Quiz 6 (Chapter 10) Flashcards
compounds that protect cells from the damage caused by oxidation
antioxidant
nutrients with antioxidant properties
Vitamin C
Vitamin E
Vitamin A (precursor for beta-carotene)
Selenium
a chemical reaction in which atoms lose electrons
oxidation
a chemical reaction in which atoms gain electrons
reduction
unstable atoms that damages cell membranes
free radicals
oxygen molecule that becomes a free radical
Reactive Oxygen Species (ROS)
What metabolic process causes free radicals?
immune system fighting infections
What environmental factors cause free radicals?
Pollution Excess sunlight Toxic substances Radiation Tobacco smoke Asbestos UV light
cannot eliminate exposure, but you can reduce it
remember this concept
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
free radicals damage cell membranes, LDLs (bad cholesterol), cell proteins, and DNA
Free Radical Damage
diseases linked with free radicals
heart disease various cancers diabetes cataracts alzheimer's disease parkinson's disease
how do antioxidants work?
stabalize free radicals or oppose oxidation
Antioxidant Vitamins
Antioxidant minerals
phytochemicals
donate their electrons of hydrogen molecules to free radicals to stabilize them and reduce oxidation damage
antioxidant vitamins
act as cofactors within enzyme systems that convert free radicals to less damaging substances that can be excreted
antioxidant minerals
help stabilize free radicals
phytochemicals
antioxidant enzymes
break down oxidized fatty acids (reducing the negative effect)
make more vitamin antioxidants available to fight other free radicals
3 most important antioxidant enzymes
superoxide dismutase
catalase
glutathione peroxide
converts free radicals to less damaging substances, such as hydrogen peroxide
superoxide dismutase
catalase
removes hydrogen peroxide from the body by converting to water and oxygen
glutathione peroxide
removes hydrogen peroxide and stops the production of free radicals in lipids
vitamin E
fat-soluble, absorbed with dietary fats
incorporated into the chtlomicron to be transported to the liver
part of liproprotein VLDL and LDL
90% stored in adipose tissue, cell membranes
forms of vitamin E
Tocopherol
Alpha-Tocopherol
tocopherol
biologically active forms of vitamin E
alpha-tocopherol
most active form, found in foods and supplements
functions of vitamin E
protects PUFAs fatty cell components, and LDLs from oxidation (lower cvd risk)
normal nerve and muscle development
enhances immune system
added to oil-based foods and skincare products to reduce rancidity and spoilage
** Improves Vitamin A absorption, if vitamin A intake is low
RDA for vitamin E
15mg alpha-tocopherol per day
UL: 1,000 mg alpha-tocopherol per day
determined to be sufficient to prevent erythrocyte hemalysis, (rupturing of RBC)
Food sources of Vitamin E
vegetable oils
nuts, seeds, soybeans
wheat germ, fortified cereals
little vitamin E in deep-fried, processed foods (Vitamin E is destroyed by exposure to oxygen, metals, ultraviolet light, and heat
Vitamin E toxicity
supplemental doses
nausea, intestinal distress, vomiting, and diarrhea
increases anticoagulants effects (asparin, coumadin, warfarin)
long-term use may cause hemorrhagic stroke
vitamin E deficiency
rare erythrocyte hemolysis leads to anemia anemia in premature infants loss of muscle coordination and reflexes, impaired vision, speech impaired immunity fat malabsorption
vitamin C
water-soluble
“a-scorbic” acid
two forms: ascorbic and dehydroascorbic acid
functions of Vitamin C
synthesis of: collagen DNA Bile neurotransmitters (seratonin) carnitine (transports long-fatty acids) hormones (epinephrine, steroids) ensures appropriate levels of thyroxine hormone antioxidant for protecting LDL cholesterol from oxidation, lungs from ozone and cigarette damage, whit blood cells (enhances immune function) reduces formation of nitrosamines (cancer causing agent found in cured and processed meats) regenerates oxidized vitamin E enhances iron absorption
RDA for Vitamin C
90mg/day (men); 75mg/day (women)
UL: 2,000mg/day for adults
smokers require and additional 35mg/day
food sources of Vitamin C
fresh fruits and vegetables
destroyed by heat and oxygen
can be leached into boiling water
minimize loss: steaming, microwaving, and stir-frying
vitamin C toxicity
only from supplements
nausea, diarrhea, nosebleeds, abdominal cramps, iron accumulation
harmful to people with hemochromatosis
hemochromatosis
absorb a lot of iron
enlarged heart
darker skin
liver damage
vitamin C deficiency
rare in developed countries
scurvy
anemia
high risk for deficiency among people with low fruit and vegetable intake, alcohol and drug abuse
scurvy
most common deficiency disease
bleeding gums, loose teeth, weakness, wounds that fail to heal, bone pain and fractures, diarrhea, depression
beta-carotene
provitamin A (inactive form [precursor] of vitamin A to be converted to active retinol) phytochemical classified as a carotenoid not absorbed as well as vitamin A
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
RDA for Beta-Carotene
not an essential nutrient so there is no RDA
6 to 10 mg of beta-carotene/day from food sources may reduce the risk for cancer and cvd
Food sources of Beta-Carotene
red, orange, yellow, and deep-green fruits and vegetables
absorbing ~20-40% of carotenoids
Heat improves digestibility and absorption
Deficiency and toxicity of Beta-Carotene
Deficiency: none known
Toxicity: none
carotenosis is reversible and harmless
supplementation is not recommended
vitamin A
fat soluble
expressed as retinol Activity Equivalents (RAE)
stored mainly in the liver (90%)
Received as retinol or retinyl esters
Active forms of Vitamin A
retinol, retinal, retinoic acid
functions of vitamin A
antioxidant, not well established
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
RDA for Vitamin A
900 micrograms/day for men
700 micrograms /day for women
UL: 3,000 micrograms/day preformed Vitamin A
Food sources of Vitamin A
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)
Toxicity of Vitamin A
mainly from supplementation
birth defects, spontaneous abortion
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
deficiency of Vitamin A
night blindness
xerophthalmia
hyperkeratosis
impaired immunity, failure of normal growth
selenium
trace mineral
part of glutathione peroxidase enzyme system and spares vitamin E
thyroxine production, basal metabolism, body temp
RDA for selenium
55 micrograms/day
UL: 400 micrograms/day
Food sources of selenium
meats, pork, seafood
toxicity of selenium
brittle hair and nails, skin rashes, vomiting, nausea, weakness, cirrhosis of the liver
deficiency of selenium
keshan disease
kashin-beck diseases
impaired immunity
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
cancer
a group of diseases characterized by cells growing out of control
tumors
immature undifferentiated cell masses that have no physiological function
malignant (cancerous); benign (harmless)
Primary steps of cancer development
initiation
promotion
progression
risk factors for cancer
smoking unhealthful diets infectious agents ultraviolet radiation physical inactivity
antioxidant that prevent cancer
enhance immune system
inhibit cancer cell growth
prevent oxidative damage to cells
cardiovascular disease (CVD)
leading cause of death in adults (U.S.)
diseases of the heart and blood vessels (coronary heart disease, hypertension, atherosclerosis)
risk factors of CVD
obesity smoking hypertension diabetes high LDL cholesterol males before age 55 females before age 65 and postmenopausal
inflammation
c-reactive protein (CRP) increases the risk factor for heart attack
marker for infammation (blood test)
high risk for heart attack in the presence of normal cholesterol levels
antioxidants and CVD
vitamins E and lycopene (scavenged free radicals, reduce low-grade inflammation, reduce blood coagulation and clot formation)
