deck_4503545 Flashcards
What are the 4 fat-soluble vitamins?
A, D, E, K
What do fat-soluble vitamins require for abspt?
Bile and dietary fat
How are these vitamins transported?
W/ fats through lymphatic system in chylomicrons
Are these vits stored? Where?
Yes, in body fat (adipose tissue)>Thus intake can vary w/o risk of deficiency
e. Not easily excreted, unlike water soluble vitaminsi. **Increase … ii. Ppl should not take supplements high in these vitamins
FIGURE OUT
What are pre-made/preformed vit A called? Is it active or inactive? Toxic?
Retinoids: retinol, retinal, retinoic acidActive (usable)May be toxic
Where are retinoids found?
Animal foods>Liver, eggs, fortified into dairy, fish
What is the provitamin/precursor form of Vit A)? Is it active or inactive? Toxic?
CarotenoidsInactiveNon-toxic
Where are carotenoids found?
Plants → Yellow, orange, red fruits and veggies>More color, more carotenoids• Frozen and canned > retail fresh»Carrots, red bell peppers, cantaloupe
What is Retinoid fxn?
> Key role in night vision>Cell differentiation (key in fetal development)>Growth regulation”needed for vision (retinal), and for growth and differentiation of cells (retinoic acid)”
What is Retinoic Acid used for?
used topically to treat certain skin conditions (e.g. acne)>Vit A is a key component>Helps cells divide more rapidly, clearing old cells
What is fxn of Carotenoids? How absorbed?
Family of Phytonutrients>Decrease cancer risk and prevent macular de-generation»>In eye, (yellow) carotenoids have been shown to decrease risk of macular degeneration>Need dietary fat to be absorbed (absorbed in chylomicron)
(???) How are preformed and precursor forms of Vit A transformed in digestive tract?
> Preformed → Retinol transformed into Retinal >Precursor → Beta-carotene transformed into Retinal in liverand intestinal mucosa»_space;Retinal is converted to Retinoic Acid, can’t covert back
What is Vit A role in Visual Cycle?
> Vit A is a component of Rhodopsin (retinal + opsin) >When light hits, Retinal molecule changes molecular form»>Bent (cis) → straight (trans)»>Signals to brain that there’s light>Retinal breaks away from opsin → brain perceives light»>Retinal is lost in cycle»>Need more to form Rhodopsin»>If insufficient Retinal, eyes have difficulty adjusting to dark”- Retinal binds to opsin in the eye to form rhodopsin. After light strikes rhodopsin to begin the visual cycle, a nerve impulse is sent to the brain so the light is perceived.- When vit A is deficient, there is a delay in the regeneration of rhodpsin that causes difficulty seeing in dim light (night blindness).”
What is Vit A role in Gene Expression and Cell Differentiation ?
> Vit A has a role in directing which genes are transcribed and translated to create diff kinds of proteins»>Impt in early development and growth”- In order to affect gene expression, retinoic acid enters the nucleus of specific target cells, where it binds to retinoic acid receptor proteins; the retinoic acid-protein complex then binds to the regulatory region of DNA.”
What is relationship btwn Vit A and Keratin?
> Vit A helps w/ turnover of cells in eye that help w/ moisture and lubrication»>W/ insufficient Vit A, body creates Keratin, which leads to a hard and dry layer in the eye
Causes and symptoms of Vit A Deficiency?
Caused by insufficient intake of Vit A, fat>Night blindness>If severe: permanent blindness>Xerophathalmia – lack of mucous synthesis»>Keratin on the eye”More severe deficiency interferes w/ cell differentiation. This impairs immune fxn and growth and causes epithelial surface of eye to become hard and dry, leading to infection and blindness.”
Causes and symptoms fo Vit A Toxicity?
Retinoids – can be toxic and can increase risk of bone fractures and birth defects»_space;>Supplements (including multivitamin) have Vitamin A in multivitamins has been related to hip fractures in postmenopausal womenCarotenoids – not toxic, but high intake can cause»_space;>Hypercarotenemia: orange hue in skin, benign»_space;>Birth defects
What are dietary and other sources of Vit D? Essential?
Vit D = “sunshine vitamin” → Produced in the skin by exposure to UV light>Not found in many foods, mostly eggs, fatty fish (salmon), and milk (fortified dairy products)>Only conditionally essential in diet if you’re not producing enough through skin
What is active form of Vit D?
Vit D3, or Cholecalciferol>Modified in liver and then activated in kidney
Vit D toxicity?
Toxic at high lvls>Flynn – toxicity not thought to be issue, even w/ supplementation, but widespread use of vit D as supplement is relatively newBook info:»>High blood and urine Ca2+ concentrations»>Depositing of Ca2+ in blood vessels and kidneys, cardiovascular damage and possibly death
Vit D fxns?
> Bone health → maintains lvls of Ca2+ and P in blood that favor bone mineralization w/ calcium phosphate>Normal fxning of parathyroid gland>Regulation of immune system
How is Vit D synthesized? Where is it activated?
Light causes 7-dehydrocholesterol to be converted to Vit D3 → Needs to be activated in liver and then kidney
Is dietary Vit D3 active or inactive?
Inactive
How does Vit D affect Ca2+ Abspt? PTH?
> Increases abspt of dietary Ca2+ through normalizing parathyroid gland>Vit D works w/ parathyroid hormone (PTH) to increase Ca2+ retention at kidney, increase release at the bone, and increase abspt at the intestine
Causes and symptoms of Vit D deficiency?
> Dietary Ca2+ can’t be absorbed efficiently>Improper bone mineralization>Abnormalities in bone structure>Cancer potential for all ages
Vit D deficiency in CHILDREN?
RICKETS=Bowed legs and abnormal ribs»>Has increased overtime bc children wearing more sunscreen and covered up
Vit D deficiency in ADULTS?
OSTEOMALACIA=Bone pain, muscle aches, increase in bone fractures
How does Vit E exist in food?
In 8 forms/isomers – we’re not able to absorb in all of those forms
What form of Vit E is the only form we can absorb and USE in the body?
Alpha-tocopherol
What is needed for Vit E to be absorbed and why?
FAT – bc packaged in chylomicron and then delivered throughout body
Why is Vit E requirement so high?
> Req is based on amount needed to maintain plasma concentrations of alpha-tocopherol that protect RBC membranes from rupturing>Requirement assumes vegetable oil intake»>Vit E is added to keep vegetable oils (high in polyunsat fats) from oxidizing
Causes and symptoms of Vit E deficiency in premature infants?
> Mother doesn’t transfer Vit E to fetus until 37weeks»>Can result in hemolytic anemia (rupture of RBCs)»>Same symptoms as iron and Vit B6 deficiency>Deficiency is rare bc vit E is plentiful in food supply and stored in many body tissues
What are some dietary sources of Vit E?
EVOO, Soybean oil, Nuts and seeds
What are some fxns of Vit E?
> Antioxidant»> Protects against cell damage by neutralizing free radicals that cause oxidative damage»>Neutralization Process: Vit E donates one of its e- to free radical → impairs further Vit E activity → Vit C can restore Vit E by replacing e-(replenishes its antioxidant potential)
Vit E in supplements vs in food?
> Supplement–no benefit, and some studies show Vit E supplements increase disease and hemorrhagic stroke risk>In food–not toxic»>Vegetable seed oils contain Vit E → used to decrease oxidation of oil
Benefits of Vit E in EVOO?
EVOO is highest in alpha tocophorol and monounsat fat >More Vit E available to body than in other veg oils bc its low in polyunsat fat