The term vitamin E describes a family of eight fat-soluble molecules with antioxidant activities: four tocopherol isoforms (-, -, -, and -tocopherol) and four tocotrienol isoforms (-, -, -, and -tocotrienol) (Figure 1). Only one form, -tocopherol, meets human vitamin E requirements (see The RDA). In the human liver, -tocopherol is the form of vitamin E that is preferentially bound to -tocopherol transfer protein (-TTP) and incorporated into lipoproteins that transport -tocopherol in the blood for delivery to extrahepatic tissues.

The term vitamin E describes a family of eight fat-soluble molecules with antioxidant activities: four tocopherol isoforms (-, -, -, and -tocopherol) and four tocotrienol isoforms (-, -, -, and -tocotrienol) (Figure 1). Only one form, -tocopherol, meets human vitamin E requirements (see The RDA). In the human liver, -tocopherol is the form of vitamin E that is preferentially bound to -tocopherol transfer protein (-TTP) and incorporated into lipoproteins that transport -tocopherol in the blood for delivery to extrahepatic tissues.