Vitamins

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B1 (thiamine) - part of what complex?

TPP (thiamine pyrophosphate)

B1 (thiamine) - cofactor for what enzymes?

pyruvate dehydrogenase (glycolysis)
alpha-ketoglutarate dehydrogenase (TCA cycle)
transketolase (HMP shunt)
branched chain AA dehydrogenase

B1 (thiamine) - people you see it with?

alcoholics (secondary to malnutrition and malabsorption) and malnourished

B1 (thiamine) - diseases of deficiency

wernicke-korsakoff syndrome, beriberi (wet and dry)

B2 (riboflavin) - function

cofactor for oxidation and reduction (e.g., FADH2)

B2 (riboflavin) - deficiency

Cheilosis, Corneal vascularization

B3 (niacin) - function

constituent of NAD+,NADP+

B3 (niacin) - derived from what amino acid?

tryptophan

B3 (niacin) - what vitamin is needed for synthesis?

B6 (pyridoxine)

B3 (niacin) - deficiency

Glossitis, Pellagra (Dermatitis, Diarrhea, Dementia)

B3 (niacin) - causes of deficiency

Hartnup disease (decreased tryptophan absorption), malignant carcinoid syndrome (increased tryptophan metabolism), and INH (decreased B6)

B3 (niacin) - excess

facial flushing (offset by aspirin)

B5 (pantothenate) - function

part of CoA and fatty acyl synthase

B5 (pantothenate) - deficiency

dermatitis, enteritis, alopecia, adrenal insufficiency

B6 (pyridoxine) - converted into what? why?

pyridoxal phosphate, a cofactor used in transamination (e.g., ALT, AST), decarboxylation reactions, glycogen phosphorylation, and heme synthesis (ALA synthase)

B6 (pyridoxine) - required for synthesis of what vitamin from what amino acid?

niacin from tryptophan

B6 (pyridoxine) - deficiency

convulsions, hyperirritability, peripheral neuropathy

B6 (pyridoxine) - what drugs induce deficiency?

INH and oral contraceptives

B12 (cobalamin) - function

cofactor for homocystein methyltransferase (transfers methyl groups as methylcobalamin) and methylmalonyl-CoA mutase

B12 (cobalamin) - foods found in

animal products

B12 (cobalamin) - can humans make it?

no; only microorganisms

B12 (cobalamin) - size of reserve

very large reserve stored in liver (years worth)

B12 (cobalamin) - causes of deficiency

malabsorption (sprue, enteritis, Diphyllobothrium latum), lack of intrinsic factor (pernicious anemia, gastric bypass surgery), absence of terminal ileum (Crohn's disease), or veganism

B12 (cobalamin) - test for nature of deficiency

Schilling's test

B12 (cobalamin) - what does deficiency do?

macrocytic, megaloblastic anemia; neurologic symptoms (paresthesias, subacute combined degeneration) due to abnormal myelin; irreversible nerve damage if prolonged deficiency

B12 (cobalamin) - sign of deficiency (urine)

methylmalonyl in urine

Folic acid - function

converted to THF, a coenzyme for 1 carbon transfer/methylation reactions; important for synthesis of nitrogenous bases in DNA and RNA

Folic acid - source

Folate is from Foliage

Folic acid - reserve size?

small reserve in liver. must eat green leaves regularly

Folic acid - deficiency

macrocytic, megaloblastic anemia; no neurologic symptoms; MOST COMMON in USA

Folic acid - when is deficiency common?

alcoholism and pregnancy

folic acid - drugs that cause deficiency?

several! (phenytoin, sulfonamides, MTX)

folic acid - why take early in pregnancy

prevent neural tube defects

common sign for folic acid, B12, or B6 deficiency

hyperhomocysteinemia

S-adenosyl-methionine

ATP + methionin = SAM; transfers methyl units; regeneration of SAM is dependent on both B12 and folate

Biotin - function

cofactor for carboxylation enzymes
-pyruvate carboxylase (forms oxaloacetate)
-acetyl-CoA carboxylase (forms malonyl-CoA)
-propionyl-CoA carboxylase (forms methylmalonyl-CoA)

Biotin - deficiency

rare. causes dermatitis, alopecia, enteritis.

Biotin - main causes of deficiency

antibiotic use or excessive ingestion of raw eggs (avidin in egg whites binds it)

Vitamin C - function

-antioxidant.
-facilitates iron absorption (keeps it reduced)
-hydroxylates proline and lysine on collagen
-necessary for dopamin beta-hydroxylase which converts dopamine to NE

Vitamin C - deficiency

swollen gums, bruising, anemia, poor wound healing

Vitamin C - sources

fruits, veggies, limes

Vitamin E - function

antioxidant (protects erythrocytes and membranes from free-radical damage)

Vitamin E - deficiency

fragile erythryocytes (hemolytic anemia), muscle weakness, neurodysfunction

Vitamin K - function

gamma carboxylation of glutamic residues on clotting proteins

Vitamin K - synthesis site

intestines by flora

Zinc - function

zinc fingers. function of 100+ enzymes

Zinc - deficiency

delayed wound healing, hypogonadism, decreased adult hair (axillary, facial, pubic). may predispose to alcoholic cirrhosis

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