Vitamin E Overview for Health Professionals

Overview of Vitamin E

• Vitamin E encompasses a group of fat-soluble compounds with antioxidant properties.
• Eight chemical forms exist: alpha-, beta-, gamma-, and delta-tocopherol; alpha-, beta-, gamma-, and delta-tocotrienol.
• Alpha-tocopherol is the primary form essential for human health.

Absorption and Metabolism

• Serum concentrations of alpha-tocopherol depend on liver uptake after absorption in the small intestine.
• The liver re secretes only alpha-tocopherol via the hepatic alpha-tocopherol transfer protein.
• Other forms of vitamin E are metabolized and excreted by the liver, leading to lower blood concentrations.

Role of Antioxidants

• Antioxidants like vitamin E protect cells from free radical damage, potentially reducing the risk of cardiovascular diseases and cancer.
• Free radicals, derived from metabolic processes and environmental factors, contribute to reactive oxygen species (ROS) formation.
• Vitamin E counteracts oxidative stress by preventing ROS production during fat oxidation.

Immune Function and Cell Signaling

• Beyond antioxidant actions, vitamin E is involved in immune system support and various metabolic processes.
• It regulates cell signaling and gene expression, affecting smooth muscle cells, platelets, and monocytes.

Cardiovascular Health

• Vitamin E enhances endothelial cell function by resisting blood cell adherence within blood vessels.
• The compound increases expression of enzymes that suppress arachidonic acid metabolism, promoting blood vessel dilation and reducing platelet aggregation.

Dietary Recommendations

• Intake values for vitamin E are established by the Dietary Reference Intakes (DRIs) from the Food and Nutrition Board.
• DRI values vary by age and gender, focusing on alpha-tocopherol, the only form found in plasma.
• Recommendations are based on serum levels that ensure protection against free radical damage, particularly in erythrocytes exposed to hydrogen peroxide.

Sources of Vitamin E

• Naturally sourced vitamin E is identified as RRR-alpha-tocopherol (d-alpha-tocopherol).
• The synthetic version is all rac-alpha-tocopherol (dl-alpha-tocopherol).