Micronutrients II - Vitamins Flashcards
What is the function of vitamins?
cofactors for enzymes
How many essential vitamins?
13
What are vitamins typically used for?
cofactors for enzymes
(not catabolized to CO2 and H2O like macronutrients)
(organic)
What type of vitamins cause problems in excess?
lipid soluble
List the 4 lipid soluble vitamins.
Vit A, D, E, K
List the 9 water soluble vitamins.
thiamin Riboflavin (B2) Niacin (B3) Pantothenic Acid (B5) Pyridoxine B6 Biotin Folate Vitamin B12 Vitamin C
There is only one role of vitamins. (T/F)
False. One vitamin can have many roles.
What are some vitamin-like compounds?
inositol (phospholipids)
choline
lipoic acid (required for pyruvate ….
PQQ (pyrrologuinoline quinone
What is thiamine used for?
Coenzyme
energy metabolism
DNA/RNA synthesis
How are fat soluble vitamins absorbed?
small intestines
- with dietary fat
- digestive enzymes from pancreas help
How are fat soluble vitamins transported and stored?
transported by specific binding proteins
liver
lipoproteins/fat droplets
What are the specific differences between Vit A, D, E, K?
Source
A - animal and plant
D - fish , mushroom, milk
E - plants
K - plants
Function
A - growth, reproduction, vision
D- calcium homeo, bone, cell differentiation
E- antioxidant, cell membrane, eye, heart
K- coenzymem, blood clotting, bone, tooth
What family of molecules make up vitamin A?
mixture of retinoids
What is the importance of Vitamin A?
gene regulation, neuronal signaling
What happens with excess vitamin A?
birth defects (teratogenic), blurred vision, liver damage
How should your source of vitamin A come from?
dietary b-carotene safer source
What can carry Vitamin A in the blood?
albumin
What is vitamin A required for in the eye? consequence
physical structure of eye; xerophthalmia
What consequences for Accutane?
birth defects; drug can stay in systems for month
What the Vitamin A RDA for men? women?
Men - 900 ug/day
Women - 700 ug/day
Vitamin A deficiency is a world-wide problem. How many preschool children are blinded
250,000 - 500,000
What does deficiency of Vitamin D lead to?
Rickets (children)
How is Vitamin D derived?
synthesized in skin when UV light is present
What is the synthesis process of Vitamin D? end product?
calcitrol
What is the group of related lipids involved in control of Ca2+?
D3
1,25-dihyroxycholecalciferol
What vitamin seems to be a general deficiency in the U.S. population?
Vitamin D
What does excess vitamin D lead to?
local tissue toxification due to calcification in tissue
There is a link between vitamin D deficiency to which diseases?
diabetes, autoimmune disease, cardiovascular, cancer
What group of molecules make up vitamin K?
phylloquinones;
K1 - green leafy vegetables
K2 - menaquinone - made by bacteria in intestines
K3 - menadione -artificial, made commercially
What inhibits vitamin K?
coumarin/warfarin (discovered due to cattle eating sweet clover hay and hemorrhaging)
What does coumarin inhibit specifically?
vitamin K epoxide reductase
What is the importance of thiamine?
helps form and break C-C bonds; heavily involved in carbohydrate metabolism
What is thiamine deficiency?
Beriberi disease;
What results from Beriberi disease?
insufficient ATP production, muscle wasting, CNS damage, edema
In whom is Beriberi disease seen?
sailors
alcoholics
What is the RDA for thiamine?
1.2 mg/day
What is Wernicke syndrome?
thiamine deficiency; associated with chronic alcoholism
Korsakoff encephalopathy
severed thiamine deficiency involving CNS
Wernicke already in place so Wernicke-Korsakoff -WK- irreversible short term memory loss
What is the function of Riboflavin?
used for electron transfer,
usually cofactors of enzymes, oxygenases, oxidoreductase
Clinically what do you see in riboflavin deficiency?
glossitis, cracking of tissues are the lips (cheilossis)
normacytic anemia
Riboflavis is heat stable but ____ sensitive.
light
What is niacin used for?
nicotinic acid is precursor for NAD
What does deficiency in niacin show physically?
pellagra (Casal’s necklace)
often on back of neck
What is the RDA for niacin?
quantified as niacin equivalents (NE)
Men - 16 mg NE/day
Women - 14 mg NE/day
What clinical symptoms do you see in niacin deficiency?
fatique, headache, apathy, depression, memory loss, dementia
Excess niacin causes what symptoms?
flushin, burning of face, arms, chest
stomach irritation
How does niacin lower cholesterol?
activates G-protein coupled receptor
What is the function of pantothenic acid?
carry acyl chains
Hard to differentiate Pantothenic deficiency from other B vitamins. What are some?
burning feet
What family of compounds comprise Pyridoxine?
pyridozal phosphate,…..
What deficiency is seen in Pyridoxine?
dermatitis
What is RDA for pyridoxine?
1.3 mg/day
What symptoms in deficiency of pyridoxine?
seizures, confusion
What drugs can bind to pyridoxal and create deficiency?
penicillinamin, isozianid (treatment of cystinuris, RA)
What is estimated RDA for biotin?
30 ug/day
What synthesizes biotin?
gut bacteria
What is the function of biotin?
carboxylase reactions in fatty acid synthesis, lipid metabolism
What is seen in biotin deficiency?
impaired glucose tolerance, mental dysfunction, anorexia, dermatitis
What is the unique feature of cyanocobalamin?
metal component
How is cyanocobalamin synthesized?
bacteria
What is the RDA for cyanocobalamin?
3 ug/day
What enzymatic reactions is cyanocobalamin involved?
intramolecular rearrangements
ribonucleotide reductrace
methyl group transfers (methionine synthesis from homocysteine>
What results in cyanocobalamin deficiency?
intimate interaction with folate; anemias
What is pernicious anemia?
megaloblastic anemia due to lack of intrinsic factor secretion;
increases with aging population
What can a B12 (cyanocobalamin) deficiency lead to?
elevated homocysteine levels which are linked to cardiovascular disease due to interference with collagen maturation
What does Metformin impair?
uptake of B12
What is plasma level to show deficiency in B12?
<148 pmol/L
What is homocystein?
removed methyl from methionine
What does elevated homocystein indicate?
low B6, B12 or THF
What is the only way to absorb B12?
IF (intrinsic factor)
What is folate vital for?
DNA synthesis
What is RDA for Folate?
3 ug/day
Single carbon transfers require?
folate
Vitamin B12
Folate deficiencies result in what type of embryologic problem?
neural tube defects
What is megablastic anemia?
caused by folate and cobalmin deficiencies
enlarge RBC
