MODULE 1 Week 2: Vitamin A & Cartenoids Flashcards
Major functions of vitamin A
- Cell growth & reproduction
- Cell differentiation
- Bone development (osteoblasts/clast)
- Immune function
- VISION
- gene expression
3 main forms of Vitamin A (retinoids)
- Retinol
- Retinal
- Retinoic acid
What are carotenoids? (Color?)
Red, orange, and yellow lipid-soluble pigments mainly found in plants
**Beta-carotene exhibit is the XXX amount of pro vitamin A activity
Greatest
Where is Vitamin A found in food?
LIVER, fatty fish (herring), dairy products, eggs
** Most common dietary carotenoids/carotenoids most commonly found in the body? (6)
- B-carotene
- Alpha-carotene
- B- crytoxanthin
- Lycopene
- Lutein
- Zeaxanthin/Cryptoxanthin
Are meat and fish major sources of carotenoids?
No
What macronutrient improves vitamin A absorption? What percent is absorbed when this is present?
Need AT LEAST 10g of fat in a meal to absorb 70-90% of dietary vitamin A
Does fiber (pectin) and vitamin E consumption improve or decrease Vitamin A absorption?
DECREASE (interferes with micelle formation)
** Vitamin A/carotenoids are typically bound to what macronutrient in our diets?
PROTEINS
** Vitamin A is typically esterfied to what ???
Fatty acids
** What % of carotenoids are absorbed? Depends on what?
5-60%
Lower for UNCOOKED/JUICES and higher in FATTY MEAL/OIL BASED SUPPLEMENTS
** Primary location where carotenoids (Alpha and beta-carotene & crytoxanthen) are converted to vitamin A
Intestinal mucosal cells
** Retinoic acid v other forms of Vitamin A: how are they transported from intestines?
Retinoic acid = bound to ALBUMIN
Retinol/retinal/others = Added to CHYLOMICRON
Primary location that chylomicrons deliver Vitamin A and carotenoids to?
Liver
**Stellate cells
Specialized cells in liver where vitamin A is stored
** Blood transport of Vitamin A depends on what 2 transport proteins (made by the liver)?
- RBP (retinol-binding protein)
2. Transthyretin
** 3 things required for optimal synthesis on RBP (retinol-binding protein)?
- Adequate protein
- Vitamin A
- ZINC
** Carotenoids are mainly delivered to what 2 locations?
- Adipose tissues
2. Liver
** The retina of the eye is especially high in what two carotenoids?
- Leutin
- Xeanthin
**Vitamin A and osteoporosis
Up regulates osteoclasts (the cells that BREAK DOWN bone/calcium)
*** Osteoporosis and up-regulated immune system
More WBC action (with unregulated immune system) means more osteoCLAST activity which means more bones are going to break down
** Osteoporosis, inflammation, estrogen
Inflammation/up regulated immune system in addition to DECREASED estrogen could play a role in osteoporosis development
** Vitamin A(retinol) palmitate is found in what foods?
- LIVER
- egg YOLKS
- Fish
- Dairy
** Night-blindness due to deficiency in what vitamin?
A
** Rhodopsin facilitates the conversion of light to X??
A neuroelectrical signal
** Vitamin A and gene expression
- 2 forms of Retinoic acid interact with DNA response elements?
Retinoic acid bins to certain receptors on DNA and influence transcription of certain proteins???????
** Teratogenesis
Process by which congenital malformations are produced in a fetus
** Vitamin A and birth defects (teratogenesis)
Toxic levels of vitamin A can lead to excessive growth and reproduction, leading to birth defects
** Carotenoids as antioxidants are especially effective in lipid soluble compartments such as?
- Plasma membrane
- Lipoproteins
** 2 main carotenoid antioxidant mechanisms of actions
- QUENCHING (non-radical species)
2. SCAVENGING (radical species = bad)
** Who wouldn’t you recommend beta-carotene to? Why?
Wouldn’t recommend to smokers because of the associations with increased risk for lung cancer
** Specific Vit A function with immune health
- Needed for T-lymphocyte function
- For antibody response to bacterial, virus, and parasitic infection
** What parts of the eye are lutein and zeaxanthin found in?
Retina (specifically macula - central retina)
** Function lutein and zeaxanthin in eye LOOK UP
- help QUENCH free radicals/effects of oxidation
-
** If there is deficient/decreased vitamin A, what happens to iron incorporation into RBCs?
If vitamin A low, there is DECREASED iron incorporation into RBCs
** Relationship between Vitamin A, iron, anemia
Low Vit A can lead to less iron incorporation into RBC.
Supplementing with Vit A can help prevent/correct anemia
** What tocopherol is Olive Oil high in?
Alpha
** What is Xeropthalmia?
Abnormal dryness of the conjunctiva and cornea of the eye (due to Vit A deficiency)
** What food (animal product) is high in vitamin a Palmitate?
Liver
** What micro minerals affect vitamin A absorption and how?
ZINC deficiency
- zinc deficiency reduces retinol binding protein capacity (therefore affecting vit A metabolism)
** Main carotenoid colors
Red, orange, yellow
Three carotenoids that are provitamins (can be converted to vitamin A)
- Beta carotene
- Alpha carotene
- Beta cryptoxanthin
** What B vitamin is needed for the formation of vitamin A (retinol) from beta carotene?
NIACIN
** Which carotenoid has the strongest anti oxidant function?
Lycopene
** Major components of carotenoid digestion & absorption (where does it happen?)
- Freed from protein by PEPSIN in the stomach
- Form fat globules
- Emulsified by BILE in duodenum
- Proteolytic enzymes hydrolyze
- & Pancreatic lipas hydrolyze vitamin in small intestines
- Form MICELLES
- Travels through intestinal epithelial cells
- Absorption occurs in duodenum and jejunum
** Synthesis of vitamin A from Beta carotene requires what B vitamin and what mineral?
Niacin & IRON?
** % / efficiency of beta carotene to retinol conversion
50%
- 11-cis retinol v 9-cis Retinoic acid functions
11-cis = VISION
9-cis = GENE EXPRESSION
** Where are carotenoids stored in the body? (Lutein and zeaxanthin?)
LIVER
Less in adipose tissue
Lutein and zeaxanthin = RETINA OF EYE
** Form of vitamin A essential for vision
11-cis retinol
** What is rhodopsin
Protein essential for vision formed from protein opsin + 11-cis retinol (Vit A)
In visual cycle, 11-cis retiNOL is converted to what?
11-cis retinAL
** Vitamin A and Accutane
Accutane in HIGH dose vitamin A; should not take Vit A supplements while on this medication
** Accutane side effects
- dry skin
- rash
- nosebleeds
- dry corners of mouth/eyes
** Forms of vitamin A involved in gene expression
- trans retinoic acid
- 9 - cis retinoic acid
** How does vitamin A play a role in gene expression
In the nucleus, Vit A interacts with nuclear receptors (bind to them) altering the activity of the cell/transcription
