CLASS NOTES: NOV. 11, 2013 NUTRITION CONCEPTSThe Fat-Soluble Vitamins: A,D,E, and K!Chapter 11 Notes- Pt. 2 !!Vitamin E •Four different tocopherol compounds •Alpha, beta, gamma, and delta • Position of methyl group • Alpha-tocopherol - vitamin E activity in the body • Antioxidant- reduces oxidation • Stop chain reaction of free radicals from producing more free radicals •Protect cells and their membranes •Protects LDLs from oxidation - also reduces oxidation of polyunsaturated oils (where we find Vitamin D) •Reduce risk of heart disease •Reduce inflammation !Vitamin E - Deficiency • Primary deficiency is rare (Most common is lack of intake) • Secondary deficiency • Diseases of fat malabsorption – cystic fibrosis • Effects of deficiency • Red blood cells break open • Erythrocyte hemolysis – premature infants Effect of deficiency: Not permanent, can correct with treatment • Neuromuscular dysfunction • Spinal cord and retina •Loss of muscle coordination and impaired vision and speech •Vitamin E treatment corrects these symptoms !Vitamin E - Toxicity • Toxicity is rare • Liver regulates vitamin E concentrations • UL is 65 times greater than recommended intake for adults •Extremely high doses of vitamin E •May interfere with vitamin K activity (Vit K important for clotting) • Enhance effect of blood clotting drugs —> hemorrhage (Vitamin E blood thinning effect) !Vitamin E- Recommendations and Foods •RDA is based on alpha-tocopherol only •Vit E content in foods overestimated Page 1CLASS NOTES: NOV. 11, 2013 NUTRITION CONCEPTS• Widespread in foods • Vegetable oils - predominant source • Seeds, nuts • Destroyed by heat processing and oxidation - fresh foods best source (overly processed foods are poor sources of Vitamin E) !Review • The primary role of vitamin E is as an antioxidant. It inhibits the destruction of polyunsaturated fatty acids in foods and in the body, fights oxidation of low- density lipoproteins, which may offer protection from heart disease. !Review with Vit E in foods • Vitamin E is easily destroyed by heat and oxidation, which means that most cooked and processed, convenient foods are poor sources. The major dietary sources are vegetable oils, which are polyunsaturated fatty acids. !Review of Vitamin E: Deficiency/Toxicity •A primary deficiency is rare because Vitamin E is widespread in foods. A secondary deficiency is more common, potentially due to the inability to absorb dietary lipids. Excess of Vitamin E can lead to hemorrhaging, due to interference with Vitamin K/clotting activity. !Vitamin K: Blood Clotting Role •Can be obtained from non-food source •Made by bacteria in the GI tract • Acts primarily in blood clotting • Essential for activation of several proteins in blood clotting process • Prothrombin – precursor of thrombin- critical to the blood clotting •Deficiency causes hemorrhaging and bleeding can occur in excess !Vitamin K: Bone remodeling role • Metabolism of bone proteins • Osteocalcin – calcium-binding protein essential for mineralization • Deficiency - low bone density !Vitamin K - Deficiency •Primary deficiency is rare •Secondary deficiency (more common) • Fat absorption falters • Some drugs disrupt vitamin K synthesis/activity • Antibiotics decrease synthesis (because antibiotics kill bacteria in GI Tract, then bacteria in GI Tract no longer contribute to Vitamin K) • Anticoagulant drugs interfere with metabolism & activity of Vitamin K Page 2CLASS NOTES: NOV. 11, 2013 NUTRITION CONCEPTS• Newborn infants (particularly susceptible) • Born with sterile intestinal tract- another reason why breast feeding so important. Mom passes along intestinal flora to the child) • Single dose of vitamin K given at birth- in the heel !Vitamin K - Toxicity • Not common • No adverse effects with high intakes • No UL • High doses can reduce effectiveness of anticoagulant drugs used to prevent blood clotting (example of blood thinning drugs, this can !Vitamin K - Sources • GI tract • Half of person’s need • Stored in liver • Food sources • Green vegetables, especially cabbage family • Vegetable oils !Review of Vitamin K • Vitamin K’s primary role is in blood clotting, which is important to prevent hemorrhaging, or excess bleeding. • Vitamin K can be made in the body by bacteria. This supplies half of the body’s needs. Risk of deficiency increases if this process does not occur due to use of antibiotics. Another reason secondary deficiency may occur is malabsorption of fat. Secondary deficiencies are more common than primary deficiencies. !Review of Vitamin K • Good sources of vitamin K include green vegetables, especially from the cabbage family. • High intakes are only a concern for those who: are taking anticoagulant drugs !The Fat-Soluble Vitamins- In Summary • Toxicities are possible b/c body stores excesses • Function of fat-soluble vitamins together • Vitamins E and A • Vit E protects vit A from oxidation • Vitamins A, D, and K • Bone growth and remodeling • Vitamins E and K • Excess of Vitamin E can interfere with blood clotting action of Vitamin K !Page 3CLASS NOTES: NOV. 11, 2013 NUTRITION CONCEPTSFat-Soluble Vitamins •Which fat-soluble vitamins can be made in the body? - Vitamins K and D •Which fat-soluble vitamins are associated with bone remodeling? - Vitamin A, D, and K •Which fat-soluble vitamins have anti-oxidant roles? - A and E (C is water soluble) !Page
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