Nutrition and Case Studies in Vitamins

Case Studies

• Case 1: A 45-year-old male presented to the OPD with generalized weakness, decreased sensation in hands and feet, blurred vision, and improper gait. He has Crohn's disease and had a small bowel resection. He smokes and drinks occasionally. Examination revealed impaired proprioception, a positive Romberg's sign, delayed tendon reflexes, and decreased bilateral visual acuity. CBC showed mild anemia.

• Case 2: A 3-day-old baby, delivered at home, was brought to the ER with sudden unconsciousness, bleeding from the nose, umbilical stump, and buccal mucosa with petechiae on the skin. The mother took antitubercular drugs during pregnancy to treat Tuberculosis.

Vitamin E and K Objectives

• The lecture will cover food sources, dietary requirements, absorption/excretion, functions, and deficiencies/symptoms associated with Vitamin E and K.

Vitamin E (Tocopherols)

• Vitamin E is a lipophilic and hydrophobic vitamin.
• Four tocopherols exist, differing in the number or position of methyl groups on the molecule: alpha, beta, gamma, and delta.
• Alpha-tocopherol is the most active form.

Vitamin E - Chemistry

• Alpha-tocopherol shows a chraman ring and a phytol radical.

Vitamin E Food Sources

• Plant sources: cottonseed oil, sunflower oil, margarine, lettuce, cabbage, and soybeans.
• Animal sources: egg, fish, shrimps, and fish liver oil.

Vitamin E Daily Allowance

• Children: 10-15 IU/day.
• Adults: 20-25 IU/day.

Vitamin E Absorption and Excretion

• Absorbed from the jejunum and ileum of the small intestine in the presence of bile salts.
• Transported through lipoproteins to storage tissues (muscle and adipose).
• Excreted in urine and feces.
• Does not efficiently cross the placenta, but is present in breast milk.

Vitamin E Metabolic Functions

• Powerful antioxidant, protecting cell membranes from free radical damage.
• Inhibits the production of reactive oxygen species when fat undergoes oxidation.
• Maintains cell membrane integrity.
• Regulates platelet aggregation and prostacyclin release.

Vitamin E Functions (Further Breakdown)

• Powerful antioxidant – Neutralizes free radicals.
• Cholesterol reducer – Lowers cholesterol levels.
• Immune booster – Supports immune function.
• Anti-inflammatory – Reduces inflammation.
• Cancer prevention – May help reduce risk of some cancers.
• Skin protection – Protects skin from damage.
• Hormone regulator – Supports hormone balance.

Vitamin E Formation of Free Radicals

• Free radicals are formed through UV light, metabolization, ionizing radiation, smoking, and air pollution.

Vitamin E Not Alone

• Vitamin E needs assistance from vitamin C, selenium, and glutathione for its antioxidant effects and regeneration.

Vitamin K

• Lipophilic and hydrophobic vitamin.
• Three compounds (with biological activity): phylloquinone, menaquinones, and menadione.
• Phylloquinone (Vitamin K1) is the dietary source, found in green vegetables.
• Menaquinones (Vitamin K2) are synthesized by intestinal bacteria.
• Menadione is a synthetic compound metabolized to phylloquinone.

Vitamin K Food Sources

• Plant sources: cauliflower, cabbage, spinach, alfalfa, soybeans, and tomatoes.
• Animal sources: egg yolk and liver.

Vitamin K Daily Allowance

• Adults: 120 mg/day (males), 90 mg/day (females) Average daily allowance is 50-100 mg/day.

Vitamin K Absorption and Excretion

• Absorbed from the jejunum and ileum of the small intestine with bile salts.
• Transported from the intestines through chylomicrons.
• Stored in small amounts in the liver.
• Excreted via feces.
• Does not efficiently cross the placenta.

Vitamin K Functions

• Blood clotting/coagulation: Activates prothrombin (factors II, VII, IX, and X).
• Bone mineralization: Important for bone development and health.
• Activation of anticoagulants: Activates protein C and S, helping to control clotting.

Vitamin K Cycle

• The cycle shows the conversion of vitamin K from a reduced form to an oxidized form for proper functions, involving enzymes like vitamin K epoxide reductase and the protein VKOR.

Vitamin K Deficiency Causes

• Reduced intake of leafy greens and fermented products (very rare, as produced by gut microbes)
• Malabsorptive conditions (celiac, sprue, steatorrhea)
• Inflammatory bowel disease (Crohn's, ulcerative colitis), cystic fibrosis, pancreatitis
• Biliary obstruction
• Chronic liver disease
• Prolonged use of antibiotics (cephalosporins, sulfonamides, antitubercular drugs, anticonvulsants)
• Blood thinners (warfarin, dicumarol), Hemorrhagic disease of the newborn

Vitamin K Deficiency Clinical Presentation

• Bleeding from the nose, gut, and mucus membranes.
• Bone pain, recurrent fractures, and osteoporosis.

Vitamin K Inhibitors (example)

• Warfarin inhibits the recycling of vitamin K by inhibiting two reactions, leading to functional deficiency and increasing excretion.
• Warfarin is a competitive inhibitor of epoxide reductase.
• In the presence of warfarin, vitamin K epoxides cannot be converted to more active forms (e.g. K quinone), and accumulate and are excreted.

Vitamin E Toxicity

• Vitamin E is the least toxic of the fat-soluble vitamins.
• No toxicity has been observed at doses up to 300 mg/day (Upper limit is 1000 mg/day).