Alpha-Tocopherol from People to Plants Is an Essential Cog in the Metabolic Machinery

Protection from oxygen, a diradical, became a necessity with the evolution of photosynthetic organisms about 2.7 billion years. α-Tocopherol plays an essential, protective role in organisms from plants to people. An overview of human conditions that result in severe vitamin E (α-tocopherol) deficiency is provided. α-Tocopherol has a critical role in the oxygen protection system by stopping lipid peroxidation, its induced damage, and cellular death by ferroptosis. Recent findings in bacteria and plants support the concept of why lipid peroxidation is so dangerous to life and why the family of tocochromanols are essential for aerobic organisms and for plants. The hypothesis that prevention of the propagation of lipid peroxidation is the basis for the α-tocopherol requirement in vertebrates is proposed and further that its absence dysregulates energy metabolism, one-carbon metabolism, and thiol homeostasis. By recruiting intermediate metabolites from adjacent pathways to sustain effective lipid hydroperoxide elimination, α-tocopherol function is linked not only to NADPH metabolism and its formation through the pentose phosphate pathway via glucose metabolism but also to sulfur-containing amino acid metabolism and to one-carbon metabolism. Evidence from humans, animals, and plants supports the hypothesis, but future studies are needed to assess the genetic sensors that detect lipid peroxidation and cause the ensuing metabolic dysregulation. Antioxid. Redox Signal. 38, 775-791.