Chapter 9: Fat-soluble Vitamins (Vitamin A) Flashcards by isabelle _

Q

other names

retinoic acid
retinal
retinol
dehydroretinol
anti-infective vitamin

A

vitamin a

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Q

vitamin a - chemistry

stable to _____ (ordinary cooking temp), _____, and _____

A

heat, acid, alkali

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Q

vitamin a - chemistry

destroyed by _____ and _____ (when become rancid) or light

A

oxidation and destruction

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Q

vitamin a - chemistry

exists in 3 forms that are found in animal tissues

A

retinol, retinal, or retinaldehyde and retinoic acid

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Q

vitamin a - chemistry

are formed when retinol combines with an organis acid

A

retinyl esters

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Q

vitamin a - chemistry

retinyl esters, retinol, and retinal are incovertible; all forms can be converted to retinol acid, a “_____”

A

terminal product

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Q

vitamin a - chemistry

are precursors of vitamin a and occur in 2 structural forms

A

carotenes

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Q

vitamin a - chemistry

carotenes occur in 2 structural forms that are present in plants (as provitamin, carotenoid precursor)

A

alpha carotene and beta carotene

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Q

vitamin a - chemistry

can undergo oxidative cleavage to 2 molecules of retinol

A

beta carotene

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Q

vitamin a - chemistry

_____ refers to a biologically active form. found in the animal foods

A

retinol esters

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Q

vitamin a - chemistry

_____ is the unit of measure

A

retinol equivalent (re)

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Q

vitamin a - chemistry

_____ and united states pharmacopeia units are used to measure vitamin a activity

A

international units (iu)

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Q

vitamin a - chemistry

RE = 1 ug retinol (_____ IU)

A

3.33

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Q

vitamin a - chemistry

1 RE = _____ beta carotene (10 IU)

A

6 ug

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Q

vitamin a - chemistry

1 RE = _____ other carotenoids

A

12 ug

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Q

vitamin a - absorption, transport, and utilization

_____ and _____ are the preformed vitamin a (easily absorbed) because it can be metabolized directly into compounds that exert biological effect of vitamin a

A

retinol and retinyl esters

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Q

vitamin a - absorption, transport, and utilization

are produced only by plants, and they function as accessory light-gathering pigments that enhance photosynthesis efficiency

A

carotenoids

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Q

vitamin a - absorption, transport, and utilization

carotenoids are the common dietary source, however, they are absorbed at much _____ rates

A

slower rates

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Q

vitamin a - absorption, transport, and utilization

retinol from food can be absorbed as such by the _____

A

intestinal wall cells

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Q

vitamin a - absorption, transport, and utilization

are hydrolyzed to free retinol and an organic acid

A

retinyl esters

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Q

vitamin a - absorption, transport, and utilization

absorption if facilitated by

A

bile

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Q

vitamin a - absorption, transport, and utilization

_____ carotene are needed to produce the vitamin a activity of 1 ug retinol

A

6 ug

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Q

vitamin a - absorption, transport, and utilization

is the predominant retinyl ester in food

A

retinyl palmate

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Q

_____% of performed dietary vitamin a is absorbed

A

75%

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vitamin a - absorption, transport, and utilization dietary beta carotene and other carotenoids, _____ is absorbed

5-50%

vitamin a - absorption, transport, and utilization stored in the _____ (90%) and _____

liver; adipose tissue

vitamin a - absorption, transport, and utilization incorporated into the _____ for transport through the _____

chylomicrons; lymphatic system

vitamin a - absorption, transport, and utilization cellular RBP and cellular retinoic acid-binding protein attach to retinol and retinoic acid, respectively; transfer to cell nucleus where they can effect gene expression

intracellular retinol-binding proteins

vitamin a - absorption, transport, and utilization storage of vitamin a occurs in the liver as _____

retinyl ester

vitamin a - absorption, transport, and utilization when in need, it is released from the liver, transported to the blood by forming a complex with a transport protein called _____

RBP

vitamin a - absorption, transport, and utilization the conversion of retinol to retinoic acid is _____

irreversible

Vitamin D - relationship with other nutrients this vitamin is needed to cleave beta carotene to retinol

Vitamin E

Vitamin D - relationship with other nutrients status of this macronutrient affects vitamin A metabolism (the transport and use of the vitamin are dependent on vitamin a-binding proteins)

protein

Vitamin D - relationship with other nutrients deficiency of this micronutrient interferes with vitamin a metabolism thru: a) reduction in the synthesis of plasma proteins particularly rbp b) decreased transport of retinol from LIVER stores *iron is needed to metabolize vitamin a from its liver stores

zinc deficiency

vitamin a - functions maintains the cornea and converts the light impulses in the retina

normal vision

vitamin a - functions when the light strikes the cornea and reached the retina, the retinal changes from a cis to a trans configuration; _____ is bleached; released by the retina, then goes back to its cis transformation and forms rhodopsin

rhodopsin

vitamin a - functions maintenance and repair of healthy _____

epithelial cels

vitamin a - functions normal _____ and _____ development

skeletal and tooth

vitamin a - functions normal reporduction

-

vitamin a - functions normal functioning of the _____ ear

middle ear

vitamin a - functions prevention of certain types of cancer (anti-cancer effect)

-

vitamin a - deficiency nyctalopia, bitot's spots, xerosis, and xeropthalmia

eye defects

vitamin a - deficiency impaired growth and development

-

vitamin a - deficiency depresses immune function

-

vitamin a - deficiency _____ of tissues

keratinization

vitamin a - deficiency cessation of bone growth, painful joints, cracks in teeth, and atrophy of dentin

hypovitaminosis a

vitamin a - toxicity (high intake) manifested by headache, dizziness, nausea, dry and itchy skin, hemoglobin losses, cessation of menstruation, induced bleeding

hypervitaminosis a

vitamin a - toxicity (high intake) yellow pigmentation of the skin

hypercarotenemia

vitamin a - toxicity (high intake) may cause birth defects

teratogenic

vitamin a - recommended intakes per day for infants (0-5 months, male and female)

380 ugRE

vitamin a - recommended intakes per day for infants (6-11 months) and children (1-9 y/o) male and female

400 ugRE

vitamin a - recommended intakes per day for adults (19->70 y/o)

males: 700 ugRE females: 600 ugRE

vitamin a - recommended intakes per day for pregnant

600 + 300 ugRE

vitamin a - recommended intakes per day for lactating

600 + 400 ugRE

in conditions with: -alcoholism -diseases of the pancreas -respiratory illness -chronic nephritis -measles -intestinal parasites -acute protein deficiency -prolonged use of neomycin -sulfate and cortisone -steatorrhea

increase vitamin a intake

vitamin a - food sources green leafy vegetables: kangkong (swamp cabbage), saluyot, camote (sweet potato) tops or leaves, and ampalaya (bitter gourd) leaves yellow fruits and vegetables (squash, carrots, ripe mango, ampalaya)

provitamin a

vitamin a - food sources liver, organ meats, egg yolk, fish liver oils, butter, and fortified margarines

preformed vitamin a

vitamin a status assessment commonly used in evaluating vitamin a status these are relatively constant unless in condition of severe deficiency or excessive intake to the point that vitamin can no longer be complexed for STORAGE IN LIVER

serum retinol

serum retinol status - criteria (for all ages) deficient

<10ug/dL

serum retinol status - criteria (for all ages) acceptable

>30 ug/dL

serum retinol status - criteria (for all ages) marginal

10-30 ug/dL