FNH 250 Antioxidants Exam Questions
And Correct Answers
Which nutrients have antioxidant properties? ...ANSWER...Vitamins A, C, E and beta-carotene.
Fat soluble: A, E. Water soluble: C
Minerals Selenium, Copper, Zinc, Magnesium, Iron.
Why do we need antioxidants? ...ANSWER...Vitamines: donate electrons to stabilize free
radicals
Minerals: activate enzymes to inhibit oxidant formation, intercept oxidants once formed, and
repair oxidant-induced injury
We need antioxidants to reduce naturally occurring reactive oxygen species (ROS), or damage
caused by ROS that have one unpaired electron in their outer orbital.
How does each vitamin act as an antioxidant (brief)? ...ANSWER...Vitamin C: donate electron to
stabilize free radical
Vitamin E: maintains membrane integrity
Vitamin A: protects LDL from oxidation (prevents heart disease)
Beta-carotene: protects against oxidation of cell membrane proteins and LDLs
How do minerals act as an antioxidant (brief)? ...ANSWER...Activate enzyme system to...
1) inhibit oxidant formation
2) Intercept oxidants once formed.
3) Repair oxidant-induced injury
4) Destroy free radicals (unstable atoms)
, What is a free radical? How are they formed? ...ANSWER...Free radicals are unstable atoms that
contain an unpaired electron in their outer orbital.
Causes:
1) Normal metabolic process (e.g., immune responses, production of ATP, oxidizing CHO, PRO,
FAT). Oxygen accepts extra electron released during a metabolic reaction (ex, in ETC) to form a
free radical.
Also, bonds between molecules can split in a way that leaves them with an unpaired electron.
2) Environmental factors: pollution, radiation exposure, UV exposure (excessive sunlight), toxic
substances, tobacco smoke.
What do free radicals target? ...ANSWER...Destabilize other molecules and damage: cell
membranes (lipids), cellular proteins, blood LDL lipoproteins, nuclear DNA.
What are some examples of free radicals? ...ANSWER...-Superoxide radical (O2*-)
-Hydroxyl radical (*OH)
-Nitric oxide (NO*)
How do vitamin antioxidants differ from mineral antioxidants? ...ANSWER...Vitamins: donate
free electron to unpaired electron in the outer orbital of the free radical, thus neutralizing the
free radical and ending it's chain reactions.
Minerals: activate enzymes to destroy free radicals (converted to less harmful molecules that
are excreted from the body)
Who is at greatest risk for vitamin E deficiency? What are the consequences?
Why? ...ANSWER...Preterm infants are at the greatest risk.
Consequence: hemolytic anemia (loss of integrity in blood cell membrane. RBC unable to carry
sufficient oxygen to cells for use in generating energy from macronutrients. Anemia; lethargy).
Why: transfer of vitamin E from mother to fetus normally occurs during the last few weeks of
pregnancy. Low stores, increased need for growth.
Oral supplementation may be needed.
And Correct Answers
Which nutrients have antioxidant properties? ...ANSWER...Vitamins A, C, E and beta-carotene.
Fat soluble: A, E. Water soluble: C
Minerals Selenium, Copper, Zinc, Magnesium, Iron.
Why do we need antioxidants? ...ANSWER...Vitamines: donate electrons to stabilize free
radicals
Minerals: activate enzymes to inhibit oxidant formation, intercept oxidants once formed, and
repair oxidant-induced injury
We need antioxidants to reduce naturally occurring reactive oxygen species (ROS), or damage
caused by ROS that have one unpaired electron in their outer orbital.
How does each vitamin act as an antioxidant (brief)? ...ANSWER...Vitamin C: donate electron to
stabilize free radical
Vitamin E: maintains membrane integrity
Vitamin A: protects LDL from oxidation (prevents heart disease)
Beta-carotene: protects against oxidation of cell membrane proteins and LDLs
How do minerals act as an antioxidant (brief)? ...ANSWER...Activate enzyme system to...
1) inhibit oxidant formation
2) Intercept oxidants once formed.
3) Repair oxidant-induced injury
4) Destroy free radicals (unstable atoms)
, What is a free radical? How are they formed? ...ANSWER...Free radicals are unstable atoms that
contain an unpaired electron in their outer orbital.
Causes:
1) Normal metabolic process (e.g., immune responses, production of ATP, oxidizing CHO, PRO,
FAT). Oxygen accepts extra electron released during a metabolic reaction (ex, in ETC) to form a
free radical.
Also, bonds between molecules can split in a way that leaves them with an unpaired electron.
2) Environmental factors: pollution, radiation exposure, UV exposure (excessive sunlight), toxic
substances, tobacco smoke.
What do free radicals target? ...ANSWER...Destabilize other molecules and damage: cell
membranes (lipids), cellular proteins, blood LDL lipoproteins, nuclear DNA.
What are some examples of free radicals? ...ANSWER...-Superoxide radical (O2*-)
-Hydroxyl radical (*OH)
-Nitric oxide (NO*)
How do vitamin antioxidants differ from mineral antioxidants? ...ANSWER...Vitamins: donate
free electron to unpaired electron in the outer orbital of the free radical, thus neutralizing the
free radical and ending it's chain reactions.
Minerals: activate enzymes to destroy free radicals (converted to less harmful molecules that
are excreted from the body)
Who is at greatest risk for vitamin E deficiency? What are the consequences?
Why? ...ANSWER...Preterm infants are at the greatest risk.
Consequence: hemolytic anemia (loss of integrity in blood cell membrane. RBC unable to carry
sufficient oxygen to cells for use in generating energy from macronutrients. Anemia; lethargy).
Why: transfer of vitamin E from mother to fetus normally occurs during the last few weeks of
pregnancy. Low stores, increased need for growth.
Oral supplementation may be needed.
