part 6, Vitamins E and K

Vitamin E

• Also known as tocopherols and tocotrienols.
• There are multiple forms including alpha, beta, gamma, and delta-tocopherol and tocotrienol.
• Alpha-tocopherol is also known as "Vitamin E".
• Vegetable oils like sunflower, rapeseed, and palm oil are sources.
• Tocopherols/tocotrienols do not form coenzymes.
• Functions as a fat-soluble antioxidant, protecting cell membranes from oxidative damage.
• Involved in smooth muscle growth and maintenance.
• Deficiency is usually due to fat malabsorption rather than a lack of dietary intake.
• Deficiency symptoms include nerve damage and hemolytic anemia.
• Excess intake antagonizes vitamin K, leading to risk of bleeding

Vitamin K

• Also known as phytomenadione (K₁) and menaquinone (K₂).
• Leafy green vegetables such as spinach, cabbage, and kale contain high levels of phytomenadione.
• Menaquinone is found in eggs, meat, and dairy products.
• Intestinal flora can convert phylloquinone to menaquinone.
• Phytomenadione acts as a cofactor, not as an enzyme.
• Functions as a cofactor in reactions that add a second carboxylic acid group onto glutamate residues of proteins to form gamma-carboxyglutamate (Gla).
• Is important in the formation of coagulation factors II (prothrombin), VII, IX, and X in the liver.
• Involved in the production of anticoagulant proteins C and S and protein Z.
• Warfarin inhibits phytomenadione's effects on coagulation.
• Deficiency is rarely due to lack of dietary intake.
• Liver damage and medication (e.g., anticoagulants) can lead to deficiency.
• Deficiency symptoms include anemia, bruising, and bleeding at the mucosal membranes (e.g., gums, nose).
• Not stored in great quantities in the liver, which makes toxicity from high doses of vitamin K1 or K2 is rare.

Vitamin E (tocopherol) functions as a fat-soluble antioxidant. Vitamin K (phylloquinone and menaquinone) is found in leafy greens and animal products. Deficiencies in Vitamin E can cause nerve damage and hemolytic anemia, while excess Vitamin E intake may lead to bleeding due to vitamin K antagonism.