Adiposity is a confounding factor which largely explains the association of serum vitamin D concentrations with C-reactive protein, leptin and adiponectin

Association Between Low Blood 25-Hydroxyvitamin D and High C-Reactive Protein Levels in Community-Dwelling Japanese People Aged 40-74 Years

Low blood 25-hydroxyvitamin D (25[OH]D) levels at which C-reactive protein (CRP) levels begin to rise vary. This study investigated the association between blood 25(OH)D and elevated CRP levels and determine the cut-off of low 25(OH)D for elevated CRP in middle-aged and older individuals in the Murakami cohort, Japan. This study used a cross-sectional study design with 2,863 subjects aged 40-74 years living in the community. Plasma 25(OH)D levels were determined with the Liaison® 25OH Vitamin D Total Assay, and serum high sensitivity CRP (hs-CRP) levels were determined with a latex nephelometry assay using an automatic analyzer. Multivariate logistic regression analysis was used to calculate odds ratios (ORs) for high hs-CRP (≥ 3 mg/L) with covariates including sex, age, BMI, physical activity, smoking, drinking, and disease history. Median age of subjects was 65 years, and median 25(OH)D level was 47.4 nmol/L. The proportion of subjects with high hs-CRP levels was 4.1%. The adjusted OR of 25(OH)D < 20 nmol/L was higher (OR = 3.22, 95% CI: 1.42-7.31) than that of the reference (25[OH]D 40-49 nmol/L). In subgroup analysis, the adjusted OR of 25(OH)D < 20 nmol/L was significantly higher than the reference in the BMI ≥ 22.8 (median) group (OR = 4.52) but not in the BMI < 22.8 group (OR = 1.61) (P for interaction = 0.0892), and the adjusted OR was significantly higher in the age ≥ 65 group (OR = 8.51) but not in the age < 65 group (OR = 2.22). Low blood 25(OH)D and high CRP levels were associated, with 25(OH)D 20 nmol/L being the cut-off, which was lower than previously reported values.

Potential roles for vitamin D in preventing and treating impulse control disorders, behavioral addictions, and substance use disorders: A scoping review

Vitamin D deficiency is a problem of endemic proportions. Vitamin D is a major regulator of dopaminergic and serotonergic circuits, pathways implicated in addictive disorders. This scoping review (OSF registered as 67yhb) examines preclinical and clinical studies exploring relationships between vitamin D in impulse control disorders, behavioral addictions, and substance use disorders. We searched Ovid MEDLINE, Embase, APA PsycInfo, Cochrane Library, Web of Science, and Scopus databases. We extracted and summarized quantitative and qualitative data through a narrative synthesis and assessed the quality of studies using the Joanna Briggs Institute (JBI) and SYRCLE (Systematic Review Centre for Laboratory Animal Experimentation) criteria. Of 5,442 initial records identified, 28 preclinical and clinical studies were included. For most conditions, we found a negative relationship between vitamin D levels and symptom presence and/or severity. While data suggest a potential beneficial effect of vitamin D on preventing or treating these conditions, there were significant limitations identified by the JBI and SYRCLE assessments. Future studies should include impulse control disorders and other under-explored conditions, address heterogeneity regarding forms, doses, and duration of exposures to vitamin D, and explore vitamin D's potential therapeutic mechanisms.

Longitudinal associations between vitamin D status and biomarkers of inflammation in a pan-European cohort of children and adolescents

PURPOSE

To investigate longitudinal associations between the vitamin D status and inflammatory markers in children and adolescents.

METHODS

Children from eight European countries from the IDEFICS/I.Family cohort with repeated measurements were included in this study. A linear mixed-effect model was used to model the association of serum 25(OH)D as independent variable and z-scores of inflammatory markers [CRP, cytokines, adipokines, combined inflammation score] as dependent variables, where one level accounts for differences between individuals and the other for changes over age within individuals.

RESULTS

A total of 1,582 children were included in the study. In the adjusted model, 25(OH)D levels were positively associated with adiponectin (β = 0.11 [95% CI 0.07; 0.16]) and negatively with the inflammation score (β = - 0.24 [95% CI - 0.40; - 0.08]) indicating that the adiponectin z-score increased by 0.11 units and the inflammation score decreased by 0.24 units per 12.5 nmol/l increase in 25(OH)D. In children with overweight or obesity, only a positive association between 25(OH)D and IP-10 was observed while in children with normal weight adiponectin was positively and the inflammation score was negatively associated. Associations of vitamin D with adiponectin and the inflammation score were stronger in girls than in boys and a positive association with TNF-α was observed only in girls.

CONCLUSION

Our results suggest that an increase in vitamin D concentrations may help to regulate inflammatory biomarkers. However, it seems to be no benefit of a better vitamin D status in children with overweight/obesity unless their weight is managed to achieve an improved inflammatory marker status.

Associations Between Body Composition, Leptin, and Vitamin D Varied by the Body Fat Percentage in Adolescents

BACKGROUND

Serum leptin levels reflects one's degree of obesity and can affect vitamin D levels. The relationship between body fat, leptin, and 25-hydroxyvitamin D (25(OH)D) has not been extensively studied in adolescents. This study aimed to investigate the correlations between body composition and leptin and 25(OH)D levels in boys and girls.

METHODS

Participants aged 12-14 years (n = 205) were grouped according to sex. After body composition was recorded using bioelectrical impedance analysis, they were classified into three groups according to body fat percentage (%BF) (< 30, ≥ 30 and < 40, and ≥ 40). Serum leptin and 25(OH)D levels were measured using the enzyme-linked immunosorbent assay (ELISA). Correlations between all variables were analyzed according to sex and the percentage of BF groups.

RESULTS

Boys and girls with %BF ≥ 30 showed no difference in body mass index (BMI), %BF, and leptin and 25(OH)D, while other variables of body composition were more common in boys than in girls. The %BF, body fat mass (BFM), and 25(OH)D of both sexes with %BF ≥ 30, and leptin levels of boys with %BF ≥ 40 increased with an increase in %BF. A negative correlation between leptin and 25(OH)D levels was found in boys with %BF < 40 and girls with %BF < 30. In the %BF ≥ 30 and < 40 groups, there were negative correlations between leptin, BFM, free fat mass, and muscle mass (MM); between leptin, 25(OH)D, and height in boys; and between 25(OH)D, body weight, BMI, and MM in girls.

CONCLUSION

A negative correlation between leptin and 25(OH)D levels varied according to sex, while for body composition, it was evident at 30 and 40% BF.

The Role of Vitamin D in Adipose Tissue Biology: Adipocyte Differentiation, Energy Metabolism, and Inflammation

Adipose tissue is composed of diverse cell types and plays a major role in energy homeostasis and inflammation at the local and systemic levels. Adipose tissue serves as the main site for vitamin D storage and is among the most important extraskeletal targets of vitamin D which can modulate multiple aspects of adipose tissue biology. Vitamin D may exert inhibitory or stimulatory effects on adipocyte differentiation depending on cell type, stage of differentiation, and the treatment time point. Moreover, vitamin D controls energy metabolism in adipose tissue by affecting fatty acid oxidation, expression of uncoupling proteins, insulin resistance, and adipokine production. Adipose tissue inflammation can have a significant impact on the metabolic disorders often associated with obesity, and vitamin D can modulate the inflammatory response of immune cells and adipocytes within the adipose tissue. This review discusses the role of adipose tissue in vitamin D metabolism, as well as the regulatory role of vitamin D in adipocyte differentiation, adipose tissue energy metabolism, and inflammation, thereby providing insights into the importance of vitamin D in adipose tissue biology.

Vitamin D in obesity and obesity-related diseases: an overview

Hypovitaminosis D and obesity represent two pandemic conditions sometimes associated with each other. Although it is known that there is a close relationship between these two health problems, the underlying pathophysiological mechanism has not yet been fully clarified. In fact, on the one hand, obesity per se seems to involve low circulating levels of vitamin D due to low sun exposure, physical activity, and intake of foods rich in vitamin D, volumetric dilution and sequestration in the adipose tissue. Conversely, since preadipocytes and adipocytes express the receptors and are involved in the metabolism of vitamin D it would seem that low levels of this vitamin may be involved in adipogenesis and therefore in the development of obesity. This connection is extremely important when considering obesity-related diseases. In fact, low vitamin D levels and severe obesity are significantly associated with some cardio-metabolic risk factors, including high Body Mass Index, waist circumference, blood pressure, impaired lipid and glycemic profile and insulin resistance, as they would seem associated with worse cardiovascular outcomes and higher cancer incidence and mortality. Therefore, the purpose of this review was to examine the recent evidence linking low vitamin D status, obesity and obesity-related diseases, highlighting the scientific achievements and the gaps to be filled with further investigations.