Vitamin E (tocopherol)
An antioxidant fat-soluble vitamin that protects cell membranes from oxidation, found in vegetable oils, nuts and seeds.
Vitamin E is a family of 8 compounds (tocopherols and tocotrienols), with alpha-tocopherol the most active. Its main function: to protect fats (cell membranes, LDL) from oxidation as a fat-soluble antioxidant. It notably protects fragile polyunsaturated fatty acids.
The original angle (the supplement paradox): vitamin E is the emblematic example of the failure of isolated antioxidants. It was thought that as a supplement it would prevent heart disease and cancer. But large trials (such as SELECT) showed at best no benefit, at worst an increase in certain risks (prostate cancer, haemorrhagic stroke) at high doses.
Why? Because:
- Vitamin E works as part of a network with vitamin C, selenium and glutathione (which “recycle” it). Isolated at a high dose, it can become pro-oxidant
- Supplements often contain a single form (synthetic alpha-tocopherol), unbalancing the other natural forms
Another illustration of the principle: antioxidants from whole foods (working together, at a moderate dose) beat concentrated supplements.
Sources: vegetable oils (sunflower, wheat germ), almonds, hazelnuts, sunflower seeds, avocado, spinach.
A practical point: the vitamin E in oils protects them from going rancid. But heating oils rich in polyunsaturated fats strongly destroys vitamin E and oxidises the fats (forming harmful compounds). Hence the point of using fragile oils (flaxseed, walnut) cold, and cooking with stable fats (olive oil, a little butter).