26.9 Biochem: Vitamins

Question 1

What are vitamins?

Answer 1

Organic compounds, essential biochemical functions (not made by the body)

Question 2

What are the fat soluble vitamins?

Answer 2

K A D E

Question 3

What are the water soluble vitamins?

Answer 3

Thiamin (B1), B2, Niacin (B3), B6, pantothenic acid, biotin, folate, B12, Vitamin C

Question 4

Where are Vit K and biotin also made?

Answer 4

Small amounts by bacteria in terminal small intestine

Question 5

What does a thiamin deficiency result in? (2) When can it be depleted?

Answer 5

Rapid depletion in starvation

Beriberi (polished rice)
Wernicke-Korsakoff (alcoholics)

Question 6

What does Beriberi result in?

Answer 6

Weakness, paralysis, anaemia and wasting

Low serum albumin–>oedema

Question 7

What happens to the tongue in riboflavin deficiency? What is this often due to?

Why?

Answer 7

Sore, swollen, magenta tongue

Chronic alcoholism

Riboflavin (B2) is a cofactor in redox, including TCA cycle

Question 8

What can a niacin deficiency result in?

How does this deficiency occur?

Answer 8

Pellagra (4Ds)

If alcoholic or only corn eaten)

Question 9

What is B6 (pyridoxine) important for? When can a deficiency occur?

Answer 9

Amino acid metabolism

Deficiency rare, but occured in 60s with OCP and high oestrogen dose

Question 10

Where does biotin come from? What can a deficiency be due to?

Answer 10

Cooked egg yolk

Deficiency from eating large amounts of raw eggs (avidin antagonises biotin)

Question 11

Who is folate deficiency common in?

Why is it important in pregnant women?

Answer 11

Elderly and chronic alcoholics

Macrocytic anaemia and spina bifida can result

Question 12

What is an indicator of folate deficiency in adults?

Answer 12

Red, painful tongue (glossitis). Papillae atrophy and surface is smooth and shiny

Question 13

What is B12 important for? What can occur in a deficiency?

Answer 13

Folate metabolism, transalkylations

Pernicious anaemia (light coloured irises, grey hair, inelastic velvety smooth skin)

Question 14

What is necessary for Vit B12 absorption?
What gene encodes it? What else can cause deficiency?

What can treat it?

Answer 14

Intrinsic factor

Encoded by the GIF gene

Autoantibodies against IF can lead to pernicious anaemia

Treat with B12 injection

Question 15

What is Vit C important for? (4)

Answer 15

Collagen synthesis
NTM metabolism
Iron absorption
Antioxidant

Question 16

What is Vit A derived from? Where is it stored? What is it imporant for?

Answer 16

B-carotene
In liver
(retinol) needed for epithelium growth and night vision

Question 17

Where is Vit D derived from? What is it important for?

Answer 17

Derived from cholesterol (requires UV light for synthesis)

important in Ca2+ regulation and bone development

Question 18

What does a vitamin D deficiency result in (young and adults)?

What is a low enough level to trigger supplement intake?

Answer 18

Young: Knock-knees and bow legs

Adult: osteomalacia

Question 19

What leaks calcium and has to be made up for by Vit D dependent gut absorption??

How much calcium is stored in bone?

Answer 19

Kidney leaks 1g/ day

1.2kg calcium stored in bone

Question 20

What does Vit E do?

Where is it found in high levels?

Answer 20

An antioxidant

Seed oils

Question 21

Why can taking antioxidants actually be a negative thing?

Answer 21

Antioxidants destroy free radicals

BUT, DNA repair gene HIF-1 needs these free radicals. Immune system also used free radicals to kill rogue cells including cancer

Question 22

Why may newborns get a Vitamin K deficiency? How do we prevent this?

Answer 22

Sterile gut, so no flora to make Vit K. Haemorrhagic disease of the newborn can be avoided with an injection