Vitamins Flashcards
Vitamin A
Source: sweet potatoes, carrots, green leafy vegetables, eggs, cheese, milk
Function: Antioxidant
Constituent of visual pigments (retinal)
Essential for normal differentiation of epithelial cells into specialized tissues (pancreatic cells, mucus-secreting)
Prevents squamous metaplasia into keratinizing epithelium
Treats: measles and AML
Found in liver and leafy vegetables
Deficiency: nigh blindness, dry scaly skin, alopecia, corneal degeneration, immune suppression, Bitots spots (keratinization of conjunctiva)
Excess: (retinol)
Acute: nausea, vomiting, vertigo, and blurred vision
Chronic: arthralgias, skin changes, alopecia, cerebral edema, psedotumor cerebri (pappilledema), hepatosplenomegaly, hyperlipidemia
teratogen: microcephaly, cleft palate, cardiac anomalies, fetal death
Vitamin D
25-OH Storage form
1,25 (OH)2 active form
Source: UVB light, fortified milk, fish, eggs, infant formula
Function: increase intestinal absorption of calcium and phosphate
increase bone mineralization
Deficiency: rickets in children (bone pain and deformity), osteomalacia in adults (bone pain and muscle weakness), hypocalcemic tetany, lax muscles (risk of falls), cancer
Excess: brain damage in young infants, calcification of arteries and other soft tissues
Breastfed infants should receive oral vitamin D
Deficiency exacerbated by low sun exposure, pigmented skin, prematurity
Excess: hypercalcemia, hypercalciuria, loss of appetite, stupor, confusion, polyuria
Seen in sarcoidosis, TB, Hodgkins and non Hodgkin’s lymphoma
Vitamin E
Tocopherol/tocotrienol
Sources: vegetable oils, nuts and seeds, margarine
Function: antioxidant (protects erythrocytes and membranes from free radical damage)
Can enhance warfarin effects
Deficiency: hemolytic anemia, acanthocytosis (spiked RBCs), muscle weakness, posterior column (loss of vibration and proprioception) and spinocerebellar tract demyelination
Excess: risk of death from bleeding and hemorrhagic stroke
Vitamin K
Sources: cooked greens, green vegetables, canola and soybean oil, intestinal bacteria, green tea, beef liver
Function: cofactor for the y-carboxylation of glutamic acid residues on various proteins required for blood clotting
synthesized by intestinal flora (factors II, VII, IX and X, proteins C and S)
Essential for hepatic microsomal carboxylase
Coenzyme for syntehsis of proteins involved in bone mineralization
Deficiency: neonatal hemorrhage with Increased PT and increase aPTT but normal BT
Can also occur after prolonged use of broad spectrum antibiotics
Not in breast milk so neonates must be given vitamin K injection at birth to prevent bleeding diathesis
Vitamin C
Acrobic Acid
Source: fruits and vegetables
Function: antioxidant,
Facilitates iron absorption by reducing it to Fe2+ state
necessary for hydroxylation of proline and lysine in collagen synthesis
Necessary fro dopamine B-hydroxylase which converts doamine to NE
Deficiency: scurvy-swollen fums, bruising, hemarthrosis, anemia, poor wound healing, perifollicular and subperiosteal hemorrhages (petechiae), corkscrew hair, peridontal infection, hyperkaratotic papular rashes
weakened immune response
seen in alcoholics, poor and elderly (live alone)
Excess: nausea, vomiting, osmotic diarrhea, fatigue, calcium oxalate nephrolithiasis,
increase risk of iron toxicity in predisposed individuals (transfusions or hereditaroy hemochromatosis)
Vitamin B9
Folic Acid
source: Green leafy vegetables, orange juice and citrus fruits, legumes, fortified grains
Function: Converted to THF a coenzyme for 1-carbon transfer/methylation reactions
Important for synthesis of nitrogenous bases in DNA and RNA
Serotinin, choline and epinephrine synthesis
Deficiency: marocytic, megaloblastic anemia, hypersegmented polymorphonuclear cells, glossitis, homocysteinemia (CV disease), no neurologic symptoms
Excess: increased tumor rates with high dose folate supplementation
Labs: increase homocysteine, normal methylmalonic acid
Seen in alcoholism and pregnancy
Phenytoin, sulfonamides, methotrexate
Supplemental maternal folic acid in early pregnancy decreases risk of neural tube defects
Vitamin B1
Thiamine
Sources: pork, meat substitutes, green peas, enriched grains
Function: thiamine pyrophosphate is a cofactor for pyruvate dehydrogenase, a-ketoglutarate, Transketolase, branched chain ketoacid dehydrogenase
Defiency: impaired glucose breakdown leadign to ATP depletion worsened by glucose infusion
Highly aerobic tissues (heart and brain) affected first
seen in malnutrition and alcoholism
Wernicke-Korsakoff syndrome: confusion, opthalmoplegia, ataxia, confabulation, personality change, memory loss (permanent)
Damage to medial dorsal nucleus of thalamus, mammillary bodies
Dry beriberi: polyneuritis (sensory and motor impairments in distal extremities), symmetrical muscle wasting
Wet beriberi: high output cardiac failure (CHF and cardiomegaly-dilated cardiomyopathy), edema
Infantile beriberi: fulminant cardiac syndrome with cardiomegaly, tachcardia, cyanosis, dyspnea and vomiting
Diagnosis: increase in RBC transketolase activity following vitamin B1 administration
Vitamin B2
Riboflavin
sources: milk, eggs, broccoli
Function: component of FAD and FMN used as cofactors in redox reactions (succinate dehydrogenase in TCA cycle)
FAD complex I of ETC
FMN comlex II of ETC
Deficiency: Cheilosis (inflammation of lips, scaling and fissures at corners of mouth), corneal vascularization, glossitis, seborrhargic dermatitis, anemia
Impairs niacin and folate function
May result in cancer, diabetes, CVD
seen in alcoholics and malnourished
Diagnosis: erthrocyte glutathione reductase assay, urinary riboflavin excretion
Vitamin B3
Niacin
Sources: fortified dry cereal, beef, eggs, milk
Derived from tryptophan
Function: Constituent NAD+ and NADP+ (used in redox reactions)-coenzyme fro dehydrogenases
synthesis requires B2 and B6
Used to treat dyslipidemia by lowering VLDL and raises HDL
Deficiency: glossitis,
severe leads to pellagra-can be caused by
Hartnup disease decreased tryptophan absorption
malignant carcinoid syndrome increased tryptophan metabolism
isoniazid decreased vitamin B6
Symptoms of pellagra: diarrhea (columnar epithelium atrophy), dementia (neural degeneration, hallucinations) and dermatitis (Casal necklace or hyperpigmentation of sun exposed limbs), depression
Common in alcoholics, and chronic diseases
Excess: facial flushing (induced by prostaglandin), hyperglycemia, hyperuricemia, ocular effects
Vitamin B6
Pyridoxine
Sources: meat, poultry, fish, corn, bananas, potatoes and sweet potatoes
Function: converted to pyridoxal phosphate a cofactor used in transamination (ALT, AST), decarboxylation reactions, glycgoen phosphorylase
synthesis of cystathionine, heme, niacin, histamine, and neurotransmitters (serotonin, epinephrine, NE, dopamine, and GABA)
Defeiciency: convulsions, hyperirritability, peripheral neuropathy (induced by isoniazid or oral contraceptives), sideroblastic anemias due to impaired hemoglobin synthesis and iron excess, depression
Excess: sensory neuropathy
Vitamin B12
Cobalamin
sources: meat, poultry, fish, milk, dairy, eggs
Synthesized by microorganisms
Functions:
co factor for homocysteine methyltransferase (transfers CH3 groups as methylcobalamin) and methlmalonyl CoA mutase
Deficiency: macrocytic, megaloblastic anemia, hypersegmented PMNs, paresthesias, and subacute combined degernation (degeneration of dorsal columns, lateral corticospinal tracts and spinocrebellar tracts) due to abnormal myelin, homocyteinemia (CVD), impaired nerual tube development in fetus
large storage pool in liver
Deficiency due to insufficient intake (vegan), malabsorption (sprue, enteritis, Diphyllobothrium latum), lack of intrinsic factor (pernicious anemia, gastric bypass surgery), absence of terminal ileum (Crohn disease)
Anti intrinsic factor diagnostic for pernicious anemia
Associated with incrased homocysteine and methylmalonic acid levels
Decreased methionine
Irreversible nerve damage if prolonged
Diagnosis: Schilling test
Vitamin B5
Pantothenate
Sources: sweet potatoes, legumes, yogurt, chicken
Function: essential component of coenzyme A and fatty acid synthase
functions of coenzyme A: fuel metabolism, protein modification, synthesis of fatty acids, phospholipids, cholesterol, and steroid hormones
Deficiency: dermatitis, enteritis, alopecia, adrenal insufficiency, parathesias, dysethesias, GI distress, fatigue/depression, infertility, weakened immune system
Vitamin B7
Biotin
Sources: intestinal flora, cauliflower, soybeans, eggs, mushrooms
Functions: 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: metabolic acidosis (due to excess pyruvate), surplus of odd chain fatty acids (due to succinyl CoA deficiency)
Dermatitis, alopecia, enteritis,
Caused by antibiotic use or excessive ingestion of raw egg whites
Iron
Sources: Fortified grains, broccoli, beef
Heme iron more readily absorbed
Phytates, polyphenols, oxalate, Ca2+, Zn2+, Mg2+ inhibit absorption Organic acids (Vit. C) enhance iron absorption
Deficiency: microcytic anemia, increase cancer risk, delay growth and brain development, alter hair and nail texture and impair immune function
Toxicity: discolor the skin and lead to cirrhosis, hepatosplenomegaly, cardiomyopathy,
Copper
Sources: chicken, chocolate, beans, instant cereal
Function: cofactor for enzymes (cytochrome c oxidase) and superoxide dismutase
Iron metabolism, catecholamine fromation and cross linking of collagen and elastin
Deficiency: impairs brain function, vascular and bone integrity and metabolic control
Toxicity: causes liver and DNA damage
