Lecture 13 - Antioxidants Flashcards
What is the role of antioxidants?
To protect cells from oxidative damage
What are the agents that protect from oxidative damage?
Vitamins quench the radicals
Minerals act as cofactors for enzymes
Phytochemcials
What is a free radical?
Something with an unpaired electron which damages lipids DNA RNA and proteins
What neutralizes free radicals?
Antioxidants
What is the definition of quench?
To get rid of, eliminate
What can antioxidants be thought of?
Dominos, a vitamin would sit inform of the domino to prevent the others from following
Why are minerals required for antioxidants?
They themselves aren’t antioxidants, but they are just required for the function
What creates free radicals?
Any normal reaction in the body
Sun
What are the available forms of vitamin A?
Retinyl Esters: True vitamin a
Beta Carotene: Precursor for vitamin a (not true)
Where are Retinyl esters in the body?
Bonded to fat in the body. Esters will separate from fat to just have retynil
What is the storage form of Vitamin a
Retinal
What is retinol involved in?
Vision related
How do we end up with retinal?
Retinyl (from animal foods) > Converted to retinol > converted into retinal
Beta-carotene (from plants) > Converted to retinal
In the body, what are the different conversions of all the retinoids?
Retinol< >Retinal> Retanoic acid
What happens when we have too much retinal?
It can be converted back to retinol
What is the hormone version of vitamin a?
Retanoic Acid
-involved in DNA, transcription, Cell division, growth, reproduction
Do carotenoids all have the same antioxidant activity?
Yes, but not all of them are converted to vitamin a
What is the pathway for vitamin a once it has been ingested?
It is fat soluble and will end up in the chylomicrons then into the lymph and blood. Once in the blood it binds to binding proteins to be carried within the body
Where is vitamin a role in protein synthesis and cell differentiation
Takes place in epithelial cells on the skin and in the mucos membranes. Vitamin a is there to make sure those cells divide properly
-promotes differentiation of epithelial and goblet cells
How does vitamin a help with reproduction and growth?
Sperm development
Fetal development
Bone remodelling
Failure of growth in children
What does vitamin a deficiency look like?
Vitamin a status
What is vitamin a status?
Amount of vitamin a for you to use is dependant on how much is in your liver as well as your protein status
What happens to vitamin a when you don’t have enough protein?
It won’t transport vitamin a
What is vitamin a deficiency dependent on?
Vitamin a status and protein tatus
Where is vitamin a stored?
In the liver
What results from a vitamin a deficiency?
- Infectious disease
- Night blindness (lack of rhodopsin and inability to recover from changes in light)
- Xerophthalmia (total blindness due to drying and softening of cornea)
- Keratinization
How does vitamin a toxicity occur?
When binding proteins in the blood become swamped, the vitamin isn’t excreted quickly so the free vitamin a can cause damage
-not seen with beta-carotene
Why isn’t vitamin a a treatment for acne?
Vitamin a itself is not used as a treatment for acne but the retinoid used to treat acne have no vitamin a activity
What are some sources of beta carotene?
Yellow+Green veggies
-any vegetable really
Preformed vitamin a in any animal protein with some fat
What is RAE and what are the conversions??
Retinal activity equivalent
1microgram of preformed vitamin a= 1RAE
12micrograms of beta-carotene= 1RAE
What is vitamin e role as an antioxidant?
Primary defender against free radicals
- prevents more free radicals from producing more free radicals
- cell membranes and other lipids
- oxidizes LDL
What is the other name for vitamin e?
Tocopherol
-alpha is the main type
How does vitamin e reduce the oxidization of LDL?
Vitamin e sits in LDL and reduced the oxidation of LDL
-blood vessels see the oxidized LDL as the enemy
Can you become vitamin e deficient?
Primary deficient is rare (fat malabsorption mainly)
-Can present in infants
What happens when you are vitamin e deficient?
Red blood cells break open due to oxidization of PUFAs in RBC membranes
-causes Erythrocyte Hemplysis
Can you become toxic from vitamin e?
Very rare, liver regulated vitamin e
-may interfere with blood clotting because vitamin e is a blood thinner, thus interfering with vitamin k
What is the UL for vitamin e?
set 65x higher than the recommended value
-based on alpha tocopherol
What happens to vitamin e when there is an increase if PUFA?
There is an increase need for vitamin e
What is a source of vitamin e?
Mostly vegetable oils
-easily destroyed by heat and oxidation
What is vitamin c role in the body as an antioxidant?
Loses electrons easily to stop free radical damage
-enhances iron absorption
Cofactor for collagen
-facilitates the binding of collagen fibres
Stress
-adrenal glands secrete vitamin c
What is the real name of vitamin c?
ascorbic acid
-anti scurvy
How much vitamin c do we need to prevent scurvy and to saturate tissue
10mg/day to prevent scurvy
100mg/day to saturate tissues
Why do smokers need more vitamin c?
Smokers are ingesting more chemicals that cause damage, in order to counteract the free radicals, more vitamin c is needed
What is the RDA for vitamin c?
It is set 7x higher than the amount deeded to prevent scurvy
Why is vitamin c harmful for kidneys?
Vitamin c is not stored in the body, and is excreted through the kidneys. If too much is being secreted it could damage kidneys
What does vitamin c deficiency look like?
Scurvy: bleeding gums and breaking capillaries
inadequate collagen, wound heal thing stops, loose teeth, dry skin
What does vitamin c toxicity look like?
Very rare
-GI distress, diarrhea
What does vitamin c have adverse effects on?
Iron overload
Why is Se important in antioxidants?
Part of glutathione peroxidase
-works synergistically with vitamin E
Where do you find Se?
Found in soils and leaches into foods
In some amino acids
Can you become deficient in Se?
Yes, but rare, ,most Canadians meet the RDA for Se
-UL set
Which vitamins work synergistically with each other?
E with Se
E with A
C with E
-they don’t work in isolation
What are the 2 lines of defence against free radicals?
- Antioxidant enzyme defence system
2. Antioxidant nutrients including photochemicals
What is atherosclerosis?
When LDL is oxidized to atherosclerosis
