So many options but one choice: the human body prefers alpha-tocopherol. A matter of stereochemistry.

alpha-Tocopherol belongs to the group of vitamin E vitamers. Recent years findings indicate that alpha-tocopherol is more than just a simple fat-soluble anti-oxidant as it was found that it can also regulate gene expression. From all vitamin E vitamers human body preferentially retains alpha-tocopherol, but the reasons for this preference are still elusive. Different studies indicated that human body, through the action of two hepatic proteins, alpha-tocopherol transfer protein (alpha-TTP) and cytochrome P450 4F2 (CYP4F2), is able to make subtle structural differences between different vitamin E forms. This is an example of stereochemistry used as a discrimination factor between molecules with different biological activities.