Effects of dietary vitamins on obesity-related metabolic parameters

The importance of thiamine availability in the thermogenic competency of human adipocytes

Brown and beige adipocytes express uncoupling protein 1 (UCP1), which is located in the inner mitochondrial membrane and facilitates the dissipation of excess energy as heat. The activation of thermogenic adipocytes is a potential therapeutic target for treating type 2 diabetes mellitus, obesity, and related co-morbidities. Therefore, identifying novel approaches to stimulate the function of these adipocytes is crucial for advancing therapeutic strategies. Currently, there are limited amount of human adipocyte cell line models available to study the regulatory mechanisms of browning and key players in thermogenesis. The Simpson-Golabi-Behmel syndrome (SGBS) preadipocyte cell line has been proven as a valuable model to investigate human adipocyte biology. In this study, we investigated how excess thiamine (vitamin B1), and the inhibition of thiamine transporters affect the expression of thermogenic markers and functional parameters during adrenergic stimulation in SGBS adipocytes. We found that limiting thiamine availability by pharmacological inhibitors impeded the dibutyryl-cAMP (db-cAMP)-dependent induction of thiamine transporter 1 and 2 (encoded by SLC19A2 and SLC19A3), UCP1, PGC1a, and other browning markers, as well as proton leak respiration which is associated with UCP1-dependent heat generation. Contrarily, excess thiamine enhanced the db-cAMP-dependent induction of thiamine transporters, while UCP1, PGC1a, and other browning markers were upregulated. In addition, abundant amounts of thiamine increased the basal, unstimulated coupled and uncoupled respiration, and the expression of mitochondrial complex subunits. Our study highlights the critical role of excess thiamine in the thermogenic activation of SGBS adipocytes and its potential to enhance thermogenesis.

Functional roles of pantothenic acid, riboflavin, thiamine, and choline in adipocyte browning in chemically induced human brown adipocytes

Brown fat is a therapeutic target for the treatment of obesity-associated metabolic diseases. However, nutritional intervention strategies for increasing the mass and activity of human brown adipocytes have not yet been established. To identify vitamins required for brown adipogenesis and adipocyte browning, chemical compound-induced brown adipocytes (ciBAs) were converted from human dermal fibroblasts under serum-free and vitamin-free conditions. Choline was found to be essential for adipogenesis. Additional treatment with pantothenic acid (PA) provided choline-induced immature adipocytes with browning properties and metabolic maturation, including uncoupling protein 1 (UCP1) expression, lipolysis, and mitochondrial respiration. However, treatment with high PA concentrations attenuated these effects along with decreased glycolysis. Transcriptome analysis showed that a low PA concentration activated metabolic genes, including the futile creatine cycle-related thermogenic genes, which was reversed by a high PA concentration. Riboflavin treatment suppressed thermogenic gene expression and increased lipolysis, implying a metabolic pathway different from that of PA. Thiamine treatment slightly activated thermogenic genes along with decreased glycolysis. In summary, our results suggest that specific B vitamins and choline are uniquely involved in the regulation of adipocyte browning via cellular energy metabolism in a concentration-dependent manner.

Association of fat-to-muscle mass ratio with physical activity and dietary protein, carbohydrate, sodium, and fiber intake in a cross-sectional study

Higher fat-to-muscle mass ratio (FMR) is reported to be a risk factor for various diseases, including type 2 diabetes and cardiovascular diseases, and mortality. Although this association suggests that reducing FMR may help to prevent certain diseases and mortality, the relationship between FMR and lifestyle factors is unclear. Therefore, we performed a cross-sectional study with the aim to elucidate this relationship. This cross-sectional study included 1518 healthy Japanese adults aged 30 to 64 years. We measured FMR in the whole body, arms, legs, and trunk and assessed various lifestyle factors. Then, we performed forced entry multiple regression analyses for FMR with the following variables: sex, age, physical activity, dietary intake, sleep quality, cigarette smoking, stress levels, and body mass index. As a result, whole-body and regional FMRs were correlated with female sex (β = 0.71); age (β = 0.06); physical activity (β = - 0.07); dietary intake of protein (β = - 0.12), carbohydrate (β = 0.04), sodium (β = 0.13), and fiber (β = - 0.16); and body mass index (β = 0.70). The results suggest that in the Japanese middle-aged population, low FMR is associated with certain lifestyle factors, i.e. higher physical activity and a diet with higher protein and fiber and lower carbohydrate and sodium, independent of age, sex, and body mass index.

The Effect of Micronutrients on Obese Phenotype of Adult Mice Is Dependent on the Experimental Environment

The environment of the test laboratory affects the reproducibility of treatment effects on physiological phenotypes of rodents and may be attributed to the plasticity of the epigenome due to nutrient-gene-environment interactions. Here, we explored the reproducibility of adding a multi-vitamin-mineral (MVM) mix to a nutrient-balanced high-fat (HF) diet on obesity, insulin resistance (IR), and gene expression in the tissues of adult male mice. Experiments of the same design were conducted in three independent animal facilities. Adult C57BL/6J male mice were fed an HF diet for 6 weeks (diet induced-obesity model) and then continued for 9-12 weeks on the HF diet with or without 5-fold additions of vitamins A, B1, B6, B12, Zn, and 2-fold Se. The addition of the MVM affected body weight, fat mass, gene expression, and markers of IR in all three locations (p < 0.05). However, the direction of the main effects was influenced by the interaction with the experimental location and its associated environmental conditions known to affect the epigenome. In conclusion, MVM supplementation influenced phenotypes and expression of genes related to adipose function in obese adult male mice, but the experimental location and its associated conditions were significant interacting factors. Preclinical studies investigating the relationship between diet and metabolic outcomes should acknowledge the plasticity of the epigenome and implement measures to reproduce studies in different locations.

The Potential Effects of Dietary Antioxidants in Obesity: A Comprehensive Review of the Literature

Obesity has become a global health concern, with its prevalence steadily increasing in recent decades. It is associated with numerous health complications, including cardiovascular diseases, diabetes, and certain types of cancer. The aetiology of obesity is multifactorial, involving genetic, environmental, and lifestyle factors. In recent years, oxidative stress has emerged as a potential contributor to obesity and its related metabolic disorders. Dietary antioxidants, which can counteract oxidative stress, have gained significant attention for their potential role in preventing and managing obesity. This comprehensive review aims to explore the impact of dietary antioxidants on obesity and its associated metabolic dysregulations, discussing the underlying mechanisms and highlighting the potential therapeutic implications.

Plasma Carotenoids and Polyphenols and Their Association with MetS: The Need for Nutritional Interventions

Metabolic syndrome (MetS) is characterized by increased pro-oxidative stress and a chronic inflammation state and their consequent alterations. Several studies have highlighted the protective effect of carotenoids and polyphenols in MetS patients. This study aimed to evaluate the plasma level of selected carotenoids and polyphenols and to determine their relationship with MetS severity, MetS components, and inflammatory markers in Polish adults with metabolic disorders. It was designed as a cross-sectional study. The final study group comprised 275 adults, including 158 women and 117 men. Data were collected on the frequency of consumption of selected food groups. Anthropometric measurements and blood samples were taken to determine the concentration of carotenoids, polyphenols, and indicators (parameters) of metabolic disorders. Plasma concentrations of selected carotenoids and polyphenols were low in adults with MetS. The highest concentrations of carotenoids and polyphenols in the blood were observed for lutein and phenolic acids (including gallic and p-coumaric acids). Nevertheless, a correlation was found between the individual bioactive compounds and MetS components. In terms of the lipid profile, our study showed that the plasma of the selected carotenoids and polyphenols positively correlated with HDL cholesterol (zeaxanthin; total carotenoids), LDL cholesterol (chlorogenic acid), triglycerides (lycopene), and the total cholesterol (kaempferol). We found that the level of CRP as a marker of inflammation negatively correlated with the concentration of zeaxanthin. In our study group, no relationship was found between the dietary antioxidant intensity and the variables studied, which may be attributed to the low frequency of consumption of the sources of bioactive compounds, such as carotenoids and polyphenols, but also to the metabolic disorders. Further research is needed to determine whether these associations are causally related to the metabolic syndrome or are a result of the pathologies of the syndrome or improper diet with a low intake of vegetables and fruit.

The Influence of Antioxidants on Oxidative Stress-Induced Vascular Aging in Obesity

Obesity is a worldwide trend that is growing in incidence very fast. Adipose tissue dysfunction caused by obesity is associated with the generation of oxidative stress. Obesity-induced oxidative stress and inflammation play a key role in the pathogenesis of vascular diseases. Vascular aging is one of the main pathogenesis mechanisms. The aim of this study is to review the effect of antioxidants on vascular aging caused by oxidative stress in obesity. In order to achieve this aim, this paper is designed to review obesity-caused adipose tissue remodeling, vascular aging generated by high levels of oxidative stress, and the effects of antioxidants on obesity, redox balance, and vascular aging. It seems that vascular diseases in obese individuals are complex networks of pathological mechanisms. In order to develop a proper therapeutic tool, first, there is a need for a better understanding of interactions between obesity, oxidative stress, and aging. Based on these interactions, this review suggests different lines of strategies that include change in lifestyle to prevent and control obesity, strategies for adipose tissue remodelling, oxidant-antioxidant balance, inflammation suppression, and strategies against vascular aging. Some antioxidants support different lines of these strategies, making them appropriate for complex conditions such as oxidative stress-induced vascular diseases in obese individuals.