Mechanisms for the prevention of vitamin E excess

Lipid Peroxidation, Ferroptosis and Antioxidants

The discovery and conceptualization of ferroptosis as regulated, iron-catalyzed cell death driven by excessive lipid peroxidation triggered re-evaluation of lipid hydroperoxides in connection with health and disease. Free and ester forms of polyunsaturated fatty acids (PUFAs) are oxidized in vivo by multiple oxidizing species to produce lipid hydroperoxides as primary products, some purposely while others unintentionally. The detailed analysis of isomer distribution of lipid hydroperoxides enables us to identify the responsible oxidants. Linoleates, the most abundant PUFA in humans, are oxidized to give multiple isomers of hydroperoxyoctadecadienoates (H(p)ODEs) as primary major products, racemic trans, trans-9- and 13-H(p)ODEs, 13(S)-cis, trans-H(p)ODE, and 10- and 12-H(p)ODEs being specific biomarker for the oxidation by free radicals, lipoxygenase (LOX), and singlet oxygen, respectively. Cholesterol is another important lipid and its hydroperoxides are produced solely by non-enzymatic oxidation, the major products being cholesterol 7-hydroperoxide and 5-hydroperoxide by free radicals and singlet oxygen, respectively. The available data obtained from human samples show that lipid hydroperoxides are produced in vivo primarily by free radical mediated lipid peroxidation and that the contribution of LOXs s and singlet oxygen is small. Multiple antioxidants having different functions play their respective roles in the physiological defense network against detrimental lipid peroxidation and ferroptosis. The fact that lipid hydroperoxides are produced in vivo mainly by free radical mediated lipid peroxidation suggests that radical scavenging antioxidants act as essential ferroptosis inhibitors, which was substantiated by many studies. Considering the reactivity and physiological concentrations, it may be said that vitamins E and C play the primary roles as biological radical scavenging antioxidants against ferroptosis by synergistic interactions. Novel synthetic antioxidants with higher reactivity than natural antioxidants have been reported and their biological effects should be assessed. The factors that determine antioxidant effects in vivo are critically reviewed.

The use of vitamin E in ocular health: Bridging omics approaches with Tocopherol and Tocotrienol in the management of glaucoma

Vitamin E, encompassing tocopherols and tocotrienols is celebrated for its powerful antioxidant properties, which help neutralize free radicals and protect cells from oxidative damage. Over the years, research has shown that both tocopherols and tocotrienols offer significant benefits, including protection against radiation damage, cholesterol regulation, cardiovascular health, and neurological disorders. This wide range of benefits highlights the need for further exploration of vitamin E's role in managing various diseases. One particularly promising area is its potential application in treating ocular diseases like glaucoma. Despite advances in treatment, current options have limitations, making the investigation of alternative approaches crucial. Omics technologies, which allow for a detailed examination of biological systems, could provide valuable insights into how tocopherols and tocotrienols work at a molecular level. Their neuroprotective and antioxidative properties make them promising candidates for glaucoma management. Additionally, the sustainability of vitamin E is noteworthy, as by-products from its production can be repurposed into valuable resources for nutraceuticals and pharmaceuticals. As research continues, integrating omics technologies with the study of vitamin E derivatives could unveil new therapeutic possibilities, further enhancing our understanding of its diverse health benefits and its potential role in preventing and managing diseases.

Genetic Factors Contributing to Interindividual Variability of α-Tocopherol Levels in Subcutaneous Adipose Tissue among Healthy Adult Males

In humans, α-tocopherol (α-TOC) is mainly stored in adipose tissue, where it participates in preventing damages induced by inflammation and reactive oxygen species. Factors, including genetic ones, that explain adipose tissue α-TOC concentration remain poorly understood. This study, therefore, aimed to characterize the interindividual variability of adipose tissue α-TOC concentration in healthy individuals and to identify single nucleotide polymorphisms (SNPs) associated with it. The study used a randomized cross-over design with 42 healthy adult males. α-TOC concentration was measured in fasting plasma and periumbilical adipose tissue samples, both at fast and 8 h after consumption of three standard meals. Partial least squares (PLS) regression was performed to identify SNPs associated with the interindividual variability of adipose tissue α-TOC concentration. Adipose tissue α-TOC concentration was not associated with fasting plasma concentration (Pearson's r = 0.24, 95% CI: [-0.08, 0.51]). There was a high interindividual variability of adipose tissue α-TOC concentration (CV = 61%). A PLS regression model comprising 10 SNPs in five genes (PPARG, ABCA1, BUD13, CD36, and MGLL) explained 60% (adjusted R2) of the variability of this concentration. The interindividual variability of adipose tissue α-TOC concentration in humans is due, at least partly, to SNPs in genes involved in α-TOC and triglyceride metabolism.

Lower risk of low bone mineral density in high vitamin E level in older people: A cross-sectional study

INTRODUCTION

Osteoporosis and osteopenia, together known as low bone mineral density (LBMD), are common problems in the elderly. LBMD may cause fragility fractures in the elderly. The relationship between Vitamin E and LBMD in old Americans is still unclear. In this study, we investigated the relationship between serum Vitamin E levels and LBMD in the elderly.

METHODS

We utilized data from the National Health and Nutrition Examination Survey (NHANES) 2017-2018 and ultimately included 378 participants aged 50 to 79. Multivariable logistic or linear regression models were applied to examine the associations between serum Vitamin E levels and LBMD, total femur or lumbar spine BMD after adjusting for covariates.

RESULTS

After adjusting for all covariates, higher serum Vitamin E levels reduced the risk of LBMD (OR 0.76; 95% CI 0.58-1.00) and were positively associated with total femur BMD (β: 0.02; 95% CI: 0.01-0.03)， after adjusting for all covariates. In the subgroup analysis, for the BMI normal group (BMI<25), the serum Vitamin E levels were positively associated with the total femur (β: 0.03; 95% CI: 0.01-0.05) and lumbar spine BMD (β: 0.04; 95% CI: 0.01-0.07). In the BMI normal group, people with high serum Vitamin E levels have a lower incidence of LBMD (OR:0.43; 95% CI: 0.21-0.88). Though the P for interaction was larger than 0.05.

CONCLUSION

This study found serum Vitamin E levels were negatively associated with LBMD in older Americans. Serum Vitamin E levels were positively associated with femur BMD in older Americans.

Vitamin E and cardiovascular diseases: an interest to public health?

Cardiovascular diseases (CVD) are the leading cause of death worldwide. From this perspective, the role of vitamin E and its metabolites in preventing CVD has been studied, being supported by the findings that low vitamin E concentrations are associated with an increased risk of cardiovascular events. Despite this, no studies have analysed the co-existence of vitamin E deficiency (VED) and CVD on the basis of population studies. Facing that, this study summarises information on the relationship between vitamin E status and CVD, providing a basis for understanding the determining and protective factors for its development. VED may be a public health problem since it has been observed to vary from 0·6% to 55·5% worldwide, with higher percentages in Asia and Europe, where CVD mortality rates stand out. Intervention studies with α-tocopherol supplementation do not confirm cardioprotective action of vitamin E, which may reflect that α-tocopherol alone does not provide cardiovascular protection to individuals, but the consumption of all isomers found in food. Considering that low concentrations of α-tocopherol can lead to a higher susceptibility to diseases involving oxidative stress in the population, in addition to the high and growing prevalence of CVD and VED, it is essential to investigate or reinterpret the mechanisms of action of vitamin E and its metabolites in the cardiovascular process to better understand the co-existence of CVD and VED. It is also important to implement public health policies and programmes aimed at promoting the consumption of natural food sources of vitamin E and healthy fats.

Vitamin E - a scoping review for Nordic Nutrition Recommendations 2023

Current evidence suggests that dietary vitamin E (as α-tocopherol) intake has a beneficial role in preventing certain chronic diseases. In contrast, there is no clear evidence for the benefit of α-tocopherol supplements in a generally healthy population. Deficiency symptoms are rare and mainly occur due to genetic or other factors affecting α-tocopherol absorption and/or metabolism, rather than a low α-tocopherol intake. No qualified systematic review was identified by the NNR2023 project for updating the dietary reference values (DRV).

Strategies to Enhance the Solubility and Bioavailability of Tocotrienols Using Self-Emulsifying Drug Delivery System

Tocotrienols have higher medicinal value, with multiple sources of evidence showing their biological properties as antioxidant, anti-inflammatory, and osteoprotective compounds. However, tocotrienol bioavailability presents an ongoing challenge in its translation into viable products. This is because tocotrienol oil is known to be a poorly water-soluble compound, making it difficult to be absorbed into the body and resulting in less effectiveness. With the potential and benefits of tocotrienol, new strategies to increase the bioavailability and efficacy of poorly absorbed tocotrienol are required when administered orally. One of the proposed formulation techniques was self-emulsification, which has proven its capacity to improve oral drug delivery of poorly water-soluble drugs by advancing the solubility and bioavailability of these active compounds. This review discusses the updated evidence on the bioavailability of tocotrienols formulated with self-emulsifying drug delivery systems (SEDDSs) from in vivo and human studies. In short, SEDDSs formulation enhances the solubility and passive permeability of tocotrienol, thus improving its oral bioavailability and biological actions. This increases its medicinal and commercial value. Furthermore, the self-emulsifying formulation presents a useful dosage form that is absorbed in vivo independent of dietary fats with consistent and enhanced levels of tocotrienol isomers. Therefore, a lipid-based formulation technique can provide an additional detailed understanding of the oral bioavailability of tocotrienols.

Attenuation of sodium arsenite mediated ovarian DNA damage, follicular atresia, and oxidative injury by combined application of vitamin E and C in post pubertal Wistar rats

Arsenic being a toxic metalloid ubiquitously persists in environment and causes several health complications including female reproductive anomalies. Epidemiological studies documented birth anomalies due to arsenic exposure. Augmented reactive oxygen species (ROS) generation and quenched antioxidant pool are foremost consequences of arsenic threat. On the contrary, Vitamin E (VE) and C (VC) are persuasive antioxidants and conventionally used in toxicity management. Present study was designed to explore the extent of efficacy of combined VE and VC (VEC) against Sodium arsenite (NaAsO2) mediated ovarian damage. Thirty-six female Wistar rats were randomly divided into three groups (Grs) and treated for consecutive 30 days; Gr I (control) was vehicle fed, Gr II (treated) was gavaged with NaAsO2 (3 mg/kg/day), Gr III (supplement) was provided with VE (400 mg/kg/day) & VC (200 mg/kg/day) along with NaAsO2. Marked histological alterations were evidenced by disorganization in oocyte, granulosa cells and zona pellucida layers in treated group. Considerable reduction of different growing follicles along with increased atretic follicles was noted in treated group. Altered activities ofΔ5 3β-Hydroxysteroid dehydrogenase and 17β-Hydroxysteroid dehydrogenase accompanied by reduced luteinizing hormone, follicle-stimulating hormone and estradiol levels were observed in treated animals. Irregular estrous cyclicity pattern was also observed due to NaAsO2 threat. Surplus ROS production affected ovarian antioxidant strata as evidenced by altered oxidative stress markers. Provoked oxidative strain further affects DNA status of ovary. However, supplementation with VEC caused notable restoration from such disparaging effects of NaAsO2 toxicities. Antioxidant and antiapoptotic attributes of those vitamins might be liable for such restoration.

Vitamin E-induced coagulopathy in a young patient: a case report

BACKGROUND

High-dose vitamin E intake is known to inhibit vitamin K-derived coagulation factor synthesis, which can cause serious bleeding events such as gastrointestinal bleeding and intracranial hemorrhage. We report a case of coagulopathy induced by marginally increased levels of vitamin E.

CASE PRESENTATION

A 31-year-old Indian man presented with oral bleeding, black tarry stools, and bruising over his back. He had been taking non-steroidal anti-inflammatory drugs for low backache and vitamin E for hair loss. He had mild anemia with normal platelet count, thrombin time, and prolonged bleeding time, activated partial thromboplastin time, and prothrombin time. Serum fibrinogen was slightly raised. Mixing studies with pooled normal plasma, aged plasma, and adsorbed plasma were suggestive of deficiency of multiple coagulation factors due to acquired vitamin K deficiency. Serum phylloquinone was normal, while prothrombin induced by vitamin K absence-II level was increased. Serum alpha-tocopherol was slightly raised. Upper gastrointestinal endoscopy showed multiple gastroduodenal erosions. A final diagnosis of vitamin E toxicity-related coagulopathy was made. The patient responded well to pantoprazole, vitamin K supplementation, multiple fresh frozen plasma transfusions, and other supportive treatments besides the discontinuation of vitamin E supplementation. The coagulation parameters normalized, and the patient was discharged with complete resolution of symptoms and remained asymptomatic during the follow-up for 6 months.

CONCLUSIONS

Vitamin E-related inhibition of vitamin K-dependent factors with coagulopathy may occur even at marginally increased levels of serum vitamin E. This risk becomes significant in patients receiving other drugs that may increase the risk of bleeding.

Amelioration of mercuric chloride-induced physiologic and histopathologic alterations in rats using vitamin E and zinc chloride supplement

The drastic effects of mercuric chloride and the protective efficiency of vitamin E and zinc chloride co-supplementation were clearly investigated in this study. Male rats were divided into four groups. The first was the control. The second received vitamin E (100 mg/kg) and zinc chloride (30 mg/kg) daily. In comparison, the third received mercuric chloride (1 mg/kg) daily, and the fourth received the same mercuric chloride dose supplemented with the same vitamin E and zinc chloride doses. Mercury promotes a significant decline in body weight. It causes a considerable reduction in total red blood cells (RBCs) count and hemoglobin concentration; however, white blood cells (WBCs) increased significantly. Significant mercury-induced elevations in hepatic and renal functions were observed. Mercury induced substantial reductions in catalase (CAT) and superoxide dismutase (SOD). Mercury caused apoptotic DNA fragmentation. It induced degeneration and necrosis in the liver and kidney. It induced necrosis, leukocyte infiltration and blood vessel congestion in the cerebral cortex. Shrinkage and deterioration of Purkinje cells of the cerebellum were observed in response to mercuric chloride toxicity. Mercuric chloride enhanced shrinking in seminiferous tubules and Leydig cells. It reduced sperm count, sperm motility, and testosterone concentration; however, it promoted abnormal sperm morphology. Administration of vitamin E and zinc chloride showed marked improvement in different parameters under investigation, however, further research is needed to determine fate of mercury.

Vitamin E and Non-Communicable Diseases: A Review

Vitamin E, a nutrient found in several foods, comprises eight lipophilic vitamers, the α-, β-, γ- and δ-tocopherols and the α-, β-, γ- and δ-tocotrienols. This vitamin is capable of exerting antioxidant and anti-inflammatory activities, and acting as immunomodulators. Despite these well-known biological activities, the findings regarding the ability of vitamin E and its serum metabolites to prevent and/or control chronic disease are often conflicting and inconsistent. In this review, we have described the metabolism of vitamin E and its interaction with the gut microbiota, considering that these factors may be partially responsible for the divergent results obtained. In addition, we focused on the correlations between vitamin E serum levels, dietary intake and/or supplementation, and the main non-communicable diseases, including diabetes mellitus, asthma, cardiovascular diseases, and the four most common cancers (breast cancer, lung cancer, colorectal cancer, and prostate cancer) with the intention of providing an overview of its health effects in the non-communicable-diseases prevention.

Treatable Ataxias: How to Find the Needle in the Haystack?

Treatable ataxias are a group of ataxic disorders with specific treatments. These disorders include genetic and metabolic disorders, immune-mediated ataxic disorders, and ataxic disorders associated with infectious and parainfectious etiology, vascular causes, toxins and chemicals, and endocrinopathies. This review provides a comprehensive overview of different treatable ataxias. The major metabolic and genetic treatable ataxic disorders include ataxia with vitamin E deficiency, abetalipoproteinemia, cerebrotendinous xanthomatosis, Niemann-Pick disease type C, autosomal recessive cerebellar ataxia due to coenzyme Q10 deficiency, glucose transporter type 1 deficiency, and episodic ataxia type 2. The treatment of these disorders includes the replacement of deficient cofactors and vitamins, dietary modifications, and other specific treatments. Treatable ataxias with immune-mediated etiologies include gluten ataxia, anti-glutamic acid decarboxylase antibody-associated ataxia, steroid-responsive encephalopathy associated with autoimmune thyroiditis, Miller-Fisher syndrome, multiple sclerosis, and paraneoplastic cerebellar degeneration. Although dietary modification with a gluten-free diet is adequate in gluten ataxia, other autoimmune ataxias are managed by short-course steroids, plasma exchange, or immunomodulation. For autoimmune ataxias secondary to malignancy, treatment of tumor can reduce ataxic symptoms. Chronic alcohol consumption, antiepileptics, anticancer drugs, exposure to insecticides, heavy metals, and recreational drugs are potentially avoidable and treatable causes of ataxia. Infective and parainfectious causes of cerebellar ataxias include acute cerebellitis, postinfectious ataxia, Whipple's disease, meningoencephalitis, and progressive multifocal leukoencephalopathy. These disorders are treated with steroids and antibiotics. Recognizing treatable disorders is of paramount importance when dealing with ataxias given that early treatment can prevent permanent neurological sequelae.

Role of Vitamin E in Neonatal Neuroprotection: A Comprehensive Narrative Review

Vitamin E (Vit E) is an essential lipophilic antioxidant and anti-inflammatory agent that has potential as a neuroprotectant in newborn infants with brain injury. Vit E has shown promise in many in vitro studies, but success in translation to in vivo animal studies and the clinical setting has been mixed, with concern of adverse effects at high intravenous doses in preterm infants. However, a recent rise in knowledge of the beneficial effects of fat emulsions containing higher levels of Vit E, along with associated improved outcomes in some neonatal co-morbidities, has led many to reconsider Vit E administration as a potential therapeutic modality to improve neurological outcomes in the setting of neonatal brain injury. This narrative review discusses Vit E's structure, mechanism(s) of action, evidence in animal models, and association with health outcomes in neonates, including both dietary and supplemental Vit E and their bioavailability and pharmacokinetics as it relates to the brain. Lastly, long-term neurodevelopmental outcomes along with gaps in current knowledge are critiqued, which to date suggests that additional translational studies in larger animal models and assessment of safety profiles of different routes and doses of administration should be explored prior to large clinical trials. Importantly, a greater understanding of the brain region(s) and cell type(s) affected by Vit E may help to target the use of Vit E as a beneficial neuroprotective agent to specific populations or types of injury seen in newborns.

Revisiting the therapeutic potential of tocotrienol

The therapeutic potential of the tocotrienol group stems from its nutraceutical properties as a dietary supplement. It is largely considered to be safe when consumed at low doses for attenuating pathophysiology as shown by animal models, in vitro assays, and ongoing human trials. Medical researchers and the allied sciences have experimented with tocotrienols for many decades, but its therapeutic potential was limited to adjuvant or concurrent treatment regimens. Recent studies have focused on targeted drug delivery by enhancing the bioavailability through carriers, self-sustained emulsions, nanoparticles, and ethosomes. Epigenetic modulation and computer remodeling are other means that will help increase chemosensitivity. This review will focus on the systemic intracellular anti-cancer, antioxidant, and anti-inflammatory mechanisms that are stimulated and/or regulated by tocotrienols while highlighting its potent therapeutic properties in a diverse group of clinical diseases.

ESPEN micronutrient guideline

BACKGROUND

Trace elements and vitamins, named together micronutrients (MNs), are essential for human metabolism. Recent research has shown the importance of MNs in common pathologies, with significant deficiencies impacting the outcome.

OBJECTIVE

This guideline aims to provide information for daily clinical nutrition practice regarding assessment of MN status, monitoring, and prescription. It proposes a consensus terminology, since many words are used imprecisely, resulting in confusion. This is particularly true for the words "deficiency", "repletion", "complement", and "supplement".

METHODS

The expert group attempted to apply the 2015 standard operating procedures (SOP) for ESPEN which focuses on disease. However, this approach could not be applied due to the multiple diseases requiring clinical nutrition resulting in one text for each MN, rather than for diseases. An extensive search of the literature was conducted in the databases Medline, PubMed, Cochrane, Google Scholar, and CINAHL. The search focused on physiological data, historical evidence (published before PubMed release in 1996), and observational and/or randomized trials. For each MN, the main functions, optimal analytical methods, impact of inflammation, potential toxicity, and provision during enteral or parenteral nutrition were addressed. The SOP wording was applied for strength of recommendations.

RESULTS

There was a limited number of interventional trials, preventing meta-analysis and leading to a low level of evidence. The recommendations underwent a consensus process, which resulted in a percentage of agreement (%): strong consensus required of >90% of votes. Altogether the guideline proposes sets of recommendations for 26 MNs, resulting in 170 single recommendations. Critical MNs were identified with deficiencies being present in numerous acute and chronic diseases. Monitoring and management strategies are proposed.

CONCLUSION

This guideline should enable addressing suboptimal and deficient status of a bundle of MNs in at-risk diseases. In particular, it offers practical advice on MN provision and monitoring during nutritional support.

Cationic N,N-Dimethylglycine Ester Prodrug of 2R-α-Tocotrienol Promotes Intestinal Absorption via Efficient Self-Micellization with Intrinsic Bile Acid Anion

The intestinal absorption of hydrophobic compounds is severely influenced by their transportation rate through the unstirred water layer in the intestinal lumen. A member of the vitamin E family, α-Tocotrienol (α-T3) has remarkable pharmacological effects, but its intestinal absorption is hampered due to its hydrophobicity. Here, we prepared three ester derivatives of 2R-α-T3, and we selected a suitable prodrug compound using rat plasma and liver microsomes. The micellization profile of the selected compound in the presence of taurocholic acid (TCA) was evaluated. After gastrostomy administration of the prodrug candidate or α-T3 solution containing TCA, AUC values were determined for α-T3 in plasma obtained from bile duct-ligated rats. Among the three types in the efficiency of the reconversion to the parent drug, α-T3 N,N-dimethylglycinate (α-T3DMG) was the best prodrug; α-T3DMG formed mixed micelles via ion pairs with anionic TCA. The solubility of α-T3DMG in n-octanol/water depended on its ratio to TCA. The AUC after α-T3DMG administration to ligated rats was 2-fold higher than that after α-T3 administration, suggesting a smooth interaction with intrinsic bile acids. In conclusion, utilization of the prodrug synthesized using N,N-dimethylglycine ester may be a beneficial approach to promote intestinal absorption of α-T3 via self-micellization with intrinsic bile acid.

Are Vitamin E Supplementation Beneficial for Female Gynaecology Health and Diseases?

Vitamin E is known as an essential vitamin, and many studies had demonstrated the importance of vitamin E throughout the reproductive process, such as miscarriage, premature birth, preeclampsia, and intrauterine growth restriction, which could be caused by a lack of vitamin E during pregnancy. Its potent antioxidant properties can counteract the oxidative stress induced by oxygen free radicals and imbalance of oxidative-antioxidant levels, hence it may play a role in maintaining the normal function of the female reproductive system. Despite the fact that vitamin E is acknowledged as the substance needed for reproduction, its beneficial effects on female fertility, gynaecological health, and diseases are still poorly understood and lacking. Therefore, the goal of this paper is to provide a summary of the known roles of vitamin E supplementation in women for gynaecological health and reproductive-related diseases, as well as its future perspective.

Shared genomic architecture between COVID-19 severity and numerous clinical and physiologic parameters revealed by LD score regression analysis

The COVID-19 pandemic has produced broad clinical manifestations, from asymptomatic infection to hospitalization and death. Despite progress from genomic and clinical epidemiology research, risk factors for developing severe COVID-19 are incompletely understood and identification of modifiable risk factors is desperately needed. We conducted linkage disequilibrium score regression (LDSR) analysis to estimate cross-trait genetic correlation between COVID-19 severity and various polygenic phenotypes. To attenuate the genetic contribution of smoking and BMI, we further conducted sensitivity analyses by pruning genomic regions associated with smoking/BMI and repeating LDSR analyses. We identified robust positive associations between the genetic architecture of severe COVID-19 and both BMI and smoking. We observed strong positive genetic correlation (rg) with diabetes (rg = 0.25) and shortness of breath walking on level ground (rg = 0.28) and novel protective associations with vitamin E (rg = - 0.53), calcium (rg = - 0.33), retinol (rg = - 0.59), Apolipoprotein A (rg = - 0.13), and HDL (rg = - 0.17), but no association with vitamin D (rg = - 0.02). Removing genomic regions associated with smoking and BMI generally attenuated the associations, but the associations with nutrient biomarkers persisted. This study provides a comprehensive assessment of the shared genetic architecture of COVID-19 severity and numerous clinical/physiologic parameters. Associations with blood and plasma-derived traits identified biomarkers for Mendelian randomization studies to explore causality and nominates therapeutic targets for clinical evaluation.

The Biological Role of Vitamins in Athletes’ Muscle, Heart and Microbiota

Physical activity, combined with adequate nutrition, is considered a protective factor against cardiovascular disease, musculoskeletal disorders, and intestinal dysbiosis. Achieving optimal performance requires a significantly high energy expenditure, which must be correctly supplied to avoid the occurrence of diseases such as muscle injuries, oxidative stress, and heart pathologies, and a decrease in physical performance during competition. Moreover, in sports activities, the replenishment of water, vitamins, and minerals consumed during training is essential for safeguarding athletes’ health. In this scenario, vitamins play a pivotal role in numerous metabolic reactions and some muscle biochemical adaptation processes induced by sports activity. Vitamins are introduced to the diet because the human body is unable to produce these micronutrients. The aim of this review is to highlight the fundamental role of vitamin supplementation in physical activity. Above all, we focus on the roles of vitamins A, B6, D, E, and K in the prevention and treatment of cardiovascular disorders, muscle injuries, and regulation of the microbiome.

Vitamin E: How much is enough, too much and why!

α-Tocopherol (α-T) is a required dietary nutrient for humans and thus is a vitamin. This narrative review focuses on vitamin E structures, functions, biological determinants and its deficiency symptoms in humans. The mechanisms for the preferential α-T tissue enrichment in the human body include the α-T transfer protein (TTPA) and the preferential metabolism of non-α-T forms. Potential new α-T biomarkers, pharmacokinetic data, and whether there are better approaches to evaluate and set the α-T dietary requirement are discussed. Finally, the possible role of α-T supplements in delay of chronic diseases and the evaluation of vitamin E safety are considered.

A Review on Vitamin E Natural Analogues and on the Design of Synthetic Vitamin E Derivatives as Cytoprotective Agents

Vitamin E, essential for human health, is widely used worldwide for therapeutic or dietary reasons. The differences in the metabolism and excretion of the multiple vitamin E forms are presented in this review. The important steps that influence the kinetics of each form and the distribution and processing of vitamin E forms by the liver are considered. The antioxidant as well as non-antioxidant properties of vitamin E forms are discussed. Finally, synthetic tocopherol and trolox derivatives, based on the design of multitarget directed compounds, are reviewed. It is demonstrated that selected derivatization of vitamin E or trolox structures can produce improved antioxidants, agents against cancer, cardiovascular and neurodegenerative disorders.

Tocopherols and Tocotrienols-Bioactive Dietary Compounds; What Is Certain, What Is Doubt?

Tocopherols and tocotrienols are natural compounds of plant origin, available in the nature. They are supplied in various amounts in a diet, mainly from vegetable oils, some oilseeds, and nuts. The main forms in the diet are α- and γ-tocopherol, due to the highest content in food products. Nevertheless, α-tocopherol is the main form of vitamin E with the highest tissue concentration. The α- forms of both tocopherols and tocotrienols are considered as the most metabolically active. Currently, research results indicate also a greater antioxidant potential of tocotrienols than tocopherols. Moreover, the biological role of vitamin E metabolites have received increasing interest. The aim of this review is to update the knowledge of tocopherol and tocotrienol bioactivity, with a particular focus on their bioavailability, distribution, and metabolism determinants in humans. Almost one hundred years after the start of research on α-tocopherol, its biological properties are still under investigation. For several decades, researchers' interest in the biological importance of other forms of vitamin E has also been growing. Some of the functions, for instance the antioxidant functions of α- and γ-tocopherols, have been confirmed in humans, while others, such as the relationship with metabolic disorders, are still under investigation. Some studies, which analyzed the biological role and mechanisms of tocopherols and tocotrienols over the past few years described new and even unexpected cellular and molecular properties that will be the subject of future research.

From Congenital Disorders of Fat Malabsorption to Understanding Intra-Enterocyte Mechanisms Behind Chylomicron Assembly and Secretion

During the last two decades, a large body of information on the events responsible for intestinal fat digestion and absorption has been accumulated. In particular, many groups have extensively focused on the absorptive phase in order to highlight the critical "players" and the main mechanisms orchestrating the assembly and secretion of chylomicrons (CM) as essential vehicles of alimentary lipids. The major aim of this article is to review understanding derived from basic science and clinical conditions associated with impaired packaging and export of CM. We have particularly insisted on inborn metabolic pathways in humans as well as on genetically modified animal models (recapitulating pathological features). The ultimate goal of this approach is that "experiments of nature" and in vivo model strategy collectively allow gaining novel mechanistic insight and filling the gap between the underlying genetic defect and the apparent clinical phenotype. Thus, uncovering the cause of disease contributes not only to understanding normal physiologic pathway, but also to capturing disorder onset, progression, treatment and prognosis.

Vitamin E catabolism in women, as modulated by food and by fat, studied using 2 deuterium-labeled α-tocopherols in a 3-phase, nonrandomized crossover study

BACKGROUND

Human vitamin E (α-tocopherol) catabolism is a mechanism for regulating whole-body α-tocopherol.

OBJECTIVES

To determine the roles of the intestine and liver on α-tocopherol catabolism as affected by fat or fasting, 2 deuterium-labeled (intravenous d6- and oral d3-) forms of α-tocopherol were used.

METHODS

Healthy women received intravenous d6-α-tocopherol and consumed d3-α-tocopherol with a 600-kcal defined liquid meal (DLM; 40% or 0% fat, n = 10) followed by controlled meals; or the 0% fat DLM (n = 7) followed by a 12-h fast (0% fat-fast), then controlled meals ≤72 h. The order of the 3-phase crossover design was not randomized and there was no blinding. Samples were analyzed by LC/MS to determine the α-tocopherol catabolites and α-carboxyethyl hydroxychromanol (α-CEHC) in urine, feces, and plasma that were catabolized from administered oral d3- and intravenous d6-α-tocopherols.

RESULTS

Urinary and plasma d3- and d6-α-CEHC concentrations varied differently with the interventions. Mean ± SEM cumulative urinary d6-α-CEHC derived from the intravenous dose excreted over 72 h during the 40% fat (2.50 ± 0.37 μmol/g creatinine) and 0% fat (2.37 ± 0.37 μmol/g creatinine) interventions were similar, but a ∼50% decrease was observed during the 0% fat-fast (1.05 ± 0.39 μmol/g creatinine) intervention (compared with 0% fat, P = 0.0005). Cumulative urinary d3-α-CEHC excretion was not significantly changed by any intervention. Total urinary and fecal excretion of catabolites accounted for <5% of each of the administered doses.

CONCLUSIONS

Differential catabolism of the intravenous d6-α-tocopherol and oral d3-α-tocopherol doses shows both liver and intestine have roles in α-tocopherol catabolism. During the 40% fat intervention, >90% of urinary d3-α-CEHC excretion was estimated to be liver-derived, whereas during fasting <50% was from the liver with the remainder from the intestine, suggesting that there was increased intestinal α-tocopherol catabolism while d3-α-tocopherol was retained in the intestine in the absence of adequate fat/food for α-tocopherol absorption.This trial was registered at clinicaltrials.gov as NCT00862433.

A Genome-wide Association Study Discovers 46 Loci of the Human Metabolome in the Hispanic Community Health Study/Study of Latinos

Variation in levels of the human metabolome reflect changes in homeostasis, providing a window into health and disease. The genetic impact on circulating metabolites in Hispanics, a population with high cardiometabolic disease burden, is largely unknown. We conducted genome-wide association analyses on 640 circulating metabolites in 3,926 Hispanic Community Health Study/Study of Latinos participants. The estimated heritability for 640 metabolites ranged between 0%-54% with a median at 2.5%. We discovered 46 variant-metabolite pairs (p value < 1.2 × 10-10, minor allele frequency ≥ 1%, proportion of variance explained [PEV] mean = 3.4%, PEVrange = 1%-22%) with generalized effects in two population-based studies and confirmed 301 known locus-metabolite associations. Half of the identified variants with generalized effect were located in genes, including five nonsynonymous variants. We identified co-localization with the expression quantitative trait loci at 105 discovered and 151 known loci-metabolites sets. rs5855544, upstream of SLC51A, was associated with higher levels of three steroid sulfates and co-localized with expression levels of SLC51A in several tissues. Mendelian randomization (MR) analysis identified several metabolites associated with coronary heart disease (CHD) and type 2 diabetes. For example, two variants located in or near CYP4F2 (rs2108622 and rs79400241, respectively), involved in vitamin E metabolism, were associated with the levels of octadecanedioate and vitamin E metabolites (gamma-CEHC and gamma-CEHC glucuronide); MR analysis showed that genetically high levels of these metabolites were associated with lower odds of CHD. Our findings document the genetic architecture of circulating metabolites in an underrepresented Hispanic/Latino community, shedding light on disease etiology.

Engineering of a functional γ-tocopherol transfer protein

α-tocopherol transfer protein (TTP) was previously reported to self-aggregate into 24-meric spheres (α-TTP_S) and to possess transcytotic potency across mono-layers of human umbilical vein endothelial cells (HUVECs). In this work, we describe the characterisation of a functional TTP variant with its vitamer selectivity shifted towards γ-tocopherol. The shift was obtained by introducing an alanine to leucine substitution into the substrate-binding pocket at position 156 through site directed mutagenesis. We report here the X-ray crystal structure of the γ-tocopherol specific particle (γ-TTP_S) at 2.24 Å resolution. γ-TTP_S features full functionality compared to its α-tocopherol specific parent including self-aggregation potency and transcytotic activity in trans-well experiments using primary HUVEC cells. The impact of the A156L mutation on TTP function is quantified in vitro by measuring the affinity towards γ-tocopherol through micro-differential scanning calorimetry and by determining its ligand-transfer activity. Finally, cell culture experiments using adherently grown HUVEC cells indicate that the protomers of γ-TTP, in contrast to α-TTP, do not counteract cytokine-mediated inflammation at a transcriptional level. Our results suggest that the A156L substitution in TTP is fully functional and has the potential to pave the way for further experiments towards the understanding of α-tocopherol homeostasis in humans.

Protective effect of pristine C60 fullerene nanoparticle in combination with curcumin against hyperglycemia-induced kidney damage in diabetes caused by streptozotocin

The present study aims to examine the protective effects of C60 fullerene (C60), Curcumin (CUR; Curcuma longa), C60 + CUR combination against oxidative stress, apoptosis, and changes in cellular level in kidney tissue of diabetic rats. Treatment practices were administered separately to groups for 8 weeks following the approval of diabetes induction. It was observed that the treatment groups had increased antioxidant potential, decreased oxidative stress levels, decreased cholesterol, alpha tocopherol, retinol levels along with improved important changes in fatty acid metabolism compared with the diabetic group. C60, CUR, and C60 + CUR were also determined to act in the direction of reducing kidney damage by activating apoptotic pathways. It can be concluded based on these findings that C60, CUR, and especially C60 + CUR combination has beneficial properties in maintaining kidney tissue and function by effectively preventing oxidative stress, apoptotic changes, and changes at the cellular level in kidney tissue under hyperglycemia conditions. PRACTICAL APPLICATIONS: C60 and CUR have various biological activities which can be indicated as antioxidant, anti-inflammatory, anticancer, neuroprotective, and hepatoprotective. It has been reported that C60 and CUR protect the cells against oxidative injury brought about by reactive oxygen species (ROS). Data acquired from the present study puts forth that C60 and C60 + CUR may be promising agents to prevent damage induced by hyperglycemic conditions in kidney tissue.

Effects of Selenium and Vitamin E on Enzymatic, Biochemical, and Immunological Biomarkers in Galleria mellonella L

To understand the effects of micronutrients have particular biological functions that are involved mainly in the antioxidant system, which has essential implications for the development of diseases, this study investigated how vitamin E, selenium, and their combination affect lipid, protein, carbohydrate, and malondialdehyde (MDA) content; antioxidant enzyme (catalase [CAT], superoxide dismutase [SOD], glutathione-S-transferase [GST]) activity; and the total hemocyte count (THC) in larvae of Galleria mellonella L. fed different diets. Diet 1 (100 µg of selenium) significantly decreased carbohydrate and lipid content. Diets 2 (100 µg of vitamin E), 3 (100 µg of selenium and vitamin E each), and 5 (Tween 80) did not significantly affect protein and carbohydrate content. Diet 2 significantly increased the lipid content compared to diet 4 (control). Diet 1 increased CAT, SOD, and GST activity and MDA content (highest at 27.64 nmol/mg protein). Diet 2 significantly decreased SOD activity and MDA content compared to other diets. Diet 1 significantly decreased the THC compared to other diets. These results suggested that selenium changes oxidative stress parameters, energy reserves, and THC in G. mellonella. These changes could be a physiological adaptation against selenium-induced oxidative stress. Vitamin E could play a protective role in selenium toxicity.

Effects of dietary hemp seed oil to sows on fatty acid profiles, nutritional and immune status of piglets

Background

The oil from industrial hemp seeds (Cannabis sativa) is an ideal source of stearidonic acid, which is a precursor fatty acid for the long-chained n-3 polyunsaturated fatty acids. These fatty acids are important for neonatal development, health and immunity. Hemp seed oil has been investigated for the influence on human health, but research on the impact in pig nutrition is scarce. The aim of our research was to study the effect of dietary hemp seed oil relative to soybean oil to lactating sows on the transfer of fatty acids to the off-spring and the effect on piglets' immune and nutritional status.

Results

The fatty acid composition of the hemp seed and the soybean oil influenced the fatty acid composition of sow plasma, colostrum and mature milk. The highest proportion of C18:3n-3, C18:4n-3 and C20:4n-6 was obtained in mature milk fat of sows fed 5% hemp seed oil diet when compared to the other dietary fat sources (5% soybean oil or a 50:50 mix of hemp and soybean oil at 5%). The effect of dietary oil supplementation to sows was reflected in the plasma fatty acids profile of piglets. Notably the proportion of C20:5n-3 and C22:5n-3 was the highest in plasma of piglets suckling sows fed hemp seed oil-containing diets, whereas no C18:4n-3 could be detected hence indicating conversion of α-linolenic acid (ALA) and stearidonic acid (SDA) to the longer chained n-3 polyunsaturated fatty acids. Dietary fat source also influenced number of born piglets, their weight gain during first week, plasma concentration of glucose and IgG, and haematological profile.

Conclusions

The hemp seed oil resulted in direct maternal supply with n-3 long-chain polyunsaturated fatty acids (LCPUFA), especially ALA and SDA, and piglets were able to convert these fatty acids obtained via the sow milk intake to C20:5n-3 and C22:5n-3. Furthermore, some interesting effects of the 5% hemp seed oil was obtained with regard to piglet initial body weight gain and glucose, which could be of interest for further research, i.e., the capability of hemp seed oil to benefit piglets during early life.

Vitamin E absorption and kinetics in healthy women, as modulated by food and by fat, studied using 2 deuterium-labeled α-tocopherols in a 3-phase crossover design

BACKGROUND

Determining the human vitamin E [α-tocopherol (α-T)] requirement is difficult, and novel approaches to assess α-T absorption and trafficking are needed.

OBJECTIVE

We hypothesized that the dual-isotope technique, using 2 deuterium-labeled [intravenous (IV) d6- and oral d3-] α-T, would be effective in determining α-T fractional absorption. Further, defined liquid meal (DLM) fat or fasting would modulate α-T fractional absorption and lipoprotein transport.

METHODS

A 3-phase cr ossover design was used. At 0 h, participants received IV d6-α-T and consumed d3-α-T with a 600-kcal DLM (40% or 0% fat) followed by controlled meals or by the 0% fat DLM, a 12-h fast, and then controlled meals. Blood samples and fecal samples were collected at intervals and analyzed by LC-MS. Pharmacokinetic parameters were calculated from plasma tracer concentrations and enrichments. Fractional absorption was calculated from d3- to d6-α-T areas under the curve, from a novel mathematical model, and from the balance method (oral d3-α-T minus fecal d3-α-T excreted).

RESULTS

Estimated α-T fractional absorption during the 40% fat intervention was 55% ± 3% (mean ± SEM; n = 10), which was 9% less than during the 0% fat intervention (64% ± 3%, n = 10; P < 0.02). Fasting had no apparent effect (56% ± 3%, n = 7), except it slowed plasma oral d3-α-T appearance. Both balance data and model outcomes confirmed that the DLM fat did not potentiate d3-α-T absorption. During the IV emulsion clearance, HDL rapidly acquired d6-α-T (21 ± 2 nmol/L plasma per minute). During the first 8 h postdosing, triglyceride-rich lipoproteins (TRLs) were preferentially d3-α-T enriched relative to LDL or HDL, showing the TRL precursor role.

CONCLUSIONS

Quantitatively, α-T absorption is not limited by fat absence or by fasting. However, α-T leaves the intestine by a process that is prolonged during fasting and potentiated by eating, suggesting that α-T absorption is highly dependent on chylomicron assembly processes. This trial was registered at clinicaltrials.gov as NCT00862433.

Preconception serum lipids and lipophilic micronutrient levels are associated with live birth rates after IVF

RESEARCH QUESTION

Is a mixture of preconception serum lipids and lipophilic micronutrients associated with clinical pregnancy and live births?

DESIGN

In this prospective cohort study, blood serum was collected on the day of oocyte retrieval for 180 women undergoing IVF at an academic reproductive health centre. Concentrations of lipids (phospholipids, total cholesterol, high- and low-density lipoproteins, and triglycerides) and lipophilic micronutrients (α-, δ-, and γ-tocopherols, retinol, β- and α-carotenes, β-cryptoxanthin, lutein and lycopene) were determined using diagnostic reagent kits and high-performance liquid chromatography. Poisson regression was used with robust variance estimation to evaluate changes in Z-scores for the mixture of serum lipid and lipophilic micronutrient concentrations as predictors of embryo implantation, clinical pregnancy and live birth, adjusted for age, body mass index (BMI), race, smoking status, infertility diagnosis, ovarian stimulation protocol and other measured lipid and lipophilic micronutrient concentrations.

RESULTS

Each SD higher serum triglyceride concentration was associated with a lower chance of live birth (RR 0.54; 95% CI 0.33 to 0.90) whereas a 1 SD higher serum α-tocopherol concentration, as part of a mixture of serum lipids and lipophilic micronutrients, was associated with a higher likelihood for a live birth (RR 1.61; 95% CI 1.11 to 2.36). Serum β-carotene concentrations were associated with live birth in a non-linear fashion; low β-carotene was associated with a lower chance of live birth and high β-carotene with a higher chance of live birth.

CONCLUSION

Although components of a mixture of lipids and lipophilic micronutrients were associated with live birth outcomes after IVF, a larger investigation is necessary to fully evaluate the potential clinical implications.

Vitamin E: Regulatory role in the cardiovascular system

Cardiovascular disease (CVD) is one of the major causes of morbidity and mortality, all around the world. Vitamin E is an important nutrient influencing key cellular and molecular mechanisms as well as gene expression regulation centrally involved in the prevention of CVD. Cell culture and animal studies have focused on the identification of vitamin E regulated signaling pathways and involvement on inflammation, lipid homeostasis, and atherosclerotic plaque stability. While some of these vitamin E functions were verified in clinical trials, some of the positive effects were not translated into beneficial outcomes in epidemiological studies. In recent years, the physiological metabolites of vitamin E, including the liver derived (long- and short-chain) metabolites and phosphorylated (α-, γ-tocopheryl phosphate) forms, have also provided novel mechanistic insight into CVD regulation that expands beyond the vitamin E precursor. It is certain that this emerging insight into the molecular and cellular action of vitamin E will help to design further studies, either in animal models or clinical trials, on the reduction of risk for CVDs. This review focuses on vitamin E-mediated preventive cardiovascular effects and discusses novel insights into the biology and mechanism of action of vitamin E metabolites in CVD. © 2019 IUBMB Life, 71(4):507-515, 2019.

Stability of antioxidant vitamins in whole human blood during overnight storage at 4°C and frozen storage up to 6 months

To determine optimal conditions for blood collection during clinical trials, where sample handling logistics might preclude prompt separation of erythrocytes from plasma, healthy subjects (n=8, 6 M/2F) were recruited and non-fasting blood samples were collected into tubes containing different anticoagulants (ethylenediaminetetra-acetic acid (EDTA), Li-heparin or Na-heparin). We hypothesized that heparin, but not EDTA, would effectively protect plasma tocopherols, ascorbic acid, and vitamin E catabolites (α- and γ-CEHC) from oxidative damage. To test this hypothesis, one set of tubes was processed immediately and plasma samples were stored at -80°C, while the other set was stored at 4°C and processed the following morning (~30 hours) and analyzed, or the samples were analyzed after 6 months of storage. Plasma ascorbic acid, as measured using HPLC with electrochemical detection (LC-ECD) decreased by 75% with overnight storage using EDTA as an anticoagulant, but was unchanged when heparin was used. Neither time prior to processing, nor anticoagulant, had any significant effects upon plasma α- or γ-tocopherols or α- or γ-CEHC concentrations. α- and γ-tocopherol concentrations remained unchanged after 6 months of storage at -80°C, when measured using either LC-ECD or LC/mass spectrometry. Thus, refrigeration of whole blood at 4°C overnight does not change plasma α- or γ-tocopherol concentrations or their catabolites. Ascorbic acid is unstable in whole blood when EDTA is used as an anticoagulant, but when whole blood is collected with heparin, it can be stored overnight and subsequently processed.

The relationship between vitamin C status, the gut-liver axis, and metabolic syndrome

Metabolic syndrome (MetS) is a constellation of cardiometabolic risk factors, which together predict increased risk of more serious chronic diseases. We propose that one consequence of dietary overnutrition is increased abundance of Gram-negative bacteria in the gut that cause increased inflammation, impaired gut function, and endotoxemia that further dysregulate the already compromised antioxidant vitamin status in MetS. This discussion is timely because "healthy" individuals are no longer the societal norm and specialized dietary requirements are needed for the growing prevalence of MetS. Further, these lines of evidence provide the foundational basis for investigation that poor vitamin C status promotes endotoxemia, leading to metabolic dysfunction that impairs vitamin E trafficking through a mechanism involving the gut-liver axis. This report will establish a critical need for translational research aimed at validating therapeutic approaches to manage endotoxemia-an early, but inflammation-inducing phenomenon, which not only occurs in MetS, but is also prognostic of more advanced metabolic disorders including type 2 diabetes mellitus, as well as the increasing severity of nonalcoholic fatty liver diseases.

Identification and expression analysis of alpha tocopherol transfer protein in chickens fed diets containing different concentrations of alpha-tocopherol

Among the eight forms of vitamin E, the liver preferentially releases α-tocopherol into the circulation and it is distributed to the non-liver tissues. In the hepatocytes, alpha tocopherol transfer protein (TTPA) specifically recognizes α-tocopherol with 2R-configuration and facilitates its intracellular transfer. The identification and characterization of TTPA expression have not been demonstrated in avian species. Therefore, the objectives of this study were to identify avian TTPAs, to compare the sequence conservation, phylogenetic relationship, protein interactions, and disease associations of chicken TTPA with those of human and vertebrate TTPA, and to characterize the tissue expression of the TTPA gene in chickens fed diets supplemented with different amounts of α-tocopherol. Our results suggest that the chicken TTPA was highly conserved with the human and vertebrate TTPA, and consisted of a cellular retinaldehyde binding protein and TRIO guanine exchange factor (CRAL_TRIO) domain. Feeding diets supplemented with increasing amounts of α-tocopherol (25 IU/Kg, 50 IU/Kg, or 100 IU/Kg) to broiler chickens had no effects on growth performance compared with feeding basal diets containing no supplemental α-tocopherol. The expression of TTPA gene was detected high in the liver of chickens in response to dietary α-tocopherol concentrations, whereas its expression was very low or undetectable in the non-liver tissues. In conclusion, the chicken TTPA protein sequence is highly conserved with other avian and vertebrate TTPA protein sequences. The higher expression of TTPA gene in the chicken liver in response to dietary α-tocopherol concentrations may suggest its crucial role in transporting α-tocopherol in the chicken liver.

Vitamin E: Regulatory Role on Signal Transduction

Vitamin E modulates signal transduction pathways by several molecular mechanisms. As a hydrophobic molecule located mainly in membranes it contributes together with other lipids to the physical and structural characteristics such as membrane stability, curvature, fluidity, and the organization into microdomains (lipid rafts). By acting as the main lipid-soluble antioxidant, it protects other lipids such as mono- and poly-unsaturated fatty acids (MUFA and PUFA, respectively) against chemical reactions with reactive oxygen and nitrogen species (ROS and RNS, respectively) and prevents membrane destabilization and cellular dysfunction. In cells, vitamin E affects signaling in redox-dependent and redox-independent molecular mechanisms by influencing the activity of enzymes and receptors involved in modulating specific signal transduction and gene expression pathways. By protecting and preventing depletion of MUFA and PUFA it indirectly enables regulatory effects that are mediated by the numerous lipid mediators derived from these lipids. In recent years, some vitamin E metabolites have been observed to affect signal transduction and gene expression and their relevance for the regulatory function of vitamin E is beginning to be elucidated. In particular, the modulation of the CD36/FAT scavenger receptor/fatty acids transporter by vitamin E may influence many cellular signaling pathways relevant for lipid homeostasis, inflammation, survival/apoptosis, angiogenesis, tumorigenesis, neurodegeneration, and senescence. Thus, vitamin E has an important role in modulating signal transduction and gene expression pathways relevant for its uptake, distribution, metabolism, and molecular action that when impaired affect physiological and patho-physiological cellular functions relevant for the prevention of a number of diseases. © 2018 IUBMB Life, 71(4):456-478, 2019.

Association of Serum Alpha-Tocopherol and Retinol with the Extent of Coronary Lesions in Coronary Artery Disease

Background and aims: Fat-soluble vitamins play an important role in the pathogenesis of cardiovascular disease and progression of atherosclerosis. This study aimed at investigating the relationship of the serum levels of alpha-tocopherol and retinol with the extent of coronary lesions in patients with coronary artery disease. Methods. Patients with coronary artery disease (n=177) aged 30-74 years, who underwent their first coronary angiography, were enrolled. The extent of coronary lesions was assessed using the Friesinger index (FI). Accordingly, patients were grouped as follows: FI = 0-4 (n=90), FI = 5-9 (n=50), and FI = 10-15 (n=37). Serum levels of vitamins were ‬determined via high-performance liquid chromatography and serum biochemical analysis. Results. Assessment of FI-based groups revealed that 50.8% patients had a coronary artery lesion to a low extent (FI 0-4). Individuals in this group were younger and had lower glucose and serum alpha-tocopherol levels than the other groups (p < 0.05). Low levels of alpha-tocopherol were more frequent in the FI 0-4 group than that in the other groups (p=0.03). No difference was observed between the mean serum retinol levels among the FI-based groups (n=0.492), and the low frequency of retinol was consistent among the FI groups (n=0.348). Conclusions. The low level of alpha-tocopherol together with the presence of dyslipidemia is probably associated with the initial events in atherosclerosis. Increased alpha-tocopherol levels in patients with more extensive coronary artery lesions may have resulted from altered vitamin E metabolism with increased oxidative stress.

Vitamin E Metabolic Effects and Genetic Variants: A Challenge for Precision Nutrition in Obesity and Associated Disturbances

Vitamin E (VE) has a recognized leading role as a contributor to the protection of cell constituents from oxidative damage. However, evidence suggests that the health benefits of VE go far beyond that of an antioxidant acting in lipophilic environments. In humans, VE is channeled toward pathways dealing with lipoproteins and cholesterol, underlining its relevance in lipid handling and metabolism. In this context, both VE intake and status may be relevant in physiopathological conditions associated with disturbances in lipid metabolism or concomitant with oxidative stress, such as obesity. However, dietary reference values for VE in obese populations have not yet been defined, and VE supplementation trials show contradictory results. Therefore, a better understanding of the role of genetic variants in genes involved in VE metabolism may be crucial to exert dietary recommendations with a higher degree of precision. In particular, genetic variability should be taken into account in targets concerning VE bioavailability per se or concomitant with impaired lipoprotein transport. Genetic variants associated with impaired VE liver balance, and the handling/resolution of oxidative stress might also be relevant, but the core information that exists at present is insufficient to deliver precise recommendations.

Weight loss program is associated with decrease α-tocopherol status in obese adults

BACKGROUND & AIMS

Studies on changes in plasma α-tocopherol levels during body fat reduction in obese persons are not clear. The aim of the present study was to assess factors associated with α-tocopherol status in obese people and to examine changes in α-tocopherol status after a 6-week AntioxObesity weight loss program.

METHODS

The study was conducted in 60 overweight or obese adults, aged 18-54 years old. Food intake data were collected using the 3-day record method and a semi-quantitative food-frequency questionnaire. Anthropometric measurements included: height (H), body weight, waist circumference (WC) and hip circumference (HC), body composition: fat mass (FM) and fat-free mass (FFM), subcutaneous fat (SF) and visceral fat (VF). Lipid profile, α-tocopherol concentration, glutathione peroxidase (GPx) activity, total antioxidant capacity (TAC) in plasma and superoxide dismutase (SOD) activity in erythrocytes were determined.

RESULTS

Energy, fat, and carbohydrate intakes decreased significantly in all subjects (P < 0.001). Body weight, WC, body mass index (BMI), waist-to height ratio (WHtR), and FM, VF and SF decreased significantly during the 6 weeks in all subjects. Plasma α-tocopherol significantly decreased during the program (P = 0.006). No changes were observed for SOD activity, but GPx activity and TAC decreased significantly (P = 0.001; P = 0,023, respectively). Plasma α-tocopherol concentration after 6 weeks of the AntioxObesity program was strongly associated with baseline plasma α-tocopherol, changes in TC, VF and FM. Low α-tocopherol status (<20 μmol/L) was found in 78% of the women and 68% of the men, after 6 weeks of the AntioxObesity program. Men were characterized by a greater decrease in weight, BMI, WC, FM, VF, SF and TAC compared to women.

CONCLUSIONS

A 6-week weight loss program lowered α-tocopherol status in overweight and obese people. Low baseline α-tocopherol status and adiposity in obese adults negatively affected α-tocopherol status after 6 weeks weight loss program. These results, coupled with excessive weight and low α-tocopherol intake, led to the finding that there was an increased risk of oxidative stress diseases in adults on a reduced diet. Long-term dietary restriction program for obese patients should be monitored to avoid α-tocopherol deficiency, and take into account higher dietary α-tocopherol requirements for obese people.

Cellular Uptake and Bioavailability of Tocotrienol-Rich Fraction in SIRT1-Inhibited Human Diploid Fibroblasts

Tocotrienol-rich fraction (TRF) is palm vitamin E that consists of tocopherol and tocotrienol. TRF is involved in important cellular regulation including delaying cellular senescence. A key regulator of cellular senescence, Sirtuin 1 (SIRT1) is involved in lipid metabolism. Thus, SIRT1 may regulate vitamin E transportation and bioavailability at cellular level. This study aimed to determine the role of SIRT1 on cellular uptake and bioavailability of TRF in human diploid fibroblasts (HDFs). SIRT1 gene in young HDFs was silenced by small interference RNA (siRNA) while SIRT1 activity was inhibited by sirtinol. TRF treatment was given for 24 h before or after SIRT1 inhibition. Cellular concentration of TRF isomers was determined according to the time points of before and after TRF treatment at 0, 24, 48, 72 and 96 h. Our results showed that all tocotrienol isomers were significantly taken up by HDFs after 24 h of TRF treatment and decreased 24 h after TRF treatment was terminated but remained in the cell up to 72 h. The uptake of α-tocopherol, α-tocotrienol and β-tocotrienol was significantly higher in senescent cells as compared to young HDFs indicating higher requirement for vitamin E in senescent cells. Inhibition of SIRT1 gene increased the uptake of all tocotrienol isomers but not α-tocopherol. However, SIRT1 inhibition at protein level decreased tocotrienol concentration. In conclusion, SIRT1 may regulate the cellular uptake and bioavailability of tocotrienol isomers in human diploid fibroblast cells while a similar regulation was not shown for α-tocopherol.

Vitamin E Analogue Protects Red Blood Cells against Storage-Induced Oxidative Damage

Background

To investigate i) the effects of Trolox® or mannitol, which represent two different classes of antioxidants, on oxidative changes generated in manually isolated red blood cells (RBCs) from citrate-phosphate-dextrose (CPD) preserved whole blood, followed by up to 20 days refrigerated storage, and ii) whether Trolox supplemented to the blood bank-manufactured saline-adenine-glucose-mannitol (SAGM) preserved RBC units would offer better storage conditions compared with SAGM alone.

Methods

The percentage of hemolysis and extracellular activity of lactate dehydrogenase (LDH) was measured to assess RBC membrane integrity. Lipid peroxidation, reduced glutathione (GSH) levels and total antioxidant capacity (TAC) were quantified by thiobarbituric acid-reactive substances (TBARS), Ellman's reagent and 2, 2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS^.+) based assay, respectively.

Results

Trolox was little more effective than mannitol in protecting against progressive RBC hemolysis. Trolox (0.125-3.125 mmol/l) inhibited storage-induced leakage of LDH, lipid peroxidation, and to a lesser extent GSH depletion. Mannitol at these concentrations neither inhibited TBARS formation nor prevented GSH depletion. RBC units stored in SAGM-Trolox had significantly lower hemolysis, LDH leakage, and lipid peroxidation level compared to RBCs stored in SAGM.

Conclusion

There is evidence of the beneficial effects of supplementing RBC-additive solutions with membrane-interacting antioxidants such as vitamin E analogues.

Water-Soluble Vitamin E-Tocopheryl Phosphate

The hydrophobicity of vitamin E poses transport and metabolic challenges to regulate its bioavailability and to prevent its accumulation in lipid-rich tissues such as adipose tissue, brain, and liver. Water-soluble precursors of vitamin E (α-tocopherol, αT), such as its esters with acetate (αTA), succinate (αTS), or phosphate (αTP), have increased solubility in water and stability against reaction with free radicals, but they are rapidly converted during their uptake into the lipid-soluble vitamin E. Therefore, the bioavailability of these precursors as intact molecules is low; nevertheless, at least for αTS and αTP, the recent research has revealed unique regulatory effects on signal transduction and gene expression and the modulation of cellular events ranging from proliferation, survival/apoptosis, lipid uptake and metabolism, phagocytosis, long term potentiation, cell migration, telomere maintenance, and angiogenesis. Moreover, water-soluble derivatives of vitamin E including some based on αTP are increasingly used as components of nanocarriers for enhanced and targeted delivery of drugs and other molecules (vitamins, including αT and αTP itself, vitamin D3, carnosine, caffeine, docosahexaenoic acid (DHA), insulin) and cofactors such as coenzyme Q10. In this review, the chemical characteristics, transport, metabolic pathways, and molecular mechanisms of action of αTP in cells and tissues are summarized and put into perspective with its possible role in the prevention of a number of diseases.

Vitamin E (α- and γ-Tocopherol) Levels in the Community: Distribution, Clinical and Biochemical Correlates, and Association with Dietary Patterns

Little is known about the distribution and determinants of circulating vitamin E levels in a German population. In this cross-sectional study we assessed the distribution of both α- and γ-tocopherol levels, identified their clinical and biochemical correlates, and assessed their relationships with a priori and a posteriori derived dietary patterns. Plasma α- and γ-tocopherol concentrations were measured using high performance liquid chromatography (HPLC) with fluorescence detection in 641 individuals (mean-age: 61 years; 40.6% women). Correlates of both markers were determined using linear regression with backward selection. Using a validated food-frequency questionnaire (FFQ), an a priori defined vitamin E-rich dietary pattern was constructed, and three a posteriori derived dietary patterns were identified by principal component analysis. Each pattern was related to α- and γ-tocopherol levels using linear regression. Median concentrations of α- and γ-tocopherol were 31.54 μmol/L and 1.35 µmol/L, respectively. 57.6% of participants had α-tocopherol levels >30 µmol/L. Triglycerides, high density lipoprotein (HDL)- and low density lipoprotein (LDL)-cholesterol, and vitamin E supplementation were identified as correlates of vitamin E levels. After excluding supplement users, a dietary pattern rich in meat, bread, fats, potatoes, and sugar/confectionery was inversely related to α-tocopherol levels (β, −0.032, SE = 0.016; p = 0.047). Prospective studies are warranted to evaluate the actual impact of the reported findings in terms of nutrition and health outcomes.