Chapter 12 - Antioxidants Flashcards
What are free radical and reactive oxygen species?
- Highly unstable compounds
- Participate in rxns involving transfer of electrons
- Initiate and propagate chain reactions leading to molecular-cellular damage
What are antioxidants?
Compounds that neutralize free radicals by donating an electron. They also sequester or bind free radicals or ROS.
What do free radicals and ROS cause damage to?
- Cell membranes
- Lipoproteins
- Proteins
- Lipids and macromolecules in the cell
- Genetic material (DNA)
Cellular damage due to free radicals and ROS contributes to what diseases?
Markers for:
* Parkinson’s
* Alzheimer’s
* Coronary artery disease
* Atherosclerosis by diabetes
* Renal disease
* Cancer
What are dietary antioxidants?
Nutrient or non-nutrients in foods that significantly decrease adverse effects of free radical & ROS on physiological functions
What vitamins are dietary antioxidants?
Vitamin E and C
What minerals act as dietary antioxidants?
Selenium, Zinc, Copper, and Manganese
What are the functions of Vitamin A? (2)
- Lipid digestion and absorption patheways
- Intracellular transport with retinol-binding protein (RBP)
What is beta-carotene?
Precursor for Vitamin A
What are three forms of Vitamin A in the body?
- Retinol (alcohol form)
- Retinal (aldehyde form)
- Retinoic acid (acid)
What form of vitamin a is found animal foods?
Retinyl esters
What form of Vitamin A is found in plant foods?
Beta-carotene
What form of vitamin a is involved in bone growth and remodelling?
Retinol
RDA Vitamin A
- Males: 900 RAE/day
- Females: 700 RAE/day
What is 1 RAE equivalent to?
1ug of retinol
How many ug of beta-carotene is equivalent to 1ug of retinol?
12ug
Food sources of Vitamin A
- Paprika
- Yellow/orange fruits and vegetables
- Dark green ‘’
- Tomatoes
- Watermelon
- Carrots
- Citrus fruits
What is the risk of Vitamin A deficiency?
- Increased incidence of infectious disease
- Increased risk of measles, malaria, HIV/AIDS
- Night blindness (lack of retinal in retina)
What is the UL for Vitamin A?
- Adults: 3000ug/day
- Infants: 600ug/day
- Children: 600-1700 ug/day
What is the risk of Vitamin A toxicity?
Risk of osteoporosis and fractures.
What are the functions of Vitamin E?
- Protects lipids for oxidation
- Cell membrane stabilization
- Interacts with other antioxidant mechanisms (Vitamin C)
RDA Vitamin E
15mg/day
Food sources of Vitamin E
- Sunflower, corn, canola, oilve oil
- Almonds
- Pumpkin
How does Vitamin E deficieny arise?
Rare; more likely due to fat malabsorption rather than low dietary intake
What are symptoms of Vitamin E deficiency?
- Hemolytic anemia
- Neuromuscular dysfunction
Can contribute to:
* Cancer
* Cardiovascular disease
* Cataracts
* Alzheimers disease
UL Vitamin E
1000mg/day
Functions of Vitamin C
- Reducing agent or electron donor in enzymatic rxns
- Adrenal gland hormones synthesis
- Collagen synthesis
- Peptide hormone synthesis
RDA Vitamin C
- Males: 90mg/day
- Females: 75mg/day
Smokers +35mg/day
What is Vitamin C deficiency?
Scurvy
Symptoms of Vitamin C deficiency
- Anemia
- Atheroclerotic plaques
- Pinpoint hemorrhages, bone fragility, joint pain
- Poor wound healing
- Bleeding gums and loosened teeth
UL Vitamin C
2000mg/day
Symptoms of Vitamin C toxicity
- Nausea, abdominal cramps, diarrhea
- Headache, fatigue, insomnia
- Hot flashes, rashes
Functions of selenium?
- Antioxidant functions with Vitamin E/C and glutathione peroxidase
RDA Selenium
55ug/day
UL Selenium
400 ug/day
Food sources of selenium
- Brazil nuts
- Seafood
- Organ meats
- Beans
What is selenium deficiency?
Predisposition to Keshan disease, a heart disease associated with virus
Symptoms of selenium deficiency
- Brittle hair and nails
- Rash
- Fatigue and irritability
- Garlic breath odour
What is a cofactor for superoxide dimutase?
- Vitamin C
- Zinc
- Copper
What is a cofactor for GSH Peroxidase?
- Vitamin C
- Selenium
- Iron as catalase
Why is it prefered that antioxidants are sourced from food?
Supplements carry an increased risk for CHD, lung cancer, and GI cancer for smokers
