Nutrition exam 4 Flashcards
(65 cards)
0
Q
Nutrients with antioxidant properties
A
◦Vitamin E
◦Vitamin C
◦Vitamin A (precursor beta-carotene)
◦Selenium
1
Q
Antioxidants
A
Compounds that protect cells from the damage caused by oxidation
◦hence, “anti”-oxidation
2
Q
Exchange Reactions
A
- Oxidation is a chemical reaction in which atoms lose electrons
- Reduction occurs when atoms gain an electron
3
Q
Free Radicals
A
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
4
Q
Reactive oxygen species (ROS):
A
oxygen molecule that becomes a free radical
5
Q
What causes free radical?
A
Metabolic processes ◦Immune system fighting infections Environmental factors ◦Pollution ◦Excess sunlight ◦Toxic substances ◦Radiation ◦Tobacco smoke ◦Asbestos
6
Q
Free radical damage
A
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
7
Q
Diseases Linked with Free Radicals
A
Free radicals damage low-density lipoproteins (LDLs), cell proteins, and DNA (faulty proteins, mutate genetic code) Increase risk for chronic diseases, including: ◦cancer ◦heart disease ◦type 2 diabetes ◦type 2 diabetes ◦arthritis ◦cataracts ◦Alzheimer's and Parkinson's diseases
8
Q
How do antioxidants work?
A
Stabilize free radicals or oppose oxidation
9
Q
Antioxidant vitamins
A
donate their electrons or hydrogen molecules to free radicals to stabilize them and reduce oxidation damage
10
Q
Antioxidant minerals
A
act as cofactors within enzyme systems that convert free radicals to less damaging substances that can be excreted
11
Q
Phytochemicals
A
help stabilize free radicals
12
Q
Antioxidant enzymes
A
◦Break down oxidized fatty acids
◦Make more vitamin antioxidants available to fight other free radicals
13
Q
Nutrients as antioxidants
A
Certain compounds stabilize free radicals and prevent damage to cells and tissues
Nutrients with antioxidant properties include:
◦Vitamin E
◦Vitamin C
◦Beta-carotene (phytochemical and precursor to vitamin A)
-vitamin A
-selenium
14
Q
LDL
A
Cholesterol from liver to the body
Live does not make LDL
14
Q
LDL
A
Cholesterol from liver to the body
Live does not make LDL
15
Q
HDL
A
Cholesterol from body to liver
15
Q
HDL
A
Cholesterol from body to liver
16
Q
VLDL
A
Liver makes
16
Q
VLDL
A
Liver makes
17
Q
Antioxidant Enzymes and Enzyme Systems
A
•Break down oxidized fatty acids •Make more vitamin antioxidants Glutathione peroxidase Catalase Superoxide dismutase
17
Q
Antioxidant Enzymes and Enzyme Systems
A
•Break down oxidized fatty acids •Make more vitamin antioxidants Glutathione peroxidase Catalase Superoxide dismutase
18
Q
Superoxide dismutase
A
◦Requires manganese
◦Removes H₂O₂
◦Stops FR production in lipidsh
18
Q
Superoxide dismutase
A
◦Requires manganese
◦Removes H₂O₂
◦Stops FR production in lipidsh
19
Glutathione peroxidase
◦Requires riboflavin
◦Converts FR to less harmful substances
◦e.g. Hydrogen peroxide
19
Glutathione peroxidase
◦Requires riboflavin
◦Converts FR to less harmful substances
◦e.g. Hydrogen peroxide
20
Catalase
◦Converts H₂O₂ to H₂O and O₂
20
Catalase
◦Converts H₂O₂ to H₂O and O₂
21
Vitamin E
```
Fat soluble, absorbed with dietary fats
◦Incorporated into
◦Chylomicron to be transported to the liver
◦Liver incorporates into VLDLs
Stored in
◦Adipose tissue
◦Cell membranes
```
21
Vitamin E
```
Fat soluble, absorbed with dietary fats
◦Incorporated into
◦Chylomicron to be transported to the liver
◦Liver incorporates into VLDLs
Stored in
◦Adipose tissue
◦Cell membranes
```
22
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)
22
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)
23
Functions of vitamin E
```
Protects against oxidation
◦PUFAs
◦Fatty cell components
◦LDLs (lower heart disease risk)
◦Added to oil-based foods and skincare products to reduce rancidity and spoilage
Normal nerve and muscle development
```
23
Functions of vitamin E
```
Protects against oxidation
◦PUFAs
◦Fatty cell components
◦LDLs (lower heart disease risk)
◦Added to oil-based foods and skincare products to reduce rancidity and spoilage
Normal nerve and muscle development
```
24
UL for vitamin E
1,000 mg alpha-tocopherol per day
24
UL for vitamin E
1,000 mg alpha-tocopherol per day
25
Food Sources of Vitamin E
```
Abundant in plant-based foods
◦Vegetable oils
◦Safflower, sunflower, canola, soybean
◦Mayonnaise
◦Salad dressing
◦Nuts, seeds, soybeans
◦Wheat germ, fortified cereals
Destroyed by exposure
◦O₂, metals, ultraviolet light and heat
◦Little vitamin E in deep-fried, processed foods
```
25
Food Sources of Vitamin E
```
Abundant in plant-based foods
◦Vegetable oils
◦Safflower, sunflower, canola, soybean
◦Mayonnaise
◦Salad dressing
◦Nuts, seeds, soybeans
◦Wheat germ, fortified cereals
Destroyed by exposure
◦O₂, metals, ultraviolet light and heat
◦Little vitamin E in deep-fried, processed foods
```
26
Vitamin E Toxicity
High supplemental may be harmful
◦Side effects nausea, intestinal distress and diarrhea
◦Interacts with anticoagulants
◦Aspirin, Coumadin
◦Long-term use may cause hemorrhagic stroke
26
Vitamin E Toxicity
High supplemental may be harmful
◦Side effects nausea, intestinal distress and diarrhea
◦Interacts with anticoagulants
◦Aspirin, Coumadin
◦Long-term use may cause hemorrhagic stroke
27
Vitamin E deficiency
```
Deficiency is rare
◦Associated with fat malabsorption
Erythrocyte hemolysis leads to anemia
Anemia in premature infants
Other deficiency symptoms:
◦Loss of muscle coordination and reflexes
◦Impaired vision, speech
◦Impaired immunity (with low selenium)
```
27
Vitamin E deficiency
```
Deficiency is rare
◦Associated with fat malabsorption
Erythrocyte hemolysis leads to anemia
Anemia in premature infants
Other deficiency symptoms:
◦Loss of muscle coordination and reflexes
◦Impaired vision, speech
◦Impaired immunity (with low selenium)
```
28
Functions of vitamin C
```
Functions of Vitamin C
Water soluble
◦Limited storage, daily consumption required
Functions include synthesis of:
◦Collagen
◦Part of all connective tissues in body
◦Other
◦DNA
◦Bile
◦Neurotransmitters
◦Serotonin
◦Carnitine
◦Transports long-chain fatty acids
◦Hormones
Antioxidant for protecting:
◦LDL-cholesterol from oxidation
◦Lungs from ozone and cigarette damage
◦White blood cells
◦Enhances immune function
◦Regenerates oxidized vitamin E in lungs
Reduces nitrosamines in stomach
◦Cancer-causing agent found in cured and processed meats
Enhances iron absorption
◦Non-heme
```
28
Functions of vitamin C
```
Water soluble
◦Limited storage, daily consumption required
synthesis of:
◦Collagen
◦Part of all connective tissues in body
◦DNA
◦Bile
◦Neurotransmitters
◦Serotonin
◦Carnitine
◦Transports long-chain fatty acids
◦Hormones
Antioxidant for protecting:
◦LDL-cholesterol from oxidation
◦Lungs from ozone and cigarette damage
◦White blood cells
◦Enhances immune function
◦Regenerates oxidized vitamin E in lungs
Reduces nitrosamines in stomach
◦Cancer-causing agent found in cured and processed meats
Enhances iron absorption
◦Non-heme
```
29
Vitamin C Requirements
```
RDA:
◦90 mg/day (men)
◦75 mg/day (women)
◦Smokers require additional 35 mg/day
◦Need also increased:
◦Healing from traumatic injury, surgery, burns
◦Use of oral contraceptives
UL: 2,000 mg/day for adults
```
30
Food Sources of Vitamin C
```
Best sources:
◦Fresh fruits and vegetables
◦Citrus
Sensitive to cooking losses
◦Can be leached into boiling water
◦Destroyed by heat and O₂
◦Limit exposure to minimize loss
◦Steaming, microwaving, stir-frying, blanching
```
31
Too Much Vitamin C?
```
Water soluble
◦Extra excreted
◦Expensive urine
◦Consuming excess is not toxic
◦Only supplements can lead to toxic doses
◦Decreased absorption at high doses
◦Usually absorbed via active transport
◦In high doses, absorbed via simple diffusion
Megadoses
◦Prooxidant effect
◦Contraindicated with hemochromatosis
◦Excess iron accumulation in the body
```
32
Not enough Vitamin C?
```
Rare in developed countries
◦Highest risk among people with
◦Low fruit and vegetable intake
◦Alcohol and drug abuse
Scurvy: (can't synthesize collagen)
◦Most common deficiency disease
◦Symptoms
◦Pinpoint hemorrhages
◦Bleeding gums, loose teeth
◦Wounds that fail to heal
◦Bone pain and fractures
Anemia can result
```
33
Beta carotene
```
Beta-Carotene
Provitamin A,
◦Inactive form (precursor) of vitamin A
◦Converted to active retinol
Phytochemical classified as a carotenoid
```
34
Retinol Activity Equivalents (RAE)
◦Used to express vitamin A content of foods
| ◦Indicates how much active vitamin A is available to the body after conversion
35
Beta carotene requirements
```
Beta-carotene is not an essential nutrient
No RDA established
Large consumption is not toxic
◦Carotenosis (carotenodermia)
◦Orange/yellow skin
◦Reversible and harmless
Supplementation is not recommended
◦Adequate amounts from fruits and vegetables
◦No known deficiency symptoms
```
36
Beta carotene functions
```
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
```
37
Vitamin A
```
Fat soluble vitamin
Active forms:
◦Retinol, retinal, retinoic acid
Stored mainly in the liver
Can't absorb if we don't have fat
```
38
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
39
Vitamin A preformed
Comes from animals
| Retinoids as a class
40
Retinal, retinol, and retinoic acid
Retinol can go to retinal, retinal can go to retinoic acid, but once it gets to the acid it can't go back
All bone health and immune function
Retinol and retinal: vision sexual reproduction
Retinoic acid: cell differentiation
41
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)
42
Vitamin A toxicity
mainly from supplements
Stored in liver so easy to become toxic
◦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
43
Deficiency of vitamin A
◦Night blindness
◦Xerophthalmia
◦Hyperkeratosis
◦Impaired immunity, failure of normal growth
44
Proformed vitamin A
From plants
| Carotenoids as class
45
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
46
Selenium deficiency
-When soil is deficient, food is too
-Soil near ocean deficient (New Zealand)
-Deficiency associated with
◦Keshan disease, a heart disease
-China. Selenium deficiency makes you more susceptible to the disease, isn't the cause
◦Kashin-Beck disease, deforming arthritis
◦Impaired immunity
47
Additional antioxidants
Copper, zinc, and manganese
- part of superoxide dismutase enzyme antioxidant complex
- Iron is part of the catalase structure
- Copper, iron, and zinc for blood health
48
Antioxidants and cancer
◦Enhance immune system
◦Inhibit cancer cell growth
◦Prevent oxidative damage to cells
49
Antioxidants and cardiovascular disease
```
◦Scavenge free radicals
◦Reduce low-grade inflammation
◦Reduce blood coagulation and clot formation
Scavenger cells remove oxidized LDL
◦Receptors bind to negatively charged LDL
◦Liberates cholesterol
◦Re-esterified in cell
◦Massive deposit of cholesterol esters
◦Locally in the blood vessel
```
