Jaymie Ticknor Intro Nutrition Science 2460 Sect 002 22 June 2014 Nutrients Involved in Antioxidant Function and Vision Chapter 8 What Are Antioxidants and How Does Our Body Use Them Antioxidants a compound that has the ability to prevent or repair the damage caused by oxidation Oxidation is a Chemical Reaction in Which Atoms Lose Electrons Compounds contain two or more different types of atom Atoms Are Composed of Particles Particles physicists learned how to split atoms into these components Nucleus the positively charged central core of an atom It is made up of two types of particles protons and neutrons bound tightly together The nucleus of an atom contains essentially all of its atomic mass Electron a negatively charged particle orbiting the nucleus of an atom During Metabolism Atoms Exchange Electrons Metabolism the process by which our body breaks down and builds up molecules Oxidation a chemical reaction in which molecules of a substance are broken down into their component atoms During oxidation the atoms involved lose electrons Reduction atoms that are capable gaining electrons during metabolism Exchange Reaction loss and gain of electrons typically results in an even exchange of electrons Oxidation Sometimes Results in the Formation of Free Radicals Stable atoms have an even number of electrons orbiting in pairs at successive distances called shells or rings from the nucleus Unpaired Electron when a stable atom loses an electron during oxidation it is left with an odd number of electrons in its outmost shell Free Radical a highly unstable atom with an unpaired electron in its outermost shell Formed during everyday body processes that produce energy Antioxidants Work by Stabilizing Free Radicals or Opposing Oxidation Antioxidants perform their role in three ways 1 Antioxidant vitamins work independently by donating their electrons or hydrogen atoms to free radicals to stabilize them and reduce the damage caused by oxidation 2 Antioxidant minerals including selenium copper iron zinc and manganese act as cofactors function properly a A mineral or other inorganic substance that is needed to allow enzymes to b These minerals function within complex antioxidant enzyme systems that convert free radicals to less damaging substances that are excreted by our bodies 3 Phytochemicals beneficial plant chemicals such as beta carotene and other compounds help stabilize free radicals and prevent damage to cells and tissues A Profile of Nutrients That Function As Antioxidants Vitamin E Tocopherols or tocotrienols the active form of vitamin E in our body Alpha tocopherol the most active or potent vitamin E compound found in food and supplements Supplements containing the natural form of vitamin E 1 IU 0 67 mg Supplements containing the synthetic form of vitamin E 1 IU 0 45 mg How Much Vitamin E Should We Consume RDA is 15 mg alpha tocopherol per day UL is 1 000 mg alpha tocopherol per day What Happen If We Consume Too Much Vitamin E A megadose of vitamin E would be 10 times the recommended amounts Anticoagulants substances that stop blood from clotting excessively Consuming too much vitamin E can cause excessive bleeding Hemorrhagic stroke long term use of standard vitamin E supplements may cause hemorrhaging in the brain What Happens If We Don t Consume Enough Vitamin E Erythrocyte Hemolysis the rupturing lysis of red blood cells erythrocytes Leads to anemia Vitamin C Functions of Vitamin C Ascorbic Acid vitamin C prevents scurvy a disease that ravaged sailors on long sea voyages centuries ago Characterized by bleeding tissues especially of the gums and is thought to have caused more than half of the deaths that occurred at sea Collagen a protein found in all the connective tissues in our body Nitrosamines vitamin C reduces this formation cancer causing agents found in foods such as cured and processed meats How Much Vitamin C Should We Consume RDA for vitamin C is 90 mg per day for men and 75 mg per day for women UL is 2 000 mg per day What Happens If We Consume Too Much Vitamin C Megadose a nutrient dose that is ten or more times greater than the recommended amount Hemochromatosis causes an excess accumulation of iron in the body Prooxidant a nutrient that promotes oxidation and oxidative cell and tissue damage Selenium Functions of Selenium Keshan disease a heart disorder caused by selenium deficiency It was first identified in children in the Keshan province of China Selenium is needed for the production of thyroxine or thyroid hormone Helps maintain our basal metabolism and body temperature RDA for selenium is 55 g per day for both men and women How Much Selenium Should We Consume UL is 400 g per day Organ meats such as liver and kidneys as well as pork and fish are good sources What Happens If We Don t Consume Enough Selenium Kashin Beck Disease a disease of the cartilage that results in deforming arthritis Symptoms include impaired immune responses infertility depression hostility impaired cognitive function and muscle pain and wasting Beta Carotene Provitamins an inactive form of a vitamin that the body can convert to an active form Ex beta carotene Converts beta carotene to the active form of vitamin A retinol thus beta carotene is a precursor of retinol Carotenoid a fat soluble plant pigment that the body stores in the liver and adipose tissues The body is able to convert certain carotenoids to vitamin A Provitamin A Carotenoids the body can convert only alpha carotene beta carotene and beta cryptoxanthin to retinol De Medicina a condition called night blindness and recommended as a cure the What is the Role of Vitamin A in Vision consumption of liver Forms of Vitamin A Retinol binding Protein carries one form of vitamin A retinol from the liver to the cells that require it vision and immune function vision and immune function vision and immune function Retinol an active alcohol form of vitamin A that plays an important role in healthy Retinal an active aldehyde form of vitamin A that plays an important role in healthy Retinoic Acid an active acid form of vitamin A that plays an important role in healthy Two units of beta carotene equals one unit of active vitamin A Vitamin A Is Essential to Sight Retina the delicate light sensitive membrane lining the inner eyeball and connected to Rhodopsin a light sensitive pigment found in the rod cells that is formed by retinal and the optic nerve contains retinal opsin Found in rod cells When light hits the retina the cells go through