Fat Soluble Vitamins Uniersity of Illinois at Chicago脂溶性维生素伊利诺伊大学芝加哥分校.pptVIP

Vitamin E Fat soluble compounds, produced by plants to prevent lipid peroxidation in their cell membranes and oil droplets Tocopherols (?, β, ?, ? ) Tocotrienols (?, β, ?, ? ) Eight stereochemical isomers of ?-Tocopherol in synthetic Vitamin E Active Inactive RRR- SRR- RSR- SSR- RRS- SRS- RSS- SSS- Different arrangement of methyl groups in the side chain starting at chromanol ring Vitamin E units 1 IU (International Unit) = 1 mg all rac-?-tocopheryl acetate = 0.67 mg RRR-?-tocopherol 1 mg RRR-?-tocopherol = 1.49 IU Vitamin E activity units Used in food tables to calculate total intake: ?-Tocopherol Equivalent (?-TE) = mg ?-tocopherol + (mg β-tocopherol x 0.5) + (mg ?-tocopherol x 0.1) + (mg ?-tocotrienol x 0.3) mg ?-tocopherol = mg ?-TE x 0.8 Vitamin E Tolerable Upper Intake Levels Vitamin E Deficiency Very rare in normal subjects AVED (ataxia and vitamin E deficiency) – defect in ?-TTP gene Abetalipoproteinemia (inability to produce chylomicrons, LDL, VLDL) Cystic fibrosis (defective fat absorption) Cholestatic liver disease Vitamin E deficiency symptoms Primary symptom – peripheral neuropathy (degeneration of large axons in sensory neurons) Ataxia Myopathy Hemolysis of RBC in vitro, using hydrogen peroxide, is indicative of low vitamin E status. Plasma level 600 μg/dL Absorption and transport of vitamin E All forms are absorbed with fat in the intestine, esters are hydrolyzed Liver binds only RRR-?-tocopherol to hepatic ?-tocopherol transfer protein (?-TTP) RRR-?-tocopherol is preferentially secreted by liver to circulating lipoproteins (VLDL, HDL, LDL) Vitamin E in Cardiovascular Disease Animal studies strongly support the prevention of CVD by vitamin E - inhibition of LDL oxidation, of smooth muscle proliferation, of platelet adhesion and aggregation - promotion of pros