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Exercise Immunology > Vitamin D > Flashcards

Vitamin D Flashcards

1
Q

Define a dietary immunostimulant?

A

Food constituents or supplements that are claimed to boost immunity and reduce the risk of infection

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2
Q

The problem linked to dietary immunostimulants in athletes?

A

The evidence for their efficacy in reducing infections (pathogens resistance) is limited

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3
Q

What is the aim of pathogen resistance?

A

Increase immunity to restrict pathogen entry

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4
Q

What is the aim of immune tolerance?

A

Reducing the duration and severity of symptoms

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5
Q

What the problem with prescribing supplements to athletes?

A

Evidence is based on data from clinically suppressed populations, therefore, there is greater potential for nutritional supplementation to have a benefit on the immune function

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6
Q

Common food sources of Vitamin D?

A 
Oily fish
Red meat
Egg yolk
Liver
Fortified food - cereals, milk, and mushrooms
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7
Q

As a general rule, what % of our Vitamin D comes from the diet?

A

10-20%

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8
Q

How is Vitamin D synthesised?

A

7-Dehydrocholestrol reacts with UV rays -> Cholecalcifol (Vitamin D3) -> liver (location of dietary Vitamin D2 and 3) -> converted to 25-hydroxyvitamin D3 -> kidney -> 1,25-dihydroxyvitamin D3 -> maintain calcium balance in the body

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9
Q

What is the active form of Vitamin D in the body?

A

1,25-dihydroxyvitamin D3

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10
Q

What’s the association between Northen Latutides and Vitamin D?

A

Between the months of November to March, there are insufficient UV-B rays to produce vitamin D

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11
Q

What is the role of Vitamin D in immunity?

A 
Bone health
Muscle function
Direct effect on innate immune function
Reduces inflammation
Reduces overactive (auto)immunity
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12
Q

How does Vitamin D directly affect innate immune function?

A

Increases monocyte oxidative burst activity
Increases antigen-presenting compounds function
Increases macrophage production of antimicrobial proteins

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13
Q

What’s a dietary source of Vitamin D3?

A

Foods

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14
Q

What’s a dietary source of Vitamin D2?

A

Supplements

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15
Q

In Bellavia et al. 2016 what’s the role of 1,25-dihydroxyvitamin D3 on immunity - Macrophages and Monocytes?

A

Increase antimicrobial peptides
Increase phagocytosis in macrophages
Decrease IL-6 and IL-12

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16
Q

In Bellavia et al. 2016 what’s the role of 1,25-dihydroxyvitamin D3 on immunity - Th17 cells?

A

Decreased differentiation in Th17 cells - promotes autoimmunity
Decrease IL-17a, IL-17F, TNF-a, and IL-21
Increase apoptosis

17
Q

In Bellavia et al. 2016 what’s the role of 1,25-dihydroxyvitamin D3 on immunity - Th1 cells?

A

Decreased differentiation in Th1 cells
Decrease TNF-a, IL-2, IL-9, IL-22
Increase apoptosis

18
Q

In Bellavia et al. 2016 what’s the role of 1,25-dihydroxyvitamin D3 on immunity - Dendritic cells?

A

Decreased expression of MHC class 2
Decreased presenting antigen cells
Decrease IL-2 and IL-23
Increase TGF-B and IL-10

19
Q

In Bellavia et al. 2016 what’s the role of 1,25-dihydroxyvitamin D3 on immunity - B-cells?

A

Decreased proliferation of B-cells
Decreased differentiation into plasma cells
Decreased secretion of immunoglobulins

20
Q

In Bellavia et al. 2016 what’s the role of 1,25-dihydroxyvitamin D3 on immunity - T-helper type-2 response?

A

Increased differentiation in Th2 cells

Increase IL-3, IL-4, IL-5, and IL-10

21
Q

In Bellavia et al. 2016 what’s the role of 1,25-dihydroxyvitamin D3 on immunity - Treg cells?

A

Increased differentiation in T-regs

Increase IL-10 and TGF-B`

22
Q

Relationship between Vitamin D concentration and self-reported URT infection? (Ginde et al. 2009)

A

The higher your Vitamin D intake the less likely you are to report a URT infection
Well established relationship

23
Q

Vitamin D and seasonal variations in respiratory infection? (Berry et al. 2011)

A

Protocol
- controlled for adiposity, lifestyle, and socio-economic factors
Results
- vitamin D status mirrors respiratory infections
- each 10nmol/L increase in 25(OH)D as associated with 7% decrease in infection

24
Q

Which increase in 25(OH)D (nmol/L) is associated with 7% decrease in infection? (Berry et al. 2011)

A

10nmol/L

25
Q

Each 10nmol/L increase in 25(OH)D is associated with what % decrease in infection? (Berry et al. 2011)

A

7%

26
Q

Vitamin D status amount UK athletes in winter? (He et al. 2013)

A

Only 5% of athletes have optimal vitamin D status throughout the year
During the winter vitamin D status is reduced
Trend suggesting that higher levels of vitamin D are associated with lower levels of URI incidence
Higher levels of vitamin D reduce symptom severity and improves vitamin D tolerance
Higher levels of vitamin D reduce symptom duration
A sub-optimal vitamin D status is associated with low saliva S-Iga secretion rate
A sub-optimal vitamin D status is associated with low plasma cathelicidin

27
Q

What is plasma cathelicidin?

A

An antimicrobial protein made by macrophages and neutrophils

28
Q

What do you need to consider when assessing studies looking at vitamin D supplementation in athletes?

A 
Duration
Diet
Dose
Environment
Method of supplementation
Prior activity level
Latitude
Sample size
Sample timing
29
Q

Vitamin D supplementation in sub-elite athletes? (He et al. 2016)

A

Protocol
- 39 endurance athletes
- latitude = 53 degrees north
- 5000 IU (125ug) of vitamin D3 (tablet) vs placebo
- 14wks during winter training
Results
- vitamin D status was increased with supplementation and decreased in the placebo (due to winter)
- increase in SIgA secretion rate, cathelicidin levels in plasma and saliva over time with vitamin D3 supplementation after 7wks, however, a decrease after 14wks

30
Q

Why might SIgA secretion rate increase with supplementation after 7wks, yet decrease after 14wks? (He et al. 2016)

A

The effect of vitamin D supplementation might occur very quickly and disappear over time
This might be due to higher exposure to infections during the winter

31
Q

Vitamin D oral spray and vitamin D levels in Gaelic footballers? (Todd et al. 2017)

A

Protocol
- 43 Gaelic footballers
- latitude = 55 degrees north
- 3000 IU (75ug) of vitamin D3 (oral spray) vs placebo
- 12wks during winter training
Results
- vitamin D status increased ith the vitamin D3 oral spray and remained low in the placebo group
- no effect of vitamin D3 oral spray on plasma cathelicidin

32
Q

What could account for the differences between He et al. (2016) and Todd et al. (2017)?

A

Dose
Post-intervention period levels of Vitamin D
Sample timing

33
Q

Why might vitamin D3 dose affect results between He et al. (2016) and Todd et al. (2017)?

A

Might be a threshold value to elicit effects

34
Q

Why might post-intervention period levels of vitamin D3 affect results between He et al. (2016) and Todd et al. (2017)?

A

Todd et al. 2017 potentially didn’t reach sufficient optimal levels to elicit effects, linked to dose

35
Q

Why might the sample timing of vitamin D3 effect results between He et al. (2016) and Todd et al. (2017)?

A

Differences have been seen at 7 wks (He et al. 2016), whereas Todd et al. 2017 only measures after 12wks

36
Q

Which is one potential reason He et al. (2016) and Todd et al. (2017) did not assess URS?

A

The number of participants was too small to meaningfully assess the association between vitamin D and URS

37
Q

Supplementation in vitamin D deficient Taekwondo athletes? (Jung et al. 2018)

A

Protocol
- 25 athletes
- latitude = 33 degrees north
- 5000 IU (125ug) of vitamin D3 vs placebo
- 4wks during winter training
Results
- vitamin D status increased with vitamin D3 supplementation and remained low in the placebo groups
- URS symptom score was lower with vitamin D3 supplementation
- no difference in SIgA concentration between the groups

Exercise Immunology (3 decks)

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