Breaking the lipid peroxidation chain reaction
Vitamin E is a group of fat soluble compounds, of which alpha-tocopherol is the form the human body preferentially retains. Its job is to interrupt lipid peroxidation, a self-propagating chain reaction in which a lipid radical reacts with oxygen to form a peroxyl radical, which then attacks a neighbouring fatty acid and continues the cycle. Left unchecked this damages the polyunsaturated fatty acids in cell membranes.
Alpha-tocopherol sits within the lipid environment of the membrane and donates a hydrogen atom to the peroxyl radical, halting propagation. In doing so it becomes a relatively stable tocopheroxyl radical, which is why it acts as a chain-breaking antioxidant rather than just a one-off scavenger.
The recycling network and the megadose caution
The tocopheroxyl radical does not have to be discarded. Other antioxidants, notably vitamin C and components of the glutathione system, can regenerate alpha-tocopherol back to its active form, so the vitamins operate as a cooperative network rather than in isolation. This regeneration partly explains why antioxidant nutrients are often studied together. High-dose vitamin E supplementation, by contrast, has not reliably shown the disease-prevention benefits once hoped for, and some trials of large doses raised safety concerns.
This is general educational information, not medical advice. Consult a qualified healthcare professional before taking high-dose vitamin E, particularly alongside blood-thinning medication.