Chapter 12 - Fat Soluble Vitamins Flashcards
What are vitamins?
essential organic compounds needed in small amounts
Are vitamins a source of energy?
NO
Vitamins needed for what?
energy metabolism
growth
development
maintenance
What are the fat-soluble vitamins?
A, D, E, K
Fat-soluble vitamins dissolve in what?
organic solvents
What are the water-soluble vitamins?
B-vitamins
Vitamin C
What are the sources of fat-soluble vitamins?
plant and/or animal depending on the vitamins
Fat-soluble vitamins absorbed with what?
dietary fats
Fat-soluble vitamins rely on what?
bile
pancreatic juices
% of fat-soluble vitamins absorbed?
40-90% under optimal conditions
Water-soluble vitamins not dependent on what?
dietary fats
% of water-soluble vitamins absorbed?
90-100%
Water-soluble vitamin absorption occurs where?
small intestine
Fat-soluble vitamins must be efficiently absorbed where?
small intestine
If absorption is decreased, what must happen?
more must be consumed
Fat-soluble issues?
GI tract disease
Pancreatic disease
What may lead to malabsorption of some B-vitamins?
alcohol abuse
Examples of vitamin absorbency diseases?
cystic fibrosis
crohns
Fat-soluble vitamins are delivered with what?
dietary fats
Fat-soluble vitamins are delivered in what?
chylomicrons
lipoproteins
What remnants contain fat-soluble vitamins?
chylomicron
What repackages these vitamins to transport to cells in the body?
liver
If not put into blood transport, what happens to these vitamins?
stored in liver or adipose tissue
Water-soluble vitamins are delivered where?
directly to bloodstream and distributed
Fat-soluble vitamins are stored where with the exception of what?
liver and adipose tissue
Vitamin K
Are fat-soluble vitamins readily excreted from the body?
NO
Describe the stores of water-soluble vitamins.
limited stores except B-12 and B-6
Are water-soluble vitamins readily excreted from the body?
yes
How often should water-soluble vitamins be consumed?
daily
Retinoids
preformed vitamin A compounds
Carotenoids
plants contain pro-vitamins to vitamin A
Where are retinoids found?
liver fish fish oils fortified milk eggs
Where are carotenoids found?
dark-green and yellow-orange veggies and fruit
70% of vitamin A in North America comes from what?
animal sources
Dietary vitamin A activity is expressed how?
Retinal Activity Equivalents (RAE)
Key functions of vitamin A
growth and development
immune function
cell differentiation
vision
During growth and development, what does vitamin A lend to?
eyes, limbs, cardiovascular system, nervous system
Vitamin A deficiency during pregnancy?
birth defects
infant mortality
How does vitamin A contribute to the immune system?
helps maintain epithelium, which is the barrier that protects the body against entry of pathogens
Is vitamin A deficiency common in North America?
no, it is rare
Is vitamin A deficiency common in developing countries?
yes
Worldwide, vitamin A deficiency is the leading cause of what?
nonaccidental blindness
What eye diseases could result from a vitamin A deficiency?
night blindness
Bitot’s spots
Keratomalacia
Xerophthalmia
How does a lack of vitamin A create night blindness?
retina regenerates rhodopsin more slowly
Bitot’s spots
gray spots caused by hardened epithelial cells
Keratomalacia
softening of the cornea
Xerophthalmia
sequence of changes in the eye, resulting in blindness
What skin disease could result from a vitamin A deficiency
follicular hyperkeratosis
Follicular hyperkeratosis
hardened keratin replaces mucous-forming epithelia
Hypervitaminosis A
long-term supplement use at 5 to 10 times RDA for retinoids
What is the UL for retinol?
3000 mg/day
Is there a UL for carotenoids?
no
What are the three kinds of vitamin A toxicity?
acute
chronic
teratogenic
Acute vitamin A toxicity
caused by one large does in a day or several large doses over a few days
Chronic vitamin A toxicity
symptoms occur with repeated intakes of 10x RDA
Teratogenic vitamin A toxicity
can cause spontaneous abortions and birth defects
Why is vitamin D the “sunshine vitamin”?
presence of sunlight allows cells to synthesize vitamin D from a cholesterol derivative
Why are there strict limitations on the categories of foods that can be fortified with vitamin D?
toxic at high levels
What foods contain vitamin D2?
fatty fish
cod liver oil
fortified milk
fortified breakfast cereals
Calcitrol
helps maintain blood levels of calcium and phosphorous, which maintains bone health
When calcium is low, what does vitamin D do?
increases intestinal absorption of calcium and phosphorous
When blood calcium levels are low, what does vitamin D do to bones?
releases calcium and phosphorous from bone to restore blood levels
When vitamin D is deficient, what happens to calcium?
dietary calcium cannot be absorbed efficiently, which can cause problems with bone mineralization and structure
What is the vitamin D deficiency found in children?
Rickets
What is the vitamin D deficiency found in adults?
Osteomalacia
Oversupplementation of vitamin D can cause what?
- high blood and urine calcium concentrations
- depositing of calcium in blood vessels and kidneys
- cardiovascular damage and possibly death
What happens during chemical reduction?
gain of electrons
What happens during chemical oxidation?
loss of electrons
What part of a REDOX reaction is dangerous?
oxidation
What is a free radical?
substance that causes oxidation to happen
ROS
reactive oxygen species
What do ROS’s do?
attack and snatch energy from other cells to satisfy themselves
Why is the formation of free radicals dangerous?
causes chain effect of cellular damage
once one is oxidized because of a free radical, it’ll go in search of its own electron
What natural processes in the body form free radicals?
metabolism
inflammation
What causes exaggerated formation of free radicals?
UV light exposure
ionizing radiation
smoking
air pollution
What do antioxidant vitamins do?
donate electrons to free radicals
What must happen to antioxidants to be used again?
must be “recharged”
Vitamin E is known as what?
amphipathic
Amphipathic
hydrophilic and hydrophobic
Active form of vitamin E
alpha-tocopherol
What is the activity level of other forms of vitamin E?
low
Where is vitamin E stored in the body?
adipose tissue
Absorption of vitamin E depends on what?
normal fat absorption
Once absorbed, what happens to vitamin E?
incorporated into chylomicrons
Good sources of vitamin E include?
anything plant based and oily
Vitamin E is highly susceptible to what
destruction by oxygen, metals, light, and heat
Is vitamin E an antioxidant?
yes
What is vitamin E “recharged” by?
vitamin C
Vitamin E can only attach to a free radical once unless?
free radical is removed by vitamin c
Is toxicity and deficiency of vitamin E common?
no, least toxic fat soluble vitamin
Two types of vitamin K
phylloquinone
menaquinones
Phylloquinone
from plants
most biologically active
Menaquinone
fish oils and meats
synthesized by bacteria in colon
Function of vitamin K
synthesis of blood clotting factors
preprothrombin —– prothrombin
% of vitamin K from gut flora?
10ish
Location of absorption for vitamin K?
large intestine
Food sources of vitamin K?
green leafies broccoli peas green beans vegetable oils
Vitamin K deficiency can cause?
uncontrolled blood loss
What can cause a secondary deficiency of vitamin K?
antibiotics
Who receives a vitamin K supplement and why?
newborns
gut is sterile