Association of variant vitamin statuses and tuberculosis development: a systematic review and meta-analysis.

BACKGROUND: Several studies have suggested an association between vitamin deficiency and the development of tuberculosis; however, the precise impact remains unclear. This study aimed to elucidate the relationship between distinct vitamin statuses and the occurrence of tuberculosis. MATERIALS AND METHODS: Retrieval was conducted using several databases without language restrictions to capture the eligible studies on tuberculosis and vitamin status. Pooled odds ratios (ORs), relative risks (RRs), and hazard ratios (HRs) were used with 95% confidence intervals (CIs) to clarify the relationship between the different vitamin statuses (A, B, D, and E) and the occurrence of tuberculosis. Subgroup analysis, sensitivity analysis, meta-regression analysis, and Galbraith plot were performed to determine sources of heterogeneity. Potential publication biases were detected using Begg's test, Egger's test, and the trim-and-fill test. RESULTS: We identified 10,266 original records from our database searches, and 69 eligible studies were considered in this study. The random-effect model showed that people with tuberculosis may exhibit vitamin A deficiency (OR = 10.66, 95%CI: 2.61-43.63, p = .001), while limited cohort studies showed that vitamin A supplementation may reduce tuberculosis occurrence. Additionally, vitamin D deficiency was identified as a risk factor for tuberculosis development (RR = 1.69, 95%CI: 1.06-2.67, p = .026), and people with tuberculosis generally had lower vitamin D levels (OR = 2.19, 95%CI: 1.76-2.73, p < .001) compared to other groups. No publication bias was detected. CONCLUSIONS: This meta-analysis indicated that people with tuberculosis exhibited low levels of vitamins A and D, while vitamin D deficiency was identified as a risk factor for tuberculosis. More randomized controlled interventions at the community levels should be recommended to determine the association between specific vitamin supplementation and tuberculosis onset.

Micronutrient deficiencies in inflammatory bowel disease: an incidence analysis.

BACKGROUND: Micronutrient deficiencies associated with malnutrition in patients with inflammatory bowel disease (IBD) can lead to complications including anemia, coagulopathy, poor wound healing, and colorectal cancer. This study aimed to investigate micronutrient deficiencies (copper, vitamins A, B 9 , E, and K) in IBD patients and highlight associated symptoms to aid in the recognition of micronutrient deficiencies. METHODS: A retrospective electronic chart review was performed on adults diagnosed with Crohn's disease or ulcerative colitis hospitalized at a tertiary care center for IBD flare between January 2013 and June 2017. Patients with serum or whole blood micronutrient levels were included. Pregnant and incarcerated patients were excluded. RESULTS: A total of 611 IBD patients (440 Crohn's disease, 171 ulcerative colitis) met the inclusion criteria. Micronutrients were assessed in a subset of IBD patients (copper: 12.3%, A: 10.1%, B 9  : 95.9%, E: 10.3%, and K: 4.6%). Overall, 10.1% of patients had micronutrient deficiencies. The proportion of patients with copper, A, B 9 , E, and K deficiencies were 25.4, 53.3, 1.9, 23.7, and 29.4% for Crohn's disease and 50, 52.9, 1.2, 43.8, and 18.2% for ulcerative colitis, respectively. The most common symptoms or historical features associated with micronutrient deficiency were anemia (copper, B 9 ), muscle weakness (copper, E) thrombocytopenia, fatigue (copper, B 9 ), diarrhea (B 9 ), dry skin, hyperkeratosis, pruritus, significant weight loss, elevated C-reactive protein (A), bleeding, and osteoporosis (K). CONCLUSION: Micronutrient deficiencies are common in IBD patients, yet they are not routinely assessed. Copper, vitamins A, E, and K deficiencies are particularly underrecognized. Associated historical features should raise suspicion and prompt assessment and treatment.

Current insights into equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy.

Equine neuroaxonal dystrophy/equine degenerative myeloencephalopathy (eNAD/EDM) is an inherited neurodegenerative disease associated with vitamin E deficiency in the first year of life. It is the second most common cause of spinal ataxia in horses euthanized for neurologic disease. Equine NAD/EDM is characterized by neurologic signs including a symmetric proprioceptive ataxia (> grade 2/5) and a wide-base stance at rest. There are currently no antemortem tests for eNAD/EDM in any breed. Conclusive diagnosis requires postmortem histologic evaluation of the brainstem and spinal cord at necropsy. Research studies on antemortem biomarkers and genetic testing are ongoing. The development of a genetic test for eNAD/EDM would have widespread impact, even if it were breed specific. Currently, the best approach to eNAD/EDM is to focus on preventing cases by providing pregnant mares and foals with access to pasture. Alternatively, dams' diets can be supplemented with high doses of water-soluble RRR-α-tocopherol during the last trimester of gestation, with continued supplementation of foals through the first two years of life. It is important to measure horses' baseline serum vitamin E levels prior to supplementing. While considered generally safe, oversupplementation of vitamin E is possible and can lead to coagulopathies.

Vitamin E nomenclature. Is RRR-α-tocopherol the only vitamin E?

It has generally been accepted that vitamin E refers to a group of tocochromanols, α-, ß-, γ-, and δ-tocopherols and the corresponding four tocotrienols. Recently, Azzi and colleagues proposed to restrict the term vitamin E only to RRR-α-tocopherol, not to other tocopherols and tocotrienols (Azzi A et al. Free Radic Biol Med. 2023; 207:178-180. doi: 10.1016/j.freeradbiomed.2023.06.029). The aim of this paper is to express our opinion on the nomenclature of vitamin E based on available scientific data. In our opinion, it would be inappropriate to exclude all the tocochromanols other than RRR-α-tocopherol from the vitamin E group at this stage when the molecular mechanisms showing how vitamin E deficiency causes diseases such as ataxia and how vitamin E prevents/reverses such diseases are not elucidated. Understanding of whole functions of tocochromanols including underlying mechanisms and dynamics is essential before revision of currently accepted definition of vitamin E. The potential roles of γ-tocopherol and tocotrienols are discussed despite whether they are vitamin function should be clarified in the future studies.

Equine neuroaxonal dystrophy/degenerative myeloencephalopathy in Gypsy Vanner horses.

BACKGROUND: Equine neuroaxonal dystrophy/degenerative myeloencephalopathy (eNAD/EDM) is a neurodegenerative disease that primarily affects young, genetically predisposed horses that are deficient in vitamin E. Equine NAD/EDM has not previously been documented in Gypsy Vanner horses (GVs). OBJECTIVES: To evaluate: (1) the clinical phenotype, blood vitamin E concentrations before and after supplementation and pedigree in a cohort of GV horses with a high prevalence of neurologic disease suspicious for eNAD/EDM and (2) to confirm eNAD/EDM in GVs through postmortem evaluation. ANIMALS: Twenty-six GVs from 1 farm in California and 2 cases from the Midwestern U.S. METHODS: Prospective observational study on Californian horses; all 26 GVs underwent neurologic examination. Pre-supplementation blood vitamin E concentration was assessed in 17- GVs. Twenty-three were supplemented orally with 10 IU/kg of liquid RRR-alpha-tocopherol once daily for 28 days. Vitamin E concentration was measured in 23 GVs after supplementation, of which 15 (65%) had pre-supplementation measurements. Two clinically affected GVs from California and the 2 Midwestern cases had necropsy confirmation of eNAD/EDM. RESULTS: Pre-supplementation blood vitamin E concentration was ≤2.0 µg/mL in 16/17 (94%) of GVs from California. Post-supplementation concentration varied, with a median of 3.39 µg/mL (range, 1.23-13.87 µg/mL), but only 12/23 (52%) were normal (≥3.0 µg/mL). Normalization of vitamin E was significantly associated with increasing age (P = .02). Euthanized horses (n = 4) had eNAD/EDM confirmed at necropsy. CONCLUSIONS AND CLINICAL IMPORTANCE: GVs could have a genetic predisposition to eNAD/EDM. Vitamin E supplementation should be considered and monitored in young GVs.

Vitamin E: Not only a single stereoisomer.

The recent publication by Azzi and colleagues puts forth the argument that only RRR-α-tocopherol should be considered as vitamin E from a physiological point of view. They base their argument primarily on the assertion that only this form has been used to treat stark vitamin E deficiency in humans (known as AVED, or Ataxia with Vitamin E Deficiency). Azzi et al. also argue that other chemically similar molecules, such as tocopherols other than α-tocopherol and tocotrienols do not provide vitamin E activity. Azzi and colleagues are correct on this second point. An investigation into the biological activities of vitamin E, and the mechanisms behind these activities, confirms that physiological vitamin E activity is limited to certain α-tocopherol forms. However, it is also clear that these activities are not restricted only to the RRR-form but include other 2R-forms as well. Indeed, the α-tocopherol transfer protein (α-TTP), which is critical to mediate vitamin E trafficking and biological activity, and genetic defects of which lead to vitamin E deficiency, binds well to all 2R-forms of α-tocopherol. Furthermore, both RRR-α-tocopherol and the other 2R-forms are maintained in human plasma and distributed to tissues and organs, whereas the 2S-stereoisomers are excreted quickly. As such, in recent years the definition of vitamin E including both 2R- and RRR-α-tocopherol has gained both broad scientific and regulatory acceptance. Consistent with this understanding, we provide evidence that AVED has indeed been treated successfully with forms in addition to RRR-α-tocopherol, again arguing against the restriction of the definition to RRR-α-tocopherol only. Finally, we provide evidence against any safety concerns utilizing the currently accepted definition of vitamin E.

Atypical retinopathy in ataxia with vitamin E deficiency: report of a sibship.

Typical retinitis pigmentosa (RP) may not be the only retinal phenotype encountered in ataxia with vitamin E deficiency (AVED). The following short case series describes a novel form of retinopathy in AVED. We describe two patients with AVED belonging to the same consanguineous sibship. Both presented an unusual retinopathy consisting of scattered, multifocal, nummular, hyperautofluorescent atrophic retinal patches. The retinopathy remained stable under vitamin E supplementation. We hypothesize these changes to be the result of arrested AVED-related RP following early supplementation with α-tocopherol acetate.

Genetic heterogeneity within a consanguineous family involving TTPA and SETX genes.

Autosomal recessive cerebellar ataxias (ARCA) constitute a highly heterogeneous group of progressive neurodegenerative disorders that typically occur prior to adulthood. Despite some clinical resemblance between these disorders, different genes are involved. We report in this study four Tunisian patients belonging to the same large consanguineous family, sharing autosomal recessive cerebellar ataxia phenotypes but with clinical, biological, electrophysiological, and radiological differences leading to the diagnosis of two distinct ARCA caused by two distinct gene defects. Two of our patients presented ataxia with the vitamin E deficiency (AVED) phenotype, and the other two presented ataxia with oculo-motor apraxia 2 (AOA2). Genetic testing confirmed the clinical diagnosis by the detection of a frameshift c.744delA pathogenic variant in the TTPA gene, which is the most frequent in Tunisia, and a new variant c.1075dupT in the SETX gene. In Tunisia, data suggest that genetic disorders are common. The combined effects of the founder effect and inbreeding, added to genetic drift, may increase the frequency of detrimental rare disorders. The genetic heterogeneity observed in this family highlights the difficulty of genetic counseling in an inbred population. The examination and genetic testing of all affected patients, not just the index patient, is essential to not miss a treatable ataxia such as AVED, as in the case of this family.

The low prevalence rate of vitamin E deficiency in urban adults of Wuhan from central China: findings from a single-center, cross-sectional study.

BACKGROUND: Vitamin E is an essential nutrient in human body famous for its antioxidant and non-antioxidant functions. However, little is known about vitamin E deficiency status in urban adults of Wuhan from central China. Our aim is to describe the distribution of both circulating and lipid-adjusted serum vitamin E concentration in urban adults of Wuhan. METHODS: We hypothesized that the prevalence rate of vitamin E deficiency would be low in Wuhan in consideration of the Chinese food composition. A cross-sectional study with 846 adults was performed in a single-center. Concentrations of vitamin E were measured by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). RESULTS: The median (interquartile range, IQR) of serum vitamin E concentration was 27.40 (22.89-33.20) µmol/L while that of serum vitamin E concentration adjusted by total cholesterol or the sum of cholesterol (TC) and triglyceride (TG) (the sum of cholesterol and triglyceride, TLs) were 6.20 (5.30-7.48) and 4.86 (4.10-5.65) mmol/mol, respectively. No significant difference of the circulating and TC-adjusted vitamin E concentration was found between male and female except for vitamin E/TLs. However, concentrations of vitamin E increased significantly (r = 0.137, P < 0.001) with age, but lipid-adjusted concentrations of vitamin E did not. On analysis of risk factors, the subjects characterized by hypercholesterolemia are more likely to exhibit higher circulating but lower lipid-adjusted vitamin E level due to adequacy of the serum carriers for delivery of vitamin E. Only 0.47% of the population were below 12 µmol/L of vitamin E defined as functional deficiency. CONCLUSION: The prevalence rate of vitamin E deficiency in urban adults of Wuhan is low, which is important and useful to clinicians for clinical decision-making in public health practice.

Vitamin E deficiency in childhood: a narrative review.

Vitamin E is an important nutrient from the earliest stages of life. It plays key roles as an antioxidant and in the maintenance of the immune system, among others. Vitamin E deficiency (VED), which occurs more frequently in children, is rarely addressed in the literature. This narrative review aims to summarise the chemistry, biology, serum indicators and clinical trials that have evaluated the impact of fortification and other relevant aspects of vitamin E, in addition to the prevalence of its deficiency, in children worldwide. Vitamin E intake in recommended amounts is essential for this nutrient to perform its functions in the body. Serum α-tocopherol is the most widely used biochemical indicator to assess the prevalence of VED. VED has been associated with symptoms secondary to fat malabsorption and may lead to peripheral neuropathy and increased erythrocyte haemolysis. Reduced concentrations of α-tocopherol may be caused by the combination of diets with low amounts of vitamin E and inadequate consumption of fats, proteins and calories. The lowest prevalence of VED was found in Asia and the highest in North America and Brazil. High proportions of VED provide evidence that this nutritional deficiency is a public health problem in children and still little addressed in the international scientific literature. The planning, evaluation and implementation of health policies aimed at combatting VED in the paediatric population are extremely important.

Estado nutricional de vitamina E e fatores de risco cardiovascular em adultos e idosos: estudo Brazuca Natal / Nutritional status of vitamin E and cardiovascular risk factors in adults and elderly people: Brazuca Natal study

Introdução: As doenças cardiovasculares (DCV) são a principal causa de morbimortalidade no mundo. Diante disso, são estudadas estratégias de prevenção e tratamento de eventos cardiovasculares. Dentre elas, a vitamina E destaca-se por suas propriedades antioxidantes e anti-inflamatórias, apoiado por descobertas de que maior ingestão dietética de vitamina E e maiores concentrações de α-tocoferol (α-TOH) sérico estão associados com menor risco de eventos cardiovasculares. Com isso, dados sobre o estado nutricional de vitamina E da população e a sua relação com os fatores de risco cardiovascular são estratégias importantes para subsidiar programas e políticas públicas voltadas a prevenção e tratamento das DCV. Objetivo: Avaliar o estado nutricional de vitamina E e a relação com fatores de risco cardiovascular em adultos e idosos do Estudo Brazuca Natal. Métodos: Trata-se de um estudo de diferentes métodos. 1) A revisão narrativa que investigou na literatura estudos populacionais sobre a relação da vitamina E e as DCV, buscando compreender se a deficiência de vitamina E (DVE) também deve ser considerada um problema de saúde pública. 2) Estudo transversal que se decompõe, a partir das variáveis dependentes, em dois artigos científicos. O primeiro artigo desse estudo buscou avaliar a prevalência de DVE e os fatores de risco cardiovascular que estão associados ao status do α-TOH sérico em adultos e idosos do estudo Brazuca Natal. Análise de regressão linear múltipla foi realizada entre o αTOH sérico (variável dependente) e fatores de risco cardiovascular. O segundo artigo do estudo transversal objetivou avaliar o consumo de vitamina E, e identificar as principais fontes alimentares consumidas do micronutriente pela população avaliada. Para tanto, foram analisadas as condições socioeconômicas e demográficas (sexo, idade, cor/raça, escolaridade, renda per capita e distrito sanitário de moradia) e o consumo alimentar de vitamina E (variável dependente). Resultados: Na revisão narrativa foi observado que a DVE pode ser um problema de saúde pública, por ocorrer uma variação de 0,6% a 55,5% de DVE em todo o mundo, com percentuais mais elevados na Ásia e na Europa, onde se destacam as elevadas taxas de mortalidade por DCV. Estudos populacionais sugerem efeitos protetores da vitamina E nas DCV, porém, estudos de intervenção com suplementação de α-TOH não confirmaram a sua ação cardioprotetora. No artigo 2 do estudo transversal foi observado que 24,8% dos adultos e idosos de Natal apresentavam DVE e 89% apresentaram baixas concentrações de αTOH circulante (abaixo de 30 µmol/L). Verificamos que as pessoas do sexo feminino tinham maiores valores médios de α-TOH sérico. Além disso, o índice de adiposidade visceral elevado e maiores valores do escore de risco global foram associados a maiores concentrações de α-TOH sérico. O artigo 3 demonstrou que 95,7% dos indivíduos apresentavam baixa ingestão de vitamina E, considerando a Estimated Average Requirement (EAR) de 12 mg/dia, com menores valores de ingestão em indivíduos acima de 40 anos, mulheres, naqueles com renda per capita menor que um salário-mínimo e com menor escolaridade. O óleo de soja, polpa de açaí e carne vermelha forneceram o maior teor de vitamina E ingerida. Conclusão: A partir da revisão narrativa, foi demonstrado que a DVE pode ser um problema de saúde pública. O estudo transversal observou uma elevada prevalência de DVE na população estudada, em que o sexo, o índice de adiposidade visceral e o escore de risco global estão associados ao α-TOH sérico. Além disso, foi observado um baixo consumo de vitamina E, principalmente, em indivíduos mais velhos, mulheres e com baixa condição socioeconômica. A maior parte da vitamina E consumida era proveniente do óleo de soja, polpa de açaí e carne vermelha, destacando-se também a vitamina E proveniente de alimentos ultraprocessados, principalmente, na população de menor renda (AU).

Introduction: Cardiovascular diseases (CVD) are the principal cause of morbidity and mortality in the world. Therefore, experts have studied strategies for preventing and treating cardiovascular events. One of this knowledge is vitamin E stands out for its antioxidant and anti-inflammatory properties, supported by findings that higher dietary intake of vitamin E and higher concentrations of serum α-tocopherol (α-TOH) are associated with a lower risk of cardiovascular events. Therefore, data on the nutritional status of vitamin E in the population and its relationship with cardiovascular risk factors are relevant strategies to support programs and public policies aimed at preventing and treating CVD. Objective: To evaluate the nutritional status of vitamin E and its association with cardiovascular risk factors in adults and older adults in the Brazuca Natal Study. Methods: This is a study of different methodological strategies. 1) The narrative review aimed to verify if surveys could demonstrate an association between serum vitamin E and the occurrence of CVD. Moreover, we would like to understand whether vitamin E deficiency (VED) should also be considered a public health problem. 2) Cross-sectional study, divided into two scientific articles. The first article of this study sought to evaluate the prevalence of VED and cardiovascular risk factors that are associated with serum α-TOH status in adults and elderly people from the Brazuca Natal study. We performed a multiple linear regression analysis between serum α-TOH (dependent variable) and cardiovascular risk factors. The second article aimed to evaluate vitamin E intake, and we would like to identify the principal food sources of this micronutrient intake. To this end, we analyzed socioeconomic and demographic conditions (sex, age, color/race, education, per capita income, and health district of residence), and vitamin E intake (dependent variable). Results: In the narrative review, we observed that VED could be a public health problem. The prevalence of VED varies from 0.6% to 55.5% in the world, with higher percentages in Asia and Europe, where the high mortality rates from CVD stand out. Population studies suggest the protective effects of vitamin E on CVD. However, intervention studies with α-TOH supplementation have not confirmed its cardioprotective action. In article 2 of the crosssectional study, we observed that 24.8% of adults and older adults in Natal had VED, and 89% had low concentrations of circulating α-TOH (below 30 µmol/L). Furthermore, high visceral adiposity index and higher global risk score values were associated with higher serum α-TOH concentrations. Article 3 demonstrated that 95.7% of individuals had a low intake of vitamin E, considering the Estimated Average Requirement (EAR) of 12 mg/day, with lower intake values in individuals over 40 years of age, women, those who have a per capita income of less than the minimum wage and with less education. Soybean oil, açaí pulp, and red meat provided the highest content of ingested vitamin E. Conclusion: From the narrative review, it was demonstrated that VED can be a public health problem. The cross-sectional study observed a high prevalence of VED in the studied population, in which sex, visceral adiposity index and global risk score are associated with serum α-TOH. Furthermore, a low consumption of vitamin E was observed, mainly in older individuals, women and those with low socioeconomic status. Most of the vitamin E consumed came from soybean oil, açaí pulp and red meat, with vitamin E also coming from ultra-processed foods, especially in the lowerincome population (AU).

Vitamin E Levels in Preterm and Full-Term Infants: A Systematic Review.

Vitamin E deficiency (VED) is associated with clinical repercussions in preterm newborns (PTN), but low levels are also found in full-term newborns (TN). As this inadequacy can compromise neurogenesis in childhood, studies are needed to assess whether there is a difference in vitamin E status among newborns according to gestational age to provide support for neonatal monitoring protocols. This systematic review presents a synthesis of the available information on the vitamin E status among PTN and TN. The review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Observational studies that evaluated alpha-tocopherol levels were searched in the databases reported in the protocol registered in PROSPERO (CRD42021165152). The Newcastle-Ottawa Scale was used to assess the methodological quality. Overall, 1809 articles were retrieved; 10 were included in the systematic review. In the PTN, the alpha-tocopherol levels ranged from 3.9 to 8.5 mmol/L, while in TN, they were 4.9 to 14.9 mmol/L, and VED ranged from 19% to 100% in newborns. Despite substantial heterogeneity in research methodology and VED classification, the results suggest that the alpha-tocopherol levels among preterm and full-term newborns is below the recommended levels. Our findings demonstrate that further investigations are needed to standardize this classification and to monitor vitamin E status in birth and postnatal with adequate bias control.

Ataxia with vitamin E deficiency in the Philippines†: A case report of two siblings.

Here we report two siblings with ataxia and peripheral neuropathy. One patient showed head tremors. Genetic analysis revealed a mutation in the hepatic α-tocopherol transfer protein (α-TTP) gene (TTPA) on chromosome 8q13. They were diagnosed with ataxia with vitamin E deficiency which is firstly reported in the Philippines. As the symptoms of ataxia with vitamin E deficiency can be alleviated with lifelong vitamin E administration, differential diagnosis from similar syndromes is important. In addition, ataxia with vitamin E deficiency causes movement disorders. Therefore, a common hereditary disease in the Philippines, X-linked dystonia-parkinsonism, could be another differential diagnosis. The Philippines is an archipelago comprising 7,107 islands, and the prevalence of rare hereditary diseases among the populations of small islands is still unclear. For neurologists, establishing a system of genetic diagnosis and counseling in rural areas remains challenging. These unresolved problems should be addressed in the near future. J. Med. Invest. 68 : 400-403, August, 2021.

The Role of Vitamin Deficiency in Liver Disease: To Supplement or Not Supplement?

Over the past few years, growing interest has been shown for the impact of dietary requirements and nutritional factors on chronic diseases. As a result, nutritional programs have been reinforced by public health policies. The precise role of micronutrients in chronic liver disease is currently receiving particular attention since abnormalities in vitamin levels are often detected. At present, treatment programs are focused on correcting vitamin deficiencies, which are frequently correlated to higher rates of comorbidities with poor outcomes. The literature reviewed here indicates that liver diseases are often related to vitamin disorders, due to both liver impairment and abnormal intake. More specific knowledge about the role of vitamins in liver disease is currently emerging from various results and recent evidence. The most significant benefits in this area may be observed when improved vitamin intake is combined with a pharmacological treatment that may also affect the progression of the liver disease, especially in the case of liver tumors. However, further studies are needed.

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.

α-Tocopherol transfer protein (α-TTP).

α-Tocopherol transfer protein (α-TTP) is so far the only known protein that specifically recognizes α-tocopherol (α-Toc), the most abundant and most biologically active form of vitamin E, in higher animals. α-TTP is highly expressed in the liver where α-TTP selects α-Toc among vitamin E forms taken up via plasma lipoproteins and promotes its secretion to circulating lipoproteins. Thus, α-TTP is a major determinant of plasma α-Toc concentrations. Familial vitamin E deficiency, also called Ataxia with vitamin E deficiency, is caused by mutations in the α-TTP gene. More than 20 different mutations have been found in the α-TTP gene worldwide, among which some missense mutations provided valuable clues to elucidate the molecular mechanisms underlying intracellular α-Toc transport. In hepatocytes, α-TTP catalyzes the vectorial transport of α-Toc from the endocytotic compartment to the plasma membrane (PM) by targeting phosphatidylinositol phosphates (PIPs) such as PI(4,5)P2. By binding PIPs at the PM, α-TTP opens the lid covering the hydrophobic pocket, thus facilitating the release of bound α-Toc to the PM.

Reflections on a century of vitamin E research: Looking at the past with an eye on the future.

The name vitamin E, was given by Barnett and Sure who suggested that the factor proposed by Evans and Bishop as substance "X," be termed vitamin "E" as the next vitamin after the A, B, C and D vitamins had been already described. The identification of vitamin E with a-tocopherol was made in 1936 by Evans' group. One year later ß-tocopherol and 11 years later δ-tocopherol were isolated. Tocotrienol (named zetatocopherol) was first described in 1957 and later isolated in 1961. The antioxidant property of tocopherols was reported by Olcott and Emerson in 1937. Inherited vitamin E deficiency, AVED, characterized by a form of neuromyopathy was first described in 1981. The disease, was localized to chromosome 8q and found to be caused by a mutation of the a-TTP gene. The subsequent paragraphs are not a comprehensive review but only critical reflections on some important aspects of vitamin E research.

GPX4 and vitamin E cooperatively protect hematopoietic stem and progenitor cells from lipid peroxidation and ferroptosis.

Ferroptosis, a newly defined mode of regulated cell death caused by unbalanced lipid redox metabolism, is implicated in various tissue injuries and tumorigenesis. However, the role of ferroptosis in stem cells has not yet been investigated. Glutathione peroxidase 4 (GPX4) is a critical suppressor of lipid peroxidation and ferroptosis. Here, we study the function of GPX4 and ferroptosis in hematopoietic stem and progenitor cells (HSPCs) in mice with Gpx4 deficiency in the hematopoietic system. We find that Gpx4 deletion solely in the hematopoietic system has no significant effect on the number and function of HSPCs in mice. Notably, hematopoietic stem cells (HSCs) and hematopoietic progenitor cells lacking Gpx4 accumulated lipid peroxidation and underwent ferroptosis in vitro. α-Tocopherol, the main component of vitamin E, was shown to rescue the Gpx4-deficient HSPCs from ferroptosis in vitro. When Gpx4 knockout mice were fed a vitamin E-depleted diet, a reduced number of HSPCs and impaired function of HSCs were found. Furthermore, increased levels of lipid peroxidation and cell death indicated that HSPCs undergo ferroptosis. Collectively, we demonstrate that GPX4 and vitamin E cooperatively maintain lipid redox balance and prevent ferroptosis in HSPCs.