Vitamin A

Function:  Antioxidant; constituent of visual pigments (retinal).  Found in liver and leagy vegetables.

Deficiency:  Night blindness, dry skin

Excess: Arthralgias, fatigue, headaches, skin changes, sore throat, alopecia.  Teratogenic (cleft palate, cardiac abnormalities

Thiamine Vitamin B1

Function:  thiamine pyrophosphate (TPP) cofactor for several enzymes

-Pyruvate Dehydrogenase (glycolysis)

-alpha-ketoglutarate dehydrogenase (TCA)

-Branched-chain AA dehydrogenase

-transketolase (HMP shunt)

Wernicke-Korsakoff syndrome and beriberi both cause neurologic and cardiac manifestations.  Seen in malnutrition and alcoholism.

Wernicke-korsakoff- confusion, ophthalmoplegia, ataxia plus memory loss, confabulation, personality change

Dry Beriberi- polyneuritis, symmetrical muscle wasting

Web Beriberi- high output cardiac failure (dilated cardiomyopathy), edema 

Deficiency in Vitamin B1 or Thiamine

Dry Beriberi- polyneuritis, symmetrical muscle wasting

Wet Beriberi- high output cardiac failure (dilated cardiomyopathy), edema 

-Deficiency in Vitamin B1 or Thiamine

Wernicke-Korsakoff syndrome and beriberi both cause neurologic and cardiac manifestations.  Seen in malnutrition and alcoholism.

Wernicke-korsakoff- confusion, ophthalmoplegia, ataxia plus memory loss, confabulation, personality change

Riboflavin Vitamin B2

Function:  cofactor in oxidation and reduction (FADH2)

Deficiency:  Cheilosis (inflammation of lips, scaling and fissures at the corners of the mouth), Corneal vascularization.

Naicin Vitamin B3

Function:  Constituent of NAD+ (used in redox  reactions).  Derived from tryptophan.  Synthesis requires Vitamin B6 (pyridoxine).

Deficiency:  Glossitis.  Severe deficiency leads to pellagra, which can be caused by Hartnup disease

Excess:  facial flushing (due to pharmacologic doses for treatment of hyperlipidemia)

Naicin Vitamin B3

-Glossitis.  Severe deficiency leads to Pellagra, which can be caused by

-Hartnup disease (decrease tryptophan absorption)

-malignant carcinoid syndrome (increased tryptophan metabolism)

-INH (decrease vitamin B6 (pyridoxine))

Pellagra:  Diarrhea, Dermatitis, Dementia

Naicin Vitamin B3

Excess:  Facial flushing due to pharmacologic doses for treatment of hyperlipidemia

Pyridoxine Vitamin B6

Function:  Converted to pyridoxal phosphate, a cofactor used in transamination (ALT and AST), decarboxylation reactions, glycogen phosphorylase, and heme synthesis.  Required for synthesis of niacin (Vitamin B3) from tryptophan.

Pyridoxine Vitamin B6

Deficiency:  convulsions, hyperirritability, peripheral neuropathy (deficiency inducible by INH and oral contraceptives)

Cobalamin Vitamin B₁₂ Found in animal products

Function: Cofactor for homocysteine methyltransferase (transfer CH₃ group as methylcobalamin) and methylmalonyl-CoA mutase

Deficiency: Macrocytic, megaloblastic anemia; neurologic symptoms

Vitamin B₁₂ Cobalamin

Deficiency:  Macrocytic, megaloblastic anemia; neurologic symptoms (paresthesias, subacute combined degeneration) due to abnormal myelin.  Prolonged deficiency leads to irreversible nervous system damage

-Deficiency usually caused by malabsorption, lack of intrinsic factor (pernicous anemia, gastric bypass), or absence of terminal ileum (Crohn's)

-Schilling test to detect etiology of deficiency

-Found in green leaves

Function:  converted to tetrahydrofolate, a coenzyme for 1-carbon transfer/methylation reactions.  Important for the synthesis of nitrogenous bases in DNA and RNA.

Deficiency:  Macrocytic, megaloblastic anemia, no neurologic symptoms (unlike Vitamin B12 deficiency).  Most common vitamin deficiency in United  states.

Deficiency:  Macrocytic, megaloblastic anemia, no neurologic symptoms (unlike Vitamin B12 deficiency).  Most common vitamin deficiency in United  states.

-Ovalocytosis and neutrophils with hypersegmented nuclei.

-deficiency can be caused by several drugs (phenytoin, sulfonamides, MTX)

-supplemental folic acid in early pregnancy reduces neural tube defects

-small reserve pool stored primarily in the liver.

-ATP + methionine --> S-adenosyl-methionine (SAM)

-SAM  transfers methyl units

-Regeneration of methionine and thus SAM is dependent on Vitamin B12 and folate

Methioine --> via SAM--> Homocysteine + CH3 (given up)

Methionine + THF <--  B12 <-- CH3 + THF

Biotin

Cofactor for carboxylation enzymes

-Pyruvate carboxylase: Pyruvate to oxaloacetate

-Acetyl-CoA carboxylase: acetyl-CoA to malonyl-CoA

-Propionyl-CoA carboxylase:  Propionyl-CoA to Methylmalonyl-Coa

Deficiency- relatively rare.  Dermatitis, alopecia, enteritis.  Caused by antibiotic use or excessive ingestion of raw eggs.

Vitamin C Asorbic Acid  In fruits and vegetables

Function:  Antioxidant

1. Facilitates iron absorption by keeping iron in Fe2+ reduced state (more absorbable)

2. Necessary for hydroxylation of proline and lysine in collagen synthesis

3.  Necessary for dopamine B-hydroxylase which converts dopamine to NE

Deficiency:  Scurvy: swollen gums, bruising, anemia, poor wound healing

Vitamin C Ascorbic acid found in fruits and vegetables

Deficiency:  Scurvy: swollen gums, bruising, anemia, poor wound healing

Vitamin D

Function:  Increase intestinal absorption of calcium and phosphate, increase bone resorption

Deficiency:  Rickets in children (bending bones), osteomalacia in adults (soft bones), hypocalcemic tetany

Excess:  Hypercalcemia, hypercalciuria, loss of appetitie, stupor, seen in sarcoidosis (increase activation of vitamin D by epithelioid macrophages)

1. D₂ = ergocalciferol- ingested from plants, used as pharmacologic agent

2. D₃ = cholecalciferol- consumed in milk, formed in sun-exposed skin.

3. 25-OH-D₃ = storage form

4. 1,25-(OH)₂D₃ (calcitriol) = active form

Vitamin E

Function:  Antioxidant (protects erythrocytes and membranes from free radical damage)

Deficiency:  Increase fragility of erythrocytes (hemolytic anemia), muscle weakness, neurodysfunction.

Vitamin K

Function: catalyzes gama-carboxylation of glutamic acid residues on various proteins concerned with blood clotting.  Made by intestinal flora.  Necessary for synthesis of clotting factors 2,7, 9, 10, and protein C and S.  Warfarin is vitamin K antagonist.

Deficiency: Neonatal hemorrhage with increase PT and increase in aPTT but normal bleeding time and after prolonged use of broad-spectrum antibiotics.

Deficiency:

-Neonatal hemorrhage with increase PT and increase in aPTT but normal bleeding time (neonates have sterile intestines and are unable to make vitamin K).  Neonates are given vitamin K injection at birth to prevent hemorrhage.

-Can occur after prolonged use of broad-spectrum antibiotics.

Function: Essential for the activity of 100+ enzymes.  Important in the formation of zinc fingers (transcription factor motif).

Deficiency: Delayed wound healing, hypogonadism, decrease adult hair (axillary, facial, pubic).  May predispose to alcoholic cirrhosis.