Chapter 10 Lecture Chapter 10: Nutrients Involved in Antioxidant Function and Vision © 2017 Pearson Education, Inc What Are Antioxidants? • Compounds that protect cells from the damage caused by oxidation • Hence, "anti"-oxidation • Some nutrients with antioxidant properties: • Vitamin E • Vitamin C • Vitamin A (precursor beta-carotene) Selenium â 2017 Pearson Education, Inc Exchange Reactions • Oxidation is a chemical reaction in which atoms lose electrons • Reduction occurs when atoms gain an electron • Oxidation-reduction reactions typically result in an even exchange of electrons, called exchange reactions © 2017 Pearson Education, Inc â 2017 Pearson Education, Inc Free Radicals Stable atoms have an even number of electrons (pairs) orbiting • Electron loss during oxidation leaves an odd number or unpaired electron • Unstable atoms are called free radicals • Reactive oxygen species (ROS): oxygen molecule that becomes a free radical © 2017 Pearson Education, Inc © 2017 Pearson Education, Inc What Causes Free Radicals? • Metabolic processes • Ex: immune system fighting infections • Environmental factors • Pollution • Excess sunlight • Toxic substances • Radiation • Tobacco smoke Asbestos â 2017 Pearson Education, Inc Free Radical Damage • Can destabilize other molecules and damage cells • Cell membrane damage: • Free radicals form within the phospholipid bilayers of cell membranes and "steal" electrons • Damaged lipid molecules cause cell membrane to lose its integrity • Causes damage to the cell and all systems affected by the cell © 2017 Pearson Education, Inc © 2017 Pearson Education, Inc Diseases Linked with Free Radicals • Free radicals damage low-density lipoproteins (LDLs), cell proteins, and DNA • Increase risk for chronic diseases, including: • Cancer • Heart disease • Type diabetes • Arthritis • Cataracts Alzheimer's and Parkinson's diseases â 2017 Pearson Education, Inc © 2017 Pearson Education, Inc Disorders Related to Free-Radicals: Cancer • Cancer: a group of diseases characterized by cells growing "out of control" • Cancer cells aggressively invade tissues and organs throughout the body • Tumors: immature undifferentiated cell masses that have no physiologic function • Malignant (cancerous) Benign (harmless) â 2017 Pearson Education, Inc Disorders Related to Free-Radicals: Cancer • Primary steps of cancer development: Initiation Promotion Progression â 2017 Pearson Education, Inc © 2017 Pearson Education, Inc Cancer • Risk factors • Tobacco use • Overweight, obesity • Poor nutrition (diets high in saturated fats; low in fruits & vegetables; excessive alcohol consumption) • Physical inactivity • Infectious agents Ultraviolet radiation â 2017 Pearson Education, Inc © 2017 Pearson Education, Inc • Human papillomavirus (HPV) © 2017 Pearson Education, Inc • A malignant melanoma lesion â 2017 Pearson Education, Inc Cancer Prevention Antioxidants play a role in cancer prevention • Enhance immune system • Inhibit cancer cell growth • Prevent oxidative damage to cells • Eat a varied, healthful diet • Be physically active • Maintain a healthy body weight • Quit smoking or don't start • Avoid infectious agents and UV radiation © 2017 Pearson Education, Inc Cardiovascular Disease (CVD) • Leading cause of death in adults (U.S.) • Diseases of the heart and blood vessels • Coronary heart disease • Hypertension (high blood pressure) • Atherosclerosis (hardening of the arteries) • Primary manifestations of CVD • Heart attack • Stroke © 2017 Pearson Education, Inc Major Risk Factors for CVD • • • • • Smoking Hypertension High blood levels of LDL cholesterol Obesity Sedentary lifestyle © 2017 Pearson Education, Inc Other Risk Factors for CVD • Low blood levels of HDL cholesterol • Diabetes • Family history of CVD • Males before age 55 • Females before age 65 • Being male older than 45 years • Being postmenopausal woman © 2017 Pearson Education, Inc Low-Grade Inflammation • May be even more important than elevated cholesterol levels • Weakens plaque in blood vessels (vessels become more fragile) • Plaques likely to burst, break away, lodge in blood vessels of heart or brain and close off blood supply, resulting in a heart attack or stroke © 2017 Pearson Education, Inc Low-Grade Inflammation • C-reactive protein (CRP) • Marker for inflammation (blood test) • Associated with high risk for heart attack in the presence of normal cholesterol levels • High CRP and high cholesterol can increase the risk for heart attack © 2017 Pearson Education, Inc Antioxidants and CVD • Antioxidants (vitamins E and lycopene) reduce damage to blood vessels: • Scavenge free radicals • Reduce low-grade inflammation • Reduce blood coagulation and clot formation • In fruits, vegetables, and whole grains • Dietary fiber (soluble):oatmeal and oat bran • Folate (reduce homocysteine-CVD risk factor) • Others (flavonoids): tea © 2017 Pearson Education, Inc ... Incorporated into the chylomicron to be transported to the liver • Incorporated into very-low-density lipoproteins (VLDLs) and is a part of low-density lipoproteins (LDLs) • 90% of vitamin E is... adipose tissue, the rest in cell membranes © 2017 Pearson Education, Inc Forms of Vitamin E • Two families of compounds: tocotrienols and tocopherols • Tocopherol compounds are the biologically... Inc Free Radical Damage Can destabilize other molecules and damage cells • Cell membrane damage: • Free radicals form within the phospholipid bilayers of cell membranes and "steal" electrons •