26.9 Biochem: Vitamins Flashcards
(22 cards)
What are vitamins?
Organic compounds, essential biochemical functions (not made by the body)
What are the fat soluble vitamins?
K A D E
What are the water soluble vitamins?
Thiamin (B1), B2, Niacin (B3), B6, pantothenic acid, biotin, folate, B12, Vitamin C
Where are Vit K and biotin also made?
Small amounts by bacteria in terminal small intestine
What does a thiamin deficiency result in? (2) When can it be depleted?
Rapid depletion in starvation
Beriberi (polished rice)
Wernicke-Korsakoff (alcoholics)
What does Beriberi result in?
Weakness, paralysis, anaemia and wasting
Low serum albumin–>oedema
What happens to the tongue in riboflavin deficiency? What is this often due to?
Why?
Sore, swollen, magenta tongue
Chronic alcoholism
Riboflavin (B2) is a cofactor in redox, including TCA cycle
What can a niacin deficiency result in?
How does this deficiency occur?
Pellagra (4Ds)
If alcoholic or only corn eaten)
What is B6 (pyridoxine) important for? When can a deficiency occur?
Amino acid metabolism
Deficiency rare, but occured in 60s with OCP and high oestrogen dose
Where does biotin come from? What can a deficiency be due to?
Cooked egg yolk
Deficiency from eating large amounts of raw eggs (avidin antagonises biotin)
Who is folate deficiency common in?
Why is it important in pregnant women?
Elderly and chronic alcoholics
Macrocytic anaemia and spina bifida can result
What is an indicator of folate deficiency in adults?
Red, painful tongue (glossitis). Papillae atrophy and surface is smooth and shiny
What is B12 important for? What can occur in a deficiency?
Folate metabolism, transalkylations
Pernicious anaemia (light coloured irises, grey hair, inelastic velvety smooth skin)
What is necessary for Vit B12 absorption?
What gene encodes it? What else can cause deficiency?
What can treat it?
Intrinsic factor
Encoded by the GIF gene
Autoantibodies against IF can lead to pernicious anaemia
Treat with B12 injection
What is Vit C important for? (4)
Collagen synthesis
NTM metabolism
Iron absorption
Antioxidant
What is Vit A derived from? Where is it stored? What is it imporant for?
B-carotene
In liver
(retinol) needed for epithelium growth and night vision
Where is Vit D derived from? What is it important for?
Derived from cholesterol (requires UV light for synthesis)
important in Ca2+ regulation and bone development
What does a vitamin D deficiency result in (young and adults)?
What is a low enough level to trigger supplement intake?
Young: Knock-knees and bow legs
Adult: osteomalacia
What leaks calcium and has to be made up for by Vit D dependent gut absorption??
How much calcium is stored in bone?
Kidney leaks 1g/ day
1.2kg calcium stored in bone
What does Vit E do?
Where is it found in high levels?
An antioxidant
Seed oils
Why can taking antioxidants actually be a negative thing?
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
Why may newborns get a Vitamin K deficiency? How do we prevent this?
Sterile gut, so no flora to make Vit K. Haemorrhagic disease of the newborn can be avoided with an injection
