Chapter 12: fat-soluble vitamins Flashcards
fat-soluble vitamins are absorbed with
dietary fat
* adequate absorption depends on bile and pancreatic lipase
fat-soluble vitamins are stored in
liver and adipose tissue
* less storage of vitamin K
retinoids
preformed vitamin A
* mostly animal sources
* found in liver, fish, fish oils, fortified milk, and eggs
retinoid functions
- growth
- development
- cell differentiation
- vision
- immune function
carotenoids
provitamin A
* need to be activated in body
* mostly plant sources (dark-green and yellow-orange vegetables and fruits)
retinal is needed in the
retina
reintal turns visual light into
nerve signals to the brain
series of steps leading to the formation of active vitamin D
vitamin D –> vitamin D3 (cholecalciferol) –> 25-dihydroxyvitamin D3 (calcifediol) –> 1-25, dihydroxyvitain D3 (calcitriol)
functions of vitamin D
calcium absorption and maintenance of levels
vitamin D may help regulate
- immune function
- the funciton of other hormones
- cell cycle
rickets
abnormal mineralization of bones in children
signs of rickets
- enlarged head, joints and ribcage
- deformed pelvis
- bowed legs
rickets can be associated with
- fat malabsorption
- cystic fibrosis
- dark skin
- low milk intake
- minimal sun exposure
osteomalacia
poor calcification of newly synthesized bone in adults
osteomalacia can be seen in adults with
- imparied fat absorption
- dark skin
- limited UV exposure
Vitamin D toxicity
upper level is set at 100mg/4000 IU day for 9 and older
above this can cause:
* excess blood calcium
* bone loss
* calcification in kidneys, heart, and lungs
tocopherols
4 types of vitamin E
* alpha, beta, gamma, delta
tocotrienols
4 tpyes of vitamin E
* alpha, beta, gamma, delta
where is vitamin E most likely to be found in the body
adipose tissue
role of vitamin E as an antioxidant in the cell membrane
antioxidant, especially in lipid-rich areas
groups susceptuble to vitamin E deficiency
- those with fat malabsorption condition
- smokers
- preterm infants
vitamin E deficiency is characterized by
- premature breakdown of RBCs, which leads to development of hemolytic anemia
- impaired immune function
- neurological changes in spinal cord and peripheral nervous system
Phylloquinones source
plants, the main biologically active form
menaquinones source
- fermented foods
- bacteria in large intestine
Vitamin K function
used for posttranslational modificaiton of proteins: coenzyme synthesis of Gla domains
key proteins with Gla:
- prothrombin and other coagulation factors
- osteocalcin
warfarin
decreased formation of the active version of vitamin K
