Micronutrients as Antioxidants Flashcards
Define Antioxidant
Agent that functions to stop oxidative stress
Radical Scavenging
accept or donate electrons to terminate chain reactions
Radical pro-oxidants
superoxide, Hydroxyl radical, nitric oxide, peroxyl radical
Non-radical oxidants
hydrogen peroxide, ozone, disulfide, hypochlorous acid
What are the antioxidants
Selenium, C, E, A, Beta-carotene, Lutein, Lycopene, Flavonoids, Glutathione, Superoxide dismutase, Glutathione peroxidase, Catalase, Thioredoxin reductase
Vitamin C Overview
ascorbate, ascorbic acid, water-soluble, ascorbic acid is an electron donor
Good sources of Vitamin C:
strawberries, oranges, kiwis, red pepper, broccoli, tomatoes
What is the UI of Vit C?
2 g/d (bloating, diarrhea)
Who might benefit from a vit c supplement?
endurance athletes
How is vitamin C absorbed and stored?
In small intestine through sodium-dependent vitamin c transporters, 80% of what is ingested is absorbed, acorbate is primary circulating form, water soluble
Vitamin C functions
Cofactor for oxygenase reactions: -neurotransmitter synthesis -carinitine synthesis -collagen synthesis Antioxidant electron donor -Increases absorption of non-heme iron absorption -prevention of protein oxidation -prevention of ldl oxidation -quenching of ros -quenching of lipid peroxidation
Vitamin C deficiency
Scurvy!
Symptoms: petechial hemorrhage, bleeding gums, ecchymoses, hyperkeratosis, joint pain, shortness of breath
At risk: cancer cachexia, poor intake, malabsorption, alcoholism
Vitamin E overview
group of fat-soluble compounds, alpha-tocopherol is the only form recognized to meet human requirements
Sources of Vit E
nuts, oils, mango, pumpkin, sweet potato,
RDA and UI of Vit E
RDA for Adult, 15mg, UL: 1,000 mg/d based on risk of hemorrhage (increases blood coagulation time)
Vitamin E absorption
taken into enterocyte, incorporated into chylomicrons->lymph-> blood about half of vit E consumed is absorbed
Functions of Vitamin E
Free radical scavenging antioxidant
cell signaling
regulation of gene expression
protection of endothelial integrity
Vitamin E deficiency and toxicity
rate, there is no storage organ for Vit E
Carotinoids overview
family of 600 fat- soluble plant pigments
alpha carotene, beta carotene, beta cryptoxanthin, lutein, zeaxantin, lycopene
carotenoids functions
antioxidant activity, light filtering, cellular communication, provitamin A activity
flavenoids overview
anthocyandidins, flavanols, flavanones, flavonols, flavones, isoflavones,
flavonoid functions
antioxidant activity, cell-signaling effects
Define oxidative stress
an imbalance in pro-oxidant and antioxidant reactions that causes macromolecular damage or disrupts biologic redox signaling
