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Sports Nutrition > W8 - Anti-oxidant Supplements > Flashcards

W8 - Anti-oxidant Supplements Flashcards

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Sports Trivia flashcards
1
Q

What are free radicals?

A

A type of reactive species

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2
Q

Environmental sources of oxidants

A

UV radiation

Pollution

Smoking

Burnt food

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3
Q

Cellular sources of oxidants

A

Oxidase enzymes

Mitochondrial respiration

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4
Q

What happens when reactive species exposure exceeds anti-oxidant defences?

A

Damage to lipids

Damage to body proteins

DNA damage

Triggers inflammation

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5
Q

When reactive species exposure exceeds antioxidant defences

What comes under damage to lipids?

A

Peroxidation

Damage to cell membranes –> Dysfunctional cells

Red NO bioavailability –> Impaired bv function

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6
Q

When reactive species exposure exceeds antioxidant defences

What comes under damage to body proteins?

A

Oxidative modification

Altered function –> ageing

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7
Q

What are the anti-oxidant systems available to combat the effects of reactive species

A

Endogenous antioxidants (enzymatic + non-enzymatic i.e uric acid)

Nutritional (VC,E+ carotene, minerals i.e copper + zinc, polyphenols i.e flavonoids)

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8
Q

What are polyphenols?

A

A nutritional source of potential antioxidants

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9
Q

What comes under polyphenols

A

Flavonoids

Lignans

Phenolic Acids

Stilbenes

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10
Q

What is the direct antioxidant property?

A

Radical scavengers

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11
Q

What is the challenge faced by polyphenols acting as radical scavengers?

A

Their bioavailability is poor

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12
Q

Develop of the poor bioavailability of polyphenols

i.e if a cherry reaches the intestines

A

Only ~5-10% of the polyphenols consumed will actually make it into circulation.

Reminder will continue down GI tract to colon due to not being able to be broken down to be absorbed.

Once in colon, broken down + exposed to the microbiome which can help break down more polyphenols to become bioavailable.

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13
Q

Uric acid in plasma

A

Uric acid is present in high levels within plasma (150-450μM)

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14
Q

Uric acid in plasma and radical scavenging capacity

A

Confers ~60% of the radical scavenging capacity of the plasma.

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15
Q

Peak plasma phenolic conc

A

<10μM.

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16
Q

What is it thought polyphenols are converted to?

A

Into a stable radical i.e pro-oxidants

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17
Q

What are pro-oxidant compounds called?

A

Semiquinones

Quinones

18
Q

What do pro-oxidants semiquinones and quinones do?

A

Trigger increased synthesis of endogenous antioxidants

= Triggering cells to prod more of the enzymatic antioxidant systems

19
Q

What does evidence suggest about phenolic compounds absorbed from polyphenols?

A

That they are able to inhibit the prod of ROS

  • Meaning they can inhibit enzymes such as NADPH oxidase
20
Q

When is there an increased generation of ROS + NOS

A

During exercise

21
Q

Half-life of reactive species

A

VERY SHORT

22
Q

Indirect markers of reactive species

A

Looking at compounds that are indicative or are markers of oxidative damage.

i.e Protein carbonyls and nitrotyrosine or MDA.

23
Q

Direct markers of reactive species

A

e- paramagnetic spin resonance which are like spin traps for specific radicals whereby it fixes them in time, preventing them from changing

24
Q

What is meant by oxidative stress?

A

When the generation of reactive species overwhelms the antioxidant defences

25
Q

ROS + NOS exposure contributes to fatigue development in various ways causing issue to…

A

Ionic gradients
E-C coupling
Central drive
Substrate depletion
By-product accumulation
Muscle perfusion

—— Their relative contribution will depend on the intensity and duration of the exercise.

26
Q

What does ROS exposure trigger?

A

Incr prod of antioxidant enzymes due to particular signalling mechanisms involving the nuclear transcription factor nrf2 which is normally bound to another protein called KEAP1.

27
Q

Can the nrf2 and KEAP1 complex enter the nucleus?

A

NO

28
Q

Why does the nrf2 and KEAP1 complex need to enter the nucleus?

A

To incr prod of antioxidant enzymes

29
Q

What happens when the nrf2 and KEAP1 complex is exposed to ROS + NOS

A

It dissociates

= Allows nrf2 to become small enough to enter the nucleus where it triggers a cascade of signalling through a whole series of proteins incl. a system called the antioxidant response element.

30
Q

What happens when the antioxidant response element is activated?

A

Triggers prod of incr level os some of our key antioxidant enzymes.

31
Q

Levels of what are sig higher in trained individuals than in sedentary individuals

A

Dismutase

Catalase

Peroxiredoxin

32
Q

What is N-acetylcysteine

A

A direct oxidant scavenger

33
Q

What can the thiol containing compound in the N-acetylcysteine do?

A

Donate a cysteine to support the function of 1 of our antioxidant systems glutathione.

34
Q

What is suggested about supplementing N-acetylcysteine?

A

That it can reduce exposure to reactive species

+

Reduce the inflammatory response post-exercise.

35
Q

N-acetylcysteine (NAC) supplementation and cycling sprint performance

A

Improved

Better tolerance of increased training intensity

36
Q

NAC supplementation for endurance and sprint performance

A

Some studies suggest NAC is better for endurance rather than sprint performance.

37
Q

Purported properties of quercetin

A

Anti-oxidant

Anticarcinogenic

Cardioprotective

Ergogenic

38
Q

500-1000mg quercetin a day…

A

Provided a 2.8% increase in endurance perf.

39
Q

7 days cherry supplementation and cycling TT perf

A

Cycling TT perf was enhanced

– Possibly via improved muscle perfusion.

Plausible mechanisms for a favourable influence on cognitive function or decision making during exercise.

40
Q

Rationale as to why we think its worth exploring antioxidants in regards to ergogenic effects

A

Seen that oxidative stress + inflammation are contributing factors to the process of muscle damage, so can antioxidants protect against muscle damage +/or improve recovery from muscle damage?

  • Benefit for athletes during intensive training +/or intense competition.
41
Q

Antioxidant vitamin supplementation on recovery from intensive exercise

A

NO sig effects

42
Q

Functional recovery from intensive exercise after 7 days pre-loading with Montmorency cherry concentrate (~550mg anthocyanin/d)

A

Enhanced functional recovery

Sports Nutrition (14 decks)

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