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

Wheat germ oil vitamin E cytoprotective effect and its nutrigenomics signature in human hepatocyte lipotoxicity

“…Vitamin E (as α-TOH) is an essential nutrient and fat-soluble antioxidant, involved in the protection of tissues from the harmful effects of oxidative stress and increased lipid peroxidation (recently reviewed in ( Brigelius-Flohé, 2021 ; Galli et al., 2017 ; Traber and Head, 2021 ). This function has long been considered particularly important in protecting the liver during the exposure to the free radical-generating agents as CCl 4 ( Parola et al., 1992 ), defects of antioxidant genes such as GPX4 ( Carlson et al., 2016 ), and lipotoxicity that is the pathogenic cue of non-alcoholic fatty liver disease (NAFLD) (recently reviewed in ( Perumpail et al., 2018 ; Sato et al., 2015 ; Svegliati-Baroni et al., 2019 )).…”

“…In fact, the racemic mixture of sVE is poor in the isomers that bind with high affinity the hepatic α-tocopherol binding protein of liver cells, i.e. primarily the 2R isomer of α-tocopherol and then the 3R isomer that corresponds to nVE ( Lauridsen et al., 2002 ; Traber and Head, 2021 ). These prevail on the other forms of the raceme in terms of cellular availability and transcriptional activity, and for the possibility to access the liver metabolism, including biotransformation pathways or incorporation into lipoprotein particles for tissue distribution ( Galli et al., 2007 ; Schubert et al., 2018 ), that are important intersection nodes for the effects of this vitamin and its metabolites to affect lipid metabolism, drug and xenobiotics detoxification, and inflammatory pathways ( Bartolini et al., 2017 ; Marinelli et al., 2020 ; Parker et al., 2004 ; Torquato et al., 2017 ; Willems et al., 2021 ).…”

Vitamin E: Where Are We Now in Vascular Diseases?

“…In the presence of LOO•, the phenolic hydroxyl group of αT undergoes an event of propagation reaction and forms into a tocopheroxyl radical, leaving LOOH and preventing the development of L• (Figure 3). The tocopheroxyl radical is much more stable and harmless as compared to the peroxyl radical, and potentially converts into tocopherol via reduction from other antioxidants, such as ascorbic acid (vitamin C) or with another tocopheroxyl radical [22]. Vitamin E is an extremely efficient antioxidant since its rate of reaction and scavenging of LOO• is much higher than the rate of peroxidation of lipid molecules by peroxyl radicals [23].…”

Plant Antioxidants in Dry Fermented Meat Products with a Healthier Lipid Profile

“…Vitamin E is an antioxidant extracted from nature common in the food industry and animal feed [ 115 , 116 ]. Tocopherols and tocotrienols are known as natural antioxidants for lipids, with α-tocopherol being the only one that meets human vitamin E requirements [ 117 ]. These compounds act as efficient free radical scavengers through the donation of a hydrogen atom to peroxyl radicals [ 92 ].…”

“…Thus, vitamin E prevents the propagation of the autocatalytic reaction since peroxyl radicals react 1000 times faster with vitamin E than with PUFA. The resulting tocopheroxyl or tocotrienoxyl radical can be reduced by vitamin C and regenerated to the corresponding vitamin E form, reinstating its antioxidant action [ 103 , 117 , 118 ]. The highest antioxidant efficacy among the α, β, γ, and δ isoforms, as well as among tocotrienols and tocopherols, is controversial in the literature [ 119 ], since the nature of the substrate modifies the antioxidant activity [ 120 ].…”