Vitamin D Supplementation for Prevention of Type 2 Diabetes Mellitus: To D or Not to D?

Exploring the Interplay between Vitamin D, Insulin Resistance, Obesity and Skeletal Health

Vitamin D (ViD), plays an important role in calcium absorption and bone mineralization, is associated with bone mineral density. Severe deficiency in ViD has long been linked to conditions such as rickets in children and osteomalacia in adults, revealing its substantial role in skeletal health. Additionally, investigations show an existing interconnection between ViD and insulin resistance (Ins-R), especially in patients with type 2 diabetes mellitus (T2DM). Obesity, in conjunction with Ins-R, may augment the risk of osteoporosis and deterioration of skeletal health. This review aims to examine recent studies on the interplay between ViD, Ins-R, obesity, and their impact on skeletal health, to offer insights into potential therapeutic strategies. Cochrane Library, Google Scholar, and Pubmed were searched to investigate relevant studies until December 2023. Current research demonstrates ViD's impact on pancreatic β-cell function, systemic inflammation, and insulin action regulation. Our findings highlight an intricate association between ViD, Ins-R, obesity, and skeletal health, providing a perspective for the prevention and/or treatment of skeletal disorders in patients with obesity, Ins-R, and T2DM.

Consensus Statement on Vitamin D Status Assessment and Supplementation: Whys, Whens, and Hows

The 6th International Conference, "Controversies in Vitamin D," was convened to discuss controversial topics, such as vitamin D metabolism, assessment, actions, and supplementation. Novel insights into vitamin D mechanisms of action suggest links with conditions that do not depend only on reduced solar exposure or diet intake and that can be detected with distinctive noncanonical vitamin D metabolites. Optimal 25-hydroxyvitamin D (25(OH)D) levels remain debated. Varying recommendations from different societies arise from evaluating different clinical or public health approaches. The lack of assay standardization also poses challenges in interpreting data from available studies, hindering rational data pooling and meta-analyses. Beyond the well-known skeletal features, interest in vitamin D's extraskeletal effects has led to clinical trials on cancer, cardiovascular risk, respiratory effects, autoimmune diseases, diabetes, and mortality. The initial negative results are likely due to enrollment of vitamin D-replete individuals. Subsequent post hoc analyses have suggested, nevertheless, potential benefits in reducing cancer incidence, autoimmune diseases, cardiovascular events, and diabetes. Oral administration of vitamin D is the preferred route. Parenteral administration is reserved for specific clinical situations. Cholecalciferol is favored due to safety and minimal monitoring requirements. Calcifediol may be used in certain conditions, while calcitriol should be limited to specific disorders in which the active metabolite is not readily produced in vivo. Further studies are needed to investigate vitamin D effects in relation to the different recommended 25(OH)D levels and the efficacy of the different supplementary formulations in achieving biochemical and clinical outcomes within the multifaced skeletal and extraskeletal potential effects of vitamin D.

The Power of Vitamin D: Is the Future in Precision Nutrition through Personalized Supplementation Plans?

In the last few decades, vitamin D has undeniably been one of the most studied nutrients. Despite our ability to produce vitamin D through sunlight exposure, its presence in several natural food sources and fortified foods, and its widespread availability as a dietary supplement, vitamin D deficiency is a serious public health problem, affecting nearly 50% of the global population. Low serum levels of vitamin D are being associated with increased susceptibility to numerous health conditions, including respiratory infections, mental health, autoimmune diseases, and different cancer types. Although the association between vitamin D status and health is well-established, the exact beneficial effects of vitamin D are still inconclusive and indefinite, especially when considering the prevention and treatment of different health conditions and the determination of an appropriate dosage to exert those beneficial effects in various population groups. Therefore, further research is needed. With constant improvements in our understanding of individual variations in vitamin D metabolism and requirements, in the future, precision nutrition and personalized supplementation plans could prove beneficial.

Vitamin D and Dyslipidemia: Is There Really a Link? A Narrative Review

Nowadays, the interest in the extraskeletal effects of vitamin D is growing. In the literature, its several possible actions have been confirmed. Vitamin D seems to have a regulatory role in many different fields-inflammation, immunity, and the endocrine system-and many studies would demonstrate a possible correlation between vitamin D and cardiovascular disease. In this paper, we deepened the relationship between vitamin D and dyslipidemia by reviewing the available literature. The results are not entirely clear-cut: on the one hand, numerous observational studies suggest a link between higher serum vitamin D levels and a beneficial lipid profile, while on the other hand, interventional studies do not demonstrate a significant effect. Understanding the possible relationship between vitamin D and dyslipidemia may represent a turning point: another link between vitamin D and the cardiovascular system.

Vitamin D and risk of developing type 2 diabetes in the SUN project: a prospective cohort study

PURPOSE

Vitamin D deficiency has been associated with multiple chronic diseases, including metabolic disorders such as insulin resistance and type 2 diabetes (T2D). The aim of the study was to analyze the association between validated predicted serum vitamin D status and the risk of developing T2D in a large prospective cohort based on a Mediterranean population.

METHODS

The SUN project is a prospective and dynamic Spanish cohort that gathers university graduates who have answered lifestyle questionnaires, including a validated Food Frequency Questionnaire. The association between predicted serum vitamin D and the risk of T2D was assessed through Cox regression models according to quartiles (Q) of predicted vitamin D at baseline. The models were adjusted for potential confounders and sensitivity analyses were performed to ensure the robustness of our findings.

RESULTS

Our study included a total of 18,594 participants and after a total follow-up of 238,078 person-years (median follow-up of 13.5 years), 209 individuals were diagnosed with incident T2D. We found a significant inverse association between predicted levels of serum vitamin D and the risk of developing T2D, after adjusting for potential confounders and performing different sensitivity analyses (hazard ratio Q4 vs. Q1: 0.48, 95% CI 0.26-0.88; p for trend = 0.032).

CONCLUSION

The outcomes suggest that higher levels of vitamin D at baseline may be associated with a reduced risk of developing T2D.

Vitamin D supplementation modulates glycated hemoglobin (HBA1c) in diabetes mellitus

Diabetes is a metabolic illness that increases protein glycosylation in hyperglycemic conditions, which can have an impact on almost every organ system in the body. The role of vitamin D in the etiology of diabetes under RAGE (receptor for advanced glycation end products) stress has recently received some attention on a global scale. Vitamin D's other skeletal benefits have generated a great deal of research. Vitamin D's function in the development of type 1 and type 2 diabetes is supported by the discovery of 1,25 (OH)2D3 and 1-Alpha-Hydroylase expression in immune cells, pancreatic beta cells, and several other organs besides the bone system. A lower HBA1c level, metabolic syndrome, and diabetes mellitus all seems to be associated with vitamin D insufficiency. Most of the cross-sectional and prospective observational studies that were used to gather human evidence revealed an inverse relationship between vitamin D level and the prevalence or incidence of elevated HBA1c in type 2 diabetes. Several trials have reported on the impact of vitamin D supplementation for glycemia or incidence of type 2 diabetes, with varying degrees of success. The current paper examines the available data for a relationship between vitamin D supplementation and HBA1c level in diabetes and discusses the biological plausibility of such a relationship.

Impaired Sensitivity to Thyroid Hormones Is Associated With Decreased Vitamin D Levels in the Euthyroid Population

CONTEXT

The relationship between vitamin D and thyroid profiles lacks consensus despite extensive investigations. Whether vitamin D levels correlate with thyroid hormone sensitivity remains largely unexplored.

OBJECTIVE

To explore the relationship between vitamin D levels and thyroid hormone sensitivity among euthyroid individuals.

METHODS

This study involved 6452 euthyroid participants. Clinical parameters, including TSH, free thyroxine, 25-hydroxyvitamin D [25(OH)D], and other relevant indicators were extracted from the National Health and Nutrition Examination Survey 2007-2012. To quantify thyroid hormone sensitivity, we calculated the Thyroid Feedback Quantile-based Index (TFQI), the TSH index (TSHI), and the thyrotropin thyroxine resistance index (TT4RI).

RESULTS

Subjects with impaired thyroid hormone sensitivity have decreased 25(OH)D levels (TFQI, TT4RI: P < 0.05; TSHI: P = .05574) following adjustment of confounding variables. Age-specific analysis found negative correlations between thyroid hormone sensitivity indices and 25(OH)D within the 20 to 60 years subgroup, turning positive in the 60 to 80 years subgroup. In females, thyroid hormone sensitivity indices and vitamin D levels were negatively linked, while in males, vitamin D's relationships with TFQI, TT4RI, and TSHI shifted from negative to positive when 25(OH)D levels exceeded 63.5 nmol/L, 56.7 nmol/L, and 56.7 nmol/L, respectively. Stratification by race revealed U-shaped curvilinear patterns resembling those found in the males. In body mass index (BMI) subanalysis, vitamin D had differing associations with thyroid hormone sensitivity indices: negative in the <25 kg/m2 and ≥30 kg/m2 subgroups and U-shaped in the 25-30 kg/m2 subgroup.

CONCLUSION

Impaired thyroid hormone sensitivity correlates with decreased vitamin D levels among euthyroid subjects, with associations varying by age, sex, race, and BMI.

Vitamin D Oral Replacement in Children With Obesity Related Asthma: VDORA1 Randomized Clinical Trial

Children with asthma and obesity are more likely to have lower vitamin D levels, but the optimal replacement dose is unknown in this population. The objective of this study is identifying a vitamin D dose in children with obesity-related asthma that safely achieves serum vitamin D levels of ≥ 40 ng/mL. This prospective multisite randomized controlled trial recruited children/adolescents with asthma and body mass index ≥ 85% for age/sex. Part 1 (dose finding), evaluated 4 oral vitamin D regimens for 16 weeks to identify a replacement dose that achieved serum vitamin D levels ≥ 40 ng/mL. Part 2 compared the replacement dose calculated from part 1 (50,000 IU loading dose with 8,000 IU daily) to standard of care (SOC) for 16 weeks to identify the proportion of children achieving target serum 25(OH)D level. Part 1 included 48 randomized participants. Part 2 included 64 participants. In Part 1, no SOC participants achieved target serum level, but 50-72.7% of participants in cohorts A-C achieved the target serum level. In part 2, 78.6% of replacement dose participants achieved target serum level compared with none in the SOC arm. No related serious adverse events were reported. This trial confirmed a 50,000 IU loading dose plus 8,000 IU daily oral vitamin D as safe and effective in increasing serum 25(OH)D levels in children/adolescents with overweight/obesity to levels ≥ 40 ng/mL. Given the critical role of vitamin D in many conditions complicating childhood obesity, these data close a critical gap in our understanding of vitamin D dosing in children.

Vitamin D Supplementation: A Review of the Evidence Arguing for a Daily Dose of 2000 International Units (50 µg) of Vitamin D for Adults in the General Population

Vitamin D deficiency is considered a public health problem due to its worldwide high prevalence and adverse clinical consequences regarding musculoskeletal health. In addition, vitamin D may also be crucial for the prevention of certain extraskeletal diseases. Despite decades of intensive scientific research, several knowledge gaps remain regarding the precise definition of vitamin D deficiency and sufficiency, the health benefits of improving vitamin D status, and the required vitamin D intakes. Consequently, various societies and expert groups have released heterogeneous recommendations on the dosages for vitamin D supplementation. In this brief narrative review, we outline and discuss recent advances regarding the scientific evidence arguing for a daily vitamin D supplementation with 2000 international units (IU) (50 µg) of vitamin D3 to prevent and treat vitamin D deficiency. According to data from randomized controlled trials (RCTs), such a dose may improve some health outcomes and is sufficient to raise and maintain serum 25(OH)D concentrations above 50 nmol/L (20 ng/mL) and above 75 nmol/L (30 ng/mL) in >99% and >90% of the general adult population, respectively. According to large vitamin D RCTs, there are no significant safety concerns in supplementing such a dose for several years, even in individuals with an already sufficient vitamin D status at baseline. A daily vitamin D supplementation with 2000 IU (50 µg) may be considered a simple, effective, and safe dosage to prevent and treat vitamin D deficiency in the adult general population.

Associations of Serum Vitamin D Concentration with Cardiovascular Risk Factors and the Healthy Lifestyle Score

Vitamin D status is reportedly associated with risk factors for cardiovascular disease (CVD), although conflicting data have been generated. The healthy lifestyle score (HLS) was formulated as a primary approach toward preventing CVD; however, data on the association between the HLS and vitamin D status remain insufficient. This study aimed to investigate the associations of CVD risk factors and the HLS with serum 25-hydroxyvitamin D concentration in adults who participated in a national survey. HLS components, including body mass index, smoking status, alcohol consumption, physical activity, and dietary pattern, as well as other risk factors, including diabetes mellitus (DM), hypertension (HTN), and dyslipidemia (DL), were fitted in multiple linear regression models to determine their association with vitamin D status. DM, HTN, and DL were inversely associated whereas a balanced dietary pattern, alcohol consumption, and physical activity were positively associated with serum vitamin D concentration (p < 0.01). Furthermore, a strong association was observed between the total HLS and serum vitamin D concentration (p for trend <0.01); the regression coefficient estimate (95% confidence interval) for the highest score was 1.41 (0.65, 2.17) (p < 0.01) compared with that for the lowest. These findings suggest that CVD risk factors and the HLS may reflect vitamin D status.

Cross-sectional study of the associations between circulating vitamin D concentrations and insulin resistance in children aged 9-10 years of South Asian, black African Caribbean and white European origins

BACKGROUND

Lower circulating vitamin D 25-hydroxyvitamin D (25(OH)D) concentrations are associated with higher type 2 diabetes risk in adults, although causality remains uncertain. However, associations between 25(OH)D and type 2 diabetes risk markers in children have been little studied, particularly in ethnic minority populations. We examined whether 25(OH)D concentrations were associated with insulin resistance in children and whether lower 25(OH)D concentrations in South Asians and black African Caribbeans could contribute to their higher insulin resistance.

METHODS

Cross-sectional study of 4650 UK primary school children aged 9-10 years of predominantly South Asian, black African Caribbean and white European ethnicity. Children had fasting blood measurements of circulating 25(OH)D metabolite concentrations, insulin and glucose.

RESULTS

Lower 25(OH)D concentrations were observed in girls, South Asians and black African Caribbeans. In analyses adjusted for age, sex, month, ethnic group and school, circulating 25(OH)D was inversely associated with fasting insulin (-0.38%, 95% CI -0.49% to -0.27%), homoeostasis model assessment (HOMA) insulin resistance (-0.39%, 95% CI -0.50% to -0.28%) and fasting glucose (-0.03%, 95% CI -0.05% to -0.02%) per nmol/L increase in 25(OH)D; associations did not differ between ethnic groups. Ethnic differences in fasting insulin and HOMA insulin resistance (higher among South Asian and black African Caribbeans) were reduced by >40% after adjustment for circulating 25(OH)D concentrations.

CONCLUSION

Circulating vitamin D was inversely associated with insulin resistance in all ethnic groups; higher insulin resistance in South Asian and black African children were partly explained by their lower vitamin D levels. Whether vitamin D supplementation can reduce emerging type 2 diabetes risk needs further evaluation.

Investigating the relationship between vitamin-D deficiency and glycemia status and lipid profile in nondiabetics and prediabetics in Saudi population

Vitamin D deficiency increases the risk of developing diabetes, dyslipidemia, and other chronic diseases. We aimed to investigate the relationship between vitamin D deficiency, glycemic levels, and lipid profiles in individuals with prediabetes and nondiabetes. This observational cross-sectional study was conducted on 249 adults who were divided into 2 groups based on the American Diabetes Association classification: nondiabetics and prediabetics. The serum vitamin D levels, lipid profiles, fasting blood glucose levels, hemoglobin A1c levels, fasting insulin levels, and insulin resistance (IR) were evaluated. The prevalence of vitamin D deficiency in all participants was 30.9%, and mean vitamin D levels were significantly [P = .0004] lower in prediabetics, who were more common in females. Furthermore, prediabetics had significantly higher serum triglycerides [P = .0006], and significantly lower serum high-density lipoprotein levels [P = .0148] than those nondiabetics. Serum cholesterol and low-density lipoprotein levels did not differ significantly between the 2 groups. 31.4% of all participants were overweight and 40.2% were obese. Furthermore, there was a strong correlation between vitamin D levels and IR and body mass indices ≥ 25 in prediabetics [r = -0.92] [P < .001]. Finally, vitamin D levels had a significant inverse relationship with glycemic parameters and IR, particularly in obese participants, but there was no significant relationship with lipid profile. In conclusion, vitamin D deficiency is common in females, regardless of whether they are prediabetics, but is more prevalent in prediabetics. Vitamin D deficiency is associated with high triglycerides and low high-density lipoprotein levels, but there were no significant changes in total cholesterol or low-density lipoprotein levels. Furthermore, vitamin D levels were negatively correlated with both fasting blood glucose and hemoglobin A1c levels, and its deficiency was strongly associated with IR especially in obese patients despite there being no significant correlation with blood lipids.

Vitamin D levels in the pre- and post-COVID-19 pandemic periods in pediatric patients with chronic kidney disease

Introduction

Vitamin D (VD) deficiency is common in children with chronic kidney disease (CKD) because of multiple factors. During the coronavirus disease 2019 (COVID-19) pandemic, it increased because of medicine shortage and no enough medical service for patients with non-COVID-19 diseases.

Objective

To analyze the effects of the COVID-19 pandemic-related lockdown on the serum levels and status of 25-hydroxyvitamin D3 (25-[OH]D) in children with CKD.

Materials and methods

This retrospective study included patients (6-18 years old) who were diagnosed with CKD stage 2-5 and routinely measured for serum VD levels between May 2019 and December 2022. Serum 25-(OH)D levels were measured before, during, and after the pandemic (2019, 2020-2021, and 2022, respectively). The daily dose of cholecalciferol supplementation and the readjustment (if required) were recorded.

Results

This study included 171 patients (median age: 12 years). Before the pandemic, the median serum VD level was 25.0 ng/mL (19.3% VD deficiency). Then, VD supplementation was adjusted to 400-1,200 UI daily in 98.8% (n = 169) of patients. During the pandemic, the median VD level decreased to 22.5 ng/mL (43.3% VD deficiency). Hence, the supplementation was readjusted, and after the pandemic, the level was 28.7 ng/mL (18.7% VD deficiency), indicating a statistically significant increase in serum VD levels from the prepandemic period (p = 0.007).

Conclusion

Decreased serum VD levels and increased VD deficiency frequency were observed in patients with CKD during the COVID-19 but improved after readjustment of supplementation.

Vitamin D improves the antidiabetic effectiveness of aerobic training via modulation of Akt, PEPCK, and G6Pase expression

BACKGROUND

Although the effect of Vitamin D Supplementation (Vit D) on several chronic diseases has been well conceded, its role in diabetes remains ambiguous. The present study investigated the interactive effects of Aerobic Training (AT) and different Vit D doses on Protein Kinase B (Akt), Phosphoenolpyruvate Carboxylase (PEPCK), and Glucose-6-Phosphatase (G6Pase) protein expressions in hepatocytes of type-2 diabetic rats.

METHODS

Fifty-six male Wistar rats were divided into 2 groups SHAM (non-diabetic control; n = 8), and diabetic (n = 48). Then, diabetic rats were divided into six groups: AT with high doses of Vit D (D + AT + HD), AT with moderate doses of Vit D (D + AT + MD), high doses of Vit D (D + HD), moderate doses of Vit D (D + MD), AT receiving vehicle (sesame oil; D + AT + oil), and control (oil-receiving). D + AT + HD and D + HD groups received 10,000 IU of Vit D; while D + AT + MD and D + MD groups receive 5000 IU of Vit D once a week by injection; D + AT + oil and SHAM groups received sesame oil. Diabetes was induced via intraperitoneal (IP) injection of streptozotocin (50 mg/kg body weight). After 2 months of intervention, serum insulin, glucose, and visceral fat were measured; protein expressions of Akt, PEPCK, and G6Pase were assessed by western blotting. The paired t-test, one-way analysis of variance (One-Way ANOVA), and the Tukey post hoc test were used at the signification level of P < 0.05.

RESULTS

Our data indicate that the diabeticization of rats increased the level of insulin, glucose, and PEPCK and G6Pase protein expressions and decreased the expression of the Akt (P < 0.05 for all variables). Combined AT and moderate or high Vit D significantly reduced body weight (P = 0.001; P = 0.001), body mass index (P = 0.001; P = 0.002), food intake (P = 0.001; P = 0.001) comparing the pre-test with the post-test, respectively. Also, AT and either high or moderate Vit D alone therapies lead to the improvement of the metabolic state, however, their combination had a more significant effect on the treatment of type 2 diabetes.

CONCLUSIONS

Findings from the present study suggested that combined Vit D supplementation and AT successfully improve liver function and attenuate insulin resistance via upregulating Akt and downregulating PEPCK and G6Pase expressions, compared with monotherapy.

The Relationship Between Non-HDL-C /HDL-C Ratio (NHHR) and Vitamin D in Type 2 Diabetes Mellitus

Purpose

The objective of this research was to examine the relationship between non-HDL cholesterol/HDL cholesterol ratio (NHHR) and vitamin D in type 2 diabetes mellitus (T2DM).

Patients and Methods

This study enrolled 617 T2DM participants. Participants were separated into two groups: no vitamin D deficiency and vitamin D deficiency. Participants were split into two categories: individuals who had a high NHHR and those with a low NHHR, with the median NHHR serving as the cut-off. Eventually, the study participants were classified into two groups by gender, which were further classified into vitamin D deficient and non-vitamin D deficient groups.

Results

NHHR values were substantially greater in vitamin D deficient group than in the non-deficient group in both male and female T2DM patients (P<0.05). The high NHHR group displayed substantially lower vitamin D levels than the low NHHR group [16.21 (12.55,21.35) vs 19.05 (14.59,24.07), P<0.001]. NHHR was discovered to be negatively and independently associated with vitamin D levels, and there was no sex difference.

Conclusion

For the first time, our research revealed a negative relationship between NHHR and vitamin D in patients with T2DM.

Comparison of calcifediol with vitamin D for prevention or cure of vitamin D deficiency

Vitamin D deficiency remains prevalent, with about 7% of the world's population living with severe vitamin D deficiency and about one third with mild deficiency. We compare the relative merits of calcifediol or 25-hydroxyvitamin D (25OHD) compared to vitamin D itself for supplementation as to prevent or cure vitamin D deficiency. The intestinal absorption of calcifediol is nearly 100% and thus higher than that of vitamin D itself. Moreover, calcifediol is absorbed by the intestinal cells and transported through the portal vein and thus immediately accessible to the circulation, while vitamin D is transported with chylomicrons through the lymph system. Therefore, in case of fat malabsorption or after bariatric surgery, calcifediol is much better absorbed in comparison with vitamin D itself. Serum 25OHD increases linearly with increasing doses of calcifediol, whereas serum 25OHD reaches a plateau when higher oral doses of vitamin D are used. Calcifediol, on a weight basis, is about 3 times more potent than vitamin D in subjects with mild vitamin D deficiency. This potency is even 6-8 times higher than vitamin D when baseline serum 25OHD is higher or when large doses are compared. In conclusion, calcifediol is an alternative option to correct vitamin D deficiency and may even be the preferred strategy in case of intestinal fat malabsorption, after bariatric surgery or in case of other conditions with suspected impaired 25-hydroxylase activity in the liver.

The Effect of Vitamin D Supplementation on Incidence of Type 2 Diabetes: A Systematic Review

With the clinical increase in Type 2 Diabetes worldwide, several interventions to decrease its incidence have been investigated. One such intervention is Vitamin D supplementation, as it affects Insulin secretion from the pancreas and Insulin receptors in the cells of the body. This systematic review addresses whether or not Vitamin D supplementation has a role in reducing the risk of developing Type 2 Diabetes. Systematic searches were conducted on PubMed, and Cochrane Library mainly but also checked Google Scholar. Randomized controlled trials, systematic trials and cohort studies were retrieved that included keywords pertaining to Vitamin D supplementation and the incidence of Type 2 Diabetes. Exclusion criteria included studies that looked at different forms of Diabetes, studies including patients aged less than 18 or more than 85 years of age and studies that were not English language. For all the trials identified, the incidence of Type 2 Diabetes among the cohort receiving vitamin D supplementation was compared to the cohort receiving placebo medication. Additionally, the Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) was analyzed to observe if there was a difference between Insulin resistance among these two cohorts between the start of the trials and the end. Thirteen randomized controlled trials were identified. Seven of these identified incidences of Type 2 Diabetes as a research outcome, out of which six showed no statistically significant impact of vitamin D on the incidence of Type 2 Diabetes. Out of the 13 trials, 10 analyzed the impact of vitamin D supplementation on patients' HOMA-IR. In six of these trials, patients receiving vitamin D supplementation had a decrease in their HOMA-IR, while it increased in 4 trials. In seven of the ten trials that analyzed for HOMA-IR, the HOMA-IR was less in the vitamin D cohort than the placebo cohort. There is insufficient evidence to suggest that vitamin D supplementation significantly reduces the incidence of Type 2 Diabetes despite its effects on insulin resistance. Further research in this area would be helpful in order to influence clinical guidelines on vitamin D supplementation among patients at risk of Type 2 Diabetes.

Bioavailability of vitamin D biofortified pork meat: results of an acute human crossover study in healthy adults

Vitamin D intakes are concerningly low. Food-based strategies are urgently warranted to increase vitamin D intakes and subsequently improve 25-hydroxyvitamin D (25(OH)D) concentrations. This acute randomised three-way crossover study investigated the efficacy of vitamin D biofortified pork derived from pigs exposed to UVB light to increase serum 25(OH)D₃ concentrations, compared to a dose-matched vitamin D₃ supplement and control pork in adults (n = 14). Blood samples were obtained at baseline and then 1.5, 3, 6, 9 and 24 h postprandially. There was a significant effect of time (p < 0.01) and a significant treatment*time interaction (p < 0.05). UV pork and supplement significantly increased within-group serum 25(OH)D₃ concentrations over timepoints (p < 0.05) (max. change 0.9 nmol/L (2.2%) UV pork, 1.5 nmol/L (3.5%) supplement, 0.7 nmol/L (1.9%) control). Vitamin D biofortified pork modestly increased 25(OH)D₃ concentrations and produced a similar response pattern as a dose-matched vitamin D supplement, but biofortification protocols should be further optimised to ensure differentiation from standard pork.

Serum 25-Hydroxyvitamin D Levels and Youth-Onset Type 2 Diabetes: A Two-Sample Mendelian Randomization Study

Observational studies have linked vitamin D insufficiency to pediatric type 2 diabetes (T2D), but evidence from vitamin D supplementation trials is sparse. Given the rising prevalence of pediatric T2D in all ethnicities, determining the protective role of vitamin D has significant public health importance. We tested whether serum 25-hydroxyvitamin D (25OHD) levels are causally linked to youth-onset T2D risk using Mendelian randomization (MR). We selected 54 single-nucleotide polymorphisms (SNPs) associated with 25OHD in a European genome-wide association study (GWAS) on 443,734 individuals and obtained their effects on pediatric T2D from the multi-ethnic PRODIGY GWAS (3006 cases/6061 controls). We applied inverse variance weighted (IVW) MR and a series of MR methods to control for pleiotropy. We undertook sensitivity analyses in ethnic sub-cohorts of PRODIGY, using SNPs in core vitamin D genes or ancestry-informed 25OHD SNPs. Multivariable MR accounted for the mediating effects of body mass index. We found that a standard deviation increase in 25OHD in the logarithmic scale did not affect youth-onset T2D risk (IVW MR odds ratio (OR) = 1.04, 95% CI = 0.96-1.13, p = 0.35) in the multi-ethnic analysis, and sensitivity, ancestry-specific and multivariable MR analyses showed consistent results. Our study had limited power to detect small/moderate effects of 25OHD (OR of pediatric T2D < 1.39 to 2.1). In conclusion, 25OHD levels are unlikely to have significant effects on the risk of youth-onset T2D across different ethnicities.

Effects of Vitamin D on Cardiovascular Risk and Oxidative Stress

INTRODUCTION

Vitamin D has been primarily studied as an important factor influencing bone and calcium metabolism. Metabolites of vitamin D are essential for whole-body calcium homeostasis, maintaining serum calcium levels within a narrow range by regulating this process in the bones and gut. Nevertheless, its deficiency is also related to increased risk of type 2 diabetes mellitus (T2DM), metabolic syndrome (MS), and cardiovascular disease (CVD)-with increased visceral adipose tissue and body mass index (BMI), as well as the frequently associated hypercholesterolemia. It has been reported that vitamin D levels are inversely related to cardiovascular (CV) risk in men and women. However, the effects of vitamin D on distinct outcomes in women and the dose of supplementation needed to improve clinical endpoints have not been established. 25-Hydroxyvitamin D [25(OH)D] reduces systemic inflammatory mediators in CVD and favors the release of anti-inflammatory cytokines from the immune system. In addition, 25(OH)D can be primarily converted into calcitriol (1,25-dihydroxycholecalciferol [1,25(OH)2D]) in the kidneys through the action of the 1-α-hydroxylase enzyme. Calcitriol, through the downregulation mechanism of renin expression, renin-angiotensin-aldosterone system (RAAS) activity, and its interaction with the vitamin D receptor, can bring CV benefits. The calcitriol form also lowers parathyroid hormone (PTH) levels by indirectly causing a reduction in aldosterone and mineralocorticoid synthesis. Elevated plasma aldosterone is related to endothelial dysfunction and CVD in hypovitaminosis D status.

CONCLUSION

Vitamin D supplementation may benefit certain risk groups, as it improves metabolic variables, reducing oxidative stress and CV outcomes. More studies are needed to define interventions with vitamin D in men and women.

Association of bisphosphonates with diabetes risk and glycemic control: a meta-analysis

Previous evidence suggests that bisphosphonates may improve glycemic control. The present meta-analysis, comprising seven studies with 1,233,844 participants, demonstrated that bisphosphonate use was significantly associated with a lower risk of diabetes. However, in the randomized controlled trial subgroup, a non-significant association was found. Further studies are needed to determine causality.

PURPOSE

This study aimed to evaluate the impact of bisphosphonates on glycemic control and the risk of incident diabetes.

METHODS

MEDLINE, Embase, and Cochrane Library were searched from inception to February 15, 2022. Experimental or observational studies that compared fasting blood glucose (FBG) and glycated hemoglobin (HbA1c) levels and the diabetes risk with and without bisphosphonates were included. Studies without relevant outcomes, only providing crude estimates, or the absence of a control group were excluded. Two reviewers independently screened the articles, extracted data, and appraised studies. The pooled relative risk (RR) and weighted mean difference (WMD) were calculated using random effects models.

RESULTS

Seven studies (n = 1,233,844) on diabetes risk were included, including two post hoc analyses of randomized controlled trials (RCTs) and five observational studies. Compared with controls, bisphosphonates (BPs) were associated with a significant decrease in the risk of diabetes (RR = 0.77; 95% CI, 0.65 to 0.90; P = 0.002). However, in the subgroup of post hoc analyses of RCTs, the association was non-significant (RR = 0.93; 95% CI, 0.74 to 1.18; P = 0.576). Moreover, three studies (n = 4906) on FBG and one (n = 60) on HbA1c were included. We observed non-significant association between BPs and changes in FBG (WMD =  - 0.61 mg/dL; 95% CI, - 2.72 to 1.49; P = 0.567) and HbA1c (WMD =  - 0.11%; 95% CI, - 0.23 to 0.01; P = 0.083).

CONCLUSION

Patients taking BPs may have a lower risk of incident diabetes than those without BPs. However, due to the high between-study heterogeneity and inconsistent findings between post hoc analyses of RCTs and observational studies, further rigorous RCTs are required to determine whether the findings are causal.

Longitudinal changes in vitamin D concentrations and the association with type 2 diabetes mellitus: the Tromsø Study

AIM

We aimed to investigate the relationship between pre- and post-diagnostic 25-hydroxyvitamin D (25(OH)D) concentrations and type 2 diabetes (T2DM) over a period of 30 years in individuals who developed T2DM compared to healthy controls.

METHODS

This case-control study included 254 participants with blood samples collected at five different time-points (T1-T5) between 1986 and 2016. Of the 254 participants, 116 were diagnosed with T2DM between T3 and T4, and were considered cases; the remaining 138 were controls. Linear mixed regression models were used to examine pre- and post-diagnostic changes in 25(OH)D concentrations, and logistic regression was used to examine associations between these concentrations and T2DM at each time-point.

RESULTS

25(OH)D concentrations at different time-points and the longitudinal change in concentrations differed between cases and controls, and by sex. For women, each 5-nmol/l increase in 25(OH)D concentrations was inversely associated with T2DM at T3 (odds-ratio, OR, 0.79), whereas for men, this same increase was positively associated with T2DM at T1 (OR 1.12). Cases experienced a significant decrease in pre-diagnostic 25(OH)D concentrations (p value < 0.01 for women, p value = 0.02 for men) and a significant increase in post-diagnostic 25(OH)D concentrations (p value < 0.01 for women, p value = 0.01 for men). As such, each 1-unit increase in month-specific z-score change between T1 and T3 was significantly inversely associated with T2DM (OR 0.51 for women, OR 0.52 for men), and each such increase between T3 and T5 was significantly positively associated with T2DM in women (OR 2.48).

CONCLUSIONS

25(OH)D concentrations seem to be affected by disease progression and type 2 diabetes diagnosis.

Association between the Triglyceride-Glucose Index and Vitamin D Status in Type 2 Diabetes Mellitus

BACKGROUND

Vitamin D deficiency (VDD) increases the risk for type 2 diabetes mellitus (T2DM), which might be related to insulin resistance (IR). We aimed to explore the association between the triglyceride-glucose (TyG) index, a reliable indicator of IR, and VDD in patients with T2DM.

METHODS

There were 1034 participants with T2DM enrolled in the Second Xiangya Hospital of Central South University. The TyG index was calculated as ln (fasting triglyceride (TG, mg/dL) × fasting blood glucose (mg/dL)/2). VDD was defined as 25-hydroxyvitamin D [25(OH)D] level <50 nmol/L.

RESULTS

Correlation analysis showed a negative association between the TyG index and 25(OH)D level. After adjustments for clinical and laboratory parameters, it was revealed that when taking the Q1 quartile of TyG index as a reference, an increasing trend of VDD prevalence was presented in the other three groups divided by TyG index quartiles, where the OR (95% CI) was 1.708 (1.132-2.576) for Q2, 2.041 (1.315-3.169) for Q3, and 2.543 (1.520-4.253) for Q4 (all p < 0.05).

CONCLUSIONS

Patients with higher TyG index were more likely to have an increased risk of VDD in T2DM population, which may be related to IR.

Reduced serum 25(OH)D is closely related to bronchial mucus plug formation in children with mycoplasma pneumonia: A prospective cohort study

Background

The relationship between vitamin D nutritional status and the formation of bronchial mucus plugs (BMPs) is unclear. The aims of the current study were to investigate associations between serum 25(OH)D levels, serum inflammatory factors, and clinical characteristics in children with mycoplasma pneumonia (MPP), and to summarize the risk factors for BMPs in children with MPP.

Methods

Clinical data from 175 children with MPP were collected and analyzed, the children were divided into a BMP group and a non-BMP group. Serum 25(OH)D levels, IL-8, and various inflammatory factors were compared in the two groups. Associations between 25(OH)D levels and IL-8, various inflammatory factors, and clinical characteristics were analyzed, and the diagnostic value of serum 25(OH)D levels was assessed.

Results

Serum 25(OH)D level was significantly lower in the BMP group (p < 0.05). Serum IL-8 level, percentages of neutrophils, and some inflammatory factors were significantly higher in the BMP group (p < 0.05). Serum 25(OH)D level was negatively correlated with IL-8, neutrophil percentage, various inflammatory factors (all p < 0.05). It was also associated with lobular infection, pleural effusion, mechanical ventilation, and mycoplasma 2,063/2,064 mutation (all p < 0.05). In multivariate regression analysis 25(OH)D [odds ratio (OR) 0.98, 95% confidence interval (CI) 0.97-0.99, p = 0.003], IL-8 (OR 1.02, 95% CI 1.00-1.04, p = 0.002), polylobular infection (OR 1.75, 95% CI 1.17-2.64, p = 0.007), and MP DNA copies (OR 0.98, 95% CI 1.04-1.01, p = 0.022) were independent risk factors for BMPs, and the area under the curve value was 0.915 (95% CI 0.895-0.935). If the serum 25(OH)D level was <50 nmol/L, the respective percentages for sensitivity, specificity, positive predictive value, and negative predictive value were 97, 81, 78.9, and 97.6%.

Conclusions

Vitamin D deficiency is common in children with MPP, and 25(OH)D levels are closely associated with inflammatory factors and disease severity in children. The serum 25 (OH) D level of MPP children with BMPs was lower than that of children without BMPs. Serum 25(OH)D can be used as a marker for the diagnosis of MPP in children with BMPs.

A meta-analysis suggests the association of reduced serum level of vitamin D and T-allele of Fok1 (rs2228570) polymorphism in the vitamin D receptor gene with celiac disease

Purpose

As an immune-modulator, vitamin D is known to regulate immune response and is implicated in disease pathogenesis. Celiac disease (CD) is a systemic autoimmune disease and susceptibility conferred by vitamin D metabolism is under investigation. Studies on the association of vitamin D metabolism and genetic polymorphisms are expected to explain CD pathogenesis. We performed a systematic review-based meta-analysis to investigate the 25(OH)D serum levels and susceptibility conferred by the genetic variants of VDR in CD.

Methods

Systematic review was conducted through a web-based literature search following stringent study inclusion-exclusion criteria. The Newcastle-Ottawa Scale and GRADE tools were used to assess the quality of evidence in studies and the study outcome. Cohen's κ value was estimated to access the reviewer's agreement. RevMan 5.4.1 was used to perform the meta-analyses. Weighted mean difference and Meta p-value was assessed for 25(OH)D serum levels. Meta-odds ratio and Z-test p-value were evaluated to estimate the allelic susceptibility of VDR variants.

Results

A total of 8 out of 12 studies were evaluated for "25(OH)D" serum level, while four studies were found eligible for SNPs (Bsm1, Apa1, Fok1, and Taq1) of VDR. Significantly higher levels [WMD = 5.49, p < 0.00001] of 25(OH)D were observed in healthy controls than in patients with CD. rs2228570-T (Fok1) [Meta-OR = 1.52, p = 0.02] was confirmed to be predisposing allele for CD.

Conclusion

Reduced serum level of 25(OH)D and association of Fok1 T-allele of VDR confirmed in this study plays a critical role in immunomodulation and maintaining barrier integrity, which is majorly implicated in CD.

Vitamin D in the older population: a consensus statement

BACKGROUND

This paper reports results from the 5th International Conference "Controversies in Vitamin D" that was held in Stresa, Italy, 15-18 September 2021. The conference is part of this series that started in 2017 and has been conducted annually since. The objective of these conferences is to identify timely and controversial topics related to Vitamin D. Dissemination of the results of the conference through publications in peer-reviewed journals is an important means by which the most up to date information can be shared with physicians, investigators, and other health care professionals. Vitamin D and aging, the subject of this paper was featured at the conference.

METHODS

Participants were selected to review available literature on assigned topics related to vitamin D and aging and to present their findings with illustrative material, the intent of which was to stimulate discussion and to arrive at a consensus. The presentations were directed towards the following areas: impact of aging on vitamin D production and levels; skeletal effects of vitamin D deficiency in the older population; falls and vitamin D in the aging; potential extra skeletal effects of vitamin D; and strategies to prevent vitamin D deficiency. A final topic was related to how vitamin D might influence the efficacy of vaccines for Covid-19.

RESULTS

Hypovitaminosis D can lead to several skeletal and extra-skeletal outcomes. Older adults are at risk for vitamin D deficiency as both production and metabolism of vitamin D change with aging due to factors, such as reduced sun exposure and reduced production capacity of the skin. Skeletal consequences of these age-related changes can include reduced bone mineral density, osteomalacia and fractures. Potential extra-skeletal effects can include added risks for falls, reduced muscle strength, diabetes, cancer, and cardiovascular disease. Strategies to avoid these vitamin D deficiency-related negative outcomes include sun exposure, food fortification, and supplementation. While aging does not diminish sufficient reserve capacity for cutaneous vitamin D production, concerns about skin cancers and practical matters for the institutionalized elderly limit this option. Supplementation with vitamin D is the best option either pharmacologically or through food fortification. Regardless of treatment strategies, interventions to restore sufficient vitamin D status will show positive results only in those who are truly deficient. Thus, treatment goals should focus on avoiding 25(OH)D serum levels <30 nmol/l, with a goal to reach levels >50 nmol/l.

CONCLUSIONS

The results of this conference has led to consensus on several issues. Vitamin D supplementation should be combined with calcium to reduce fractures in the older population. The goal for adequate Vitamin D status should be to reach a serum level of 25(OH)D >50 nmol/l. It appears that daily low-dose vitamin D regimens reduce the risk of falling, especially in the elderly, compared with infrequent, large bolus doses that may increase it. The role of Vitamin D supplementation on muscle strength remains to be clarified. On the other hand, supplementation decreases the risk of progression to T2D from prediabetes among those who are Vitamin Ddeficient. Of three possible strategies to establish vitamin D sufficiency - sunshine exposure, food fortification, and supplementation - the latter seems to be the most effective and practical in the aging population.

Vitamin D metabolism and extraskeletal outcomes: an update

Vitamin D deficiency is a general health problem affecting individuals at all stages of life and on different continents. The musculoskeletal effects of vitamin D are well known. Its deficiency causes rickets, osteomalacia, and secondary hyperparathyroidism and increases the risk of fractures. Clinical and experimental evidence suggests that vitamin D performs multiple extraskeletal functions. Several tissues unrelated to calcium and phosphate metabolism express vitamin D receptor (VDR) and are directly or indirectly influenced by 1,25(OH)₂D (calcitriol). Some also express the enzyme 1 alpha-hydroxylase (CYP27B1) and produce 1,25(OH)₂D, inducing autocrine or paracrine effects. Among the pleiotropic effects of vitamin D are the regulation of cell proliferation and differentiation, hormone secretion, and immune function. In this review, we outline vitamin D physiology and the outcomes of recent large RCTs on its potential extraskeletal effects. Those studies exhibit a need for continued clinical analysis to elucidate whether vitamin D status can influence extraskeletal health. Longer longitudinal follow-up and standardized assays are crucial to better assess potential outcomes.

Association between vitamin D deficiency and the risk of prevalent type 2 diabetes and incident prediabetes: A prospective cohort study using data from The Irish Longitudinal Study on Ageing (TILDA)

BACKGROUND

It is hypothesized that vitamin D contributes to the aetiology of type 2 diabetes mellitus (diabetes). This study's objective was to examine the relationships between baseline vitamin D status (as measured by plasma 25-hydroxyvitamin D concentration) and both prevalent diabetes and prospective risk of developing diabetes, including prediabetes, in a population with historically low levels of vitamin D.

METHODS

In this prospective cohort study, data from The Irish Longitudinal Study on Ageing (TILDA), a nationally representative cohort of adults aged ≥50 years residing in Ireland were analysed, including wave 1 (October 2009-June 2011) (n = 5272) and wave 3 (March 2014-October 2015) (n = 3828). Those aged <50 years at baseline or who did not complete the health assessment were excluded. Logistic regression models examined the associations between baseline vitamin D concentration (nmol/L) with prevalent diabetes status and incident diabetes/prediabetes collected at a 4-year follow-up. Models were adjusted for age, sex, education, body mass index, smoking history, physical activity, use of statins, and the season in which the vitamin D concentration was sampled.

FINDINGS

Deficient baseline vitamin D concentration was cross-sectionally associated with an increased likelihood of having prevalent diabetes (Relative Risk Ratio [RRR] 1·5, 95% CI: 1·03, 2·18; p = 0·037). In longitudinal analyses evaluating diabetes status 4 years later, there was a 62% increased likelihood (RRR: 1·62, 95% CI: 1·12, 2·35; p = 0·011) of developing prediabetes for those with vitamin D <30 nmol/L compared to those with ≥75 nmol/L. The rate of progression from prediabetes to diabetes between wave 1 and 3 was observed to be 32·5%.

INTERPRETATION

Those with lower concentrations of vitamin D, as measured by 25-hydroxyvitamin D, may have different risk profiles with regards to their glycaemic status. Our study had limited power due to the low incidence of diabetes but showed strong associations with incident prediabetes, so further research is required. Optimising vitamin D status at a population level may significantly reduce diabetes.

FUNDING

TILDA is funded by Atlantic Philanthropies, the Irish Department of Health, and Irish Life, while additional funding was provided by the Irish Department of Agriculture, Food and the Marine (13F492) to cover the cost of 25-hydroxyvitamin D analysis.

Vitamin D, parathyroid hormone, glucose metabolism and incident diabetes in the multiethnic study of atherosclerosis

INTRODUCTION

Higher concentrations of serum 25-hydroxyvitamin D (25(OH)D) and lower concentrations of parathyroid hormone (PTH) are associated with lower insulin resistance and incident diabetes in non-Hispanic White and Hispanic Americans. Results are mixed in other populations, with no observational studies in a large multiethnic cohort. The association of serum 25(OH)D with diabetes may vary by adiposity level.

RESEARCH DESIGN AND METHODS

Among 5611 participants in the Multi-Ethnic Study of Atherosclerosis without diabetes at baseline, cross-sectional associations of serum 25(OH)D with homeostasis model assessment of insulin resistance (HOMA-IR) and HOMA-β were examined using linear regressions. The association of 25(OH)D with incident diabetes over 9 years was examined using Cox proportional hazard regression.

RESULTS

Black Americans had the highest proportion of individuals with 25(OH)D<20 ng/mL (61%) and White Americans had the least (17%). Serum 25(OH)D was inversely associated with HOMA-IR in fully adjusted models (-0.34% difference in HOMA-IR per ng/mL higher 25(OH)D, p<0.0001). Longitudinally, a 1 ng/mL higher serum 25(OH)D was associated with 2% lower risk of incident diabetes (HR 0.982, CI 0.974 to 0.991), and a 1 pg/mL higher serum PTH was associated with 1% higher risk of incident diabetes (HR 1.007, CI 1.004 to 1.010), both prior to adjustment for waist circumference. After adjusting for waist circumference, a 1 ng/mL higher 25(OH)D was associated with 1% lower risk of incident diabetes (HR 0.991, CI 0.983 to 1.000). The magnitude of association of serum 25(OH)D with incident diabetes was largest at lower waist circumference (p for interaction=0.025). There was no heterogeneity by race/ethnicity (p=0.317).

CONCLUSIONS

Serum 25(OH)D is inversely associated with insulin resistance and incident diabetes in a diverse cohort, including non-Hispanic White, Black, Hispanic and Chinese Americans. Future research should explore mechanisms for the interaction between serum 25(OH)D and adiposity in this relationship.

Associations of Serum Total 25OHD, 25OHD3, and epi-25OHD3 with Insulin Resistance: Cross-Sectional Analysis of the National Health and Nutrition Examination Survey, 2011–2016

Background: Vitamin D may have a role in insulin sensitivity. However, the data on the association between various metabolites of Vitamin D and insulin-related parameters have been limited. Methods: We identified 6026 adults aged 20–80 years who participated in the 2011–2016 National Health and Nutrition Examination Survey (NHANES). Serum total 25OHD, 25OHD3, and epi-25OHD3, fasting glucose, insulin, and HOMA2-IR were obtained from the NHANES data. The association between serum Vitamin D-related values and insulin resistance was analyzed using a generalized linear model. For risk analysis, multifactorial logistic regression was used. Results: The median total 25-hydroxyvitamin D level, 25-hydroxyvitamin D3 level, and 3-epi-25-hydroxyvitamin D3 level were 62.5 nmol/L, 58.8 nmol/L, and 3.3 nmol/L, respectively. After adjustment for sex, age, race, ethnicity, and education status, the ORs for the insulin resistance of participants of total 25-hydroxyvitamin D, 25-hydroxyvitamin D3, and 3-epi-25-hydroxyvitamin D3 were 0.32 (95% CI 0.24, 0.43), 0.34 (95% CI 0.26, 0.44), and 0.64 (95% CI 0.53, 0.77), respectively. After an adjustment for body mass index, diabetes, and drinking and smoking, the ORs for the insulin resistance of the participants for total 25-hydroxyvitamin D, 25-hydroxyvitamin D3, and 3-epi-25-hydroxyvitamin D3 were 0.56 (95% CI 0.40, 0.78), 0.63 (95% CI 0.46, 0.85), and 0.99 (95% CI 0.80, 1.24), respectively. Conclusions: Our study provides suggestive evidence for the association between Vitamin D concentrations and a lower risk of insulin resistance. Evidence from larger and more adequately powered cohort studies is needed to confirm our results.

Alterations in circulating levels of vitamin D binding protein, total and bioavailability of vitamin D in diabetic retinopathy patients

AIMS

This study aimed to investigate the association between circulating levels of vitamin D binding protein (VDBP) and its genotypes and diabetic retinopathy risk.

METHODS

This case-control study recruited 154 patients with type 2 diabetes mellitus; 62 with diabetic retinopathy (DR) and 92 without DR and diabetic nephropathy (DN). Circulating levels of 25-hydroxyvitamin D3 and VDBP levels were measured in the patients. The genotype and phenotype of VDBP were evaluated based on two common VDBP variations; rs7041 and rs4588.

RESULTS

Serum levels of VDBP were significantly lower in patients with DR than in patients without DR and/or DN (Ln-VDBP (μg/ml): 6.14 ± 0.92 vs. 6.73 ± 1.45, p = 0.001) even after adjustment for age, sex, body mass index, disease duration, estimated glomerular filtration rate (eGFR), HbA1C, insulin therapy profile, and serum levels of 25(OH)D. The distribution of VDBP phenotypes and genotypes in the two studied groups were nearly the same, and the distribution was similar to that of the general population.

CONCLUSIONS

In this study, we found the association between lower circulating levels of VDBP and risk of DR. However, the precise mechanism linking these two remains unknown. Further and more in-depth research is needed to find out the underlying causes of the relationship.

Lifestyle, Eating Habits, and Health Behaviors Among Dietary Supplement Users in Three European Countries

Dietary supplements (DS) are used by about 30-50% of adults in developed countries. However, only a few studies have compared the characteristics of DS users in different nations. This study aimed to identify and compare selected health-related behaviors of DS users from three European countries. A total of 3,588 adults (32.08 ± 8.04 years) from Poland (1,030 females, 287 males), Germany (994 females, 190 males), and the United Kingdom (911 females, 176 males) were included in the analysis. The study was based on a self-administered survey consisting of 70 questions regarding baseline characteristics, lifestyle, eating, and health habits. The associations of the obtained results were compared using the Kruskal-Wallis test, Pearson Chi-Square test, and Cramer's V value. The highest percentage of DS users (56.98%, n = 2,044) had a correct body weight, while higher body weight values were observed in 39.19% (n = 1,406). In terms of lifestyle, statistically significant differences (p < 0.05) were noted for alcohol consumption and the level of physical activity. Fruit and vegetables were most often consumed a few times a weeks (34.67%, n = 1,244). A similar result was observed for the consumption of whole grain (37.76%, n = 1,355), dairy (39.99%, n = 1,435), eggs (49.67%, n = 1,782), and meat (51.45%, n = 1,846). Most DS users did not have a chronic disease (66.72%, n = 2,394). Among the other conditions, a frequent occurrence (a few times a weeks) of gastrointestinal problems (28.29%, n = 1,015) and concentration disorders (29.15%, n = 1,046) was noted. Cramer's V values (<0.3) indicated a weak (but significant p < 0.05) relationship between the country of residence and most of the analyzed variables. In conclusion, DS users were characterized by a healthy lifestyle with appropriate behaviors but not healthy eating habits.

Association of Vitamin D Anabolism-Related Gene Polymorphisms and Susceptibility to Uterine Leiomyomas

Background: Uterine leiomyomas (ULs) is the most common gynecological benign tumor in women. Our previous study showed that the phenomenon of vitamin D deficiency existed in patients with ULs. However, the association of vitamin D anabolism-related gene polymorphisms and susceptibility to ULs was unclear.

Methods: Vitamin D anabolism-related gene polymorphisms in 110 patients with ULs and 110 healthy controls were detected by sequencing and the differences of the 92 SNPs were analyzed in the two groups via chi-square test. To verify the association between the significantly different SNPs and the risk of ULs, the SNPs were genotyped in another 340 patients and 340 healthy controls. Additionally, an unconditional logistic regression model was conducted to calculate the odds ratio (OR) of ULs occurrence and the 95% confidence interval (CI), adjusting for age and BMI.

Findings: In sequencing samples, there were differences in DHCR7 rs1044482 C > T (p = 0.008) and NADSYN1 rs2276360 G > C (p = 0.025) between patients with ULs and healthy controls. DHCR7 rs1044482 was related to the susceptibility to ULs in validation samples (heterogeneous: adjusted OR = 1.967, p = 0.002; homogenous: adjusted OR = 2.494, p = 0.002; additive: adjusted OR = 1.485, p < 0.041; and dominant: adjusted OR = 2.084, p < 0.001). Stratified analysis further showed that the DHCR7 rs1044482 polymorphisms were associated with ULs risks in women over 40 and with 18.5–25.0 BMI. In contrast to the wild-type CG haplotype vectors, individuals with TC haplotypes had a higher risk of developing ULs.

Interpretation: The vitamin D anabolism-related gene DHCR7 rs1044482 C > T polymorphism was a risk factor of ULs, especially in patients over 40 with 18.5–25.0 BMI, while the relationship between NADSYN1 rs2276360 and ULs risk was not clear.

Efficacy and Safety of Nutrient Supplements for Glycaemic Control and Insulin Resistance in Type 2 Diabetes: An Umbrella Review and Hierarchical Evidence Synthesis

Background: Nutrient supplements are widely used for type 2 diabetes (T2D), yet evidence-based guidance for clinicians is lacking. Methods: We searched the four electronic databases from November 2015−December 2021. The most recent, most comprehensive, high-ranked systematic reviews, meta-analyses, and/or umbrella reviews of randomised controlled trials in adults with T2D were included. Data were extracted on study characteristics, aggregate outcome measures per group (glycaemic control, measures of insulin sensitivity and secretion), adverse events, and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) assessments. Quality was assessed using A Measurement Tool to Assess Systematic Reviews Version 2.0 (AMSTAR 2). Results: Twelve meta-analyses and one umbrella review were included. There was very low certainty evidence that chromium, Vitamin C, and omega-3 polyunsaturated fatty acids (Ω-3 PUFAs) were superior to placebo for the primary outcome of glycated hemoglobin (HbA1c) (Mean Difference/MD −0.54, −0.54 and ES −0.27, respectively). Probiotics were superior to placebo for HbA1c (Weighted Mean Difference/WMD −0.43%). There was very low certainty evidence that Vitamin D was superior to placebo for lowering HbA1c in trials of <6 months (MD −0.17%). Magnesium, zinc, Vitamin C, probiotics, and polyphenols were superior to placebo for FBG. Vitamin D was superior to placebo for insulin resistance. Data on safety was limited. Conclusions: Future research should identify who may benefit from nutrient supplementation, safety, and optimal regimens and formulations.

Abnormal glucose tolerance in women with prior gestational diabetes mellitus: a 4-year follow-up study

BACKGROUND

Adoption of the International Association of Diabetes and Pregnancy Study Group (IADPSG) criteria for diagnosis of gestational diabetes mellitus (GDM) varies worldwide. Early detection of women at increased risk of developing type 2 diabetes mellitus (T2DM) following GDM enables initiation of measures to delay disease onset.

OBJECTIVES

To determine the 4-year cumulative incidence and risk factors for developing abnormal glucose tolerance (AGT) among women with previous GDM using modified IADPSG criteria. Additionally, to review post-natal attendance at diabetes screening and the impact of post-partum lifestyle modifications and breastfeeding on the risk of T2DM development.

METHODS

Four hundred twenty-six women with a prior history of GDM were invited to participate in the study, 4 years after the index pregnancy. The following were completed: body measurements, oral glucose tolerance test (OGTT), glycated haemoglobin (HbA1c), vitamin D, and other biochemistry measurements. Participants also completed a lifestyle questionnaire.

RESULTS

Of the 74 women who participated, 15 (20%) had AGT. Predictive factors for AGT development were as follows: fasting glucose levels (p = 0.004), HbA1c (p = 0.008) at GDM diagnosis, and early pregnancy BMI (p = 0.001). Thirty-three (45%) women had not attended their postnatal screening. The odds ratio of the association between breastfeeding and AGT development was 0.16 (95% CI: 0.05 to 0.53).

CONCLUSION

The proportion of women who develop AGT after a diagnosis of GDM remains high. The factors associated with progression to AGT are available at GDM diagnosis. Preventing AGT in this group is possible by supporting breastfeeding. Attendance at post-natal screening should also be encouraged.

Serum 25-hydroxyvitamin D might be negatively associated with hyperuricemia in U.S. adults: an analysis of the National Health and Nutrition Examination Survey 2007-2014

PURPOSE

The results of previous studies on the relationship between serum 25-hydroxyvitamin D [25(OH)D] and hyperuricemia are controversial. We hypothesized that serum 25(OH)D concentrations of U.S. adults would negatively correlate with the risk of hyperuricemia.

METHOD

Data came from the National Health and Nutrition Examination Survey 2007-2014 were used, after excluding those who met at least one of the exclusion criteria, a total of 9096 male individuals and 9500 female individuals aged 18 years or older were included. Binary logistic regression analysis and restricted cubic spline with fully adjusted confounding factors were applied to evaluate the association between serum 25(OH)D and hyperuricemia. We further performed stratified analysis and sensitivity analysis to minimize the influence of gender, metabolic syndrome, obesity and renal dysfunction on the above association.

RESULTS

We found a negative correlation between serum 25(OH)D and hyperuricemia. In the binary logistic regression analysis, compared with the highest serum 25(OH)D quartile [Q4: 25(OH)D > 77.10 nmol/L] group, the odds ratios (95% confidence intervals) in the lowest quartile [Q1: 25(OH)D ≤ 43.20 nmol/L] was 1.46 (1.22-1.75) in the fully adjusted model. Restricted cubic spline analysis showed L-shaped and non-linear relationships between 25(OH)D and hyperuricemia. In sensitivity analysis, after restricting to participants without significant renal dysfunction and obesity, the above association remained significant. After restricting to participants who were diagnosed as metabolic syndrome, above association remained significant in the fully adjusted model. In stratified analysis by gender, the association remained significant among males and females.

CONCLUSIONS

Serum 25(OH)D might be inversely associated with hyperuricemia in general U.S. adults. From our study, for people with unexplained hyperuricemia, screening for serum Vitamin D concentration might be necessary.

Association of Vitamin D Status and COVID-19-Related Hospitalization and Mortality

BACKGROUND

The relationship between vitamin D status and COVID-19-related clinical outcomes is controversial. Prior studies have been conducted in smaller, single-site, or homogeneous populations limiting adjustments for social determinants of health (race/ethnicity and poverty) common to both vitamin D deficiency and COVID-19 outcomes.

OBJECTIVE

To evaluate the dose-response relationship between continuous 25(OH)D and risk for COVID-19-related hospitalization and mortality after adjusting for covariates associated with both vitamin D deficiency and COVID-19 outcomes.

DESIGN

Retrospective cohort study.

PATIENTS

Veteran patients receiving care in US Department of Veteran Affairs (VA) health care facilities with a positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test and a blood 25(OH)D test between February 20, 2020, and November 8, 2020, followed for up to 60 days.

MAIN MEASURES

Exposure was blood 25(OH)D concentration ascertained closest to and within 15 to 90 days preceding an index positive SARS-CoV-2 test. Co-primary study outcomes were COVID-19-related inpatient hospitalization requiring airborne, droplet, contact, or other isolation and mortality ascertained within 60 days of an index positive SARS-CoV-2 test.

KEY RESULTS

Of 4,599 veterans with a positive SARS-CoV-2 test, vitamin D deficiency (< 20 ng/mL) was identified in 665 (14.5%); 964 (21.0%) were hospitalized; and 340 (7.4%) died. After adjusting for all covariates, including race/ethnicity and poverty, there was a significant independent inverse dose-response relationship between increasing continuous 25(OH)D concentrations (from 15 to 60 ng/mL) and decreasing probability of COVID-19-related hospitalization (from 24.1 to 18.7%, p=0.009) and mortality (from 10.4 to 5.7%, p=0.001). In modeling 25(OH)D as a log-transformed continuous variable, the greatest risk for hospitalization and death was observed at lower 25(OH)D concentrations.

CONCLUSIONS

Continuous blood 25(OH)D concentrations are independently associated with COVID-19-related hospitalization and mortality in an inverse dose-response relationship in this large racially and ethnically diverse cohort of VA patients. Randomized controlled trials are needed to evaluate the impact of vitamin D supplementation on COVID-19-related outcomes.

Exploring diet associations with Covid-19 and other diseases: a Network Analysis-based approach

The current global pandemic, Covid-19, is a severe threat to human health and existence especially when it is mutating very frequently. Being a novel disease, Covid-19 is impacting the patients with comorbidities and is predicted to have long-term consequences, even for those who have recovered from it. To clearly recognize its impact, it is important to comprehend the complex relationship between Covid-19 and other diseases. It is also being observed that people with good immune system are less susceptible to the disease. It is perceived that if a correlation between Covid-19, other diseases, and diet is realized, then caregivers would be able to enhance their further course of medical action and recommendations. Network Analysis is one such technique that can bring forth such complex interdependencies and associations. In this paper, a Network Analysis–based approach has been proposed for analyzing the interplay of diets/foods along with Covid-19 and other diseases. Relationships between Covid-19, diabetes mellitus type 2 (T2DM), non-alcoholic fatty liver disease (NAFLD), and diets have been curated, visualized, and further analyzed in this study so as to predict unknown associations. Network algorithms including Louvain graph algorithm (LA), K nearest neighbors (KNN), and Page rank algorithms (PR) have been employed for predicting a total of 60 disease-diet associations, out of which 46 have been found to be either significant in disease risk prevention/mitigation or in its progression as validated using PubMed literature. A precision of 76.7% has been achieved which is significant considering the involvement of a novel disease like Covid-19. The generated interdependencies can be further explored by medical professionals and caregivers in order to plan healthy eating patterns for Covid-19 patients. The proposed approach can also be utilized for finding beneficial diets for different combinations of comorbidities with Covid-19 as per the underlying health conditions of a patient.

The health effects of vitamin D supplementation: evidence from human studies

Vitamin D supplementation can prevent and cure nutritional rickets in infants and children. Preclinical and observational data suggest that the vitamin D endocrine system has a wide spectrum of skeletal and extra-skeletal activities. There is consensus that severe vitamin D deficiency (serum 25-hydroxyvitamin D (25OHD) concentration <30 nmol/l) should be corrected, whereas most guidelines recommend serum 25OHD concentrations of >50 nmol/l for optimal bone health in older adults. However, the causal link between vitamin D and many extra-skeletal outcomes remains unclear. The VITAL, ViDA and D2d randomized clinical trials (combined number of participants >30,000) indicated that vitamin D supplementation of vitamin D-replete adults (baseline serum 25OHD >50 nmol/l) does not prevent cancer, cardiovascular events, falls or progression to type 2 diabetes mellitus. Post hoc analysis has suggested some extra-skeletal benefits for individuals with vitamin D deficiency. Over 60 Mendelian randomization studies, designed to minimize bias from confounding, have evaluated the consequences of lifelong genetically lowered serum 25OHD concentrations on various outcomes and most studies have found null effects. Four Mendelian randomization studies found an increased risk of multiple sclerosis in individuals with genetically lowered serum 25OHD concentrations. In conclusion, supplementation of vitamin D-replete individuals does not provide demonstrable health benefits. This conclusion does not contradict older guidelines that severe vitamin D deficiency should be prevented or corrected.

Critical Appraisal of Large Vitamin D Randomized Controlled Trials

As a consequence of epidemiological studies showing significant associations of vitamin D deficiency with a variety of adverse extra-skeletal clinical outcomes including cardiovascular diseases, cancer, and mortality, large vitamin D randomized controlled trials (RCTs) have been designed and conducted over the last few years. The vast majority of these trials did not restrict their study populations to individuals with vitamin D deficiency, and some even allowed moderate vitamin D supplementation in the placebo groups. In these RCTs, there were no significant effects on the primary outcomes, including cancer, cardiovascular events, and mortality, but explorative outcome analyses and meta-analyses revealed indications for potential benefits such as reductions in cancer mortality or acute respiratory infections. Importantly, data from RCTs with relatively high doses of vitamin D supplementation did, by the vast majority, not show significant safety issues, except for trials in critically or severely ill patients or in those using very high intermittent vitamin D doses. The recent large vitamin D RCTs did not challenge the beneficial effects of vitamin D regarding rickets and osteomalacia, that therefore continue to provide the scientific basis for nutritional vitamin D guidelines and recommendations. There remains a great need to evaluate the effects of vitamin D treatment in populations with vitamin D deficiency or certain characteristics suggesting a high sensitivity to treatment. Outcomes and limitations of recently published large vitamin D RCTs must inform the design of future vitamin D or nutrition trials that should use more personalized approaches.

New Approaches to Assess Mechanisms of Action of Selective Vitamin D Analogues

Recent studies of transcription have revealed an advanced set of overarching principles that govern vitamin D action on a genome-wide scale. These tenets of vitamin D transcription have emerged as a result of the application of now well-established techniques of chromatin immunoprecipitation coupled to next-generation DNA sequencing that have now been linked directly to CRISPR-Cas9 genomic editing in culture cells and in mouse tissues in vivo. Accordingly, these techniques have established that the vitamin D hormone modulates sets of cell-type specific genes via an initial action that involves rapid binding of the VDR-ligand complex to multiple enhancer elements at open chromatin sites that drive the expression of individual genes. Importantly, a sequential set of downstream events follows this initial binding that results in rapid histone acetylation at these sites, the recruitment of additional histone modifiers across the gene locus, and in many cases, the appearance of H3K36me3 and RNA polymerase II across gene bodies. The measured recruitment of these factors and/or activities and their presence at specific regions in the gene locus correlate with the emerging presence of cognate transcripts, thereby highlighting sequential molecular events that occur during activation of most genes both in vitro and in vivo. These features provide a novel approach to the study of vitamin D analogs and their actions in vivo and suggest that they can be used for synthetic compound evaluation and to select for novel tissue- and gene-specific features. This may be particularly useful for ligand activation of nuclear receptors given the targeting of these factors directly to genetic sites in the nucleus.

Can vitamin D be considered an adiponectin secretagogue? A systematic review and meta-analysis

There is some evidence for ameliorating effect of vitamin D on glycemic and lipidemic status which are likely to be mediated through other molecules including adiponectin. However, the overall results have been controversial. This study was conducted to evaluate the effect of vitamin D supplementation on serum adiponectin concentration. MEDLINE, PubMed, Embase, Cochrane Library, and Google Scholar were searched and 402 studies were found in a preliminary search. After screening of titles and abstracts nine studies were selected. Pooled data showed no significant effect on adiponectin concentrations (mean difference (MD) 0.37, 95 % CI: -0.1 to 0.87). However, there was a significant effect in a subgroup of participants who had diabetes (MD: 0.03, 95 % CI: 0.00 to 0.05, p = 0.029). The treatment effect on adiponectin concentrations was significant in those trials that used supplementation on a daily basis (MD: 0.03, 95 % CI: 0.00 to 0.05, p = 0.028) and vitamin D plus calcium (MD: 0.04, 95 % CI: 0.01 to 0.07, p = 0.014). The meta-regression revealed a significant association between BMI and age of participants at baseline and the treatment effect (B, -0.144, 95 % CI: -0.276 to -0.011, p = 0.033 and B, -0.043, 95 % CI: -0.075 to -0.012, p = 0.006). The results of this meta-analysis study indicates that vitamin D may be considered an adiponectin secretagogue in subjects with diabetes and this effect may be potentiated if vitamin D intake is on daily basis and in combination with calcium but can be weakened by increasing BMI.

Efficacy of Dietary and Supplementation Interventions for Individuals with Type 2 Diabetes

The prevalence of Type 2 diabetes (T2D) is increasing, which creates a large economic burden. Diet is a critical factor in the treatment and management of T2D; however, there are a large number of dietary approaches and a general lack of consensus regarding the efficacy of each. Therefore, the purpose of this narrative review is twofold: (1) to critically evaluate the effects of various dietary strategies on diabetes management and treatment, such as Mediterranean diet, plant-based diet, low-calorie and very low-calorie diets, intermittent fasting, low-carbohydrate and very low-carbohydrate diets, and low glycemic diets and (2) to examine several purported supplements, such as protein, branched-chain amino acids, creatine, and vitamin D to improve glucose control and body composition. This review can serve as a resource for those wanting to evaluate the evidence supporting the various dietary strategies and supplements that may help manage T2D.

Vitamin D and Cardiovascular Disease: An Updated Narrative Review

During the last two decades, the potential impact of vitamin D on the risk of cardiovascular disease (CVD) has been rigorously studied. Data regarding the effect of vitamin D on CVD risk are puzzling: observational data indicate an inverse nonlinear association between vitamin D status and CVD events, with the highest CVD risk at severe vitamin D deficiency; however, preclinical data and randomized controlled trials (RCTs) show several beneficial effects of vitamin D on the surrogate parameters of vascular and cardiac function. By contrast, Mendelian randomization studies and large RCTs in the general population and in patients with chronic kidney disease, a high-risk group for CVD events, largely report no significant beneficial effect of vitamin D treatment on CVD events. In patients with rickets and osteomalacia, cardiovascular complications are infrequently reported, except for an increased risk of heart failure. In conclusion, there is no strong evidence for beneficial vitamin D effects on CVD risk, either in the general population or in high-risk groups. Whether some subgroups such as individuals with severe vitamin D deficiency or a combination of low vitamin D status with specific gene variants and/or certain nutrition/lifestyle factors would benefit from vitamin D (metabolite) administration, remains to be studied.

Prevalence of people at risk of developing type 2 diabetes mellitus and the involvement of community pharmacies in a national screening campaign: a pioneer action in Brazil

BACKGROUND

Brazil is one of top 10 countries with the highest number of people with diabetes mellitus (DM), affecting 16.8 million peoples. It is estimated that 7.7 million people (20-79 years) in the country have not yet been diagnosed, representing an under-diagnosis rate of 46.0%. Herein we aimed to screen people for high blood glucose or risk for developing type 2 DM (T2DM) through community pharmacies in Brazil.

METHODS

A cross-sectional study was carried out in November 2018, involving 977 pharmacists from 345 municipalities in Brazil. The study evaluated people between 20 and 79 years old without a previous diagnosis of DM. Glycemia was considered high when its value was ≥ 100 mg/dL fasting and ≥ 140 mg/dL in a casual feeding state. The FINDRISC (Finnish Diabetes Risk Score) was used to estimate the risk for developing T2DM. The prevalence of high blood glucose was estimated and the associated factors were obtained using Poisson's multivariate analysis with robust variance.

RESULTS

During the national screening campaign, 17,580 people were tested with the majority of the consultations (78.2%) being carried out in private pharmacies. The population was composed mainly of women (59.5%) and people aged between 20 and 45 years (47.9%). The frequency of participants with high blood glucose was 18.4% (95% CI 17.9-19.0). Considering the FINDRISC, 22.7% of people had a high or very high risk for T2DM. The risk factors associated with high blood glucose were: Body Mass Index > 25 kg/m2, abdominal circumference > 94 cm for men and > 80 cm for women; education level below 15 years of study, no daily intake of vegetables and fruits; previous diagnosis of arterial hypertension; history of high blood glucose and family history of DM.

CONCLUSIONS

This is the largest screening study that evaluated the frequency of high blood glucose and its associated factors in a population without a previous diagnosis ever performed in community pharmacies in Brazil. These results may help to improve public health policies and reinforce the role of pharmacists in screening and education actions aimed at this undiagnosed population in a continent-size country such as Brazil.