Vitamin B1, B2, B3 Flashcards
What is the name of VB1?
Thiamin
What is the structure of Thiamin
pyrimidine and thiazole
Thiamin/B1 coenzyme form
TDP and TPP
Thiamin/B1 sources
yeast, pork, legumes, whole and enriched grains,
sunflower seeds
Thiamin/B1 functions
- energy transformation
- NADPH and pentose
- Nerve conduction
Role of Thiamin/B1 in energy transformation
- TDP (TPP) functions as coenzyme in catalyzing decarboxylation of
pyruvate and α-ketoglutarate - pyruvate to acetyl CoA (pyruvate dehydrogenase complex)
- α-ketoglutarate to succinyl CoA
- Both of these reactions are important for release of energy from
food in formation of ATP
Role of Thiamin/B1 in NADPH and pentose
- TDP needed for transketolase reaction which forms pentoses
- Pentoses used in synthesis of nucleic acids for RNA/DNA
Thiamin/B1 deficiency disease/symp
Beriberi- muscle weakness and wasting or heart failure with edema
Wernicke-korsakoff-neurological disorder
Thiamin/B1 at risk
elderly and increased need with elevated metabolism such as fever or hyperthyroidism
Thiamin/B1 toxicity
- Supplementation is quite safe
- No UL
- Large doses may be helpful with MSUD
Thiamin/B1 assessment
- Erythrocyte Transketolase Activity
- Most sensitive measure, if elevated after
thiamin addition, indicates deficiency
What is the name of vitamin B2
Riboflavin
Riboflavin/B2 structure
flavin + ribitol
Riboflavin/B2 coenzymes
FMN and FAD
Riboflavin/B2 sources
Milk, dairy products, eggs, meat,
legumes, enriched grains
Riboflavin/B2 is sensitive to
UV light
Riboflavin/B2 Functions
- Energy transformation
* ETS, pyruvate and succinate dehydrogenase - Purine catabolism (xanthine oxidase)
- Vitamin B6 activation
- Folate activation
- Reduction of glutathione
- Niacin synthesis
Riboflavin/B2 deficiency symptoms
- Cheilosis – cracking of lips
- Angular stomatitis – cracking of corner of mouth
- Glossitis – inflammation of tongue, magenta tongue
Riboflavin/B2 deficiency at risk groups
- Elderly
- Some cancers
- Alcoholism
- Elevated metabolism
Riboflavin/B2 toxicity
none
Riboflavin/B2 assessment
- Red Cell Glutathione Reductase
- FAD important in reducing glutathione
Niacin/B3 coenzyme
- Nicotinic acid, nicotinamide
- Coenzyme forms: NAD, NADH, NADP, NADPH
Niacin Sources
Food: MFP, enriched grains, legumes
* Synthesis from tryptophan
60 mg try = 1 mg niacin
niacin B3 functions
- Energy Transformation
* ETS, glycolysis, pyruvate dehydrogenase, Krebs cycle, B-oxidation - HMP shunt (NADP)
- HMP shunt (NADPH)
- Conversion of vitamin C, glutathione, folate to reduced states
- Lower cholesterol
* Nicotinic acid in large doses may decrease VLDL and LDL and increase
HDL
* Side effects: release of histamine (flushing), liver injury, competition
with urate for excretion, itching, elevated glucose
Niacin B3 deficiency symptoms
Pellagra (4 Ds):
* Dermatitis
* Diarrhea
* Dementia
* Death
Niacin B3 deficiencyat risk
- Isoniazid users (reduce niacin synthesis)
- Low intake (alcoholics)
- elevated metabolism
- Low pro/low tryptophan diet (corn)
Niacin B3 toxicity
- Nicotinic acid side effects: release of histamine
(flushing), liver injury, competition with urate for
excretion, itching, elevated glucose - Niacinamide–little known side effects
Niacin B3 assessment
- Ratio of N’methly-2-pyridone-5-carboxamide to
N’methly nicotinamide (urinary metab of
nicotinamide)
