Vitamins Flashcards
vitamins - overview
*small organic molecules essential for: (1) DNA and protein synthesis; (2) enzyme & transporter function; (3) many other metabolic processes
*vitamins CANNOT be synthesized (must be acquired from the diet)
water soluble vitamins
*thiamine (B1)
*riboflavin (B2)
*niacin (B3)
*pantothenic acid (B5)
*pyridoxine (B6)
*biotin (B7)
*folic acid (B9)
*cobalamin (B12)
*ascorbate (C)
note - B vitamins and vitamin C are water-soluble
fat soluble vitamins
*retinol (A)
*calciferol (D)
*tocopherol (E)
*menaquinones (K)
ADEK vitamins are the fat-soluble vitamins
vitamin B1 - name
thiamine
vitamin B3 - name
niacin
vitamin B2 - name
riboflavin
vitamin B5 - name
pantothenic acid
vitamin B6 - name
pyridoxine
vitamin B7 - name
biotin
vitamin B9 - name
folic acid
vitamin B12 - name
cobalamin
vitamin C - name
ascorbate
vitamin A - name
retinol
vitamin D - name
calciferol
vitamin E - name
tocopherol
vitamin K - name
menaquinones
vitamin B1 (thiamine) - function
*coenzyme for:
-pyruvate dehydrogenase
-alpha-ketoglutarate dehydrogenase
-branched chain ketoacid dehydrogenase
*synthesis of neurotransmitters acetylcholine and GABA
vitamin B1 (thiamine) - sources
*origin = bacteria, fungi, & plants
*found in fortified breads and cereals, fish, lean meats and milk
vitamin B1 (thiamine) - populations at risk for deficiency
*chronic alcoholism!
*bariatric surgery patients
*poor diet (esp. in elderly)
*orthorexia
*severe malabsorption
*short gut syndrome
vitamin B1 (thiamine) - deficiency diseases
*beri-beri (wet or dry)
*Wernicke-Korsakoff syndrome
*marked by peripheral neurologic, cerebral, and cardiovascular abnormalities
Beri-Beri
*caused by vitamin B1 (thiamine) deficiency
*neurologic dysfunction (dry) or neuro dysfunction + heart dysfunction (wet)
*sx: ophthalmoplegia, peripheral edema, peripheral neuropathy, +/- congestive heart failure (wet)
Wernicke-Korsakoff Syndrome
*caused by vitamin B1 (thiamine) deficiency
*sx: short-term memory loss, ataxia, confabulation
*often seen in alcoholics
vitamin B1 (thiamine) - pharmacologic uses
*management of alcoholism
*post-bariatric surgery (supplementation)
*pregnancy
*total parenteral nutrition (TPN)
vitamin B3 (niacin) - sources
*dairy, poultry, fish, lean meats, nut, eggs
vitamin B3 (niacin) - functions
*precursor of the coenzymes: NAD and NADP
*energy metabolism, cell signaling, DNA repair
vitamin B3 (niacin) - deficiency disease
pellagra
note - pellagra is characterized by dermatitis, diarrhea, and dementia
pellagra
*vitamin B3 (niacin) deficiency
*sx: dermatitis, diarrhea, & dementia (the 3 D’s); glossitis and cheilosis (swelling of tongue/lips)
vitamin B3 (niacin) - populations at risk for deficiency
*corn as main dietary staple
*impoverished populations
*chronic alcoholism
*carcinoid syndrome
vitamin B3 (niacin) - pharmacologic uses
*treatment of hyperlipidemia (rarely used now)
*post bariatric surgery
vitamin B3 (niacin) - toxicity
*cutaneous flushing, diarrhea
*increased LFTs, hepatitis, glucose intolerance
vitamin B9 (folic acid) - sources
*beans and legumes, citrus fruits and juices, whole grains, dark green leafy vegetables, poultry, pork, shellfish, liver
vitamin B9 (folic acid) - functions
*cofactor in methyl group transfer reactions
*critical for synthesis of DNA, glutathione, hormones, phospholipids, and neurotransmitters
vitamin B9 (folic acid) - deficiency diseases
*neural tube defects (in fetus)
*megaloblastic anemia
vitamin B9 (folic acid) - populations at risk for deficiency
*severe malabsorption
*drug and food antagonists
*poor diet in the elderly
*bariatric surgery patients
vitamin B9 (folic acid) - pharmacologic uses
*adequate amounts of folate BEFORE CONCEPTION and DURING PREGNANCY prevent neural tube defects such as spina bifida
vitamin B12 (cobalamin) - sources
*synthesized only by microorganisms (product of bacterial metabolism)
*naturally found in: eggs, meat, poultry, shellfish, milk and milk products
*added to fortified grain products (cereals)
vitamin B12 (cobalamin) - functions
*cofactor in methyl group transfer reactions
*critical for synthesis of DNA, glutathione, hormones, phospholipids
vitamin B12 (cobalamin) - deficiency diseases
*megaloblastic anemia
*subacute combined degeneration (posterior columns of spinal cord; irreversible)
vitamin C (ascorbic acid) - sources
*citrus fruits, green peppers, strawberries, tomatoes, broccoli and sweet and white potatoes
vitamin C (ascorbic acid) - function
*aqueous phase antioxidant (protects us from free radicals)
*cofactor for collagen biosynthesis
*facilitates dietary iron absorption (reduces Fe3+ to Fe2+)
*regenerates vitamin E radicals
*role in folate activation
vitamin C (ascorbic acid) - deficiency disease
scurvy
scurvy
*deficiency in vitamin C (ascorbic acid)
*sx: severe periodontal disease, cutaneous hemorrhage, poor wound healing
vitamin C (ascorbic acid) - populations at risk for deficiency
*cigarette smokers
*severe malnutrition, cachexia
fat soluble vitamins - differences from water soluble vitamins
*absorption of fat soluble vitamins requires the presence and efficient absorption of dietary fat!!
*can be stored (in liver and adipose tissue)
*can be toxic in excess
fat soluble vitamins - absorption
*solubilized in lumen in mixed micelles
*packaged in chylomicrons and secreted into lymph
*taken up by the liver in chylomicron remnants
*secreted in plasma bound to transport proteins
vitamin A (retinol) - sources
*animal sources such as eggs, meat, and dairy products
*produced from beta-carotene, which comes from green, leafy veggies and intensely colored fruits and veggies
vitamin A (retinol) - functions
*visual pigment synthesis
*maintains ocular structures
*transport by retinol-binding protein
*bone growth & development
*modulates epithelial cell function
*key role in embryo development
vitamin A (retinol) - deficiency diseases
*keratomalacia
*hyperkeratosis
*night blindness
vitamin A (retinol) - toxicity
*teratogenic effects
*hypervitaminous A syndrome
*hepatotoxicity
vitamin A (retinol) - populations at risk for deficiency
*fat malabsorption syndromes!!!
*poor diet in the elderly
*some underdeveloped countries
vitamin D (calciferol) - sources
*the body itself makes vitamin D when it is exposed to the sun (UV-B light); we make it out of cholesterol
*cheese, butter, margarine, fortified milk, fish, fortified cereals
vitamin D (calciferol) - physiologic actions
*gut: increased calcium and phosphorous absorption
*kidney: increased distal calcium reabsorption
*bone: facilitates mineralization
*multiple effects on growth, cell repair, and immune function
vitamin D (calciferol) - deficiency diseases
*RICKETS (in children)
*osteoporosis (in adults)
vitamin D (calciferol) - populations at risk for deficiency
*fat malabsorption syndromes!
*elderly & homebound
*populations in northern latitudes (less sun)
*advanced kidney disease
vitamin D (calciferol) - toxicity
*hypercalcemia, weakness
*kidney stones
vitamin D (calciferol) - pharmacologic use
*prevention of hypocalcemia in renal failure and after parathyroidectomy
*used as an adjunct in treating osteopenia and osteoporosis
vitamin E (tocopherol) - sources
*corn, nuts, olives, green leafy veggies, vegetable oils, wheat germ
vitamin E (tocopherol) - functions
*membrane antioxidant (protects from free radicals)
vitamin E (tocopherol) - deficiency disease
*hemolytic anemia (rare, seen only in those with severe fat malabsorption)
vitamin E (tocopherol) - populations at risk for deficiency
*biliary atresia
*cystic fibrosis
*short bowel syndrome
*severe pancreatic insufficiency
*genetic abnormalities
vitamin K (menaquinones) - sources
*plant sources: cabbage, cauliflower, spinach, other green leafy veggies, cereals
*bacterial sources also
vitamin K (menaquinones) - function
*liver synthesis of CLOTTING FACTORS II, VII, IX, X, prothrombin, proteins S and C
*bone homestasis
*reduced vitamin K is a cofactor for conversion of glutamic acid residues in target proteins to gamma glutamic acid
*brain development
*bone synthesis
vitamin K (menaquinones) - deficiency disease
*bruisability & bleeding
vitamin K (menaquinones) - populations at risk for deficiency
*premies & neonates
*fat malabsorption syndromes
*patients on chronic antibiotics (because bacteria supplement our vitamin K pool)
*short bowel syndrome
vitamin K (menaquinones) - pharmacologic uses
*acute reversal of coumarin (warfarin) induced anticoagulation
*stabilization of anticoagulation in patients taking coumarin Rx
