Vitamin E

Vitamin E (alpha-tocopherol) is a fat-soluble vitamin and a powerful antioxidant.

It was originally discovered as dietary factor essential for reproduction in rats. Its molecular properties make vitamin E an efficent scavenger of reactive oxygen and nitrogen species.  Therefore it prevents oxidative damage associated with many diseases.

There are eight isomers of alpha-tocopherol, but only one isomer (RRR) is found in food and is known as “natural source” vitamin E. This vitamin is abundant in olive, vegetable and sunflower oils, wheat germs, leafy green vegetables, whole grains and nuts.

The Most Relevant Recent Scientific Reviews

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Tocotrienols: The promising analogues of vitamin E for cancer therapeutics.

Despite the significant advancements in the diagnosis and treatment of cancer, it still remains one of the most fatal diseases in the world due to the lack of sensitive diagnosis methods and effective drugs. Therefore, discovering novel therapies that are safe, efficacious and affordable are required for the better management of this disease. Tocotrienols, analogues of vitamin E have gained increased attention due to their safety and efficacy. Extensive research over the past several years has strongly indicated that tocotrienols can efficiently prevent/inhibit the growth of different cancers such as cancers of blood, brain, breast, cervical, colon, liver, lung, pancreas, prostate, skin, stomach etc. This is mainly accredited to their ability to modulate various molecular targets involved in cancer cell proliferation, survival, invasion, angiogenesis, and metastasis such as NF-κB, STAT3, Akt/mTOR, etc. In addition, increasing lines of evidence has shown that tocotrienols can sensitize cancer cells to chemotherapeutic agents such as celecoxib, doxorubicin, erlotinib, gefitinib, gemcitabine, paclitaxel, statin etc. Moreover, several clinical trials have confirmed the safety and tolerability of tocotrienols in humans. This reviewsummarizes the potential of tocotrienols for the prevention and treatment of different cancers based on the available in vitro, in vivo and clinical studies.

Potential roles of vitamin E in age-related changes in skeletal muscle health.

Skeletal muscle disorders including sarcopenia are prevalent during the complex biological process of aging. Loss of muscle mass and strength commonly seen in sarcopenia is induced by impaired neuromuscular innervation, transition of skeletal muscle fiber type, and reduced muscle regenerative capacity, all attributable to chronic inflammation, oxidative stress, and mitochondrial dysfunction. Current literature suggests that vitamin E molecules (α-, β-, γ-, δ-tocopherols and the corresponding tocotrienols) with their antioxidant and anti-inflammatory capabilities may mitigate age-associated skeletal dysfunction and enhance muscle regeneration, thus attenuating sarcopenia. Preclinical and human experimental studies show that vitamin E benefits myoblast proliferation, differentiation, survival, membrane repair, mitochondrial efficiency, muscle mass, muscle contractile properties, and exercise capacity. Limited number of human cross-sectional observational studies reveal positive associations between serum tocopherol level and muscle strength. Several factors, including difficulties in validating vitamin E intake and deficiency, variations in muscle-protective activity and metabolism of diverse forms of vitamin E, and lack of understanding of the mechanisms of action, preclude randomized clinical trials of vitamin E in people with sarcopenia. Future research should consider long-term clinical trials of with adequate sample size, advanced imaging technology and omics approaches to investigate underlying mechanisms and assess clinically meaningful parameters such as muscle strength, physical performance, and muscle mass in sarcopenia prevention and/or treatment.

Vitamin E as an Antioxidant in Female Reproductive Health.

Vitamin E was first discovered in 1922 as a substance necessary for reproduction. Following this discovery, vitamin E was extensively studied, and it has become widely known as a powerful lipid-soluble antioxidant. There has been increasing interest in the role of vitamin E as an antioxidant, as it has been discovered to lower body cholesterol levels and act as an anticancer agent. Numerous studies have reported that vitamin E exhibits anti-proliferative, anti-survival, pro-apoptotic, and anti-angiogenic effects in cancer, as well as anti-inflammatory activities. There are various reports on the benefits of vitamin E on health in general. However, despite it being initially discovered as a vitamin necessary for reproduction, to date, studies relating to its effects in this area are lacking. Hence, this paper was written with the intention of providing a review of the known roles of vitamin E as an antioxidant in female reproductive health.

Vitamin E for antipsychotic-induced tardive dyskinesia.

BACKGROUND: Antipsychotic (neuroleptic) medication is used extensively to treat people with chronic mental illnesses. Its use, however, is associated with adverse effects, including movement disorders such as tardive dyskinesia (TD) – a problem often seen as repetitive involuntary movements around the mouth and face. Vitamin E has been proposed as a treatment to prevent or decrease TD. OBJECTIVES:The primary objective was to determine the clinical effects of vitamin E in people with schizophrenia or other chronic mental illness who had developed antipsychotic-induced TD.The secondary objectives were:1. to examine whether the effect of vitamin E was maintained as duration of follow-up increased;2. to test the hypothesis that the use of vitamin E is most effective for those with early onset TD (less than five years) SEARCH METHODS: We searched the Cochrane Schizophrenia Group Trials Register (July 2015 and April 2017), inspected references of all identified studies for further trials and contacted authors of trials for additional information. SELECTION CRITERIA: We included reports if they were controlled trials dealing with people with antipsychotic-induced TD and schizophrenia who remained on their antipsychotic medication and had been randomly allocated to either vitamin E or to a placebo, no intervention, or any other intervention. DATA COLLECTION AND ANALYSIS: We independently extracted data from these trials and we estimated risk ratios (RR) or mean differences (MD), with 95% confidence intervals (CI). We assumed that people who left early had no improvement. We assessed risk of bias and created a ‘Summary of findings’ table using GRADE. MAIN RESULTS: The review now includes 13 poorly reported randomised trials (total 478 people), all participants were adults with chronic psychiatric disorders, mostly schizophrenia, and antipsychotic-induced TD. There was no clear difference between vitamin E and placebo for the outcome of TD: not improved to a clinically important extent (6 RCTs, N = 264, RR 0.95, 95% CI 0.89 to 1.01, low-quality evidence). However, people allocated to placebo may show more deterioration of their symptoms compared with those given vitamin E (5 RCTs, N = 85, RR 0.23, 95% CI 0.07 to 0.76, low-quality evidence). There was no evidence of a difference in the incidence of any adverse effects (9 RCTs, N = 205, RR 1.21, 95% CI 0.35 to 4.15, very low-quality evidence), extrapyramidal adverse effects (1 RCT, N = 104, MD 1.10, 95% CI -1.02 to 3.22, very low-quality evidence), or acceptability of treatment (measured by participants leaving the study early) (medium term, 8 RCTs, N = 232, RR 1.07, 95% CI 0.64 to 1.80, very low-quality evidence). No trials reported on social confidence, social inclusion, social networks, or personalised quality of life, outcomes designated important to patients. There is no trial-based information regarding the effect of vitamin E for those with early onset of TD. AUTHORS’ CONCLUSIONS: Small trials of limited quality suggest that vitamin E may protect against deterioration of TD. There is no evidence that vitamin E improves symptoms of this problematic and disfiguring condition once established. New and better trials are indicated in this under-researched area, and, of the many adjunctive treatments that have been given for TD, vitamin E would be a good choice for further evaluation.

Role of Vitamin E in the Treatment of Alzheimer’s Disease: Evidence from Animal Models.

Alzheimer’s disease (AD) is a neurodegenerative disorder representing the major cause of dementia. It is characterized by memory loss, and cognitive and behavioral decline. In particular, the hallmarks of the pathology are amyloid-β (Aβ) plaques and neurofibrillary tangles (NFTs), formed by aggregated hyperphosphorylated tau protein. Oxidative stress plays a main role in AD, and it is involved in initiation and progression of AD. It is well known that Aβ induced oxidative stress, promoting reactive oxygen species (ROS) production and consequently lipid peroxidation, protein oxidation, tau hyperphosphorylation, results in toxic effects on synapses and neurons. In turn, oxidative stress can increase Aβ production. For these reasons, the administration of an antioxidant therapy in AD patients was suggested. The term vitamin E includes different fat-soluble compounds, divided into tocopherols and tocotrienols, that possess antioxidant action. α-Tocopherol is the most studied, but some studies suggested that tocotrienols may have different health promoting capacities. In this review, we focused our attention on the effects of vitamin E supplementation in AD animal models and AD patients or older population. Experimental models showed that vitamin E supplementation, by decreasing oxidative stress, may be a good strategy to improve cognitive and memory deficits. Furthermore, the combination of vitamin E with other antioxidant or anti-inflammatory compounds may increase its efficacy. However, even if some trials have evidenced some benefits, the effects of vitamin E in AD patients are still under debate.