Exam 2 - Fat soluble Vitamins A, D, E, K

how are fat soluble vitamins absorbed

passive diffusion via micelles

how are fat soluble vitamins transported

via lipoproteins

enterocytes use which lipoprotein to transport fat soluble vitamins

chylomicrons

what are the fat soluble vitamins

A, D, E, K

which two fat soluble vitamins require digestion

A, E

how much fat is needed to enhance absorption of fat soluble vitamins

5-10g

what are the 2 forms of Vit A

preformed (active)

proformed

preformed vit A is found in what products?

animal

what is the storage form of vit A

retinol Ester

what form of Vit A do we eat

retinol ester

retinol oxidizes to form the aldehyde version called: ___ which oxidizes to form the carboxylic acid form called: ___

retinal, retinoic acid

proformed vitamin a is found in what products

plants: red, orange, yellow colors

carotenoids

carotenoids have an important function, what is this

act as an antioxidant

absorption of proformed carotenoids is limited compared to preformed vit a, what is one way that can enhance absorption of the proformed version

cooking

which form of Vitamin A is super toxic? How does the body combat this?

Retinol (alcohol)

binds to cellular retinol binding protein (CRBP)

where is Retinol reesterified to a retinol ester? What enzyme does this?

enterocyte

lecithin: retinol acyl transferase

where is 70% of vitamin A stored

liver

what are the 3 ways Vitamin A is dealt with by the body

use, store, export

what is required to allow vitamin a to leave the liver

zinc and protein

zinc and protein allow vitamin a to leave the liver because they aid in forming what

retinol binding protein

what is the main function of retinol

reproduction and growth

retinol can oxidize to form retinal. What is the function of this form?

vision (part of rhodopsin)

retinol can also be converted into retinoid acid. What is the function of this acid?

gene expression, cell differentiation, immune system support

certain genes contain retinoic acid receptors (RAR) or retinoic X receptors (RXR). What do these receptors facilitate

expression of specific genes

____-retinol activates the JAK/STAT pathway which leads to genes of the nucleus affecting regulation of ____ and lipid metabolism

CRB, insulin

what is the most utilized form of vitamin a

retinoic acid

decreased vitamin A can lead to decreased rhodopsin being created by the rods of the retina. This can lead to what

night blindness

what is an example of vitamin a playing a role in cell differentiation

keratinizing cells mature into mucus secreting cells

a deficiency in Vitamin A can lead to what skin condition

follicular hyperkeratosis - failure of keratizing cells to mature

carotenoids have no dietary toxicity, but too much supplementation can lead to increase risk for ___

cancer

too much of the preformed version of vitamin a can lead to what

birth defects, blurred vision, bone fractures

what is the primary cause of a vitamin a deficiency? what is the secondary cause?

inadequate intake

fatty malabsorption

someone can be low in what cofactor and look like they are deficient in vitamin a

zinc

what are some vitamin a deficiency symptoms

night blindness

dry eye (xerophthalmia)

bitot's spots (keratin in eye)

Vit A deficiency is the leading cause of _____ blindness in the world? It is the leading cause of ____ blindness in children?

preventable, nutritional

who is at risk of vit a deficiency

premature infants

pregnant women

cystic fibrosis patients

excess dietary vitamin A decreases absorption of what vitamin? what does this lead to?

k, decreased clotting

vitamin A is required for absorption, transportation, and utilization of what

iron

what is the alternative name for vitamin d

calciferol

what is the animal form of vitamin d

cholecalciferol - D3

what is the plant form of vitamin d

ergocalciferol - D2

where does cholecalciferol get activated

kidney

what enzyme works in the kidney to activate vitamin d

1 alpha-hydroxylase

calciferol gets converted to ____ in the liver via 25-hydroxylase. After this, it goes to the kidney to become the active form called _____

calcidiol (25-hydroxyvitamin), calcitriol (1,25-dihydroxyvitamin)

which form of vitamin d is used as a biomarker? why?

calcidiol (25-hydroxyvitamin)

longer half life

where is most vitamin d found

in the blood

where is vitamin d stored

adipose, tiny amounts in muscle

what is the number one function of vitamin d

calcium and phosphorus homeostasis for bone mineralization

besides its affect on bone, what does vitamin d have a role in

gene expression, cell signaling, immune system, muscle

what stimulates PTH release? what does PTH stimulate in relation to vitamin d?

low calcium, induces alpha-hydroxylase in the kidney -> activates calcitriol -> stimulates synthesis of calcium binding proteins

Vitamin D has a nongenomic function meaning it plays a role in membrane-initiated steroid signaling (MISS) to increase intracellular ___ concentrations

calcium

what is the RDA for vitamin d for 0-1 year olds

400 IU, 10 mcg

what is the RDA for vitamin d for 1-70 year olds

600 IU, 15 mcg

what is the RDA for vitamin d for those over 70 years old

800 IU, 20 mcg

what are some factors that influence vitamin d

season, cloud coverage, latitude, skin color, sunscreen, age, malabs, obesity

most of the vitamin d we consume comes from what

fortified foods

what are some sources of dietary vitamin d

cows milk, fish

deficiency of vitamin d in children can lead to what condition? what about adults?

rickets

osteomalacia

what are some symptoms of vitamin d deficiency

bowed legs

BILATERAL knee pain

muscle weakness

bone pain

what are some at risk populations for vitamin d deficiency

breastfed infants, older adults, high skin pigmentation, fatty malab, obese

what are some complications associated with toxicity of vitamin d

hypercalcemia and hyperphosphatemia

kidney stones from calcification of soft tissues

who is recommended to take supplements of vitamin d

breastfed infants, fatty malab patients

what is the alternative name for vitamin e

tocopherol

what is the form of vitamin e that has been recognized to meet human requirements

alpha-tocopherol

what is the other form of vitamin e besides tocopherol

tocotrienol

both tocopherol and tocotrienol can be found in what forms

alpha, beta, delta, and gamma

vitamin e in the ester form requires what to be digested

pancreatic esterase and duodenal mucosal esterase

once vitamin e is digested, how is it absorbed?

passive diffusion as a micelle

how does vitamin e enter cells

LDL uptake

vitamin e is the main ___ in LDL

antioxidant

where is vitamin e found in the body? why?

membranes

protect he PUFAs in the membrane from oxidation

C is the key to E

what does this mean?

vitamin c is necessary for vitamin e regeneration

how does vitamin e play a role in immune system function

inhibits protein kinase C, controls T cell function

Vitamin e can inhibit which pathways of arachidonic acid metabolism

COX, LOX

what can vitamin e increase production of to inhibit platelet aggregation and increase vasodilation

prostacyclins

too much vitamin E can cause ___ blood

thin

what are the main dietary sources of vitamin E

oils, nuts, seeds

it is found in germ

in its natural form, what isomer(s) is/are present? What about the synthetic form?

only biologically active form - alpha-tocopherol

all 8 isomers are in a supplement

is hypovitaminosis E common

no

what are symptoms of hypovitaminosis E in premature infants

hemolytic anemia

hypovitaminosis E can lead to what symptoms

neuropathy and retinopathy from disturbed myelin production, skeletal myopathy, impaired immune response

who is most at risk for hypovitaminosis E

premature infants

fatty malab

supplementation of vitamin e can lead to hypervitaminosis E which can inhibit activity of which vitamin

K - decreased clotting and thin blood

what is the cofactor for antioxidant enzyme glutathione peroxidase which works with vitamin e

selenium

a diet high in what requires more vitamin e intake to protect against oxifation

fat

what is the form of vitamin k that is found in green plants and is the majority of vitamin k that we eat

phylloquinone -K1

what is the alternative name for vitamin k

phylloquinone

what is the form of vitamin k that is made by bacteria in the LI and found in animals

menaquinone - K2

does vitamin k require digestion? how is it absorbed?

no

micelles via passive diffusion

where is phylloquinone stored

cell membranes of lungs, kidneys, bone marrow, pancreas, heart, brain, and adrenals

how quickly does the liver metabolize vitamin k? what does this mean?

rapidly, we need to eat it every day

what is a major function of vitamin k

act as a coenzyme

when acting as a coenzyme, vitamin k makes ____ by adding carboxylic acid to a structure

carboxyglutamate

why is carboxyglutamate production and important function of vitamin K

they are calcium binding sites and are found on clotting factors

carboxyglutamate is required for what functions

clotting, bone formation

what are major sources of phylloquinones

dark leafy greens, broccoli, kiwi, beans, peas

what are major sources of menaquinones

natto (fermented soybeans), meat, dairy, eggs

who is at risk for vitamin k deficiency

newborns, malab patients, those who have prolonged antibiotic use

because newborns are at risk for vitamin k deficiency, what are they often given at birth

vitamin k shot to prevent bleeding in the brain

what are symptoms of hypovitaminosis K

increased bleeding, poor bone growth