Vitamin D and obesity: current perspectives and future directions. Proc Nutr Soc. 2015;74:115-124. [PMID: 25359323 DOI: 10.1017/s0029665114001578]

Metabolic Syndrome, Inflammation, Oxidative Stress, and Vitamin D Levels in Children and Adolescents with Obesity

Metabolic syndrome (MetS) is associated with systemic inflammation, oxidative stress, and hypovitaminosis D. Our aim was to determine whether vitamin D mediates inflammation and oxidative stress, assessed through selected biomarkers, in children with obesity and/or MetS. Eighty children with normal weight, overweight, or obesity were analyzed for serum vitamin D, C-reactive protein, leukocytes, adiponectin, monocyte chemoattractant protein-1, myeloperoxidase, interferon-inducible T-cell alpha chemoattractant (I-TAC/CXCL11), superoxide dismutase-1, fasting lipid and glucose levels, ultrasound-measured abdominal fat thickness, waist circumference, body mass index and blood pressure. Children with obesity or overweight had lower vitamin D levels, increased blood pressure, visceral and subcutaneous fat thickness, and higher leukocytes, C-reactive protein, and myeloperoxidase levels. Those with MetS also had lower adiponectin levels. Vitamin D levels are negatively correlated with body mass index, waist circumference, and visceral and subcutaneous fat thickness. Correlation, mediation, and regression analyses showed no link between vitamin D and inflammatory/oxidative stress variables. The novel biomarker I-TAC did not correlate with obesity or vitamin D status. Our results indicate that vitamin D does not significantly mediate inflammation or oxidative stress in children and adolescents with obesity and/or MetS. Selected inflammation/oxidative stress biomarkers appear to be altered primarily due to obesity rather than vitamin D status.

Association Between 25-hydroxyvitamin D Levels and Adverse Pregnancy Outcomes in Systemic Lupus Erythematosus

OBJECTIVE

We evaluated the association of 25-hydroxyvitamin D (25(OH)D) levels with adverse pregnancy outcomes in systemic lupus erythematosus (SLE).

METHODS

The Hopkins Lupus Cohort includes visits of pregnant patients, including assessment of 25(OH)D levels at each visit. We examined the relationship between 25(OH)D levels and adverse pregnancy outcomes (miscarriage, preterm delivery, and small for gestational age). We also used a time-to-event analysis to assess whether time-varying of 25(OH)D levels were associated with time to miscarriage or preterm delivery.

RESULTS

In subgroups of patients defined by the average of 25(OH)D levels, we observed significantly different risks of miscarriage (P = 0.0045), preterm delivery (P = 0.0007), and the composite measure of all three adverse pregnancy outcomes (P = 0.011). The highest risks were observed among those with the lowest or highest levels of vitamin D. Nine of 10 pregnant patients with low vitamin D levels during the second trimester resulted in having a premature delivery. The time-to-event model confirmed the same U-shaped association after adjustment for SLE disease activity; however, the increased risk among those with highest levels of vitamin D was not statistically significant. Body mass index did not appear to be a confounding factor.

CONCLUSION

Our study is not able to prove causation, but the results strongly suggest an association of 25(OH)D at both lower and higher levels with adverse pregnancy outcomes. We recommend the monitoring of maternal serum 25(OH)D levels during SLE pregnancies, aiming for the ideal range of 40 to 59 ng/mL.

Spatial analysis of the prevalence of abdominal obesity in middle-aged and older adult people in China: exploring the relationship with meteorological factors based on gender differences

Background

In recent years, the incidence of abdominal obesity among the middle-aged and older adult population in China has significantly increased. However, the gender disparities in the spatial distribution of abdominal obesity incidence and its relationship with meteorological factors among this demographic in China remain unclear. This gap in knowledge highlights the need for further research to understand these dynamics and inform targeted public health strategies.

Methods

This study utilized data from the 2015 China Health and Retirement Longitudinal Study (CHARLS) to analyze the incidence of abdominal obesity among the middle-aged and older adult population in China. Additionally, meteorological data were collected from the National Meteorological Information Center. Using Moran's I index and Getis-Ord Gi* statistical methods, the spatial distribution characteristics of abdominal obesity incidence were examined. The influence of various meteorological factors on the incidence of abdominal obesity in middle-aged and older adult males and females was investigated using the q statistic from the Geodetector method. Furthermore, Multi-Scale Geographically Weighted Regression (MGWR) analysis was employed to explore the impact of meteorological factors on the spatial heterogeneity of abdominal obesity incidence from a gender perspective.

Results

The spatial distribution of abdominal obesity among middle-aged and older adult individuals in China exhibits a decreasing trend from northwest to southeast, with notable spatial autocorrelation. Hotspots are concentrated in North and Northeast China, while cold spots are observed in Southwest China. Gender differences have minimal impact on spatial clustering characteristics. Meteorological factors, including temperature, sunlight, precipitation, wind speed, humidity, and atmospheric pressure, influence incidence rates. Notably, temperature and sunlight exert a greater impact on females, while wind speed has a reduced effect. Interactions among various meteorological factors generally demonstrate bivariate enhancement without significant gender disparities. However, gender disparities are evident in the influence of specific meteorological variables such as annual maximum, average, and minimum temperatures, as well as sunlight duration and precipitation, on the spatial heterogeneity of abdominal obesity incidence.

Conclusion

Meteorological factors show a significant association with abdominal obesity prevalence in middle-aged and older adults, with temperature factors playing a prominent role. However, this relationship is influenced by gender differences and spatial heterogeneity. These findings suggest that effective public health policies should be not only gender-sensitive but also locally adapted.

The correlation of obesity status with serum 25-hydroxyvitamin D in US Asian adults: NHANES 2011-2018

BACKGROUND

There is a correlation between obesity and 25-hydroxyvitamin D (25OHD) that tends to be negative. However, this relationship varies among different races. In this study, Asian adults with and without obesity were compared in terms of their levels of 25OHD.

METHODS

We carried out a cross-sectional analysis on 2664 non-Hispanic Asian adults who participated in the National Health and Nutrition Examination Survey (NHANES) conducted between 2011 and 2018. To examine the connection between obese status, body mass index (BMI), waist circumference (WC) and weight, and 25OHD, we ran multivariate linear regression models and multivariate logistic regression models.

RESULTS

After adjusting for all confounding factors, obesity status shows a significant positive correlation with vitamin D deficiency (model 3: OR = 2.318, 95% CI:1.317, 4.082). This positive correlation remains significant in males (males: OR = 2.713, 95% CI: -13.398, 5.217). In all three models, a negative association was observed between obesity status and 25OHD (model 1: β = -4.535, 95% CI: -6.987, -2.083; model 2 β = -4.249, 95% CI: -6.549, -2.039; model 3 β = -1.734, 95% CI: -7.285, 3.816). After controlling for covariates, there was a significant negative correlation between WC and 25OHD when stratified by gender and obesity status in both males with and without obesity (males with obesity: β = -1.461, 95% CI: -2.485, -0.436; males without obesity: β = -0.855. 95% CI: -1.499, -0.210). In males with obesity, there was a very strong positive connection between body weight and 25OHD (β = 0.912, 95% CI: 0.227, 1.597). In addition, neither gender's obese individuals showed a significant link between BMI and 25OHD.

CONCLUSION

This study demonstrated a positive correlation between obesity and vitamin D deficiency and a negative correlation between obesity and 25OHD in Asian American adults. Additionally, among male obese individuals, there was a significant negative correlation between WC and 25OHD, an observation that needs to be validated in further prospective studies.

Nutrient intake and adherence to the Nordic nutrition recommendations in a Swedish cohort with abdominal obesity

BACKGROUND

The Nordic Nutrition Recommendations (NNR) are developed to promote public health and to prevent food-related diseases such as obesity and cardiovascular diseases.

OBJECTIVE

To investigate the nutrient intake and adherence to the NNR in a Swedish cohort with abdominal obesity.

DESIGN

Dietary intake data were collected using 3-day food diaries and anthropometry and clinical chemistry parameters were measured at baseline of a long-term intervention studying weight-loss management.

RESULTS

Eighty-seven subjects with abdominal obesity successfully completed a 3-day food diary. Twelve of these subjects were excluded for further analysis due to implausible low-energy reporting. The remaining 75 subjects (76% females) had mean age of 52.3 ± 10.1 years and a mean body mass index of 34.3 ± 3.1 kg/m2. Mean total fat intake (41.2 ± 7.0E%) was exceeded by 56% of the sample size compared to the maximum recommended intake (RI) of 40E%, whereas mean carbohydrate intake (40.4 ± 8.0E%) was lower than the RI (45-60E%). The intake of saturated fatty acids was high compared to the NNR with only 2 women and none of men reported intakes within the RI of <10 E%. Adherence to the RI for dietary fibre was very low (16.0% and 13.3% when expressed as g/d and g/MJ, respectively). Analyses of micronutrient intake showed lowest adherences for vitamin D and sodium.

CONCLUSIONS

The nutrient intake in our subjects compared to NNR was rather low with a high total fat intake, particularly too high intake of saturated fatty acids, high salt consumption, and very low dietary fibre and vitamin D intake. More effort is clearly needed to promote healthy dietary habits among subjects with obesity.

No evidence of a causal relationship between miscarriage and 25-hydroxyvitamin D: a Mendelian randomization study

STUDY QUESTION

Is there a causal relationship between 25-hydroxyvitamin D (25OHD) and miscarriage?

SUMMARY ANSWER

In this study, little evidence of a causal relationship was found between low serum 25OHD concentration or vitamin D deficiency and the risk of miscarriages.

WHAT IS KNOWN ALREADY

Associations between low vitamin D levels and increased risk of miscarriage have been reported, but causality is unclear.

STUDY DESIGN SIZE DURATION

The latest and largest genome-wide association studies (GWAS) for serum 25OHD concentration (n = 417 580), vitamin D deficiency (426 cases and 354 812 controls), miscarriage (16 906 cases and 149 622 controls), and the number of miscarriages (n = 78 700) were used to explore the causal association between serum vitamin D levels and miscarriage by two-sample Mendelian randomization analysis.

PARTICIPANTS/MATERIALS SETTING METHODS

This study was based on summary GWAS results from the FinnGen database and the UK Biobank. The random-effect inverse-variance weighted method was regarded as the primary analysis; MR-Egger, weighted median, weighted mode, simple mode, and MR-pleiotropy residual sum and outlier (MR-PRESSO) were further employed as complementary methods. MR-Egger intercept analysis and MR-PRESSO were employed to test pleiotropy, and Cochran's Q statistic and leave-one-out sensitivity analysis were used to determine the heterogeneity and robustness of the overall estimates, respectively.

MAIN RESULTS AND THE ROLE OF CHANCE

There was insufficient evidence of causal associations between serum 25OHD concentration and miscarriage (odds ratio (OR) = 0.995, 95% CI: 0.888 to 1.114, P = 0.927), or the number of miscarriages (β = -0.004, 95% CI: -0.040 to 0.032, P = 0.829). Furthermore, little evidence of causality between genetically determined vitamin D deficiency to miscarriage (OR = 0.993, 95% CI: 0.966 to 1.021, P = 0.624), or the number of miscarriages (β = 0.001, 95% CI: -0.009 to 0.011, P = 0.828), was observed. The results of the sensitivity analysis were robust, and no significant heterogeneity or horizontal pleiotropy was found.

LIMITATIONS REASONS FOR CAUTION

This study is limited by the absence of female-specific GWAS data and the limited amount of GWAS data available for this study, as well as the need for caution in generalizing the findings to non-European ethnic groups.

WIDER IMPLICATIONS OF THE FINDINGS

These findings enhance the current understanding of the intricate association between vitamin D and pregnancy outcomes, challenging prevailing beliefs regarding the strong association with miscarriage. The results provide a special perspective that may prompt further exploration and potentially offer insights for guiding future research and informing clinical guidelines pertaining to the management of miscarriage.

STUDY FUNDING/COMPETING INTERESTS

This project was supported by the Hubei Provincial Natural Science Foundation Program General Surface Project (2022CFB200), the Key Research & Developmental Program of of Hubei Province (2022BCA042), the Fundamental Research Funds for the Central Universities (2042022gf0007, 2042022kf1210), and the Interdisciplinary Innovative Talents Foundation from Renmin Hospital of Wuhan University (JCRCWL-2022-001, JCRCYG-2022-009). All authors have no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

Unraveling the Connection: Visceral Adipose Tissue and Vitamin D Levels in Obesity

Vitamin D deficiency and insufficiency are widespread on a global scale, with multiple factors playing a role in their development, such as limited exposure to sunlight, inadequate dietary consumption, as well as obesity and abdominal fat accumulation. Abdominal obesity, assessed with waist circumference (WC), is associated with metabolic syndrome and has been linked to low vitamin D levels. This study aimed to investigate the relationship between visceral adipose tissue (VAT) and vitamin D levels, particularly examining the potential threshold for vitamin D storage and sequestration using adipose tissue. The study was conducted between 2020 and 2022 with 58 patients from an internal medicine outpatient department. Patients with certain medical conditions and those taking medications affecting bone metabolism were excluded. Blood samples were collected at baseline and after 6 months of monthly cholecalciferol supplementation. Ultrasonography was used to evaluate adipose tissue measurements, including subcutaneous adipose tissue thickness, VAT, preperitoneal adipose tissue (PPAT), and prerenal adipose tissue (PRAT). Anthropometric measures such as the waist-to-hip ratio and waist-to-height ratio were also assessed. The results showed that all subjects had significant hypovitaminosis D at baseline. After 6 months of supplementation, the mean increase in vitamin D levels was 9.6 ng/mL, with 55.2% of subjects becoming deficient. The study revealed a significant correlation between follow-up vitamin D levels and waist circumference, hip circumference, and VAT. VAT exhibited a strong correlation not only with vitamin D levels but also with waist circumference. When analyzing gender differences, males showed a higher weight and waist-to-hip ratio, while females had higher body adiposity indexes and subcutaneous adipose tissue measurements. In conclusion, this study highlights the relationship between VAT and vitamin D levels, emphasizing the potential role of adipose tissue in vitamin D availability. Waist circumference was identified as a surrogate measure for VAT evaluation. Furthermore, the study showed variations in vitamin D response to supplementation between genders, with a higher percentage of males reaching normal vitamin D levels. Predictive factors for vitamin D levels differed between genders, with waist circumference being a significant predictor in males and body adiposity index in females.

A weighted quantile sum regression with penalized weights and two indices

Background

New statistical methodologies were developed in the last decade to face the challenges of estimating the effects of exposure to multiple chemicals. Weighted Quantile Sum (WQS) regression is a recent statistical method that allows estimating a mixture effect associated with a specific health effect and identifying the components that characterize the mixture effect.

Objectives

In this study, we propose an extension of WQS regression that estimates two mixture effects of chemicals on a health outcome in the same model through the inclusion of two indices, one in the positive direction and one in the negative direction, with the introduction of a penalization term.

Methods

To evaluate the performance of this new model we performed both a simulation study and a real case study where we assessed the effects of nutrients on obesity among adults using the National Health and Nutrition Examination Survey (NHANES) data.

Results

The method showed good performance in estimating both the regression parameter and the weights associated with the single elements when the penalized term was set equal to the magnitude of the Akaike information criterion of the unpenalized WQS regression. The two indices further helped to give a better estimate of the parameters [Positive direction Median Error (PME): 0.022; Negative direction Median Error (NME): -0.044] compared to the standard WQS without the penalization term (PME: -0.227; NME: 0.215). In the case study, WQS with two indices was able to find a significant effect of nutrients on obesity in both directions identifying sodium and magnesium as the main actors in the positive and negative association, respectively.

Discussion

Through this work, we introduced an extension of WQS regression that improved the accuracy of the parameter estimates when considering a mixture of elements that can have both a protective and a harmful effect on the outcome; and the advantage of adding a penalization term when estimating the weights.

Supplementation of hyaluronic acid injections with vitamin D improve knee function by attenuating synovial fluid oxidative stress in osteoarthritis patients with vitamin D insufficiency

Objectives

There is still controversy about the effect of vitamin D supplementation on osteoarthritis (OA). The purpose of this study was to investigate the effects of vitamin D supplementation with Hyaluronic acid (HA) injection on OA.

Methods

We investigated serum vitamin D levels and oxidative stress (OS) in synovial fluid from patients with OA who underwent total knee arthroplasty (grade IV, n = 24) and HA injection (grade II and III, n = 40). The effects of HA injection with or without oral vitamin D supplementation on synovial fluid OS and knee pain and function were then further investigated. Finally, patients underwent HA injection were divided into two groups according to vitamin D levels (vitamin D &lt; or &gt; 30 ng/ml), and the efficacy of the two groups were compared.

Results

The results showed that the levels of glutathione peroxidase (GSH-PX) (P &lt; 0.05) in the synovial fluid were lower in patients with stage IV OA than that in patients with stage II-III OA, while the levels of malondialdehyde (MDA) (P &lt; 0.05) and lactate dehydrogenase (LDH) (P &lt; 0.01) were significantly higher. Moreover, we found that age, BMI and vitamin D levels were significantly associated with the levels of oxidants and/or antioxidants in synovial fluid, and that vitamin D was significantly negatively correlated with BMI (R = −0.3527, p = 0.0043). Supplementation of HA injections with vitamin D significantly reduced the OS status in synovial fluid, attenuated knee pain and improved knee function in OA patients with vitamin D insufficiency.

Conclusion

We conclude that maintenance of vitamin D sufficiency may be beneficial for the treatment of OA by improving OS in synovial fluid.

Potential benefits of vitamin D supplementation on pregnancy

BACKGROUND

The level of vitamin D in pregnant women and the effect of vitamin D supplementation are lack in Taiwan.

OBJECTIVE

To investigate the vitamin D serum level and the effect of its supplementation on pregnancy.

METHODS

We included 1048 pregnant women who underwent prenatal exam with known serum 25-hydroxyvitamin D3 [25(OH)D3] levels and delivery at the Mackay Memorial Hospital, Taipei, Taiwan during 2015-2018. A daily dose 2000 IU of vitamin D was given, starting at 12-16 weeks of pregnancy, to reach the level of 20 ng/mL, and then a maintenance dose of 800 IU/day was given. The other 3654 women without vitamin D supplementation delivered in 2018 served as control group. Pregnancy outcomes were recorded for analysis.

RESULTS

Over 80% of the 1048 pregnant women were vitamin D deficiency. There was an inverse correlation between serum vitamin D levels and maternal body mass index (p = 0.0366). We compared 375 women with serum vitamin D levels increased above 30 ng/mL after supplementation with control group. The rates of preterm birth, low birth weight, and postpartum hemorrhage between these 2 groups were 6.67% vs. 11.19% (p = 0.007), 6.40% vs. 10.0% (p = 0.025), and 1.33% vs. 3.20% (p = 0.04), respectively.

CONCLUSIONS

Vitamin D deficiency is very prevalent in pregnant women, especially those with high BMI, in Taiwan. It can be corrected by adequate vitamin D supplementation, which may decrease the risk of pregnancy complications and bring benefits to the fetus.

Response to vitamin D replacement therapy in obese children and adolescents with vitamin D deficiency: a randomized controlled trial

OBJECTIVES

Vitamin D deficiency is common in the pediatric group with obesity and is a risk factor for metabolic syndrome. Supplementation of vitamin D may require higher dosing than in normal-weight children. The aim of our study was to investigate the response of supplementation on vitamin D levels and the metabolic profile in youths with obesity.

METHODS

Children and adolescents with obesity (Body mass index >2.3 SDS, age ≤18 years) and hypovitaminosis D (level <20 μg/L) who entered a residential weight-loss program in Belgium, were included during summer. Subjects were randomized: Group 1 received 6,000 IU vitamin D daily for 12 weeks, whereas Group 2 simultaneously participating in the weight-loss program received no supplementation. Differences in vitamin D levels, weight, insulin resistance, lipid patterns, and blood pressure after 12 weeks were assessed.

RESULTS

A total of 42 subjects (12-18 years) with hypovitaminosis D were included, group 1 (n=22) received supplementation after randomization. After 12 weeks, a median increase in vitamin D levels of 28.2 (24.1-33.0) and 6.7 (4.1-8.4) µg/L was observed in group 1 and group 2, respectively (p-value<0.001), resulting in vitamin D sufficiency in 100 and 60% of subjects. No significant differences in weight loss (p-value 0.695), insulin resistance (p-value 0.078), lipid patterns (p-value 0.438), or blood pressure (p-value 0.511) were observed between both groups after 12 weeks of treatment.

CONCLUSIONS

Supplementation with 6,000 IU vitamin D daily during 12 weeks in children and adolescents with obesity and hypovitaminosis D is safe and sufficient to reach vitamin D sufficiency. However, no positive effects on weight loss, insulin resistance, lipid patterns, or blood pressure were observed.

Determinants of Secondary Hyperparathyroidism 1 Year After One-Anastomosis Gastric Bypass or Sleeve Gastrectomy

PURPOSE

Bariatric surgery alters the anatomic and physiological structure of the gastrointestinal tract, predisposing patients to the malabsorption of nutrients. The purpose of this study was to determine the prevalence and determinants of secondary hyperparathyroidism (SHPT) in the patients undergoing either one-anastomosis gastric bypass (OAGB) or sleeve gastrectomy (SG).

MATERIALS AND METHODS

A total of 517 patients (without SHPT at the baseline) who had undergone OAGB or SG were prospectively assessed 1 year after the surgery. Anthropometric parameters, calcium, intact parathyroid hormone (iPTH), and 25(OH)D levels were compared according to the surgery type before and 1 year after surgery. Multiple logistic regression models were used to evaluate possible SHPT predictors after bariatric surgery.

RESULTS

The overall prevalence of SHPT was 12.6% after surgery, significantly different between the OAGB and SG groups (17.1 vs. 9.9%, respectively). The serum levels of albumin-corrected calcium and 25(OH)D were not significantly different between the two groups. The patients undergoing OAGB had significantly higher serum levels of ALP (198.2 vs. 156.6) compared to the subjects undergoing SG. Higher iPTH levels preoperatively, lower 1-year excess weight loss%, and OAGB surgery seemed to be independent predictors for SHPT 1 year after surgery.

CONCLUSION

Morbidly-obese patients undergoing OAGB had a higher risk of SHPT than their counterparts undergoing SG, whereas 25(OH)D deficiency and calcium levels did not differ between the two groups. The OAGB procedure, preoperative iPTH levels, and 1-year weight loss were predictors of postoperative SHPT development.

Efficacy of vitamin D supplementation on child and adolescent overweight/obesity: a systematic review and meta-analysis of randomized controlled trials

The global prevalence of overweight and obesity in children and adolescents has been increasing. Child and adolescent overweight/obesity has been demonstrated to be partially associated with vitamin D deficiency. This systematic review and meta-analysis aims to assess the efficacy of vitamin D supplementation on child and adolescent overweight/obesity. PubMed, Embase, Cochrane Library, and Web of science were searched from inception to June 20th, 2022. Randomized controlled trials (RCTs) assessing the efficacy of vitamin D on child and adolescent overweight/obesity were included. The Cochrane bias risk assessment tool was used to assess the bias risk of included studies, and subgroup analysis was conducted based on different administration dosages. All data-analyses were performed using R 4.2.1. There were 1502 articles retrieved, and 10 eligible studies were finally included, with a total of 595 participants. Meta-analysis showed no differences in LDL, TC, TG, BMI, ALP, Ca, and PTH between vitamin-D (Vit-D) group and placebo, while Vit-D group resulted in improved HOMA-IR[WMD =  - 0.348, 95%CI (- 0.477, - 0.219), p = 0.26]. Subgroup-analysis showed no significant difference in the increase of 25-(OH)-D between subgroups (p = 0.39), whereas the serum 25-(OH)-D level was increased under different Vit-D doses [WMD = 6.973, 95%CI (3.072, 10.873)]. High daily dose (≥ 4000 IU/d) of Vit-D might decrease CRP and increase HDL levels.   Conclusion: High dose of Vit-D supplementation (over 4000 IU/d) would reduce several cardiometabolic risk indicators and improve insulin resistance. More high-quality and large-scale RCTs are needed to provide more robust evidence. What is Known: • Vit-D deficiency is common in overweight/obesity (OW/OB) children and adolescents. • Previous randomized studies on the benefit of Vit-D supplementation to OW/OB children and adolescents are inconsistent. What is New: • This is the first meta-analysis conducted to assess the efficacy of Vit-D supplementation on child and adolescent OW/OB. • High dose of Vit-D supplementation is beneficial to cardiovascular metabolism, and improve insulin resistance on child and adolescent OW/OB.

The mediating role of bariatric surgery in the metabolic relationship between parathyroid hormone and 25-hydroxyvitamin D

Vitamin D metabolism is altered in obese individuals. Our findings indicated that in patients with severe obesity, a relatively low 25(OH)D concentration was required to suppress PTH. The PTH inflection point increased following surgery-induced weight loss, highlighting 25(OH)D different regulation mechanisms in patients with obesity.

INTRODUCTION

An optimal and sufficient concentration of 25-hydroxyvitamin D (25(OH)D) has been suggested as the level required to maximally suppress intact parathyroid hormone (iPTH). We evaluated the role of surgery-induced weight loss in determining the threshold(s) of 25(OH)D required to suppress iPTH.

METHODS

This study was conducted in the framework of the Tehran Obesity Treatment Study (TOTS). We prospectively analyzed 687 patients with severe obesity who participated in the TOTS and underwent bariatric surgery from March 2013 to March 2019. The patients were followed for 1 year after surgery. Anthropometric parameters and serum levels of iPTH, 25OHD, phosphorous, and calcium were measured. Nonlinear and piecewise linear regression was used to evaluate the relationship between 25(OH)D and iPTH and to determine the 25(OH)D-suppression point at which iPTH was maximally suppressed.

RESULTS

Body mass index was 44.6 kg/m² at the baseline and decreased to 29.7 kg/m² 1 year after surgery (P < 0.05). Before the surgery, iPTH and 25(OH)D showed an exponential relationship; iPTH began to decrease rapidly at 25(OH)D concentration of 12 ng/mL, reaching maximal suppression at 30 ng/mL. However, the relationship between 25(OH)D and iPTH was non-exponential 1 year after surgery. The piecewise linear regression model revealed the 25(OH)D concentration of 21 ng/mL as the inflection point following surgery-induced weight loss.

CONCLUSION

In patients with severe obesity, PTH was suppressed at a relatively lower concentration of 25(OH)D; this threshold increased following surgery-induced weight loss. These findings suggest a role for bariatric surgery in regulating 25(OH)D metabolism in patients with obesity.

Genetics, genomics, and diet interactions in obesity in the Latin American environment

Obesity is a chronic disease characterized by abnormal or excessive fat accumulation that could impact an individual's health; moreover, the World Health Organization (WHO) has declared obesity a global epidemic since 1997. In Latin America, in 2016, reports indicated that 24.2% of the adult population was obese. The environmental factor or specific behaviors like dietary intake or physical activity have a vital role in the development of a condition like obesity, but the interaction of genes could contribute to that predisposition. Hence, it is vital to understand the relationship between genes and disease. Indeed, genetics in nutrition studies the genetic variations and their effect on dietary response; while genomics in nutrition studies the role of nutrients in gene expression. The present review represents a compendium of the dietary behaviors in the Latin American environment and the interactions of genes with their single nucleotide polymorphisms (SNPs) associated with obesity, including the risk allele frequencies in the Latin American population. Additionally, a bibliographical selection of several studies has been included; these studies examined the impact that dietary patterns in Latin American environments have on the expression of numerous genes involved in obesity-associated metabolic pathways.

Additive effects of obesity and vitamin D insufficiency on all-cause and cause-specific mortality

Obesity and vitamin D deficiency are both considered risk factors for mortality, but the potential additive effects of vitamin D status and obesity on mortality has not been well-studied. We aimed to examine the possible additive effects of obesity and vitamin D status on all-cause and cause-specific mortality. The data from the NHANES III (1988–1994) and NHANES 2001–2014 surveys were used, and multivariate Cox regression models were performed to assess the additive effects of vitamin D status and overweight/obesity/abdominal obesity on the all-cause, cardiovascular and cancer mortality, by stratifying Cox Hazard Ratios (HRs) across different categories of vitamin D status and body mass index (BMI) and waist circumference (WC) categories. The models were adjusted for age, race/ethnicity, gender, educational level, family income to poverty ratio, leisure-time physical activity, smoking, and drinking. Across all BMI/WC categories, there was an additive effect of the vitamin D both insufficiency and deficiency on all mortality rates, with deficiency having much stronger effect than insufficiency. Interestingly, the effect of vitamin D deficiency overcame the effect of obesity on all mortality rates. The highest HRs for overall and cardiovascular mortality were observed among vitamin D deficient obese/abdominally obese subjects, while for cancer mortality among vitamin D deficient normal weight/non-abdominally obese subjects. In stratified analyses, regarding all-cause mortality, there was an additive effect of the vitamin D both insufficiency and deficiency in all BMI/WC categories. Regarding cardiovascular mortality, there was an additive effect of vitamin D deficiency in all BMI/WC categories, but the additive effect of vitamin D insufficiency reached significance only in normal weight subjects. Regarding cancer mortality, the effect did not reach significance among obese subjects for vitamin D deficiency, while for insufficiency, significance was reached only among non-abdominally obese subjects. Interestingly, vitamin D surplus was associated with increased risk for cancer mortality in obese subjects, but there was an inadequate number of subjects in this category to make proper judgment. In conclusion, vitamin D insufficiency and deficiency gradually increase risk for mortality across all BMI/WC categories. In our analyses, vitamin D deficiency overcame the effect of obesity on mortality rates.

Consumption of probiotic yogurt and vitamin D-fortified yogurt increases fasting level of GLP-1 in obese adults undergoing low-calorie diet: A double-blind randomized controlled trial

Energy restriction and manipulation of macronutrient composition of the diet are the main approaches that are used by people who aim to lose weight. When such strategies are employed, appetite and endocrine regulators of satiety, such as gut peptides, all are deeply affected. The gut microbiota-brain axis controls energy homeostasis in humans by affecting central satiety and gut peptides. The purpose of this study was to evaluate if the synergistic effect of probiotics and vitamin D in yogurt matrix can modulate this effect. In the double-blind, randomized, placebo-controlled trial, 140 obese adults were randomly allocated into four groups: 1) regular yogurt plus low-calorie diet; 2) PY plus low-calorie diet; 3) vitamin D-fortified yogurt plus low-calorie diet, and 4) probiotic and vitamin D co-fortified yogurt plus low-calorie diet. All groups were encouraged to increase their physical activity. Glucagon-like peptide-1 (GLP-1), peptide Tyrosin-Tysrosin (PYY), ghrelin, anthropometric variables, insulin, fasting blood sugar (FBS), insulin resistance/sensitivity, 1,25(OH)2 D3, dietary intake, and physical activity were measured before and after 10 weeks. The difference between groups for GLP-1 after 10 weeks was significant after adjusting for baseline GLP-1 and protein intake as confounders. PY showed the largest effect size (ES) on GLP-1 (p = 14.2) and FBS (p = 14) compared with others. Pairwise comparison of yogurts effect sizes on GLP-1 showed a significant difference in group 1 vs. group 2 (p = .001), group 1 vs. group 3 (p = .003), and group 1 vs. group 4 (p = .048). Vitamin D-fortified yogurt had the largest effect size on the serum level of vitamin D and it showed a significant difference with RY (p = .018) and PY (p = .002). Consumption of vitamin D-fortified yogurt and PY could be regarded as a promising approach during calorie restriction.

Vitamin D supplementation positively affects anthropometric indices: Evidence obtained from an umbrella meta-analysis

Despite the growing evidence from meta-analyses on vitamin D's anti-obesity properties, their results are controversial. The current umbrella review was performed to assess the available evidence and provide a conclusive explanation in this regard. The international databases PubMed, Scopus, Embase, Web of Science and Google Scholar were systematically searched till March, 2022. A random-effects model was used to run the meta-analysis. All meta-analyses that examined the effect of vitamin D supplementation on BW, BMI, WC, and fat mass were included. Findings of 14 meta-analyses revealed that vitamin D supplementation reduced body mass index (BMI) (ES: -0.11 kg/m2; 95% CI: -0.18, -0.05, p?0.001; I 2 = 61.0%, p < 0.001), and waist circumference (WC) (ES = -0.79 cm; 95% CI: -1.20, -0.37; p < 0.001; I 2 = 46.5%, p = 0.096) in comparison to control group. However, the effects of vitamin D on body weight (ES = -0.16 kg, 95% CI: -0.36, 0.04; p = 0.125; I 2 = 57.0%, p = 0.017), and fat mass (ES: 0.02, 95% CI: -0.20, 0.24, p = 0.868; I 2 = 0.0%, p = 0.531) were not considerable. Vitamin D supplementation significantly improved levels of obesity indices such as BMI, and WC.

The joint association of serum vitamin D status and cardiorespiratory fitness with obesity and metabolic syndrome in Tehranian adults

We aimed to assess the individual and joint association of serum vitamin D and cardiorespiratory fitness (CRF) with obesity and metabolic syndrome (MetSyn). In this cross-sectional study 270 adults with an age range of 18 years and older were recruited from health centers from five districts in Tehran, Iran. CRF was assessed with Bruce protocol. MetSyn was defined based on International Diabetes Federation 2009. The odds ratio (OR) and 95 % confidence interval (CI) of obesity and MetSyn across tertiles of serum vitamin D and CRF were estimated with control for confounders. The results indicated that neither 25(OH)D nor 1,25(OH)D was associated with obesity and MetSyn. There was a strong inverse association between CRF and general (P_-trend < 0.001) and abdominal adiposity (P_-trend: 0.001). The joint association of vitamin D and CRF indicated that the inverse association of CRF with obesity was stronger in those with high serum vitamin D than those with low serum vitamin D and this joint association remained after considering age and diet quality. There was a significant inverse association for those with low serum 25(OH)D and high CRF (OR: 0.12, 95 % CI: 0.04-0.81; P = 0.02) compared to those with low serum 25(OH)D and low CRF in the crude model. Also, the OR of general obesity was 0.17 (95 % CI: 0.02-0.79; P = 0.03) for those with high CRF and low serum 1,25(OH)D compare with the reference group. Our findings indicated a strong inverse association between CRF and obesity, especially in those with high serum vitamin D.

Association between metabolic body composition status and vitamin D deficiency: A cross-sectional study

This study aimed to investigate the risk of vitamin D deficiency in a relatively healthy Asian population, with (i) metabolically healthy normal weight (MHNW) (homeostasis model assessment-insulin resistance [HOMA-IR] < 2. 5 without metabolic syndrome [MS], body mass index [BMI] < 25), (ii) metabolically healthy obesity (MHO) (HOMA-IR < 2.5, without MS, BMI ≥ 25), (iii) metabolically unhealthy normal weight (MUNW) (HOMA-IR ≥ 2.5, or with MS, BMI < 25), and (iv) metabolically unhealthy obesity (MUO) (HOMA-IR ≥ 2.5, or with MS, BMI ≥ 25) stratified by age and sex. This cross-sectional study involved 6,655 participants aged ≥ 18 years who underwent health checkups between 2013 and 2016 at the Chang Gung Memorial Hospital. Cardiometabolic and inflammatory markers including anthropometric variables, glycemic indices, lipid profiles, high-sensitivity C-reactive protein (hs-CRP), and serum 25-hydroxy vitamin D levels, were retrospectively investigated. Compared to the MHNW group, the MHO group showed a higher odds ratio (OR) [1.35, 95% confidence interval (CI) 1.05-1.73] for vitamin D deficiency in men aged < 50 years. By contrast, in men aged > 50 years, the risk of vitamin D deficiency was higher in the MUO group (OR 1.44, 95% CI 1.05-1.97). Among women aged < and ≥ 50 years, the MUO group demonstrated the highest risk for vitamin D deficiency, OR 2.33 vs. 1.54, respectively. Our study revealed that in women of all ages and men aged > 50 years, MUO is associated with vitamin D deficiency and elevated levels of metabolic biomarkers. Among men aged < 50 years, MHO had the highest OR for vitamin D deficiency.

Vitamin D status among Kashmiri tribal population: A cross-sectional community-based study

Background & objectives

Vitamin D deficiency (VDD) is prevalent across all age groups in general population of India but studies among tribal populations are scanty. This study aimed to evaluate the prevalence of VDD in the indigenous tribal population of the Kashmir valley and examine associated risk factors.

Methods

In this cross-sectional investigation, a total of 1732 apparently healthy tribal participants (n=786 males and n=946 females) were sampled from five districts of Kashmir valley by using probability proportional to size method. Serum 25-hydroxy vitamin D (25(OH)D) levels were classified as per the Endocrine Society (ES) recommendations: deficiency (<20 ng/ml), insufficiency (20-30 ng/ml) and sufficiency (>30 ng/ml). The serum 25(OH)D levels were assessed in relation to various demographic characteristics such as age, sex, education, smoking, sun exposure, body mass index and physical activity.

Results

The mean age of the male participants was 43.79±18.47 yr with a mean body mass index (BMI) of 20.50±7.53 kg/m^[2], while the mean age of female participants was 35.47±14.92 yr with mean BMI of 22.24±4.73 kg/m². As per the ES guidelines 1143 of 1732 (66%) subjects had VDD, 254 (14.71%) had insufficient and 334 (19.3%) had sufficient serum 25(OH)D levels. VDD was equally prevalent in male and female participants. Serum 25(OH)D levels correlated positively with serum calcium, phosphorous and negatively with serum alkaline phosphatase. Gender, sun exposure, altitude, physical activity and BMI did not seem to contribute significantly to VDD risk.

Interpretation & conclusions

VD deficiency is highly prevalent among Kashmiri tribals, although the magnitude seems to be lower as compared to the general population. These preliminary data are likely to pave way for further studies analyzing the impact of vitamin D supplementation with analysis of functional outcomes.

Vitamin D is associated with body composition and fat intake, but not with cardiometabolic parameters in adults with obesity

Adults with obesity are at higher risk for developing hypovitaminosis D. Some studies suggest that reduced levels of serum 25-hydroxyvitamin D (25(OH)D) may also be related to disorders in cardiometabolic parameters. However, because of the association between 25(OH)D and obesity, we hypothesized that body composition can be a confounding factor in the association of 25(OH)D with cardiometabolic parameters, and that 25(OH)D is inversely associated with body composition and cardiometabolic parameters and directly associated with fat intake. The aim of this study was to analyze the associations between 25(OH)D with body composition, fat intake, and cardiometabolic parameters in adults with obesity. This cross-sectional study consisted of 52 adults with obesity (61.53% female; 37.50 ± 6.88 years; body mass index [BMI]: 33.60 ± 2.89 kg/m²). Cardiometabolic parameters (fasting blood glucose, insulin resistance index, C-reactive protein, blood pressure, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, and cholesterol), body mass, BMI, waist circumference, body fat percentage, and fat intake were evaluated. Body mass was negatively associated with 25(OH)D (β = -0.108; P = .048; and R² = 0.090) and BMI (β = -0.621; P = .031; and R² = 0.103), both adjusted for fat intake. 25(OH)D was positively associated with fat intake (β = 0.129; P = .045 and R² = 0.078) adjusted for sex, age, and skin color. Cardiometabolic parameters were not associated with 25(OH)D, even after adjusted by body composition variables. However, the high prevalence of hypovitaminosis D (75%) and the negative association between 25(OH)D and body composition reinforce the importance of analyzing and monitoring vitamin D status in this population.

Vitamin D supplementation and total cancer incidence and mortality by daily vs. infrequent large-bolus dosing strategies: a meta-analysis of randomised controlled trials

BACKGROUND

Efficacy of vitamin D supplementation may vary by dosing strategies and adiposity. To address such heterogeneity, we performed a meta-analysis of randomised controlled trials of vitamin D supplementation and total cancer outcomes.

METHODS

PubMed and Embase were searched through January 2022. Summary relative risk (SRR) and 95% confidence interval (CI) were estimated using the DerSimonian-Laird random-effects model.

RESULTS

For total cancer incidence (12 trials), the SRR for vitamin D supplementation vs. control group was 0.99 (95% CI, 0.94-1.03; P = 0.54; I² = 0%). No significant association was observed regardless of whether the supplement was given daily or infrequently in a large-bolus. Yet, among trials testing daily supplementation, a significant inverse association was observed among normal-weight individuals (SRR, 0.76; 95% CI, 0.64-0.90; P = 0.001, I² = 0%), but not among overweight or obese individuals (P_{heterogeneity} = 0.02). For total cancer mortality (six trials), the SRR was 0.92 (95% CI, 0.82-1.03; P = 0.17; I² = 33%). A significant inverse association emerged (SRR, 0.87; 95% CI, 0.78-0.96; P = 0.007; I² = 0%) among studies testing daily supplementations but not among studies that testing infrequent large-bolus supplementations (P_{heterogeneity} = 0.09).

CONCLUSIONS

For vitamin D supplementation, daily dosing, but not infrequent large-bolus dosing, reduced total cancer mortality. For total cancer incidence, bolus dosing did not reduce the risk and the benefits of daily dosing were limited to normal-weight individuals.

Vitamin D Supplementation Improves Mitochondrial Function and Reduces Inflammation in Placentae of Obese Women

Background

About 30% of women entering pregnancy in the US are obese. We have previously reported mitochondrial dysregulation and increased inflammation in the placentae of obese women. Vitamin D (VitD) is a major player in calcium uptake and was shown to modulate mitochondrial respiration and the immune/inflammation system. Studies show decreased VitD levels in obese individuals; however, the effect of maternal obesity on VitD metabolism and its association with placental function remains understudied.

Methods

Maternal and cord blood plasma and placental samples were collected upon C-section from normal-weight (NW, body mass index [BMI]<25) and obese (OB, BMI>30) women with uncomplicated pregnancies at term. We measured 25(OH)D3 (calcidiol) levels in maternal and cord blood plasma using ELISA. We assessed the expression of CYP27B1, an activator of calcidiol, and Vitamin D receptor (VDR) in placentae from NW and OB, and women with gestational diabetes and preeclampsia. In addition, we examined the effects of VitD supplementation on mitochondrial function and inflammation in trophoblasts from NW and OB, using the Seahorse Bioanalyzer and Western blot, respectively.

Results

Vitamin D levels in blood from OB but not NW women and in cord blood from babies born to NW and OB women showed a significant inverse correlation with maternal pre-pregnancy BMI (r=-0.50, p<0.1 and r=-0.55, p=0.004 respectively). Cord plasma VitD levels showed a positive correlation with placental efficiency, i.e., the ratio between fetal and placental weight, as well as with maternal blood VitD levels (r=0.69 and 0.83 respectively, p<0.00). While we found no changes in CYP27B1 in OB vs. NW women, VDR expression were decreased by 50% (p<0.03) independent of fetal sex. No changes in VDR expression relative to BMI-matched controls were observed in the placentae of women with gestational diabetes or preeclampsia. Cytotrophoblasts isolated from placentae of OB women showed a dose-dependent increase in VDR expression after 24-hour treatment with calcitriol (10 nM and 100 nM), an active form of VitD. Trophoblasts isolated from OB women and treated with calcitriol improved mitochondrial respiration (p<0.05). We also found a two-fold increase in expression of the NLRP3 inflammasome and the pro-inflammatory cytokine IL-18 in trophoblasts isolated from placentae of OB women (p<0.05), with IL-18 expression being reversed by calcitriol treatment (100 nM).

Conclusions

We show that VitD deficiency is at least partially responsible for mitochondrial dysfunction and increased inflammation in the placentae of obese women. Vitamin D supplementation could be beneficial in improving placental dysfunction seen in obese women.

Vitamin D Supplementation on Carotid Remodeling and Stiffness in Obese Adolescents

Obesity is associated with vitamin D (VD) deficiency and arterial stiffness. This randomized control trial assessed the effects of VD supplementation during a weight-loss program on carotid intima-media thickness (IMT) and carotid compliance in obese adolescents. Participants were randomly assigned to receive either a 12-week lifestyle program with VD supplementation (n = 13), a lifestyle program without VD supplementation (n = 13) or a control group composed of normal-weight adolescents (n = 18). Serum total and free 25-hydroxyvitamin D (25(OH)D), IMT and carotid compliance were measured before and after the trial. Insufficiency in 25(OH)D concentration was found in 73% of obese participants compared to 22% among controls. Obese adolescents had lower free 25(OH)D and displayed higher IMT but lower carotid compliance than controls. Free 25(OH)D and IMT were negatively correlated in adolescents displaying VD insufficiency at baseline. After three months, total and free 25(OH)D increased in both groups. The changes of IMT and carotid compliance were similar between groups. The changes in IMT were correlated with the changes in total 25(OH)D in obese adolescents with VD insufficiency at baseline (r = −0.59, p = 0.03). While the lifestyle program with VD supplementation did not affect carotid compliance, IMT reduction was improved in obese adolescents.

Vitamin D is negatively associated with triglyceride in overweight/obese patients with type 2 diabetes

PURPOSE

Vitamin D has been identified to have a relation to the development of insulin resistance-related diseases, such as type 2 diabetes (T2D). T2D is often associated with obesity and dyslipidemia. Our study aimed to analyze the relationship between vitamin D and lipid profile in patients with T2D.

METHODS

A total of 446 T2D patients who were hospitalized from January 2015 to December 2016 were recruited. Baseline characteristics were recorded, including body mass index (BMI), serum level of 25 hydroxy vitamin D (25(OH)D), and other biochemical indicators. T2D patients were divided into normal-weight group and overweight/obese group according to their BMI. Subgroup analysis was conducted after patients were subdivided using the quartet-method according to serum level of 25(OH)D. Differences in glucose and lipid metabolism indicators were analyzed. The correlation between serum 25(OH)D and lipid profiles was assessed by the multiple linear regression.

RESULTS

The levels of serum 25(OH)D and high-density lipoprotein cholesterol in T2D patients of overweight/obesity group were significantly lower than those in normal-weight group, while the levels of triglyceride (TG) and HOMA-IR were significantly higher (P < 0.05). Subgroup analysis uncovered that total cholesterol (TC) and TG levels were lower with higher 25(OH)D in normal weight T2D patients. In overweight/obese T2D patients, TG level was lower in patients with higher 25(OH)D (P < 0.05). There were no significant differences in low-density lipoprotein cholesterol (LDL-C), fasting blood glucose (FBG), fasting insulin (FINS), and hemoglobin Alc (HbAlc) among Q1-Q4 in both normal weight and overweight/obese groups. Pearson test showed that serum 25(OH)D was positively correlated with high density lipoprotein cholesterol (HDL-C), and negatively correlated with TC and TG. Serum 25(OH)D was unrelated to low density lipoprotein cholesterol (LDL-C) in both groups. Multiple linear regression analysis only demonstrated an independent negative correlation between 25(OH)D and TG levels in the overweight/obese group (P < 0.01).

CONCLUSIONS

In overweight/obese patients with T2D, serum 25(OH)D was independently, negatively correlated with TG. Vitamin D supplementation should be guaranteed in patients with diabetes, especially with obese T2D.

Cholecalciferol Supplementation Does Not Affect the Risk of HIV Progression, Viral Suppression, Comorbidities, Weight Loss, and Depression among Tanzanian Adults Initiating Antiretroviral Therapy: Secondary Outcomes of a Randomized Trial

BACKGROUND

Observational studies suggest that blood concentrations of 25-hydroxyvitamin D [25(OH)D] are associated with morbidity, viral suppression, and mortality among adults living with HIV.

OBJECTIVES

We evaluated the effect of cholecalciferol (vitamin D3) supplementation on the risk of HIV disease progression, HIV-1 viral suppression, comorbidities, weight change, and depression among HIV-infected individuals that were initiating antiretroviral therapy (ART) in Dar es Salaam, Tanzania.

METHODS

We conducted a randomized, double-blind, placebo-controlled trial of vitamin D3 supplementation among 4000 HIV-infected adult men and nonpregnant women initiating ART with insufficient serum 25(OH)D concentrations (<30 ng/mL). Participants were randomly assigned to receive either weekly 50,000-IU doses for 4 wk followed by daily 2000 IU vitamin D3 until 1 y or a matching placebo regimen given in weekly followed by daily doses until 1 y. Participants were followed up at weekly visits for the first month followed by monthly visits thereafter. We conducted intent-to-treat analyses to assess the effect of vitamin D3 supplementation on the secondary trial outcomes of HIV progression or death, viral suppression, comorbidities, change in BMI, >10% weight loss, incident wasting, and depression.

RESULTS

During follow-up, 345 participants (17.2%) in the vitamin D3 group and 371 participants (18.6%) in the placebo group experienced HIV disease progression or death and there was no difference in risk between groups (RR: 0.91; 95% CI: 0.79, 1.06). Vitamin D3 supplementation did not affect the risk of an unsuppressed HIV-1 viral load (>1000 copies/mL) after 6 mo (RR: 1.10; 95% CI: 0.87, 1.41) and there was also no effect on change in BMI, risk of >10% weight loss, wasting, comorbidities, and depression (P values >0.05).

CONCLUSIONS

Vitamin D supplementation did not affect the risk of HIV progression, viral suppression, common morbidities, weight-related indicators, or depression among adults initiating ART in Tanzania.This trial was registered at clinicaltrials.gov as NCT01798680.

The relationship between vitamin D deficiency, body composition, and physical/cognitive functions

Vitamin D deficiency is still an important subject due to its significant effects on various tissues and functions. We found a relationship between vitamin D deficiency and increase in adipose tissue thicknesses. This situation reveals the importance of vitamin D supplementation, the harms of weight gain and obesity, and the importance of a balanced diet.

PURPOSE

Although the relationship between vitamin D (VitD) levels with body composition and physical/cognitive functions have been investigated in various studies, however, there is no study evaluating all these parameters together. In accordance with, we aimed to evaluate the relationship between VitD deficiency with body composition (i.e., skin, subcutaneous fat, and muscle thicknesses) and physical/cognitive functions.

METHODS

A total of 203 adults (78 M, 125 F, aged 19-91 years) who had recent 25-OH-vitamin D measurements were included. Ultrasonographic (US) measurements (skin, subcutaneous fat, and muscle thicknesses) were made from the dorsum of the hand, and anterior sides of forearm, arm, and thigh. Handgrip strength, gait speed, Timed Up and Go Test, and Chair Stand Test were evaluated. Additionally, cognitive status was also evaluated with Mini-Mental State Exam.

RESULTS

Subjects were classified as VitD deficient group (< 20 ng/ml, N = 125) and control group (≥ 20 ng/ml, N = 78). The groups were not significantly different as regards age, gender, and anthropometric measurements (all p > 0.05). Subcutaneous fat tissues were thicker in the VitD deficient group (all p < 0.05). All the other US measurements and functional/cognitive tests were not significantly different between the groups (all p > 0.05). According to linear regression analyses, body mass index (BMI) was independently related with all subcutaneous fat thicknesses in both genders, and VitD deficiency was related with all subcutaneous fat thicknesses in females and anterior forearm subcutaneous fat thickness in males (all p < 0.05).

CONCLUSION

We imply that together with BMI, VitD deficiency is independently related with increased regional subcutaneous fat tissue. We also underscore the role of US measurements for evaluation of body composition in related clinical scenarios.

The role of serum 25 (OH) vitamin D level in the correlation between lipid profile, body mass index (BMI), and blood pressure

BACKGROUND AND AIMS

Since the prevalence of vitamin D deficiency is high in some countries, such as Iran, and the trend of hypertension and obesity is increasing, this study aimed to investigate the serum level of vitamin D and explore its correlation and association with obesity, blood pressure, fasting blood sugar (FBS), and lipid profile. Our hypothesis is that serum vitamin D levels are associated with risk factors for cardiometabolic disease such as hypertension.

METHODS

The results of this article were extracted from a cross-sectional study with a sample size of 720 people in the winter of 2020. The serum level of 25 OH vit D was measured using the ELISA method. In addition, lipid profiles were measured using the Auto Analyzer photometry method.

RESULTS

Serum levels of vitamin D (25 (OH) vitamin D) were significantly higher in the control group compared to the case group (29.5 ± 16.3 vs. 26.7 ± 14.5; P-value = 0.016). The significant association between body mass index (BMI) and FBS (Beta unadjusted:0.024, 95%CI 0.009:0.038; Beta adjusted:0.020,95%CI 0.005:0.034), and triglyceride (Beta unadjusted:0.009, 95%CI 0.006:0.012; Beta adjusted:0.008,95%CI 0.005:0.011), and an inverse association HDL-C (Beta unadjusted:-0.079,95%CI -0.123:-0.036; Beta adjusted:-0.065,95%CI -0.111:-0.019) were seen in both unadjusted and adjusted models.

CONCLUSION

In conclusion, we report that obese people had significantly lower serum vitamin D levels than normal-weight people. There is also a significant correlation between BMI and blood pressure.

Moderate Sun Exposure Is the Complementor in Insufficient Vitamin D Consumers

Background and Aims

Vitamin (Vit) D plays a vital role in human health, and the prevalence of Vit D deficiency worldwide has been a rising concern. This study investigates the serum 25-hydroxy-Vit D [25(OH)D] status in healthy US civilians and identifies how the two main sources, sun exposure and dietary Vit D intake, determine the final 25(OH)D levels in individuals.

Methods

A total of 2,360 of participants from The National Health and Nutrition Examination Survey (NHANES) 2009–2014 were analyzed. We divided the levels of sun exposure and dietary Vit D intake of all subjects into 10 strata and gave a score ranging from 1 to 10 points, respectively. Scores 1–5 in sun exposure and dietary intake were considered as relatively low exposure groups, whereas scores 6–10 were considered as relatively high exposure groups. Serum Vit D inadequacy was defined as <50 nmol/L. Linear and logistic regression analyses were used to examine the associations between sources of Vit D and serum 25(OH)D levels.

Results

In relatively low Vit D intake groups (Vit D intake score 1–5), relatively high sun exposure (sun exposure score >5) resulted in higher serum 25(OH)D levels (average 57 nmol/L) compared with relatively low sun exposure (sun exposure score <5) (average 50 nmol/L), whereas this difference became negligible in high intake groups (Vit D intake score 6–10). Moreover, the greatest slope occurred in the low Vit D intake curve (decile 3 of Vit D intake), which shows increased sun exposure time causing the greatest degree of change in serum 25(OH)D level in this group.

Conclusion

Sun exposure can significantly make up for deficiencies in subjects who consume insufficient dietary Vit D. Compared with the extra cost and time for building habits of Vit D supplementation, moderate sun exposure appears to be a simple and costless means for the public to start in daily practice.

Dairy intake and long-term body weight status in German children and adolescents: results from the DONALD study

PURPOSE

To analyse the association between intake of total dairy (TD) and types of dairy [liquid dairy (LD), solid dairy (SD), low-fat dairy (LFD), high-fat dairy (HFD), high sugar dairy (HSD), low-sugar dairy (LSD), not fermented dairy (NFD), as well as fermented dairy (FD)] and long-term changes in body weight status and composition among children and adolescents in Germany.

METHODS

In total, 9999 3-day dietary records collected between 1985 and 2019 by 1126 participants (3.5-18.5 years; boys: 50.8%) of the Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) study were analysed. Polynomial mixed-effects regression models were used to examine whether changes (median follow-up: 9 years) in the intake of TD and dairy types (in 100 g/1000 kcal total energy intake) were associated with changes in body-mass-index-standard-deviation-score (BMI-SDS); fat mass index (FMI); fat-free mass index (FFMI) over time.

RESULTS

An individual increase in TD intake was slightly but significantly associated with an increase in BMI-SDS (β = 0.0092; p = 0.0371), FMI (β = 0.022; p = 0.0162), and FFMI (β = 0.0156; p = 0.0417) after adjustment for potential confounder. Analyses for LD (BMI-SDS: β = 0.0139; p = 0.0052; FMI: β = 0.0258; p = 0.0125; FFMI: β = 0.0239; p = 0.0052) and LSD intake (BMI-SDS: β = 0.0132; p = 0.0041, FMI: β = 0.02; p = 0.0316, FFMI: β = 0.0183; p = 0.0189) showed similar results to TD. Both processing method and fat content showed no association with body composition in our analyses.

CONCLUSION

Increases in TD, LD, and LSD intake showed small but significant increases in BMI and concomitant increases in fat mass and lean mass. However, the observed changes were too small to expect biological or physiological meaningful effects. Overall, our results showed that policies to promote dairy intake in childhood are to be welcomed, as no negative effects on body composition are expected, while the intake of important nutrients for growth is ensured. The type of dairy does not seem to matter.

Relationship between the double burden of malnutrition and mental health in overweight and obese adult women

The co-existence of overweight or obesity with concurrent deficiency of one or more nutrients is referred to as double burden of malnutrition (DBM), and numerous mental health impairments have been associated with a variety of nutrient deficiencies. Although DBM is relevant for several health outcomes, the ubiquitous involvement of vitamin D across multiple systems and tissues suggests D insufficiency as a viable target for nutritional modification. The present study aimed to evaluate the contribution of DBM and mental health among adult women. Study participants included 300 women, aged 18–59 years, who presented to one of the 25 health centres in Tehran. Participants with a body mass index (BMI) of greater than 25 kg/m² and a plasma concentration of 25-hydroxy vitamin D [25(OH)D] of >20 ng/ml were considered to have DBM. The 147-item food frequency questionnaire was used to estimate their dietary intake. Mental health status was assessed using the depression, anxiety and stress scales-21 (DASS-21). The mean ± standard deviation age, weight and BMI of the participants were 36⋅49 ± 8⋅38, 80⋅89 ± 12⋅45 kg and 31⋅04 ± 4⋅31 kg/m², respectively. DBM was significantly associated with stress, after adjusting for potential confounders, including age, energy and marital status in model 1 (OR = 1⋅28, 95 % confidence interval (CI) 1⋅00, 1⋅65, P < 0⋅04) v. the crude model (OR = 1⋅22; 95 % CI 0⋅96, 1⋅55, P = 0⋅09). No significant association was seen among DBM and DASS-21 outcomes. In this cross-sectional study, stress and DBM were significantly associated. While vitamin D insufficiency was associated with mental health and obesity in opposing directions. Elucidation of whether vitamin D supplementation can improve mental health impairments requires further evaluation.

Maternal excess adiposity and serum 25-hydroxyvitamin D < 50 nmol/L are associated with elevated whole body fat mass in healthy breastfed neonates

BACKGROUND

Vitamin D status of pregnant women is associated with body composition of the offspring. The objective of this study was to assess whether the association between maternal vitamin D status and neonatal adiposity is modified by maternal adiposity preconception.

METHODS

Healthy mothers and their term appropriate weight for gestational age (AGA) infants (n = 142; 59% male, Greater Montreal, March 2016-2019) were studied at birth and 1 month postpartum (2-6 weeks). Newborn (24-36 h) serum was collected to measure total 25-hydroxyvitamin D [25(OH)D] (immunoassay); maternal pre-pregnancy BMI was obtained from the medical record. Anthropometry, body composition (dual-energy X-ray absorptiometry) and serum 25(OH)D were measured at 2-6 weeks postpartum in mothers and infants. Mothers were grouped into 4 categories based on their vitamin D status (sufficient 25(OH)D ≥ 50 nmol/L vs. at risk of being insufficient < 50 nmol/L) and pre-pregnancy BMI (< 25 vs. ≥25 kg/m2): insufficient-recommended weight (I-RW, n = 24); insufficient-overweight/obese (I-OW/O, n = 21); sufficient-recommended weight (S-RW, n = 69); and sufficient-overweight/obese (S-OW/O, n = 28). Partial correlation and linear fixed effects model were used while adjusting for covariates.

RESULTS

At birth, infant serum 25(OH)D mean concentrations were below 50 nmol/L, the cut-point for sufficiency, for both maternal pre-pregnancy BMI categories; 47.8 [95%CI: 43.8, 51.9] nmol/L if BMI < 25 kg/m2 and 38.1 [95%CI: 33.5, 42.7] nmol/L if BMI ≥25 kg/m2. Infant serum 25(OH)D concentrations at birth (r = 0.77; P < 0.0001) and 1 month (r = 0.59, P < 0.0001) were positively correlated with maternal postpartum serum 25(OH)D concentrations. Maternal serum 25(OH)D concentration was weakly correlated with maternal percent whole body fat mass (r = - 0.26, P = 0.002). Infants of mothers in I-OW/O had higher fat mass versus those of mothers in S-OW/O (914.0 [95%CI: 766.4, 1061.6] vs. 780.7 [95%CI: 659.3, 902.0] g; effect size [Hedges' g: 0.42]; P = 0.04 adjusting for covariates) with magnitude of difference of 220.4 g or ~ 28% difference.

CONCLUSIONS

Maternal and neonatal vitamin D status are positively correlated. In this study, maternal adiposity and serum 25(OH)D < 50 nmol/L are dual exposures for neonatal adiposity. These findings reinforce the importance of vitamin D supplementation early in infancy irrespective of vitamin D stores acquired in utero and maternal weight status.

Interaction between Dietary Fat Intake and Metabolic Genetic Risk Score on 25-Hydroxyvitamin D Concentrations in a Turkish Adult Population

Previous studies have pointed out a link between vitamin D status and metabolic traits, however, consistent evidence has not been provided yet. This cross-sectional study has used a nutrigenetic approach to investigate the interaction between metabolic-genetic risk score (GRS) and dietary intake on serum 25-hydroxyvitamin D [25(OH)D] concentrations in 396 unrelated Turkish adults, aged 24-50 years. Serum 25(OH)D concentration was significantly lower in those with a metabolic-GRS ≥ 1 risk allele than those with a metabolic-GRS < 1 risk allele (p = 0.020). A significant interaction between metabolic-GRS and dietary fat intake (energy%) on serum 25(OH)D levels was identified (Pinteraction = 0.040). Participants carrying a metabolic-GRS ≥ 1 risk allele and consuming a high fat diet (≥38% of energy = 122.3 ± 52.51 g/day) had significantly lower serum 25(OH)D concentration (p = 0.006) in comparison to those consuming a low-fat diet (<38% of energy = 82.5 ± 37.36 g/d). In conclusion, our study suggests a novel interaction between metabolic-GRS and dietary fat intake on serum 25(OH)D level, which emphasises that following the current dietary fat intake recommendation (<35% total fat) could be important in reducing the prevalence of vitamin D deficiency in this Turkish population. Nevertheless, further larger studies are needed to verify this interaction, before implementing personalized dietary recommendations for the maintenance of optimal vitamin D status.

The Association Between GC Gene Polymorphisms and Metabolic Syndrome in Chinese Rural Population: A Case-Control Study

BACKGROUND

GC (group-specific component globulin) encoding VDBP (Vitamin D binding protein) polymorphisms have been associated with susceptibility to some diseases such as diabetes, obesity, osteoporosis, and polycystic ovary syndrome, but the evidence for metabolic syndrome (MetS) in the Chinese rural population is inconclusive. Therefore, we investigated the relationship between GC variants (rs7041, rs4588, rs2282679, and rs705117) and MetS risk as well as VDBP levels in the Chinese rural population.

PATIENTS AND METHODS

The participants (range of age: 20-90 years) of this case-control study were recruited from the northern Chinese Han rural population. We matched 445 MetS cases with non-MetS controls in a 1:1 ratio by sex, age (within 5 years). Real-time PCR technology was carried out by TaqMan assays to examine the four variants of rs7041, rs4588, rs2282679, and rs705117 within the GC gene. To identify the association of GC gene polymorphisms with MetS, we calculated ORs using a conditional logistic regression model adjusted for potential confounding factors.

RESULTS

We observed inverse associations of CA and AA genotypes of rs4588 with risk of MetS (OR = 0.678, 95% CI 0.505-0.910, P = 0.010; 0.603, 95% CI 0.373-0.973, P = 0.039, respectively) compared with carriers of CC genotype. A similar relationship was also found between rs2282679 and MetS, showing that carrying AC genotype of rs2282679 can decrease the risk of MetS (OR = 0.683, 95% CI 0.509-0.917, P = 0.011) compared with carriers of AA genotype. The results of correlation analysis between MetS components and GC polymorphisms showed that the ORs of AA genotype of rs4588 with high level of TG (triglycerides) and low level of HDL-C (high-density lipoprotein cholesterol) were 0.473 (95% CI 0.245-0.911, P = 0.025) and 0.268 (95% CI 0.117-0.615, P = 0.002), respectively; the ORs of CC genotype of rs2282679 with high level of TG and low level of HDL-C were 0.428 (95% CI 0.217-0.842, P = 0.014) and 0.263 (95% CI 0.110-0.628, P = 0.003), respectively. However, there was no significant association between the concentration of VDBP and MetS risk.

CONCLUSION

Among the Chinese rural population, GC polymorphism was associated with lower metabolic syndrome susceptibility, which might be through affecting blood lipid levels (TG and HDL-C).

25-hydroxyvitamin D and testosterone levels association through body mass index: A cross-sectional study of young men with obesity

BACKGROUNDS

Vitamin D and testosterone deficiency have been widely related to obesity. However, only a few studies have investigated the effect of vitamin D on testosterone in the context of obesity, in which controversial results have been raised.

OBJECTIVES

The purpose of this study was to determine the relationship between serum 25-hydroxyvitamin D (25(OH)D) and testosterone levels in young men with different grade of obesity.

DESIGN AND METHODS

This cross-sectional study included 269 healthy young men with obesity (body mass index (BMI) ≥ 30 kg/m²). Participants were divided into two groups based on their serum 25(OH)D levels (134 subjects with vitamin D sufficiency and 135 participants with vitamin D deficiency, according to the 50^th percentile of 25(OH)D). Serum 25(OH)D and sex hormones have been measured. The relationships between 25(OH)D, sex hormones, and obesity grades were investigated with linear and binary logistic regression analyses, as well as mediation analysis.

RESULTS

Compared to the 25(OH)D sufficiency group, total and free testosterone levels were found to be decreased, whereas serum androstenedione levels were increased in the 25(OH)D deficiency group (p<0.05). Using multivariable lineal regression analyses, 25(OH)D was correlated with the majority of sex hormones (p<0.05). When mediation with BMI was performed, the direct effect between 25(OH)D and sex hormones disappeared, and only the indirect effect via BMI remained (demonstrating the importance of BMI). Furthermore, after controlling for age and smoking status, we discovered that total testosterone and SHBG were both significantly associated with 25(OH)D (p<0.05) in subjects with obesity type III. Using a mediation analysis, we discovered that BMI had a partial effect on the association between 25(OH)D and total testosterone levels in morbidly obese participants, indicating that a direct association between 25(OH)D and total testosterone levels, and that BMI partially mediated this association.

CONCLUSIONS

Serum 25(OH)D is associated with total testosterone levels in only those subjects with morbid obesity, suggesting a specific benefit in severe cases of obesity. Additional research is needed to elucidate possible common mechanisms.

Association and interaction between vitamin D level and metabolic syndrome for non-alcoholic fatty liver disease

INTRODUCTION/OBJECTIVES

Previous studies have shown conflicting results regarding the association between hypovitaminosis D and non-alcoholic fatty liver disease (NAFLD). The aim of this study is to explore the individual and combined effect of hypovitaminosis D and metabolic syndrome (MS) on NAFLD.

MATERIALS AND METHODS

In this cross-sectional study, 874 subjects were enrolled. 25(OH)D was assessed by a sequential competitive immuno-fluoro-assay method. The Fatty Liver Index (FLI) was used for NAFLD screening. Binary logistic regression and additive interaction were performed to investigate the association between vitamin D status, MS and NAFLD.

RESULTS

Severe vitamin D deficiency was found to be positively related to NAFLD, with a higher risk in women than in men (OR = 6.4, 95% CI [2.8-15], p < 0.0001 vs. OR = 5.8, 95% CI [1.9-17.7], p = 0.002). In men, this association was partially masked by obesity. The additive interaction with MS was significant in women but not in men, the relative excess risk due to interaction was of 7.2, 95% CI [1.3-12.9], p = 0.02), the attributable proportion due to the combined effect was of 0.6, 95% CI [0.4-0.8], p < 0.0001. The interaction mechanism is synergistic; the synergy index: was of 2.9, 95% CI [1.6-5.3], p = 0.0006.

CONCLUSION

A positive association has been found between severe vitamin D deficiency and NAFLD. Moreover, an excess risk in women combining both MS and severe vitamin D deficiency was quantified.

Pleurotus eryngii improves postprandial glycaemia, hunger and fullness perception, and enhances ghrelin suppression in people with metabolically unhealthy obesity

The aim of this study was to examine potential postprandial benefits of Pleurotus eryngii in nineteen volunteers with metabolically unhealthy obesity. An acute, randomized, crossover-designed trial comparing a meal with Pleurotus eryngii and a control meal was performed. The two meals matched in macronutrient and caloric content. Participants consumed both meals in random order after an overnight fast. Blood samples were drawn before and 30, 60, 90, 120, 150 and 180 min after meal consumption (in total 266 samples) to determine glucose, insulin, ghrelin, peptide YY, glucagon-like peptide-1 and glicentin. Visual analog scales measuring the subjective perception of hunger and fullness were completed at the same time points. The test meal resulted in lower glucose incremental area under the curve (iAUC). Additionally, the iAUC of the ghrelin response over time was substantially lower after the test meal (p = 0.033). Lower desire to eat and higher fullness was reflected by significantly lower hunger iAUC (p = 0.046) and higher fullness iAUC (p = 0.042) after the test meal. No differences in insulin, PYY, GLP-1 and glicentin were observed. Pleurotus eryngii can ameliorate postprandial glycaemia, appetite and regulate ghrelin levels at the postprandial state. This effect is attributed to the bioactive polysaccharides that inhibit the activity of enzymes catalysing carbohydrate hydrolysis, cause a delayed gastric emptying and glucose absorption.

Joint effect of 25-hydroxyvitamin D and secondhand smoke exposure on hypertension in non-smoking women of childbearing age: NHANES 2007-2014

BACKGROUND

Vitamin D deficiency (VDD) may increase the risk of hypertension in women of childbearing age, who may be exposed to secondhand smoke (SHS) simultaneously. Till now, few studies have investigated the joint effects of VDD and SHS on hypertension in this population. We evaluated whether exposure to SHS modified the association between VDD and hypertension.

METHODS

Data from National Health and Nutrition Examination Surveys (NHANES) 2007-2014 were analyzed. Our research subjects were 2826 nonsmoking and nonpregnant women of childbearing age (20-44 years old). Hypertension was defined based either on systolic blood pressure (SBP) ≥ 130 mmHg and/or diastolic blood pressure (DBP) ≥ 80 mmHg or on now taking prescribed medicine for hypertension. The directed acyclic graphs (DAG) and the back-door criterion were used to select a minimal sufficient adjustment set of variables (MSAs) that would identify the unconfounded effect of 25(OH)D and hypertension. The interactive effect of VDD and SHS on hypertension was evaluated by using logistic regression models, followed by strata-specific analyses.

RESULTS

The prevalence of VDD in the hypertension group was significantly higher than that in the non-hypertension group (48.2% vs 41.0%, P = 0.008), as well as the exposure rate of SHS (39.1% vs 33.8%, P = 0.017). VDD was independently associated with nearly 50% increased risk of hypertension [adjusted odds ratio (aOR) = 1.43, 95% confidence interval (CI): 1.01, 2.04], while no significant association was observed between SHS and hypertension. However, SHS showed a significant synergistic effect on VDD with a higher aOR of 1.79 (95% CI: 1.14, 2.80) (P_interaction = 0.011). This synergistic effect was more obvious when stratified by BMI (in overweight women, aOR, 95% CI =4.74, 1.65-13.60 for interaction vs 2.33, 1.01-5.38 for VDD only) and race (in Non-Hispanic Black women, aOR, 95% CI =5.11, 1.58-16.54 for interaction vs 2.69, 1.10-6.62 for VDD only).

CONCLUSION

There exist synergistic effects of SHS and VDD on the prevalence of hypertension in American women of childbearing age, with more significant effects in women who were overweight or Non-Hispanic Black. Further studies are warranted to verify this finding in other populations, and the molecular mechanisms underlying the joint effect of SHS and VDD need to be elucidated.

Vitamin D supplementation and energy and metabolic homoeostasis in obese and overweight subjects: a protocol for a systematic review

INTRODUCTION

Obesity and vitamin D deficiency are major public health problems. According to the pathophysiological mechanism of obesity as well as the bidirectional relationship between obesity and vitamin D metabolism and storage, vitamin D supplementation in obese and overweight subjects could have beneficial effects on the energy and metabolic homoeostasis. This review will assess the efficacy of vitamin D supplementation on the energy and metabolic homoeostasis in overweight and obese subjects.

METHODS AND ANALYSIS

In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols, we retrieved the relevant literature from the following electronic bibliographic databases: MEDLINE/PubMed, EMBASE and the Cochrane Central Register of Controlled Trials, from inception to June 2021. A manual search of the reference lists of all the relevant research articles will be performed to identify additional studies. We will include randomised controlled trials (RCTs) published in English that examine the effects of vitamin D supplementation on energy and metabolic homoeostasis in overweight and obese subjects. RCTs with multiple vitamin D groups will also be included. Two reviewers will independently complete the article selection, data extraction and rating. The bias tool from the Cochrane Handbook for Systematic Reviews of Interventions was used to assess the methodological quality of the included studies. A narrative or quantitative synthesis will be performed based on the available data. The planned start and end dates for the study were 1 February 2021 and 1 March 2022.

ETHICS AND DISSEMINATION

Ethical approval will not be required for this review. The results of this review will be disseminated in a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42021228981.

Serum 25-hydroxyvitamin D concentrations are inversely associated with body adiposity measurements but the association with bone mass is non-linear in postmenopausal women

Vitamin D deficiency has been linked to increased adiposity and decreased bone density. It is not known if vitamin D is linked to adiposity measures and bone mass in postmenopausal Qatar women. We investigated an association between serum vitamin D [25-hydroxyvitmain D (25(OH)D)] and adiposity measurements in postmenopausal women using Qatar Biobank data (n = 935). The post-menopausal status was self-reported by participants. Multivariate adjusted regression was applied to determine the association between serum 25(OH)D and body adiposity markers and bone mass. Serum 25(OH)D was significantly, inversely associated with body mass index (p < 0.0005), waist circumference (0.044), fat mass (p < 0.003), gynoid fat (p < 0.001), and android fat (p < 0.009). Serum 25(OH)D appeared to have an inverse 'U' association with several adiposity measures. Overall, body adiposity markers were the lowest in the 4^th quartile serum 25(OH)D and significantly lower compared to the 1^st quartile serum 25(OH)D. In multivariable adjusted analysis, no association was found between serum 25(OH)D concentration and bone mass when serum 25(OH)D was categorized. In a continuous variable analysis, the association between 25(OH)D and bone mass was significant, non-linear, inverse 'U'. In conclusion, serum 25-hydroxyvitamin D was inversely associated with adiposity measures and non-linearly associated to bone mass in postmenopausal Qatari women.

Effect of vitamin D supplementation on microvascular reactivity in obese adolescents: A randomized controlled trial

BACKGROUND AND AIM

Childhood obesity is associated with vitamin D (VD) deficiency and vascular dysfunction. Considering evidence indicates that VD may improve vascular function, this study, for the first time, assessed the effect of VD supplementation on microvascular reactivity in obese adolescents (OA).

METHODS AND RESULTS

This randomized controlled trial included 26 OA, receiving fruit juice with (n = 13) or without VD (4000 IU/d; n = 13) over a 3-month lifestyle program, as well as 23 normal-weight adolescents (controls). The primary outcome was the pre-to-post-program change in microvascular reactivity determined by laser speckle contrast imaging with acetylcholine and sodium nitroprusside iontophoresis. Changes in 25 hydroxyvitamin D (25(OH)D), flow-mediated dilation (FMD), nitrate-mediated dilation (NMD), insulin resistance (HOMA-IR) and inflammatory markers (C-reactive protein [CRP]) were monitored. At inclusion, in comparison to controls, OA exhibited lower total and free 25(OH)D, impaired microvascular responses, and impaired FMD, but similar NMD. After the lifestyle program, total and free 25(OH)D increased in all OA, with a greater increase in those receiving VD supplements. HOMA-IR and CRP decreased in all OA. Neither FMD nor NMD were altered in either group. Endothelium-dependent microvascular reactivity only increased in the VD-supplemented group, reaching values comparable to that of controls. Similar results were found when analyzing only OA with a VD deficiency at baseline.

CONCLUSION

VD supplementation during a lifestyle program attenuated microvascular dysfunction in OA without altering macrovascular function.

REGISTRATION NUMBER FOR CLINICAL TRIAL

NCT02400151.

The Role of Diet in Bone and Mineral Metabolism and Secondary Hyperparathyroidism

Bone disorders are a common complication of chronic kidney disease (CKD), obesity and gut malabsorption. Secondary hyperparathyroidism (SHPT) is defined as an appropriate increase in parathyroid hormone (PTH) secretion, driven by either reduced serum calcium or increased phosphate concentrations, due to an underlying condition. The available evidence on the effects of dietary advice on secondary hyperparathyroidism confirms the benefit of a diet characterized by decreased phosphate intake, avoiding low calcium and vitamin D consumption (recommended intakes 1000-1200 mg/day and 400-800 UI/day, respectively). In addition, low protein intake in CKD patients is associated with a better control of SHPT risk factors, although its strength in avoiding hyperphosphatemia and the resulting outcomes are debated, mostly for dialyzed patients. Ultimately, a consensus on the effect of dietary acid loads in the prevention of SHPT is still lacking. In conclusion, a reasonable approach for reducing the risk for secondary hyperparathyroidism is to individualize dietary manipulation based on existing risk factors and concomitant medical conditions. More studies are needed to evaluate long-term outcomes of a balanced diet on the management and prevention of secondary hyperparathyroidism in at-risk patients at.

Vitamin D Intake and Brain Cortical Thickness in Community-Dwelling Overweight Older Adults: A Cross-Sectional Study

BACKGROUND

Vitamin D is critical to brain health and a promising candidate to prevent cognitive decline and onset of Alzheimer disease (AD), although the underlying brain mechanisms are unclear.

OBJECTIVES

This study aimed to determine the association between vitamin D intake and brain cortical thickness in older adults.

METHODS

This was a cross-sectional investigation of 263 cognitively unimpaired participants, aged 65 y and older, participating in the MIND (Mediterranean-DASH Intervention for Neurodegenerative Delay) trial (an ongoing study testing the effects of a 3-y diet intervention on cognitive decline). Vitamin D intake, from diet and supplements, was ascertained from an FFQ. Linear regression analysis, adjusted for age, sex, race, education, income, cognitive and physical activities, and cardiovascular disease risk factors, was used to determine the association between vitamin D intake and cortical thickness of the whole brain, lobes, and AD signature.

RESULTS

Total vitamin D intake was associated with cortical thickness of the temporal lobe and AD signature. Compared with individuals in the lowest quartile of total vitamin D intake [median: 140 international units (IU)/d], those in the highest quartile (median: 1439 IU/d) had a 0.038-mm (95% CI: 0.006, 0.069 mm) thicker temporal lobe and 0.041-mm (95% CI: 0.012, 0.070 mm) thicker AD signature. Most vitamin D intake was from supplements, and supplemental intake was also associated with cortical thickness. Compared with those who used no supplement, individuals taking 800-1000 IU/d and >1000 IU/d of supplemental vitamin D had a 0.039-mm (95% CI: 0.013, 0.066 mm) and 0.047-mm (95% CI: 0.013, 0.081 mm) thicker temporal lobe and a 0.037-mm (95% CI: 0.013, 0.061 mm) and 0.046-mm (95% CI: 0.015, 0.077 mm) thicker AD signature, respectively. Dietary vitamin D was not related to brain cortical thickness in our sample.

CONCLUSIONS

In cognitively unimpaired older adults, total and supplemental vitamin D intakes were associated with cortical thickness in regions vulnerable to AD.This trial was registered at clinicaltrials.gov as NCT02817074.

Associations between Diet Quality and Anthropometric Measures in White Postmenopausal Women

The purpose of this cross-sectional study was to examine the relationship between diet and anthropometric measures in postmenopausal women. Data collected from 937 women enrolled in the Minnesota Green Tea Trial (NTC00917735) were used for this analysis. Dietary intake and health-related data were collected via questionnaires. Body weight, height, and waist circumference (WC) were measured by the study staff. The mean age of participants was 59.8 years and mean WC was 83 cm. Approximately 30% of the participants had WC greater than 88 cm. Healthy Eating Index-2015 score was 72.6 and the Dietary Inflammatory Index score was 0. Intakes of whole grains, dairy, protein, sodium, and saturated fat did not meet the dietary guidelines. Only 12.5% consumed the recommended daily amount of calcium (mean intake = 765 mg/day). When calcium supplements were considered, only 35.2% of the participants had adequate intakes, even though 68.9% reported taking a calcium supplement. We found that age and number of medications taken were significantly associated with waist circumference (p = 0.005). Women who reported taking two or more medications had greater WC (85 cm) compared to women who reported not taking any medications (82.2 cm), p = 0.002. Our findings suggest that achieving adequate calcium and vitamin D intake may be challenging to postmenopausal women.

Daily intake of yogurt drink fortified either with vitamin D alone or in combination with added calcium causes a thyroid-independent increase of resting metabolic rate in adults with type 2 diabetes: a randomized double blind clinical trial

We investigated the effect of daily intake of yogurt drink fortified with either vitamin D alone or with added calcium on resting metabolic rate (RMR), thyroid hormones and homeostatic model assessment for insulin resistance (HOMA-IR) in subjects with type 2 diabetes (T2D). A total of 75 adult subjects with T2D were randomly assigned to one of the three groups to receive either D-fortified yogurt drink (DY; 1000 IU vitamin D/d), Ca-D-fortified yogurt drink (CDY; 1000 IU vitamin D plus 500 mg calcium), or plain yogurt drink (PY) for 12 weeks. All assessments were done at the baseline and after the intervention. The concentrations of anti-thyroid peroxidase antibody (anti-TPO-Ab), intact parathyroid hormone (iPTH) and thyroid stimulating hormone (TSH) had significant decline compared with baseline values only in CDY group. The mean RMR increased in both DY and CDY groups (p<0.001 for both). Also, changes of serum concentrations of 25(OH)D (B= 2.96, 95%CI= 1.3- 4.6, p=0.001) and iPTH (B= -2.41, 95%CI= -4.5- -0.31, p=0.025) remained significant predictors of RMR changes even after adjustment for changes of serum concentrations of TSH (B= -18.2, 95%CI= -61.7- 25.2, p=0.406). Daily intake of vitamin D together with calcium at physiological doses has attenuating effect on anti-TPO-Ab and TSH. Also, vitamin D with or without added calcium causes a significant thyroid-independent increase in RMR in euthyroid subjects with T2D. Registered at clinicaltrials.gov as NCT01229891. Novelty: Daily intake of vitamin D with calcium at physiological doses has attenuating effect on anti-TPO-Ab and TSH. Vitamin D with or without added calcium causes a thyroid-independent increase in RMR in euthyroid subjects with T2D.

Vitamin D and Obesity: Current Evidence and Controversies

PURPOSE OF REVIEW

Evidence from observational studies suggests that obesity is associated with low vitamin D. As both obesity and hypovitaminosis D present an alarmingly increased prevalence worldwide, there is an intense research interest to clarify all aspects of this association. This review summarizes current evidence from meta-analyses investigating vitamin D status in obesity, including the effects of weight loss and bariatric surgery on vitamin D status and the outcomes of vitamin D supplementation on body weight. We also discuss potential pathophysiologic mechanisms and important controversies.

RECENT FINDINGS

Data from meta-analyses consistently support an inverse association of vitamin D levels with body weight. However, the impact of weight loss on improving vitamin D status is small, while studies on the supplementation with vitamin D after bariatric surgery have shown conflicting results regarding vitamin D status. Moreover, interventional studies do not support a beneficial effect of vitamin D supplementation on body weight. These findings warrant a cautious interpretation due to important methodological limitations and confounding factors, such as high heterogeneity of studies, variable methods of determination of vitamin D and definition of deficiency/insufficiency, use of various adiposity measures and definitions of obesity, and inadequate adjustment for confounding variables influencing vitamin D levels. The underlying pathogenetic mechanisms associating low vitamin D in obesity include volumetric dilution, sequestration into adipose tissue, limited sunlight exposure, and decreased vitamin D synthesis in the adipose tissue and liver. Experimental studies have demonstrated that low vitamin D may be implicated in adipose tissue differentiation and growth leading to obesity either by regulation of gene expression or through modulation of parathyroid hormone, calcium, and leptin. Obesity is associated with low vitamin D status but weight loss has little effect on improving this; vitamin D supplementation is also not associated with weight loss. Evidence regarding vitamin D status after bariatric surgery is contradicting. The link between vitamin D and obesity remains controversial due to important limitations and confounding of studies. More research is needed to clarify the complex interplay between vitamin D and adiposity.

Association of Vitamin D status with Visceral Adiposity Index and Lipid Accumulation Product Index among a Group of Iranian People

There is a growing body of evidence linking vitamin D and its antiadipogenic activity with body composition. The aim of this study was to investigate the association between vitamin D levels, visceral adiposity index (VAI), and lipid accumulation product index among a group of Iranian people. This cross-sectional study was conducted with 270 Iranian adults. Body composition was measured via bio-impedance analysis. The 25-hydroxyvitamin D [25(OH)D] was also measured using the enzyme-linked immunosorbent assay method. The VAI and lipid accumulation product index were calculated. Multiple linear and logistic regression after controlling for confounder was used to report the results. Multiple linear regression showed that serum 25(OH)D levels were positively correlated with age (crude: β ± standard error [SE] = 0.23 ± 0.06, p ≤ 0.001; model I: β ± SE = 0.18 ± 0.05, p = 0.002) and percent body fat (crude: β ± SE = 0.10 ± 0.04, p = 0.02). Binary logistic regression analysis showed a higher chance of greater percent body fat and lipid accumulation product index in the crude model (odds ratio [OR], 2.05; 95% confidence interval [CI], 1.13–3.72 for percent body fat and OR, 2.07; 95% CI, 1.14–3.76 for lipid accumulation product index), which disappeared after adjusting for covariates. Adults with higher vitamin D levels had higher scores of percent body fat and lipid accumulation product index. More longitudinal studies are needed to confirm these results.

Vitamin D Sources, Metabolism, and Deficiency: Available Compounds and Guidelines for Its Treatment

Studies on vitamin/hormone D deficiency have received a vast amount of attention in recent years, particularly concerning recommendations, guidelines, and treatments. Moreover, vitamin D’s role as a hormone has been confirmed in various enzymatic, metabolic, physiological, and pathophysiological processes related to many organs and systems in the human body. This growing interest is mostly due to the evidence that modest-to-severe vitamin D deficiency is widely prevalent around the world. There is broad agreement that optimal vitamin D status is necessary for bones, muscles, and one’s general health, as well as for the efficacy of antiresorptive and anabolic bone-forming treatments. Food supplementation with vitamin D, or the use of vitamin D supplements, are current strategies to improve vitamin D levels and treat deficiency. This article reviews consolidated and emerging concepts about vitamin D/hormone D metabolism, food sources, deficiency, as well as the different vitamin D supplements available, and current recommendations on the proper use of these compounds.

Effect of low-fat dairy products fortified with 1500IU nano encapsulated vitamin D3 on cardiometabolic indicators in adults with abdominal obesity: a total blinded randomized controlled trial

BACKGROUND & AIMS

Vitamin D deficiency is widespread worldwide. In this study, we aimed to evaluate the effect of a nano encapsulated form of vitamin D used for fortifying low-fat dairy products (milk and yogurt) on anthropometric indices, glycemic status, and lipid profile in subjects with abdominal obesity.

METHODS

In a totally (quadruple) blinded, randomized, and parallel-controlled trial, 306 individuals with abdominal obesity were randomly allocated to one of four groups: fortified low-fat yogurt (FY, 1500 IU nano encapsulated vitamin D₃ per 150 g/d), non-fortified low-fat yogurt (nFY), fortified low-fat milk (FM, 1500 IU nano encapsulated vitamin D₃ per 200 g/d), non-fortified low-fat milk (nFM), for 10 weeks (nFM and nFY, were considered as the control groups). Anthropometric and biochemical parameters were measured at baseline and after a ten-week trial in Mashhad, Iran.

RESULTS

After the ten-week intervention, we found a significant increase in serum concentration of 25(OH)D in both the FM and FY groups compared to the respective control groups (19.10 ± 5.69 ng/mL and 20.88 ± 5.76 ng/mL respectively, p < .001). We observed a significant reduction in weight to hip ratio (p = .04) and a significant improvement in triglyceride (p < .001) and HDL-C (p = .01) only in FM group compared to nFM group. Also, we found a significant reduction in fasting serum insulin (p < .001), and a significant improvement of HOMA-IR (p < .001) and QUICKI (p < .001) in both intervention groups compared to their placebos.

CONCLUSIONS

An intake of fortified dairy products containing nano-encapsulated vitamin D₃ was associated with an improvement in some measures of anthropometric indices, glucose homeostasis, and lipid profiles, particularly in individuals receiving fortified milk. Hence, along with other benefits, fortification of dairy products with vitamin D may be an effective approach to improve some cardiometabolic indicators, such as insulin resistance.

TRIAL REGISTRATION NUMBER

IRCT20101130005280N27.