Vitamins Flashcards
Fat soluble vitamins
Vitamins A,D,E, and K
Two water soluble vitamins that are stored in the liver
B12 and folate
4 major functions of vitamin A
Antioxidant
Constituent of visual pigments (retinal)
Essential for normal differentiation of epithelial cells
Prevents squamous metaplasia
Two conditions that can be treated with vitamin A
Measles and AML, subtype M3
Symptoms of vitamin A deficiency
Night blindness, dry skin, keratomalacia, squamous metaplasia
Symptoms of vitamin A excess
Arthralgias, fatigue, headaches, skin changes, sore throat, alopecia,
Teratogenic (cleft palate, cardiac abnormalities): pregnancy test and two forms of contraception are needed before isotretinoin is used for severe acne
4 enzymes that use vitamin B1 as a cofactor
Pyruvate dehydrogenase (links glycolysis to TCA)
Alpha-ketoglutarate dehydrogenase (TCA)
Transketolase (HMP shunt)
BCAA dehydrogenase
3 conditions seen in vitamin B1 deficiency
Wernicke-Korsakoff: confusion, ophthalmoplegia, ataxia (classic triad) + confabulation, personality change, memory loss (permanent)
Dry beriberi: polyneuritis, symmetrical muscle wasting
Wet beriberi: high output cardiac failure (dilated cardiomyopathy), edema
Condition seen with chronic thiamine deficiency that affects cerebellum
Alcoholic cerebellar degeneration: loss of Purkinje cells in anterior lobes and vermis
Causes progressive, wide-based gait ataxia, truncal instability, intention tremor
Function of vitamin B2 (riboflavin)
Cofactor in oxidation and reduction (e.g. FADH2)
Symptoms of B2 deficiency
Cheilosis (inflammation of lips, scaling and fissures at the corners of the mouth), corneal vascularization, magenta colored tongue
Function of vitamin B3 (niacin)
Constituent of NAD+ ,NADP+ (used in redox reactions)
Amino acid necessary for synthesis of niacin
Tryptophan, also requires vitamin B6
Symptoms of niacin deficiency
Glossitis and severe deficiency leads to pellagra (diarrhea, dermatitis, dementia)
Conditions where niacin deficiency may be seen
Hartnup’s (decreased tryptophan absorption), malignant carcinoid syndrome (increased tryptophan metabolism), and isoniazid therapy (decreased B6)
Symptoms of niacin excess
Facial flushing (can prevent with aspirin pre-treatment)
Function of vitamin B5 (pantothenate)
Essential component of CoA (a cofactor for acyl transfers) and fatty acid synthase
Symptoms of vitamin B5 defieciency
Dermatitis, enteritis, alopecia, adrenal insufficiency
Function of vitamin B6 (pyridoxine)
Cofactor used in transamination reactions, decarboxylation reactions, and glycogen phosphorylase
Symptoms of vitamin B6 deficiency
Convulsions, hyperirritability, peripheral neuropathy (seen in isoniazid use), sideroblastic anemias due to impaired hemoglobin synthesis and iron excess
Function of vitamin B7 (biotin)
Cofactor for carboxylation enzymes including:
1) pyruvate carboxylase
2) acetyl-CoA carboxylase
3) propionyl-CoA carboxylase
Function of vitamin B9 (folic acid)
Converted to THF, a coenzyme for 1 carbon transfers/methylation reactions
Also important for synthesis of nitrogenous bases in DNA and RNA
Symptoms of folic acid deficiency
Macrocytic, megaloblastic anemia (no neurologic symptoms), homocysteinemia (increased risk for DVT and atherosclerosis)
Function of vitamin B12
Cofactor for homocysteine methyltransferase (transfers methyl groups) and methylmalonyl-CoA mutase