Vitamins Flashcards
Fat soluble vitamins
Vitamins A, D, E, K
Water Soluble Vitamins
Vitamins C, B1, B2, B6, B12, folate, biotin, pantothenic acid
niacin
Vitamin A function
fat soluble vitamin
binds to cell nuclear receptors
provitamin A (carotene) - structure equivalent of 2 vitamin A molecules
processing of Vitamin A
Beta-carotene into retinal & then to retinol (active form) & retinoic acid
transport for Vitamin A
retinal binding protein
active form of vitamin A
retinol (OH group on the end)
toxic level of vitamin A
anything over 100 ug/dl
importance of vitamin A
growth, reproduction, immune system
cell differentiation - maintains epithelial integrity
vision- part of rhodopsin
Vitamin A role in vision
retinol is oxidized in rods of eye retina to retinal
the complexed w/ opsin to form Rhodopsin
sight in dim light
Vitamin A deficiency
lead to night-blindness- seen in malabsorption, liver impairment, premature infant loss of hair joint pain headaches drowsiness vomiting
Hypervitaminosis A
vitamin A toxicity > 140 ug/dl in plasma
measured by HPLC
Vitamin E
(alpha-tocopherol); anti-oxidant - primary defense against oxidation of unsaturated lipids & cells
Vitamin E metabolism
40% absorbed from GI, attaches to chylomicrons for transport to liver
then transported via VLDL to cells
excreted through feces
deficiency of vitamin E
shows hemolytic anemia
can see in premature infants, fat malabsorption in adults
measured by HPLC
Vitamin K function
(napthoquinone); essential for coagulation factors
Vitamin K dependent coagulation factors
II, VII, IX, X also protein C & S
source of vitamin K
50% diet & 50% gut bacteria
absorbed into body via bile salts
lack of vitamin K
leads to hemorrhagic crisis
usually related to GI malabsorption & antibiotics
testing for vitamin K
use Prothrombin time (PT) -extended time
liver disease will also show low coag proteins but may not be vit K related
vitamin K toxicity
usually not seen in adults
children with vit K supplement at birth can see increase in bilirbuin
supplements rich in vit K : garlic, gingko, & ginseing
Vitamin D function
1,25 DHCC facilitates calcium (& phosphorus) absorption
D2
ergocalciferol - not naturally occurring
D3
cholecalciferol
can make from sunshine on 7-dehydro-cholesterol
vitamin D absorption
absorb from gut; attaches to chylomicrons for transport to liver
stored in liver
excreted in bile
vitamin D stimulates
ca2+ absorption along w/ phosphorus from intestine
w/ PTH- increases mobilization of ca2+ from bone to circulation
has apoptotic effect - cancerous cells/ loses growth regulation
vitamin D deficiencies
children- ricketts
osteomalacia- softening of the bone
AED- hinder vit D absorption
any malabsorption condition or renal issue
vitamin D toxicity
children hyperparathryoidism hypophosphatemia pregnancy excess vitD leading to excess calcium deposits in heart & kidneys (damage can be irreversible)
laboratory testing for vitamin D
calcium testing - PTH, serum Ca2+, urine Ca2+
assay 25-OH-cholecalciferol or 25-OH vit D3 by immunassay or HPLC
vitamin B1 (thiamine)
used to make thiamine pyrophosphate TPP - important coenzyme
needed for decarboxylase subunits of dehydrogenase complexes