W1

Question 1

Sources of VD

Answer 1

Sunlights (facilitates conversion of or prod of VD in the skin)

Cod-liver oil

Wild salmon

Yoghurt

Egg yolk

Mushrooms

Question 2

RNI for VD

Answer 2

10 micrograms/day

Question 3

How do we produce vitamin D in the skin?

Answer 3

Skins exposure to UV b radiation triggers the conversion of 7-dehydrocholesterol through a 2 step process.

Question 4

What is step 1 of the 2 step process to producing VD in the skin?

Answer 4

7-dehydrocholesterol –> pre-cholecalciferol (VD2)

Question 5

What is step 2 of the 2 step process to producing VD in the skin?

Answer 5

pre-cholecalciferol (VD2)–> cholecalciferol (VD3)

Question 6

What happens once VD2 or VD3 enters circulation?

Answer 6

Can be converted or activated by an enzyme in the liver to produce 25[OH] D2 or “D3.

Question 7

What enzyme in the liver aids in production of 25[OH] D2 or “D3

Answer 7

Hepatic 25-hydroxylase

Question 8

Where does 25[OH] D2 or “D3 travel to?

Answer 8

Kidney

Question 9

What happens to 25[OH] D2 or “D3 at the kidney?

Answer 9

2nd activation stage = prod of active form of VD.

Can then act on target tissues.

Question 10

Functions of VD

Answer 10

Aids in calcium absorption = role in Ca2+ homeostasis

Bone metabolism

NM function

Immune function

CV function

Mitochondrial function

Question 11

Function of VD

Immune function

Answer 11

Improved macrophage + monocyte function

⬆️ URTI rate w/ poor VD status

Question 12

In the process of producing VD in the body, which substance is the one measured in blood samples and why?

Answer 12

25[OH] D2 / “D3 in the first step of activation by the liver

To quantify VD status of ind

Question 13

What is the target serum conc for athletes?

Answer 13

~75nmol.L-1 to achieve optimal performance

Question 14

How can the target serum conc be achieved by elite athletes

Answer 14

Through supplementation of 4000 IU per day of VD.

Question 15

Cannabidoil in Rugby

Answer 15

Kasper et al. 2020

26% players have or are using CBD

41% over 28yrs have or are using CBD - Pot. due to feeling more pain + having slower recoveries

14% perceived improvement in pain or soreness

Question 16

Why is there a high risk of obtaining a doping infringement from taking a commercially available CBD oil supplement?

Answer 16

Hard for suppliers/producers to guarantee that their supplement contains ONLY CBD = high risk to athletes being tested.

Question 17

What does a recent review state about the supplements tested for purity?

Answer 17

58% supplements tested are contaminated

Martinez-Sanz et al, 2017

Question 18

What is inadequate Vitamin D status as indicated by ?

Answer 18

measurement of blood 25(OH)D (< 30 – 50 nmol.l-1 or 12 - 20 ng.ml-1).