Hypovitaminosis D in type 2 diabetes: relation with features of the metabolic syndrome and glycemic control

Circulating 25-hydroxyvitamin D is associated with metabolic phenotypes of obesity: National Food and Nutrition Surveillance

Different phenotypes of obesity are each related with different complications and comorbidities. We hypothesized that suboptimal vitamin D status is directly associated with an unhealthy metabolic status, especially if allied with obesity. This cross-sectional study was performed in the framework of the National Food and Nutrition Surveillance. Overall, 1098 men and women participated in this study. In addition to height and weight, serum concentrations of 25-hydroxyvitamin D (25(OH)D) and glycemic and lipidemic status were evaluated. Then participants were classified into 4 groups based on body mass index and lipidemic and glycemic profile status, as follows: hyperglycemic-dyslipidemic obese (HDO), hyperglycemic-dyslipidemic nonobese (HDNO), normoglycemic-normolipidemic obese (NNO), and normoglycemic-normolipidemic nonobese (NNNO). In this study, 31.6% of participants were classified as HDO, 7.5% as HDNO, 34.5% as NNO, and 26.4% as NNNO. The frequency of suboptimal vitamin D status was more prevalent in HDO (81.8%) than in other phenotypes (HDNO, 80%; NNO, 77.6%; NNNO, 73.8%; P = .015). In the multivariate model, suboptimal vitamin D status significantly increased the odds of being NNO (odds ratio [OR], 1.28; 95% CI, 0.84-1.95), HDNO (OR, 1.48; 95% CI, 0.77-2.83), and HDO (OR, 1.73; 95% CI, 1.11-2.7) compared with the NNNO group. Likewise, in multivariate model, per each unit (ng/mL) increment in 25(OH)D concentration, the odds of HDNO and HDO decreased significantly by 4% (OR, 0.96; 95% CI, 0.94-0.98) and 7% (OR, 0.93; 95% CI, 0.92-0.95), respectively. The results of the study showed a significant relationship between serum 25(OH)D concentrations and metabolic obesity phenotypes; these data confirm the association between suboptimal vitamin D status and metabolic complications, especially in obese individuals.

Perspective: Nutritional Strategies Targeting the Gut Microbiome to Mitigate COVID-19 Outcomes

More than a year has passed since the first reported case of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection in the city of Wuhan in China's Hubei Province. Until now, few antiviral medications (e.g., remdesivir) or drugs that target inflammatory complications associated with SARS-CoV2 infection have been considered safe by public health authorities. By the end of November 2020, this crisis had led to >1 million deaths and revealed the high susceptibility of people with pre-existing comorbidities (e.g., obesity, diabetes, coronary heart disease, hypertension) to suffer from a severe form of the disease. Elderly people have also been found to be highly susceptible to SARS-CoV2 infection and morbidity. Gastrointestinal manifestations and gut microbial alterations observed in SARS-CoV2-infected hospitalized patients have raised awareness of the potential role of intestinal mechanisms in increasing the severity of the disease. It is therefore critically important to find alternative or complementary approaches, not only to prevent or treat the disease, but also to reduce its growing societal and economic burden. In this review, we explore potential nutritional strategies that implicate the use of polyphenols, probiotics, vitamin D, and ω-3 fatty acids with a focus on the gut microbiome, and that could lead to concrete recommendations that are easily applicable to both vulnerable people with pre-existing metabolic comorbidities and the elderly, but also to the general population.

Association of Serum 25-Hydroxyvitamin D Level With Metabolic Phenotypes of Obesity in Children and Adolescents: The CASPIAN-V Study

Background and Objective: Different metabolic phenotypes of obesity are related to cardiometabolic risk factors in children and adolescents. Vitamin D, as one important factor, could be related to different subgroups of metabolic obesity and might affect metabolic disorders. The purpose of this study was to evaluate the relationship between serum 25-hydroxyvitamin D concentration and subsets of metabolic phenotypes of obesity in children and adolescents. Methods: This nationwide cross-sectional study was conducted in the framework of the fifth survey of a national surveillance program, the CASPIAN study. Overall, 2,594 students aged 7-18 years were assessed for 25-hydroxyvitamin D status. Metabolic syndrome (MetS) was defined according to the ATP III criteria modified for the pediatric age group. Participants were classified into four metabolic phenotypes of obesity according to categories of the BMI and metabolic status: "metabolically healthy obese" (MHO), "metabolically non-healthy non-obese" (MNHNO), "metabolically non-healthy obese" (MNHO), and "metabolically healthy non-obese" (MHNO). Multinomial logistic regression analysis was performed for evaluating the association of 25-hydroxyvitamin D status with different metabolic phenotypes of obesity. Results: In this study, 85.2% of participants were classified as MHNO, 11.0 % as MHO, 2.5% as MNHNO, and 1.3% as MNHO. The frequency of hypovitaminosis D was more prevalent in MNHO (85.3%) than in other phenotypes (MHNO: 70%; MHO: 76.5%; MNHNO: 78.1%, respectively; p < 0.05). In the multivariate model, hypovitaminosis D significantly increased the odds of being MHO (OR: 1.46; 95% CI: 1.07-1.77) and MNHO (OR: 2.89; 1.05-8.31) compared to the healthy group. Likewise, in multivariate model, per each unit (ng/mL) increment in 25-hydroxyvitamin D concentration, the odds of MNHNO and MNHO decreased significantly by 7% (OR: 0.93; 0.91-0.96) and 6% (OR: 0.94; 0.91-0.98) respectively. Conclusion: Our results support the hypothesis that 25-hydroxyvitamin D concentration is associated with metabolic obesity phenotypes. Longitudinal studies are necessary to assess the clinical impacts of this finding.

Dietary Whole Egg Reduces Body Weight Gain in a Dose-Dependent Manner in Zucker Diabetic Fatty Rats

BACKGROUND

We previously reported that a whole-egg-based diet attenuated weight gain in rats with type 2 diabetes (T2D) and more effectively maintained vitamin D status than an equivalent amount of supplemental cholecalciferol.

OBJECTIVES

The objective of this study was to determine the lowest dose of whole egg effective at maintaining vitamin D homeostasis and attenuating the obese phenotype in T2D rats.

METHODS

Zucker diabetic fatty (ZDF) rats (n = 40; age 6 wk; prediabetic) and their lean controls (n = 40; age 6 wk) were randomly assigned to a diet containing 20% casein (CAS) or 20%, 10%, 5%, or 2.5% protein from whole egg (20% EGG, 10% EGG, 5% EGG, and 2.5% EGG, respectively). All diets contained 20% total protein (wt:wt). All rats received their respective diets for 8 wk, at a stage of growth and development that translates to adolescence in humans, until 14 wk of age, a point at which ZDF rats exhibit overt T2D. Weight gain was measured 5 d/wk, and circulating 25-hydroxyvitamin D [25(OH)D] was measured by ELISA. Mean values were compared by 2-factor ANOVA.

RESULTS

The 20% EGG diet maintained serum 25(OH)D at 30 nmol/L in ZDF rats, whereas the 10%, 5%, and 2.5% EGG diets did not prevent insufficiency, resulting in mean serum 25(OH)D concentrations of 24 nmol/L in ZDF rats. Body weight gain was reduced by 29% (P < 0.001) and 31% (P < 0.001) in ZDF rats consuming 20% and 10% EGG diets, respectively, and by 16% (P = 0.004) and 12% (P = 0.030) in ZDF rats consuming 5% and 2.5% EGG diets, respectively, compared with CAS.

CONCLUSIONS

Whole-egg-based diets exerted a dose-dependent response with respect to attenuating weight gain. These data could support dietary recommendations aimed at body weight management in individuals predisposed to obesity and T2D.

Interactions between vitamin D binding protein variants and major dietary patterns on the odds of metabolic syndrome and its components in apparently healthy adults

BACKGROUND

Recent studies have shown that the risks of chronic diseases resulting from high-risk alleles, such as cardiovascular diseases and metabolic syndrome (MetS), can be affected by various dietary patterns. Among the genes affected by environmental factors are those associated with vitamin D binding protein (DBP).

METHODS

This cross-sectional study was conducted on a random sample of 265 apparently healthy adults aged 18-50. MetS was defined according to the adult treatment panel III criteria. Major dietary patterns were determined using factor analysis on 24 food groups, using a valid and reliable 147-item food frequency questionnaire (FFQ). DBP genotypes were determined by polymerase chain reactions-restriction fragment length polymorphism (PCR-RFLP).

RESULTS

After adjustment for confounder factors, results demonstrated strong interactions between, on the one hand, a high intake of healthy pattern and DBP haplotype (rs7041/rs4588 major alleles) and on the other, low MetS odds (OR = 0.64, 95% CI 0.47-0.87, P ≤ 0.001), serum triglyceride levels (OR = 0.72, 95% CI 0.56-0.93, P = 0.01) and fasting blood glucose (OR = 0.36, 95% CI 0.14-0.96, P = 0.04). Also, individuals with a higher adherence to traditional dietary patterns demonstrated reduced odds of high waist circumference among the major allele (low-risk allele) carriers of rs7041/rs4588 (OR = 0.69, 95% CI 0.55-0.88, P = 0. 003). Interactions were also seen between high traditional pattern intake and DBP haplotype elevated blood pressure odds (OR = 1.31, 95% CI 1.02-1.68, P = 0.02).

CONCLUSIONS

The present evidence indicates that interactions between healthy dietary patterns with DBP haplotypes (Gc 1F, Gc 1S and Gc 2) and traditional dietary patterns with DBP haplotypes may be effective in reducing the odds of MetS and some of its components through consuming healthy food groups and inherited low risk alleles.

Body Mass Index, Vitamin D, and Type 2 Diabetes: A Systematic Review and Meta-Analysis

The deficiency of vitamin D is prevalent all over the world. Studies have shown that vitamin D may play an important role in the development of obesity. The current study was conducted to quantitatively evaluate the association between serum 25-(OH) vitamin D levels and the risk of obesity in both diabetic and non-diabetic subjects. A systematic review and meta-analysis of observational studies was carried out for that purpose. We searched the Medline, PubMed, and Embase databases throughout all of March 2018. A total of fifty five observational studies for both diabetic and non-diabetic subjects were finally included in the meta-analysis. The data were analyzed by comprehensive meta-analysis software version 3 and the random effects model was used to analyze the data. The meta-analysis showed an overall inverse relationship between serum vitamin D status and body mass index (BMI) in studies of both diabetic (r = −0.173, 95% = −0.241 to −0.103, p = 0.000) and non-diabetic (r = −0.152, 95% = −0.187 to −0.116, p = 0.000) subjects. The evidence of publication bias was not found in this meta-analysis. In conclusion, the deficiency of vitamin D is associated with an increased level of BMI in the studies of both diabetic and non-diabetic subjects. Reliable evidence from well-designed future randomized controlled trials is required to confirm the findings from observational studies and to find out the potential regulatory effects of vitamin D supplementation to lower BMI.

Dietary Whole Egg Consumption Attenuates Body Weight Gain and Is More Effective than Supplemental Cholecalciferol in Maintaining Vitamin D Balance in Type 2 Diabetic Rats

Background: Type 2 diabetes (T2D) is characterized by vitamin D insufficiency owing to excessive urinary loss of 25-hydroxycholecalciferol [25(OH)D]. We previously reported that a diet containing dried whole egg, a rich source of vitamin D, was effective at maintaining circulating 25(OH)D concentrations in rats with T2D. Furthermore, whole egg consumption reduced body weight gain in rats with T2D.Objective: This study was conducted to compare whole egg consumption with supplemental cholecalciferol with respect to vitamin D balance, weight gain, and body composition in rats with T2D.Methods: Male Zucker diabetic fatty (ZDF) rats (n = 24) and their lean controls (n = 24) were obtained at 5 wk of age and randomly assigned to 3 treatment groups: a casein-based diet (CAS), a dried whole egg-based diet (WE), or a casein-based diet containing supplemental cholecalciferol (CAS+D) at the same amount of cholecalciferol provided by WE (37.6 μg/kg diet). Rats were fed their respective diets for 8 wk. Weight gain and food intake were measured daily, circulating 25(OH)D concentrations were measured by ELISA, and body composition was analyzed by dual X-ray absorptiometry.Results: Weight gain and percentage of body fat were reduced by ∼20% and 11%, respectively, in ZDF rats fed WE compared with ZDF rats fed CAS or CAS+D. ZDF rats fed CAS had 21% lower serum 25(OH)D concentrations than lean rats fed CAS. In ZDF rats, WE consumption increased serum 25(OH)D concentrations 130% compared with CAS, whereas consumption of CAS+D increased serum 25(OH)D concentrations 35% compared with CAS.Conclusions: Our data suggest that dietary consumption of whole eggs is more effective than supplemental cholecalciferol in maintaining circulating 25(OH)D concentrations in rats with T2D. Moreover, whole egg consumption attenuated weight gain and reduced percentage of body fat in ZDF rats. These data may support new dietary recommendations targeting the prevention of vitamin D insufficiency in T2D.

Body Composition is Associated With Bone and Glucose Metabolism in Postmenopausal Women With Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is associated with increased fracture risk; the underlying mechanism remains unexplained. This study aimed to investigate the relationships between body composition and bone and glucose metabolism in postmenopausal women with T2DM. Dual-energy X-ray absorptiometry was used to measure bone mineral density (BMD) and body composition. A total of 68 postmenopausal women with T2DM and 71 controls were eligible for the study. In contrast to normal BMD in T2DM, a similar prevalence of low-trauma fractures was observed in both groups. T2DM women had significantly higher Trunk fat% and A/G ratio and significantly lower Legs LM% and Legs FM%. Legs LM% was significantly lower in fractured T2DM group and negatively correlated with glycaemia and HbA1c (p<0.01). Serum osteocalcin was significantly lower in T2DM and inversely correlated with FM%, Trunk FM% and A/G ratio (p<0.01) and positively correlated with Legs FM% and total LM% (p<0.05). In conclusion, abdominal obesity and decrease in muscle mass may contribute to low bone formation in T2DM women. Further research is needed to unravel underlying pathophysiological mechanisms and to determine whether maintenance of muscle mass, especially in the lower extremities and/or reduction of central fat mass can prevent fractures.

Vitamin D Status and Supplementation in the Critically Ill

Vitamin D deficiency has recently been recognized as a widespread global disorder. Generally considered a direct extension of malnutrition, even subclinical hypovitaminosis D is now recognized in adequately nourished populations. Compared to the general population, the prevalence of hypovitaminosis D is greater in the critically ill population. In fact, several studies have shown poorer outcomes in critically ill patients discovered to be vitamin D deficient or insufficient. Controversy persists regarding vitamin D measurements, quantity of supplementation, and appropriate target level in various populations. Vitamin D has a vital role in calcium homeostasis and extra-skeletal health, such as immune function. Therefore, vitamin D supplementation may have a role for improving outcomes in critically ill patients. In this review, we will first discuss the metabolism and function of vitamin D under normal physiologic conditions. We will then explore the prevalence and prognostic value of vitamin D deficiency in critical illness. Finally, we will examine recent trials focusing on appropriate dosing, route of administration, and outcomes associated with vitamin D supplementation in the ICU.

25-Hydroxyvitamin D and Parathyroid Hormone Levels Are Independently Associated with the Hemoglobin A1c Level of Korean Type 2 Diabetic Patients: The Dong-Gu Study

In type 2 diabetic patients, the relationships between 25-hydroxyvitamin D and parathyroid hormone levels, and glycemic control, remain unclear. We evaluated associations between 25-hydroxyvitamin D, parathyroid hormone, and hemoglobin A_1c levels after adjusting for other covariates, including log transformed 25-hydroxyvitamin D levels and log transformed parathyroid hormone levels, in Korean patients with type 2 diabetes. In total, 1,175 patients with type 2 diabetes were selected from 8,857 individuals who completed the baseline survey of the Dong-gu study, conducted in Korea from 2007 to 2010. After adjusting for other covariates, we found that the mean hemoglobin A_1c level was inversely associated with the 25-hydroxyvitamin D level (Q1: 7.47% [7.30–7.63], Q2: 7.25% [7.09–7.40], Q3: 7.17% [7.02–7.32], Q4: 7.19% [7.02–7.35]; p for trend = 0.021, p for between groups = 0.050) and the parathyroid hormone level (Q1: 7.35% [7.19–7.51], Q2: 7.34% [7.19–7.50], Q3: 7.28% [7.13–7.43], Q4: 7.09% [6.94–7.24]; p for trend = 0.022, p for between groups = 0.048). However, the mean fasting glucose level was not associated with either the 25-hydroxyvitamin D or parathyroid hormone level. In conclusion, inverse associations were evident between hemoglobin A_1c, 25-hydroxyvitamin D and parathyroid hormone levels in Korean patients with type 2 diabetes. The associations remained significant after adjusting for other covariates, including the log transformed 25-hydroxyvitamin D levels and log transformed parathyroid hormone levels.

High Prevalence of Hypovitaminosis D in Postmenopausal Women with Type 2 Diabetes Mellitus

The link between vitamin D and type 2 diabetes mellitus (T2DM) is intensively studied. This study aims to define the serum concentration of 25-hydroxyvitamin D (25-OH D) and to investigate the relationship between 25-OH D status, glycated hemoglobin (HbA1c) and body composition in postmenopausal women with T2DM and in non-diabetic controls. In this cross-sectional study, 75 women with T2DM and 32 control subjects were selected. Serum 25-OH D, intact parathyroid hormone (PTH), calcium, fasting glucose and HbA1c, were measured. The mean 25-OH D level was 21.4 ± 11.4 ng/ml (range 4.1–50.7 ng/ml) in diabetic women and 30.3 ± 9.4 ng/ml (range 10.8–54.2 ng/ml) in control group (p<0.001). The prevalence of hypovitaminosis D (< 30 ng/ml) was higher in vitamin D3 non-supplemented T2DM women (89% vs. 63% controls); the difference diminished in vitamin D3 (500–1000 IU per day) supplemented subgroups (45% diabetics vs. 42% controls). In T2DM women, 25-OH D levels were not associated to HbA1c, duration of diabetes, fasting glucose and PTH levels, however, 25-OH D levels negatively associated with body mass index (p=0.011), total body fat mass (p=0.005) and total body lean mass (p=0.004). The prevalence of hypovitaminosis D is higher in non-supplemented postmenopausal women with T2DM than in non-diabetic controls (89% vs. 63%). Obesity is a risk factor for vitamin D insufficiency in T2DM postmenopausal women. Further studies evaluating relationships between fat, muscle, bone and vitamin D metabolism in T2DM patients are warranted.

The Potential Protective Action of Vitamin D in Hepatic Insulin Resistance and Pancreatic Islet Dysfunction in Type 2 Diabetes Mellitus

Vitamin D deficiency (i.e., hypovitaminosis D) is associated with increased insulin resistance, impaired insulin secretion, and poorly controlled glucose homeostasis, and thus is correlated with the risk of metabolic diseases, including type 2 diabetes mellitus (T2DM). The liver plays key roles in glucose and lipid metabolism, and its dysregulation leads to abnormalities in hepatic glucose output and triglyceride accumulation. Meanwhile, the pancreatic islets are constituted in large part by insulin-secreting β cells. Consequently, islet dysfunction, such as occurs in T2DM, produces hyperglycemia. In this review, we provide a critical appraisal of the modulatory actions of vitamin D in hepatic insulin sensitivity and islet insulin secretion, and we discuss the potential roles of a local vitamin D signaling in regulating hepatic and pancreatic islet functions. This information provides a scientific basis for establishing the benefits of the maintenance, or dietary manipulation, of adequate vitamin D status in the prevention and management of obesity-induced T2DM and non-alcoholic fatty liver disease.