Water soluble vitamins Flashcards
What is one of the main roles of B vitamins?
Provides co-enzymes for energy motabolism
How are B vitamins excreted?
In urine
B vitamin strorage
There is no B vitamin storage site
How many B vitamins are there?
8
What is the name of B1?
Thiamin
What is the name of B2?
Riboflavin
What is the name of B3?
Niacin
What is the name of B5?
Pantothenic acid
What is the name of B12?
Cobalamin
What are the individual B vitamins?
Thiamin Riboflavin Niacin Pantothenic acid Vitamin B6 Biotin Folic acid Cobalamin
What is the name of B7?
Biotin
What is the name of B9?
Folic acid
What is thiamin pyrophosphate involved in?
Converting pyruvate to acetyl CoA
Citric acid cycle
Required during pentose phosphate pathway
Affects nervous system
Affects formation of acetyl choline from ecetyl CoA
What coenzyme is thiamin important for?
Thiamin pyrophoshate (TPP)
What doe thiamin pyrophosphate do in the pentose phosphate pathway?
Produces ribose-5-phosphate for nucleic acid synthesis
What are the symptoms of thiamin deficiency?
Loss of appetite
Cardiac enlargement
Oedema
Increased pyruvate and lactate
What are sources of thiamin?
Whole grains
Meat and fish
Pulses
Nuts
What is the RDI of thiamin?
1 mg/day
What can cause thiamin levels in foods to be reduced?
Cooking
Exposure to light
Polyphenols
Excessive consumption of what can interfere with thiamin absorption into blood circulation?
Alcohol
What can a thiamin deficiency lead to?
Either dry or wet beriberi (never at the same time)
Dry beriberi
Thiamin defeciency
Causes loss of sensation in feet and inabality to lift feet
Wet beriberi
Thiamin deficiency
Pyruvate and lactate accumulate in the blood
This causes intense vasodilation
Results in cardiac failure, odeoma and cardiac enlargment
Wernicke-Korsakoff syndrome
Common in alcoholics
Thiamin is needed for alcohol metabolism
Alcohol consumption inhibits thiamin absorption
Causes loss of recent memory, low consciousness and coordination and paralysis of eye movement
Which disease caused by thiamin deficiency happens to active people?
Beriberi
Which disease caused by thiamin deficiency happens to inactive people?
Wernicke-Korsakoff syndrome
What coeznymes are riboflavin part of?
Flavin mononuecleotide (FMN) Flavin adenine dinucleotide (FAD)
What are the coenzymes of riboflavin involved in?
Electron transport chain
Krebs cycle
Fatty acid oxidation
Amino acid oxidation
What are the source of riboflavin?
Milk and milk products Eggs Liver Kidney Fortified breakfast cereals
What destroys riboflavin?
Exposure to light
What does riboflavin deficiency cause?
Lesions to the margin of the lips and the corners of the mouth
Magenta coloured tongue
Affects lipid metabolism
What is the RDI of riboflavin?
1.3 mg/day
Why might riboflavin deficiency give some resistance to malaria?
Parasite may require lots of it
May be because red blood cells have fragile membranes
What coenzymes is niacin part of?
NAD
NADP
What are the coenzymes of niacin involved in?
NAD - plays central role in the electron transport chain
NADP - important in fatty acid synthesis
What foods are a source of niacin?
Meat, especially liver and kidney Fish Peanuts Bran Pulses Wholemeal wheat Coffee
What is the other main source of niacin?
Produced from tryptophan in the liver
What is the RDI of niacin?
14 mg/day in women
16 mg/day in men
What disease does niacin deficiency cause?
Pellagra
What are the 3D’s of pellagra?
Dermatitis
Diarrhoea
Delirium/dementia
What are the symptoms of pellagra?
Skin inflammation
Skin lesions
Pigmentation
Cracking of skin
What factors can affect niacin?
Excess leucine inhibits synthesis of NAD from tryptophan
Estrogen metabolites inhibit trptophan metabolism in women
What is the metabolically active form of vitamin B6?
Pyridoxal 5’-phosphate (PLP)
What is pryidoxal 5’-phosphate a major coenzyme in?
Transamination, deamination and synthesis of non-essential amino acids
Homcysteine metabolism
Formation of niacin from tryptophan
What other B vitamin is required in the formation of niacin from tryptophan?
B6
What are the food sources of vitamin B6?
Meats Whole grain products Vegetables Bananas Nuts
What is the RDI of vitamin B6?
1.5 mg/day
Vitamin B6 and glycogen phosphorylase
B6 is associated with the enzyme glycogen phosphorylase
This enzyme is part of glycolysis
What are the symptoms of vitamin B6 deficiency?
Weakness Sleeplessness Dermatitis Anaemia Impaired immunit
Influence of biotin
Coenzyme for carboxylase enzymes involved in metabolic pathways
Coenzyme for pyruvate carboxylase in gluconeogenesis
Induces synthesis of key enzymes of glycolysis and gluconeogenesis
What are the main sources of biotin?
Food sources
Produced by bacteria in large intestine
Which form of vitamin B is very rare to have a deficiency?
Biotin
Symptoms of biotin deficiency
Skin rash Loss of hair Anorexia Hypercholsterolemia Depression
RDI of biotin
30 ug/day
What is pantothenic acid contribute to? (proteins)
Coenzyme A
Acyl carrier protein (ACP)
What is pantothenic acid involved in?
TCA cycle
Fatty acid synthesis
Lipid synthesis
What are the symptoms of pantothenic acid deficiency?
Depression Insomnia Fatigue Vomiting Muscle weakness Burning sensation in feet
What is the RDI of pentothenic acid?
5 mg/day
What forms does folic acid naturally occur in?
Tetrahydrofolate (THF)
5,10-methylene THF
What does the THF form of folic acid influence?
1-carbon transfers such as methylation to form thymidylate
Purine and pyrimidine synthesis
Re-methylation of homocysteine to methionine
What does a deficiency of folic acid cause?
Reduced ability for cell division
Which B vitamin is required in larger amounts during pregnancy?
What does not matching the required amount cause?
Folic acid:
Megaloblastic anaemia
Neural tube defects
What are the RDIs for folic acid?
400 ug/day
Pregnant women - 600 ug/day
Lactating women - 500 ug/day
What are the food sources of folic acid?
Leafy vegetables Liver Kidney Beans Beetroot Bran Peanuts Wholemeal bread Eggs Bananas
What B vitamin does folic acid interact with and how?
Vitamin B12 (cobalamin) Masks symptoms of B12 deficiency with correcting associated neurological symptoms
What coenzymes have vitamin B12 present?
Methylcobalamin
Deoxyadenosyl cobalamin
What are the sources of vitamin B12?
Synthesised by bacteria
Food intake
What enzymes are dependant on vitamin B12?
Methylmalonyl CoA mutase
Methionine synthase
What are the food sources of vitamin B12?
Meat Fish Shellfish Milk Egg Cheese Yoghurt
Which vitamin is not present in any plant food sources?
Vitamin B12
What does the absorption of vitamin B12 depend upon?
Intrinsic factors
What happens when there are not enough intrinsic factors present?
Vitamin B12 deficiency
What are the outcomes of vitamin B12 deficiency?
Pernicious anaemia (release of immature RBCs in to the blood stream) Vitamin 12 neuropathy (spinal cord degeneration)
What is the RDI of vitamin 12?
2.5 ug/day
Vitamin C
Ascorbic acid
Strong antioxidant
Co-factor for many enzymes
What is vitamin C important in?
Collagen synethsis
Iron conversion from ferric form to more soluble ferrous form
Enhances absorption of non-haem iron
What reduces plasma ascorbic acid levels?
Smoking
What are the food sources of ascorbic acid (vitamin C)
Citrus fruits
Peppers
Potatoes
Brassica vegetables
What is the RDI of vitamin C?
40 mg/day
What does vitamin C deficiency cause?
Scurvy
What are the main characteristics of scurvy and what causes them?
Bleeding gums and anaemia
Caused by impaired synthesis and repair of collagen and fragile capillaires
