Water soluble vitamins Flashcards
3 general features of WSVs
- precursors to coenzymes involved in intermediary metabolism
- all but vitamin B12 are in vegetables
- deficiency in all but B12 leads to clinical symptoms within weeks due to low body stores
Vitamin B1 also called:
thiamine
diseases associated with thiamine (B1) deficiency
- Korsakoff’s Disease in alcohol abusers
- Beriberi - peripheral neuropathy and dilated cardiomyopathy
thiamine (B1) physiological importance
- coenzyme for enzymes involved in carb metabolism, specifically pyruvate dehydrogenase, a-ketoglutarate dehydrogenase, transketolase
vitamin B2 also known as
riboflavin
riboflavin (B2) physiological importance
- precursor of flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) coenzymes
symptoms of riboflavin (B2) deficiency
- fissuring at angles of mouth
- dermatitis
- purple tongue
vitamin B3 also known as
Niacin
niacin (B3) physiological importance
- precursor to NAD and NADP coenzymes
symptoms of niacin (B3) deficiency
- pellagra “sour skin”, dermatitis, diarrhea, dementia, death (lots of D words!)
- Hartnup disease and carcinoid syndrome because of reduced tryptophan uptake/metabolism
why is niacin (B3) not really a vitamin?
- body can make it from tryptophan
therapeutic use of niacin (B3)
- used to lower LDL and VLDL cholesterol in type 2b hyperlipoproteinemia
vitamin B5 also known as
pantothenic acid
pantothenic acid (B5) significance
- component of CoA
- no disease associated with deficiency
- found in FAS
vitamin B6 compounds
- pyridoxine, pyridoxal, pyridoxamine
- precursors for pyridoxal phosphate, coenzyme for amino acid reactions
vitamin B6 therapeutic use
- binds to antituberculous drug Isoniazid
- routine prescribed together with Isoniazid to prevent functional deficiency, characterized by seizures
vitamin B7 also known as
Biotin
Biotin (B7) physiological significance
- coenzyme in decarboxylation reactions that is covalently bound to specific lysine residues
- found in ACC
symptoms of Biotin (B7) deficiency
- caused by eating greater than 20 eggs per day
- eggs contain biotin-binding protein Avidin
- dermatitis, glossitis, nausea
vitamin B9 also known as
Folate
Folate (B9) physiological importance
- necessary for one carbon metabolism, including purine and thymadine (DNA) synthesis
Folate (B9) deficiency
- causes megaloblastic anemia in adults and neural tube defects in fetus
folate (B9) therapeutic use
- given in first trimester of pregnancy to prevent defects
- supplemented in enriched foods since 1998
vitamin B12 also known as
cobalamin
cobalamin (B12) physiological significance
- precursor of methyl cobalamin which is needed to synthesize methionine from homocysteine in blood cells
- precursor of deoxyadenosycobalamin, which is needed for fatty acid metabolism in brain cells
difference between B12 and other vitamins
- B12 not produced by plants
- requires intrinsic factor for intestinal absorption
cobalamin (B12) deficiency
- seen in vegans and those with pernicious anemia (no intrinsic factor)
- megaloblastic anemia
- subacute combined degeneration of spinal chord
- dementia
etiology of megaloblastic anemia in B12 deficiency
- lack of B12 blocks metabolism of N5-methyl-tetrahydrofolate which then cannot be used for DNA synthesis
- symptoms only appear after years of deficiency due to large body stores
treatment of B12 deficiency
- pernicious anemia treated with intramuscular B12 injections, circumvents need for intrinsic factor
- folate supplementation ameliorates megaloblastic anemia caused by deficiencies of B12 or folate
- folate does not treat spinal chord degeneration
vitamin C also known as
ascorbic acid
ascorbic acid (C) physiological significance
necessary for post-translational hydroxylation of proline, especially in collagen
ascorbic acid (C) deficiency
- scurvy - bleeding gums, hemorrhages around corkscrew hair follicles, bone pain caused by bleeding underneath periosteum, poor wound healing
ascorbic acid (C) mega-dose
can cause oxalic acid kidney stones
