Effectiveness of vitamin D therapy in improving metabolomic biomarkers in obesity phenotypes: Two randomized clinical trials

From metabolomics to energy balance physiology

Omics technologies are transforming our understanding of disease mechanisms and reshaping clinical practice. By enabling high-throughput, unbiased data collection at various molecular levels - including genes (genomics), mRNA (transcriptomics), proteins (proteomics), and metabolites (metabolomics) - omics approaches offer a comprehensive view of biological states in both health and disease. Among these, metabolomics has emerged as a pivotal tool, rapidly evolving beyond diagnostics to become a cutting-edge technique for pinpointing metabolites that regulate key physiological processes. This chapter reviews the advances in metabolomics, its integration with other omics approaches, and its applications, particularly emphasizing energy homeostasis. By incorporating metabolomic insights into physiology, we move closer to an integrative understanding of biological systems, laying the groundwork for novel therapies to combat obesity and related metabolic disorders.

Omics experiments in Iran, a review in endocrine and metabolism disorders studies

Objective

The aim of this study was to evaluate the status of scientific research output of omics in regards to human diseases with more attention shifted toward endocrine and metabolism disorders in Iran, in order to find scientific gaps and also to design future plans for further investigations in this field.

Methods

Extensive search was performed in the electronic databases of Scopus and PubMed, and documents published by Iranian authors up to 27 December 2020 were extracted. Articles related to human diseases were included and categorized based on their types and topics.

Results

A total of 904 publications were found. Followed by checking their titles and abstracts, 327 studies were included. The trend of publication has been increasing during the past years. Regarding this subject, the highest number of publications was in the field of malignant disorders with 82 publications followed by reproductive system diseases and infectious diseases with 33 publications in each subject. Only 12 articles were found in the field of endocrinology and metabolism. The most popular techniques used in those reports were two-dimensional electrophoresis coupled with mass spectrometry (34.4 %) followed by NMR (22.6 %), LC/MS/MS (15 %).

Conclusions

Omics studies in Iran are a relatively new approach and the number of original articles regarding endocrine disorders in humans is limited. Providing appropriate infrastructures including lab facilities with high technology instruments can improve the quality and quantity of basic and clinical researches in this field.

Poor vitamin D status was associated with increased appendicular fat deposition in US Adults: Data from 2011-2018 National Health and Nutrition Examination Survey

The aim of the study was to explore the relationship between serum 25-hydroxyvitamin D [25(OH)D] concentrations and regional body fat deposition in 2011-2018 National Health and Nutrition Examination Survey participants aged 18 to 59 years. We hypothesized that serum 25(OH)D concentrations were negatively associated with total, appendicular, and truncal fat deposition. Serum 25(OH)D concentration was categorized into sufficient (≥75.0 nM), insufficient (50.0-74.9 nM), and deficient (<50.0 nM) groups. Fat mass (FM) was measured by dual-energy X-ray absorptiometry, and FM index (FMI) was calculated by dividing FM (kg) with height2 (m2). Multivariant linear regression and Granger causal analysis were performed to assess the causal relationship between vitamin D status and regional FMIs. Overall serum 25(OH)D concentrations were negatively associated with total (β = -0.029, standard error [SE] = 0.002), trunk (β = -0.015, SE = 0.001), arms (β = -0.004, SE = 3.09 × 10-4), and legs (β = -0.010, SE = 0.001) FMIs in all participants (P < .001, respectively); however, after stratified by vitamin D status and BMI, the negative associations were only observed in individuals with vitamin D deficiency and obesity. The causal analysis indicated that serum 25(OH)D concentrations may causally reduce the arms (F = 4.917, probability [P] = 0.007), legs (F = 5.783, P = 0.003), and total (F = 3.202, P = 0.041) FMIs except for trunk FMI but not vice versa. In conclusion, poor vitamin D status was associated with increased total and appendicular body fat deposition in US adults, particularly in participants with obesity.

The link between obesity and insulin resistance among children: Effects of key metabolites

BACKGROUND

Childhood obesity became a severe public health challenge, and insulin resistance (IR) was one of the common complications. Both obesity and IR were considered as the basis of metabolic disorders. However, it is unclear which common key metabolites are associated with childhood obesity and IR.

METHODS

The children were divided into normal weight and overweight/obese groups. Fasting blood glucose and fasting insulin were measured, and homeostasis model assessment of insulin resistance was calculated. Liquid chromatography-tandem mass spectrometry was applied for metabonomic analysis. Multiple linear regression analysis and correlation analysis explored the relationships between obesity, IR, and metabolites. Random forests were used to rank the importance of differential metabolites, and relative operating characteristic curves were used for prediction.

RESULTS

A total of 88 normal-weight children and 171 obese/overweight children participated in the study. There was a significant difference between the two groups in 30 metabolites. Childhood obesity was significantly associated with 10 amino acid metabolites and 20 fatty acid metabolites. There were 12 metabolites significantly correlated with IR. The ranking of metabolites in random forest showed that glutamine, tyrosine, and alanine were important in amino acids, and pyruvic-ox-2, ethylmalonic-2, and phenyllactic-2 were important in fatty acids. The area under the curve of body mass index standard deviation  score (BMI-SDS) combined with key amino acid metabolites and fatty acid metabolites for predicting IR was 80.0% and 76.6%, respectively.

CONCLUSIONS

There are common key metabolites related to IR and obese children, and these key metabolites combined with BMI-SDS could effectively predict the risk of IR.

Influence of Vitamin D Status and Supplementation on Metabolomic Profiles of Older Adults

Metabolomics can identify metabolite patterns associated with different nutrition phenotypes and determine changes in metabolism in response to nutrition interventions. Vitamin D insufficiency is associated with increased metabolic disease risk; however, the role of vitamin D in metabolic health is not fully understood. This randomised, placebo-controlled trial (RCT) examined the influence of vitamin D status and the effect of vitamin D supplementation on metabolomic profiles in older adults. Healthy adults aged 50+ were randomly assigned to consume 20 µg vitamin D3 or a placebo daily for 4 weeks. Serum samples were collected at baseline and post-intervention for 25(OH)D and metabolomics analysis via liquid chromatography tandem mass spectrometry (LC-MS/MS). Pearson's correlation examined relationships between 25(OH)D and metabolite concentrations. GLM ANCOVA compared metabolite concentrations between vitamin D-insufficient (<50 nmol/L) and -sufficient (>50 nmol/L) participants. The repeated-measures general linear model of covariance (RM GLM ANCOVA) examined changes in metabolites over time. Out of 132 metabolites, 2 short chain fatty acid concentrations were higher in the insufficient participants compared to sufficient participants, and 11 glycerophospholipid concentrations were lower in insufficient participants compared to sufficient participants at baseline. Three acylcarnitine concentrations decreased with vitamin D supplementation in vitamin D-insufficient participants. Our findings suggest that vitamin D status influences lipid metabolism in healthy older adults and supports the use of metabolomics in vitamin D research.

Vitamin D is directly associated with favorable glycemic, lipid, and inflammatory profiles in individuals with at least one component of metabolic syndrome irrespective of total adiposity: Pró-Saúde Study, Brazil

Vitamin D insufficiency has been suggested as a risk factor for several metabolic disorders. The objective of the study was to investigate the association between serum 25 hydroxyvitamin D [25(OH)D] and metabolic health markers of Brazilian individuals with normal-weight, overweight or obesity. We hypothesized that serum 25(OH)D would be inversely associated with glycemic, lipid and inflammatory markers indicative of metabolic abnormality. Data of 511 individuals (33-79 years), recruited from a longitudinal investigation (Pró-Saúde Study), were analyzed cross-sectionally. Anthropometric, biochemical, body composition, socio-demographic and lifestyle data were collected. Based on body mass index (BMI; normal weight, overweight, obesity) and metabolic health (metabolically healthy (MH) and metabolically unhealthy (MU)) categories, the participants were classified into 6 phenotypes. Individuals having zero components of the metabolic syndrome were considered as "MH". MH obesity was frequent in 2.0% of the participants and 56.0% exhibited vitamin D insufficiency (<20 ng/mL). In the subgroups of the same BMI category, there were no significant differences in 25(OH)D concentrations between individuals classified as MH and MU. After adjustments (including %body fat and BMI), an inverse association was observed between 25(OH)D and visceral adipose tissue (B = -6.46, 95% confidence interval, CI: -12.87, -0.04), leptin (B = -0.09, 95% confidence interval, CI: -0.14, -0.03), insulin (B = -0.21, 95%CI: -0.34, -0.07), HOMA-IR (B = -0.06, 95%CI: -0.10, -0.02), triglycerides (B = -2.44, 95%CI: -3.66, -1.22), and TNF-α (B = -0.12, 95%CI: -0.24, -0.005) only in MU individuals. Our results indicate that the association of 25(OH)D concentrations with a favorable biochemical profile (glycemic, lipidic and inflammatory) seems to depend on the individual's overall metabolic health, suggesting more benefits from higher serum vitamin D in MU individuals, regardless of their adiposity.

Insulin Resistance in Obese Children: What Can Metabolomics and Adipokine Modelling Contribute?

The evolution of obesity and its resulting comorbidities differs depending upon the age of the subject. The dramatic rise in childhood obesity has resulted in specific needs in defining obesity-associated entities with this disease. Indeed, even the definition of obesity differs for pediatric patients from that employed in adults. Regardless of age, one of the earliest metabolic complications observed in obesity involves perturbations in glucose metabolism that can eventually lead to type 2 diabetes. In children, the incidence of type 2 diabetes is infrequent compared to that observed in adults, even with the same degree of obesity. In contrast, insulin resistance is reported to be frequently observed in children and adolescents with obesity. As this condition can be prerequisite to further metabolic complications, identification of biological markers as predictive risk factors would be of tremendous clinical utility. Analysis of obesity-induced modifications of the adipokine profile has been one classic approach in the identification of biomarkers. Recent studies emphasize the utility of metabolomics in the analysis of metabolic characteristics in children with obesity with or without insulin resistance. These studies have been performed with targeted or untargeted approaches, employing different methodologies. This review summarizes some of the advances in this field while emphasizing the importance of the different techniques employed.

Maternal Liver Metabolic Response to Chronic Vitamin D Deficiency Is Determined by Mouse Strain Genetic Background

BACKGROUND

Liver metabolite concentrations have the potential to be key biomarkers of systemic metabolic dysfunction and overall health. However, for most conditions we do not know the extent to which genetic differences regulate susceptibility to metabolic responses. This limits our ability to detect and diagnose effects in heterogeneous populations.

OBJECTIVES

Here, we investigated the extent to which naturally occurring genetic differences regulate maternal liver metabolic response to vitamin D deficiency (VDD), particularly during perinatal periods when such changes can adversely affect maternal and fetal health.

METHODS

We used a panel of 8 inbred Collaborative Cross (CC) mouse strains, each with a different genetic background (72 dams, 3-6/treatment group, per strain). We identified robust maternal liver metabolic responses to vitamin D depletion before and during gestation and lactation using a vitamin-D-deficient (VDD; 0 IU vitamin D3/kg) or -sufficient diet (1000 IU vitamin D3/kg). We then identified VDD-induced metabolite changes influenced by strain genetic background.

RESULTS

We detected a significant VDD effect by orthogonal partial least squares discriminant analysis (Q2 = 0.266, pQ2 = 0.002): primarily, altered concentrations of 78 metabolites involved in lipid, amino acid, and nucleotide metabolism (variable importance to projection score ≥1.5). Metabolites in unsaturated fatty acid and glycerophospholipid metabolism pathways were significantly enriched [False Discovery Rate (FDR) <0.05]. VDD also significantly altered concentrations of putative markers of uremic toxemia, acylglycerols, and dipeptides. The extent of the metabolic response to VDD was strongly dependent on genetic strain, ranging from robustly responsive to nonresponsive. Two strains (CC017/Unc and CC032/GeniUnc) were particularly sensitive to VDD; however, each strain altered different pathways.

CONCLUSIONS

These novel findings demonstrate that maternal VDD induces different liver metabolic effects in different genetic backgrounds. Strains with differing susceptibility and metabolic response to VDD represent unique tools to identify causal susceptibility factors and further elucidate the role of VDD-induced metabolic changes in maternal and/or fetal health for ultimately translating findings to human populations.