1. Nutrients Involved in Antioxidant Function10
Nutrients Involved in Antioxidant Function

2. What Are Antioxidants?
Compounds that protect cells from the damage caused by oxidation
Nutrients with antioxidant properties:
Vitamin E
Vitamin C
Vitamin A (precursor beta-carotene)
Selenium

3. Exchange Reactions
Oxidation is a chemical reaction in which atoms lose electrons
Reduction occurs when atoms gain a electron
Exchange reactions consists of 2 parts. (a) During oxidation, molecules lose electrons. (b) In the second part of the reaction, molecules gain electrons, which is called reduction.

5. 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
When an oxygen molecule becomes a free radical, it is specifically referred to as a reactive oxygen species (ROS).
Free Radical Formation

6. What Causes Free Radicals?
Metabolic processes
Immune system fighting infections
Environmental factors
Pollution
Excess sunlight
Toxic substances
Radiation
Tobacco smoke
Asbestos

7. Cell Damage
Free radicals form within the phospholipid bilayers of cell membranes and steal electrons
Damaged lipid molecules cause cell membrane to lose its integrity
Cell membrane is unable to regulate the movements of fluids and nutrients into and out of the cell. This loss of cell integrity causes damage to the cell and to all systems affected by this cell. Free radicals damage cell membranes, low-density lipoproteins (LDLs), cell proteins, and DNA.

9. Diseases Linked with Free Radicals
Free radicals damage low-density lipoproteins (LDLs), cell proteins, and DNA
Increase risk for chronic diseases
Heart disease
Various cancers
Diabetes
Cataracts
Alzheimer’s disease
Parkinson’s disease

10. How Do Antioxidants Work?
Stabilize free radicals or oppose oxidation
Antioxidant vitamins donate their electrons or hydrogen molecules to free radicals to stabilize them and reduce oxidation damage
Antioxidant minerals act as cofactors within enzyme systems that convert free radicals to less damaging substances that can be excreted .

11. Antioxidant Enzymes Antioxidant enzyme systems
Break down oxidized fatty acids
Make more vitamin antioxidants available to fight other free radicals

12. Antioxidant Enzymes Antioxidant enzymes:
Superoxide dismutase converts free radicals to less damaging substances, such as hydrogen peroxide
Catalase removes hydrogen peroxide from the body
Glutathione peroxidase removes hydrogen peroxide

13. Antioxidants
Other compounds stabilize free radicals and prevent damage to cells and tissues
Nutrients with antioxidant properties:
Vitamin E
Vitamin C
Vitamin A
Beta-carotene (precursor to vitamin A)
Selenium

14. Vitamin E Fat soluble, absorbed with dietary fats
Incorporated into the chylomicron to be transported to the liver
Incorporated into very-low-density lipoproteins (VLDLs)
Stored in adipose tissue, cell membranes

15. Forms of Vitamin E
Tocopherol compounds are the biologically active forms
Alpha-tocopherol is most active (potent), found in food and supplements
RDA: expressed as alpha-tocopherol (mg/day)
Food labels and supplements: expressed as alpha-tocopherol equivalents or International Units (IU)

17. Functions of Vitamin E
Protects polyunsaturated fatty acids (PUFAs), fatty cell components, and LDLs from oxidization (lower heart disease risk)
Added to oil-based foods and skincare products to reduce rancidity and spoilage
Normal nerve and muscle development
Enhances immune system
Promotes vitamin A absorption, if low

18. RDA for Vitamin E RDA: 15 mg alpha-tocopherol per day
Determined to be sufficient to prevent erythrocyte hemolysis, rupturing (lysis) of red blood cells (erythrocytes)
Tolerable Upper Intake Level (UL): 1,000 mg alpha-tocopherol per day

19. Food Sources of Vitamin E
Vitamin E is widespread in foods
Vegetable oils (safflower, sunflower, canola, soybean), mayonnaise, salad dressing
Nuts, seeds, soybeans
Wheat germ, fortified cereals
Vitamin E is destroyed by exposure to oxygen, metals, ultraviolet light, and heat
Little vitamin E in deep-fried, processed foods

22. Vitamin E toxicity
High supplemental doses of vitamin E may be harmful for certain individuals
Side effects: nausea, intestinal distress, and diarrhea
Interacts with anticoagulants (aspirin, Coumadin)
Long-term use may cause hemorrhagic stroke

23. Vitamin E Deficiency Deficiency is rare
Erythrocyte hemolysis (rupturing of red blood cells) leads to anemia
Anemia in premature infants
Symptoms: loss of muscle coordination and reflexes; impaired vision, speech
Impaired immunity (with low selenium)
Associated with fat malabsorption

24. Vitamin C and Its Functions
Water soluble
Functions—synthesis of:
Collagen (prevents scurvy)
DNA
Bile
Neurotransmitters (serotonin)
Carnitine (transports long-chain fatty acids)
Hormones (thyroxine, epinephrine, steroids)

26. More Functions of Vitamin C
Antioxidant for protecting:
LDL-cholesterol from oxidation
Lungs from ozone and cigarette damage
White blood cells (enhances immune function)
Reduces nitrosamines, cancer-causing agent found in cured and processed meats
Regenerates oxidized vitamin E
Enhances iron absorption

28. Vitamin C Requirements
RDA: 90 mg/day (men), 75 mg/day (women)
UL: 2,000 mg/day for adults
Smokers require additional 35 mg/day
Other situations requiring more vitamin C:
Healing from traumatic injury, surgery, burns
Use of oral contraceptives

29. Food Sources of Vitamin C
Best sources: fresh fruits and vegetables
Destroyed by heat and oxygen
Can be leached into boiling water
Minimize loss: steaming, microwaving, and stir-frying

31. Too Much Vitamin C? Water soluble
Extra excreted; consuming excess is not toxic
Only supplements can lead to toxic doses
Megadoses
Long-term excess of 2,000 mg/day: nausea, diarrhea, nosebleeds, and abdominal cramps
Harmful for people with hemochromatosis (excess iron accumulation in the body)

32. Not Enough Vitamin C? Rare in developed countries
Scurvy: most common deficiency disease
Symptoms: bleeding gums, loose teeth, weakness, wounds that fail to heal, bone pain and fractures, diarrhea, depression
Anemia can result
High risk for deficiency among people with
Low fruit and vegetable intake
Alcohol and drug abuse

33. Beta-Carotene
Provitamin A, inactive form (precursor) of vitamin A to be converted to active retinol
Phytochemical classified as a carotenoid
Expressed in food as Retinol Activity Equivalents (RAE), which indicates how much active vitamin A is available to the body after conversion

35. Functions of Beta-Carotene
Weak antioxidant
Fights lipid oxidation in cell membranes
Enhances immune system
Protects skin from UV-ray damage
Protects eyes from damage, preventing or delaying age-related vision impairment

36. Beta-Carotene Requirements
Beta-carotene is not an essential nutrient
No RDA established
Consuming 6 to 10 mg of beta-carotene per day from food sources may reduce the risks for cancer and heart disease
Food sources: red, orange, yellow, and deep-green fruits and vegetables
Heat improves digestibility and absorption

38. Beta-Carotene Requirements
Large consumption is not toxic
Carotenosis (carotenodermia): reversible and harmless
Supplementation is not recommended; adequate amounts from fruits and vegetables
Not enough?
No known deficiency symptoms

39. Vitamin A Fat soluble Active forms: retinol, retinal, retinoic acid
Stored mainly in the liver
Expressed as Retinol Activity Equivalents (RAE)
International Units (IU) for vitamin A on food labels or dietary supplements

41. Functions of Vitamin A
Antioxidant, scavenges free radicals and protects LDL from oxidation
Essential for healthy vision
Cell differentiation, process by which stem cells mature into specialized cells
Sperm production and fertilization
Bone growth
Vitamin A and Epithelial Tissue

43. Vitamin A Requirements
RDA is 900 micrograms/day for men, 700 micrograms/day for women
UL: 3,000 micrograms/day preformed vitamin A
Food sources
Animal (liver, eggs, dairy, fortified foods)
Plants (dark-green, orange, and deep-yellow fruits and vegetables that are high in beta-carotene can be converted to vitamin A)

45. Vitamin A Requirements
Highly toxic, mainly from supplements
Birth defects, spontaneous abortion
Symptoms: fatigue, loss of appetite, blurred vision, hair loss, skin disorders, bone and joint pain, abdominal pain, nausea, diarrhea, and damage to the liver and nervous system

46. Vitamin A Requirements
Deficiency
Night blindness
Xerophthalmia
Hyperkeratosis
Impaired immunity, failure of normal growth
Vitamin A and the Visual Cycle

48. Selenium Trace mineral needed in small amounts
Antioxidant (part of glutathione peroxidase enzyme system): spares vitamin E
Thyroxine (thyroid hormone) production: basal metabolism, body temperature
RDA: 55 µg/day; UL: 400 µg/day
Sources: organ meats, pork, seafood

51. Selenium Toxicity can occur from supplements
Brittle hair and nails, skin rashes, vomiting, nausea, weakness, cirrhosis of the liver
Deficiency associated with
Keshan disease, a heart disease
Kashin-Beck disease, deforming arthritis
Impaired immunity

53. Additional Antioxidants
Copper, zinc, and manganese are part of the superoxide dismutase enzyme antioxidant complex
Iron is part of the catalase structure
Copper, iron, and zinc for blood health
Manganese: important cofactor in carbohydrate metabolism

54. Cancer
A group of diseases characterized by cells growing “out of control”
Tumors: immature undifferentiated cell masses that have no physiologic function
Malignant (cancerous); benign (harmless)
Primary steps of cancer development:
Initiation
Promotion
Progression

56. Cancer Risk Risk factors Tobacco use Unhealthful diet
Infectious agents
Ultraviolet radiation
Physical inactivity
ABC Video Tobacco Addiction

61. Cancer Risk Antioxidants prevent cancer Enhance immune system
Inhibit cancer cell growth
Prevent oxidative damage to cells

62. 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

63. Major Risk Factors for CVD
Smoking
Hypertension
High blood levels of LDL cholesterol
Obesity
Sedentary lifestyle

64. 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

65. Low-Grade Inflammation
More important than elevated cholesterol?
Weakens plaque in blood vessels (more fragile)
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

66. 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

67. 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

68. Age-Related Vision Impairment
Macular degeneration
Leading cause of blindness
Deterioration of center portion of retina
Loss of the ability to see details
Cataract
Damaged portion of eye’s lens (cloudy vision)
Impaired adjustment from dark to bright light

70. Age-Related Vision Impairment
Possible role of antioxidants
Supplements may reduce progression of macular degeneration
Mixed results from cataract research
Current research does not support the use of antioxidant supplements to prevent these two diseases of aging