Overview
This lecture covers the roles, sources, and health implications of vitamins E and K, as well as practical advice on intake and supplementation.
Vitamin E
- Vitamin E is a group of compounds, with alpha-tocopherol being the most common and active form.
- Primary sources include unprocessed plant oils, nuts, and seeds; processing reduces vitamin E content.
- Vitamin E is sensitive to light and heat, and is destroyed during frying and by exposure to light.
- Recommended Dietary Allowance (RDA) is about 15 mg, but most Americans consume less than this.
- Major functions: strong antioxidant (protects cell membranes) and acts as an anticoagulant (blood thinner).
- Low intake raises risk of cancer, heart disease, cataracts, and weakened immunity.
- Over-supplementation can cause excessive bleeding (hemorrhagic effects) and interfere with vitamin K and other antioxidants.
- High intake is especially concerning for individuals on blood-thinning medications or preparing for surgery.
Vitamin K
- Vitamin K includes several compounds: phylloquinones (plants), menaquinones (animal/fish products and gut bacteria), and menadione (synthetic).
- Gut bacteria produce about 10% of our vitamin K requirement.
- Main dietary sources: green leafy vegetables, some vegetable oils, margarine, and animal products.
- Critical functions: enables blood clotting (coagulation) and supports bone metabolism by binding calcium in bones.
- Deficiency risks increase after long-term antibiotic use (destroys gut bacteria) and GI issues; main symptom is excessive bleeding.
- Toxicity is rare except when taking blood thinners; excess intake can oppose medication effects.
- Consistent intake is important for those on anticoagulant medication; infants receive vitamin K injections at birth due to low initial stores.
Key Terms & Definitions
- Alpha-tocopherol — most active form of vitamin E.
- Antioxidant — a compound that protects cells from damage by neutralizing free radicals.
- Anticoagulant — agent that prevents blood clotting.
- Phylloquinone — plant-based form of vitamin K.
- Menaquinone — animal/gut bacteria form of vitamin K.
- Coagulation — the process of blood clot formation.
Action Items / Next Steps
- Review your 3-day food recall to assess vitamin E and D intake.
- Read the final textbook sections on supplements and antioxidants.
- Identify groups that may benefit from vitamin supplementation.
- Complete textbook quizzes and review the eye health antioxidant fact sheet.