Why shouldn't vitamin E supplements be taken for at least one week before surgery?

The reason why food and medication is not allowed 1 week priory for surgery because, it raises your blood pressure rises from digestion and possible drug interaction.

Risen blood pressure increases the risk of bleeding, myocardial infarction, Cardiac arrest and more.

Vitamin E acts as a Anti Coagulant, which causes the blood pressure to rise.

Basically your body needs to be as relaxed as it can get if any damages occurs during surgeries to ensure a safer recovery.