81 - Vitamins, Water- and Fat-soluble Flashcards
Alternative name for NAD and NADP
Niacin
Alternative name for Thiamin
TP
Alternative name for FAD, FMN
Riboflavin
Alternative name for vitamin B6
Pantothenic acid
Alternative name for pantothenic acid
CoA
Role of thiamin (B1)
1-3
1) Coenzyme in decarboxylation
2) Carbohydrate, fat, protein metabolism
3) Nerve function
Sources of B1
Wholemeal breads
Effect of B1 deficiency
1-3
1) Rapid onset (have small B1 stores)
2) Develop beriberi
3) Wernicke-Korsakoff syndrome in alcoholics
Very important reaction mediated by thiamin (B1)
Converting pyruvate to acetyl CoA (acetyl CoA to begin Kreb’s cycle)
Organ particularly affected by beriberi
Liver (becomes necrotic)
How does wet beriberi arise?
Liver becomes necrotic, serum albumin production drops, pitting oedema arises
Most common nutritional defect in Australia
Wernicke-Korsakoff syndrome (thiamin deficiency affecting nervous system)
Clinical sign of riboflavin deficiency
Sore, swollen, oedematous, magenta-coloured tongue
Role of riboflavin
Cofactor in specific redox reactions, EG in the Kreb’s cycle
Role of niacin (B3 or nicotinic acid)
1
2
1) Electron carrier (NAD, NADP)
2) Carbohydrate, fat, protein metabolism
Effect of B3 deficiency
Pellagra (dermatitis, diarrhoea, dementia, death)
Role of vitamin B6
Amino acid metabolism
Sources of B6
Nuts, bananas
Effect of B6 deficiency
Rare.
Can be reduced be excessive oestrogen levels (EG with very early contraceptive pills)
Need depends on protein intake
Role of biotin
1
2
1) Adding CO2
2) Glucose, fat, amino acid synthesis
Food sources of biotin
1-3
1) Brewer’s yeast
2) Cooked egg yolk
3) Soy beans
Clinical effect of biotin deficiency
Skin of hands is shiny, dry, scaly.
Role of folate
‘One carbon’ metabolism (EG amino acids, fat, purines for DNA synthesis)
Sources of folate
Green vegetables
Liver
Demographic in which folate deficiency is common
Elderly
Chronic alcoholics
Effects of folate deficiency
1-3
1) Macrocytic anaemia
2) Neural tube defects (spina bifida)
3) Glossitis (with papillae atrophy, leaving a shiny surface)
What can lead to spina bifida?
Folate deficiency in pregnancy
Possible negative side-effect of public increase in folate intake
Increase in incidence of cancer (folate assists with rapidly-replicating cells)
Role of vitamin B12
Folate metabolism
Transalkylation
Food sources of B12
Meat
Egg yolk
Cheese
Effect of B12 deficiency
Neurological disorders Pernicious anaemia (yellow tint to skin, prematurely blonde or grey hair)
Unusual component of B12
Cobalt (hence ‘cobalmin’)
Necessary factor for B12 absorption
Intrinsic factor.
Produced by parietal cells of the stomach
Ways in which B12 deficiency can arise
Dietary
Intrinsic factor defect
Role of vitamin C
1-4
1) Cofactor in collagen synthesis
2) Neurotransmitter metabolism
3) Iron absorption
4) Antioxidant
Food sources of vitamin C
Citrus fruits
Cabbage
Alternative name for vitamin C
Ascorbic acid
Manner in which people with scurvy die
Collagen in arteries breaks down
What is vitamin A derived from?
Beta carotene
Where is vitamin A stored?
Liver
Roles of vitamin A
1
2
1) Retinal (important for vision)
2) Retinol important in epithelial growth (healthy skin and eyes - corneal epithelium)
From what is vitamin D derived from?
Cholesterol
What does vitamin D require for synthesis?
UV
Role of vitamin D
Ca2+ regulation (particularly absorption from the gut) and bone development
Effect of vitamin D deficiency
Rickets in the young.
Osteomalacia in adults.
Organs in which vitamin D is synthesised
Skin then the liver
Why is it essential to consume Ca2+?
Lose about 1g per day through kidneys
Effect of excessive vitamin D
Calcification of the kidneys
Role of vitamin E
Antioxidant.
Inserts into membranes and intercepts free radicals
Where is vitamin E found?
Seed oils
Role of vitamin K
Important in blood clotting.
Activated thrombin causes fibrinogen to convert to fibrin and form a
blood clot. Inadequate clotting leads to haemorrhage.
Source of vitamin K
Gut flora make a lot of vitamin K
