Purpose of review: Vitamin E deficiency in humans has lead to the discovery of regulatory mechanisms that control plasma α-tocopherol concentrations and prevent the accumulation of other molecules with vitamin E-antioxidant activity, such as γ-tocopherol. This review describes these regulatory mechanisms.
Recent findings: α-tocopherol regulatory proteins have been cloned and crystallized and their mechanisms of action are under intense scrutiny. Studies of vitamin E metabolism suggest that xenobiotic metabolism may not only regulate vitamin E concentrations, but that vitamin E may regulate xenobiotic clearance pathways.
Summary: Advances in our understanding of vitamin E nutrition suggest that vitamin E is a potent molecule that is closely regulated such that α-tocopherol is at the appropriate tissue concentrations necessary for some as yet to be described functions.