alpha-Tocopherol is the only form of vitamin E in vitamin supplements, whereas gamma-tocopherol is the predominant form of vitamin E in the US diet. gamma-Tocopherol has beneficial properties as an anti-inflammatory and possibly anti-atherogenic and anticancer agent. Excess a-tocopherol taken in supplements causes a reduction of gamma-tocopherol concentration in plasma. The biochemical mechanism of this effect, which is important to human nutrition, has recently been elucidated.