fortification.

A simple questionnaire for the prediction of vitamin D deficiency in Japanese adults (Vitaimn D Deficiency questionnaire for Japanese: VDDQ-J)

Vitamin D deficiency (VDD) is associated with an increased risk of various diseases. Serum 25-hydroxyvitamin D [25(OH)D] concentration is the best marker for vitamin D status and its concentration < 20 ng/mL indicates VDD. However, its measurement is not easily applicable for the evaluation of vitamin D status in the general population because of its cost. Therefore, we aimed to develop a simple questionnaire for easily identifying the risk of VDD. From the total sample (649 healthy subjects aged 19-70 years), 434 and 215 subjects were randomly assigned to the derivation and the validation cohort, respectively. Prediction model for VDD was developed by backward logistic regression analysis. The regression β coefficients of the significant predictors were transformed into integral numbers and used for the individual score. These individual scores were summed to calculate the total risk score (VDD questionnaire for Japanese score: VDDQ-J score). VDD was present in 54.1% of the total subjects. The model for the prediction of VDD consisted of 7 predictors. Areas under the curve were 0.78 and 0.75 in the data set of internal validation and of the external validation, respectively. The cutoff value was determined to be 31 points (range 0-54) with the sensitivity/specificity and positive predictive value/negative predictive value of 61%/79%, and 81%/57%, respectively. Our VDDQ-J score is easy to answer by the wide range of subjects, and well predicts VDD. This risk score would be useful to identify subjects at risk for VDD both in clinical and epidemiological settings.

Vitamin D Status and Components of Metabolic Syndrome in Older Subjects from Northern Finland (Latitude 65°North)

INTRODUCTION

Vitamin D deficiency has been linked to the increased risk of several chronic diseases, especially in people living in the Northern Latitudes. The aim of this study was to assess the vitamin D status in older subjects born in 1945 in Northern Finland (latitude 65°North), and to examine its associations to components of metabolic syndrome (MetS).

METHODS

In this cross-sectional study, we invited 904 subjects born in 1945 from the Oulu region (Oulu45 cohort), out of an original cohort of 1332 subjects. In the cohort, plasma 25 hydroxyvitamin D (25OHD) levels were determined by an enzyme immunoassay of 263 men and 373 women, with a mean age baseline of 69±0.5 years old. We assessed the participants' usage of vitamin D supplements, as well as their lifestyle factors, using a questionnaire.

RESULTS

Nearly 80% of the subjects had low vitamin D levels [either vitamin D deficient (<50 nmol/L) or insufficient (50 - 75 nmol/L)], and only 20% of the participants had sufficient vitamin D levels (>75 nmol/L) (based on the American Endocrine Society guidelines). The low vitamin D status was associated with a high prevalence of MetS; a significantly higher number of subjects with MetS (41%) had low vitamin D levels in comparison to the non-MetS subjects (38%) (p ≤ 0.05). The subjects under vitamin D supplementation had a significantly lower incidence of MetS (42.6% vs 57.4%) and its components in comparison to the non-supplemented subjects (p ≤ 0.05).

CONCLUSIONS

Low vitamin D levels are a risk factor for MetS amongst other lifestyle factors, such as dietary habits and physical inactivity, among older subjects in the Northern Latitudes (65°North). Optimal supplementation of vitamin D, along with rich dietary sources of vitamin D, are highly recommended for older subjects as a means to positively affect, e.g., hypertension, insulin resistance, and obesity, as components of the MetS.

The association of work-related stressors and their changes over time with the development of metabolic syndrome: The Furukawa Nutrition and Health Study

Objective:

To investigate associations of work-related stressors and their changes over time with the risk of developing metabolic syndrome (MetS) among Japanese manufacturing workers.

Methods:

Participants were 1,040 employees aged 19 to 68 years who were free from MetS at baseline and completed the three year-interval follow-up survey. MetS was defined according to the Joint Interim Statement. Work-related stressors (job strain, job demands, job control, and worksite social support) were assessed based on the Job Content Questionnaire and were split into two categories (low and high) by the median value at each survey. Multivariable logistic regression was performed to investigate the associations of baseline work-related stressors and their changes over time with the incidence of MetS.

Results:

Three years later, 61 workers developed MetS. Higher job demands at baseline were significantly associated with a lower risk of MetS (adjusted odds ratio 0.46, 95% confidential interval: 0.24, 0.89). In the analyses of the changes in stressors over time, those whose job demands changed from low to high showed significantly higher risk of MetS (adjusted odds ratio 3.27, 95% confidential interval: 1.46, 7.34), compared with those who reported low job demands in both surveys.

Conclusions:

Results suggest that an increase in job demands over time, but not higher job demands at baseline, is associated with increased risk of MetS.

Fat-soluble micronutrients and metabolic syndrome

PURPOSE OF REVIEW

Metabolic syndrome (MetS) is associated with increased risk of obesity, type 2 diabetes mellitus and cardiovascular diseases. MetS prevalence has been associated with diet inadequacy. Conversely, the cumulative incidence of MetS has been inversely associated with a Mediterranean-style diet that includes many different health-beneficial nutrients. Adherence to a Mediterranean-style diet could reduce or at least stabilize metabolic risk factors.

RECENT FINDINGS

Low serum level of fat-soluble micronutrients, such as carotenoids, vitamin (vit) A, D and E, has been linked to MetS. Fat-soluble micronutrients could contribute to prevent MetS thanks to their antioxidant and anti-inflammatory properties (vit E, carotenoids) or to their central role as hormone regulators (vit D) and/or lipid metabolism and glucose homeostasis sensors (vit D and E).

SUMMARY

This review summarizes recent epidemiological studies linking fat-soluble micronutrients to MetS and highlights new evidence on their mechanisms of actions.