Mixed Tocopherols Clinical Evidence

American Journal of Clinical Nutrition

Liu M, et al. Mixed tocopherols inhibit platelet aggregation in humans: potential mechanisms. 2003 Mar;77(3):700-6.

Can supplementing with mixed tocopherols benefit cardiac health?

Studies have shown that people who eat diets high in vitamin E have fewer heart attacks. However, recent clinical studies have not found a cardiovascular benefit to supplementing with alpha-tocopherol, a form of vitamin E. Could it be that other types of tocopherols, specifically gamma-tocopherol, needs to be present for cardiac benefits to be realized?

Study Type:
Human clinical intervention trial

Study Design:
Subjects were divided into 3 groups. One took mixed tocopherols, one took alpha-tocopherols and the last acted as controls. Researchers analyzed platelet aggregation (a dangerous process whereby blood platelets clump together and can form clots), levels of nitric oxide (which signals smooth muscles to relax and improves blood pressure), and levels of endothelial cell nitric oxide snythase (ecNOS), an enzyme that catalyzes the synthesis of nitric oxide in cells lining blood vessels. They also measured levels of superoxide dismutase (SOD), an antioxidant.

46 subjects

160 mg mixed tocopherols (100 mg gamma, 40 mg delta and 20 mg alpha)/day for 8 weeks

Platelet aggregation was significantly reduced in the mixed tocopherol group but not in the alpa tocopherol group or in the control group. Mixed tocopherols were better able than alpha tocopherol to regulate the release of nitric oxide and activate ecNOS. Both tocopherol groups had increased SOD levels.

Mixed tocopherols were more potent in preventing platelet aggregation than was alpha-tocopherol alone. Effects of mixed tocopherols were associated with increased NO release, ecNOS activation, and SOD protein content in platelets, which may contribute to the effect on platelet aggregation.

Mixed Tocopherols Mechanism of Action

Mixed tocopherols may reduce platelet aggregation by increasing the release of nitric oxide (especially in the cells that line blood vessels). Nitric oxide relaxes blood vessels, an action which can reduce barriers to red blood cell circulation. Nitric oxide also inhibits platelets’ tendency to clot.

Mixed tocopherols also increase levels of superoxide dismutase, an antioxidant that combats an inflammation-causing free radical called superoxide anion. Free radicals and inflammation can increase blood clots, whereas increased SOD levels in red blood cells reduce the tendency for blood to clot.