Exam 1: Fat Soluble Vitamins Flashcards
1
Q
Fat soluble vitamins
A
Vitamins A, D, E, K
2
Q
T/F Vitamins A, D, E, and K require 5-10 grams of fat for bile secretion in digestion and absorption
A
True
3
Q
Fat-soluble vitamins are absorbed by _______ diffusion
A
Passive
4
Q
Fat soluble vitamins are transported with _____ in ________
A
Lipids
Lipoproteins
5
Q
Fat soluble vitamins are able to be stored in the _______ and ________ which means they can be toxic in large amounts
A
Liver
Adipose tissue
6
Q
Emulsifier made from cholesterol in the liver and stored in the gallbladder.
A
Bile
7
Q
What causes secretion of bile?
A
Fat-rich chyme entering the small intestine signals the release of CCK which stimulates gallbladder contraction and releasing of bile through the Sphincter of Oddi into the small intestine
8
Q
Another name for Vitamin A is ______
A
Retinoids
9
Q
Types of Vitamin A and what each types best known function is
A
- Retinol (alcohol form) = Reproduction and growth
- Retinal (aldehyde form) = Vision
- Retinoic acid (carboxylic form) = Cell differentiation
10
Q
Vitamin A that comes from animal products attached to an ester. Is this considered active or inactive?
A
Preformed (Retinol Esters)
Active
11
Q
What is the usual preformed retinol ester?
A
Palmitic acid
12
Q
Precursor to vitamin A that comes from plant products. Used only when we don’t get enough preformed vitamin A in the diet
A
Proformed vitamin A
13
Q
Main proformed vitamin A precursor that comes from plants.
A
Carotenoids
14
Q
T/F Carotenoids are antioxidants
A
True
15
Q
It takes __ times as much proformed vitamin A to equal preformed vitamin A activity
A
12x
16
Q
What % of carotenoids can be converted to retinol?
A
<10% (of 600 known carotenoids)
17
Q
Carotenoids are usually bound to a _____ while Retinol esters are bound to both a _______ and _______ in food
A
Carotenoids = fatty acid (carotenoid ester)
Retinol Esters = fatty acid and protein
18
Q
Make vitamin A soluble
A
Bile
19
Q
What kinds of enzymes are able to remove fatty acids and protein from retinol esters?
A
Fatty acids = Lipases (esterace)
Protein = Proteases (pepsin)
20
Q
Where do proteases and lipases act on retinol esters in the body?
A
Proteases = stomach and small intestine Lipases = small intestine
21
Q
Free retinol and carotenoids are incorporated into _____
A
Micelles
22
Q
Where in the small intestine is vitamin A absorbed by passive diffusion?
A
Duodenum and jejunum
23
Q
What is retinol bound to after passive diffusion into the enterocyte?
A
Cellular-retinol binding protein (CRBP)
24
Q
After being bound to CRBP, retinol is reesterified to a retinol ester in the enterocyte by:
A
Lecithin: Retinol Acyl Transferase (LRAT)
25
Reesterified Retional esters in the enterocyte are incorporated into:
Chylomicrons
26
What happens if retinol intake is low?
1) Carotenoids are metabolized into 2 retinals
2) Retinals are either bound to CRBP, reduced to retinol, esterified via LRAT and incorporated into chylomicrons OR retinal is oxidized to retinoic acid and travels to the liver bound to a protein
27
What protein binds to retinoic acid and transports it to the liver when retinol intake is low?
Albumin
28
What happens if retinol intake is adequate?
Carotenoids are incorporated into chylomicrons
29
T/F Patients with low protein status cannot mobilize retinol out of the liver
True
30
How does vitamin A deficiency cause night blindness?
Retinal is combined with Opsin to form rhodopsin, which is important for vision in dim light and highly concentrated in the rods of the retina. Low vitamin A means low Retinal, low retinal means low rhodopsin which causes night blindness
31
How does a vitamin A deficiency cause Hyperkeratinization?
Retinoic acid from vitamin A is important for rapidly dividing cells by directing keratin synthesis (causes immature keratinocytes to mature into mature cells). Low vitamin A prevents the creation of mature mucus-secreting cells in respiratory, GI, and urinary tracts from keratin producing cells causing Hyperkeratinization (dry eyes, dry mouth, constipation, and dry mucus
32
_____ vitamin A stimulates osteoblast activity while ______ vitamin A stimulates osteoclast activity, both of which can cause an increased risk of pathologic fractures.
Low (deficiency) = stimulates osteoblasts
| High (excessive) = stimulates osteoclasts
33
T/F Retionic acid interacts with ribosomes in the rough ER to stimulate production of enzymes and growth factors
FALSE.
| Retionic acid interacts with the DNA in the nucleus into stimulate production of enzymes and growth factors
34
Low levels of this impact sperm mobility and quality
Retinol
35
This stimulates phagocytosis, cytokine production, and maintains natural killer cell concentrations
Retinoic acid
36
Function of carotenoids
- Antioxidant (quenches ROS)
| - Cell growth and differentiation (some may inhibit growth and proliferation of several cancer lines)
37
Preformed Vitamin A sources
Liver
Fish
Fortified dairy
Eggs
38
Proformed Vitamin A sources
```
Carrots
Dark green leafy veggies
Sweet potatoes
Tomatoes
Cantaloupe
```
39
Primary and secondary cause of hypovitaminosis A
A.k.a. Vitamin A deficiency
Primary = inadequate intake
Secondary = fatty malabsorption (inadequate fat or abnormality in bile production, enzymes, liver diseases, etc. prevents proper absorption)
40
Vitamin A deficiency symptoms
- Night blindness
- Xerophthalmia (dry eyes = inadequate mucus production [hyperkeratosis)
- Bitot's spots
- Permanent blindness (MC in developing countries)
- Impaired reproduction
- Depressed immune symptom
- Skin problems (hyperkeratosis)
41
Who is at risk of vitamin A deficiency?
- Children in developing countries
| - Patient with fat malabsorption
42
Major symptom of someone with fatty malabsorption?
Steatorrhea (fat in stools = stinky mineral colored stool)
43
Symptoms of acute hypervitaminosis A
A.k.a. Vitamin A toxicity
- nausea, vomiting, headache, ****double vision***, dizziness
- Taking a single dose of over 200,000 RAE
44
Symptoms of chronic hypervitaminosis A
A.k.a. Vitamin A toxicity
- No specific symptom to indicate toxicity
- Chronic intake of >7000 RAE/day
45
T/F Vitamin A is safe for women to megadose during pregnancy
FALSE.
| Vitamin A toxicity can cause birth defects (teratogenic)
46
Acne medication that contains retinoic acid and is teratogenic
Accutane
47
T/F The TUL limit for Carotenoid is 3,000 RAE per day
FALSE.
| Carotenoid has no TUL
48
Major symptom of ingesting 4-5 ounces of carrots per day for several months
Yellow/orange skin (Carotenoid toxicity)
49
T/F While considered safe in plant based foods, supplements of carotenoids does increase your risk of lung cancer, heart disease, and death in smokers and former smokers
True
50
What did high levels of alpha-tocopherol (high vitamin E) and beta-carotene have on cancer prevention?
- AT decreased prostate cancer by 32%
| - BC increased risk of lung cancer in heavy smokers and light drinkers by 18%
51
What did the trial showing high levels of beta-carotene and retinol show?
Increased risk of lung cancer, cardiovascular disease, and all-cause mortality (1.28, 1.26, 1.17, respectfully)
-Trial was stopped 2 years early, but even after 6 years, the female risk for all 3 issues was increased by 40%
52
Known as the sunshine vitamin. Made from cholesterol
Vitamin D
53
Animal form of vitamin D
Cholecalciferol (Vitamin D3)
54
Plant form of Vitamin D
Ergocalciferol (Vitamin D2)
55
50% of Vitamin D from food is absorbed into the small intestine (mostly ___ ) by means of ________
Ileum
| Passive diffusion
56
Of the 50% of vitamin D absorbed from food, what happens next?
40%- bound to vitamin D binding protein (DBP) and sent to the liver
60%- packed into chylomicrons and sent to the liver
57
How is vitamin D3 absorbed from the skin reach the liver?
Vitamin D3 is bound to DBP and sent to the liver (similar to 40% of vitamin D from food)
58
Enzymes used to convert inactive vitamin D to its active form
Hydroxylases
59
Hydroxylases belong to what part of enzymes in the liver?
Cytochrome P450 enzymes
60
T/F Calcidiol has a shorter half life than Calcitrol
FALSE.
- Calcidiol (inactive 25-hydroxy vitamin D3)= 60 day 1/2 life
- Calcitrol (active 1,25-hydroxy vitamin D3)= 4-6 hour 1/2 life
61
Enzyme found in all cells that limits amount of active calcitriol (active 1,25-hydroxy vitamin D3)
24-hydroxylase
62
Where is the highest concentration of 24-hydroxylase found?
Kidneys
63
A mutation in gene coding for 24-hydroxylase leads to ______
Hypercalcemia
64
What organs contain Vitamin D3, Calcidiol, and Calcitriol?
Vitamin D3 = Skin
Calcidiol = Liver
Calcitriol = Kidneys
65
T/F Only the skin, liver, and kidneys contain vitamin D receptors
FALSE.
| All cells contain vitamin D receptors (known to control >200 genes)
66
Vitamin D functions
- Calcium and phosphorus homeostasis (via gene expression)
- Cell differentiation and growth (prevents cancerous cells from replicating and important for immune system, nerves and prevention of CVD, MS, etc.)
67
Hormone secreted from this gland in response to low blood calcium
Parathyroid hormone (PTH) from the parathyroid gland
68
How does release of PTH cause increased calcium absorption and decreased calcium excretion?
- PTH induces hydroxylase in kidneys
- Hydroxylase activates calcitriol
- Calcitriol stimulates synthesis of calcium-binding proteins
- Calcium binding proteins increase calcium absorption and decreases calcium excretion
69
Vitamin E Vitamers
Tocopherol
| Tocotrienol
70
Most common Vitamin E vitaminers that we eat or gain in supplements
Tocopherol
71
Difference between natural and synthetic vitamin E
Natural- only biological active isomers present
| Synthetic- fatty acid attached and is a racemic mixture of isomers
72
T/F Natural Vitamin E contains alpha-tocopherol only while Vitamin E supplements contains a mixture of tocopherols and tocotrienols
FALSE.
- Natural vitamin E contains a mixture of tocopherols and tocotrienols
- Vitamin E supplements contain only alpha-tocopherol only
73
T/F Vitamin E supplements do not prevent cancer, heart disease, all-cause mortality, etc.
True
74
The fatty acid is removed from tocopherols and tocotrienols by the enzyme:
Lipase
75
About 50% of tocopherols and tocotrienols and absorbed by ___________ in the small intestine (mostly the ______)
Passive diffusion
| Jejunum
76
After being absorbed in the small intestine, tocopherols and tocotrienols are packaged into _________ and sent to the _____
Chylomicrons
| Liver
77
What protein is added to the tocopherols and tocotrienols after being packaged and sent to the liver as chylomicrons?
alpha-tocopherol transport protein (a-TTP)
78
Most alpha-tocopherol and some gamma-tocopherol and tacotrienals and incorporated into _____
VLDL
79
T/F 10% of vitamin E is stored in adipose tissue
FALSE.
| 90% of vitamin E is stored in adipose tissue
80
Function of Vitamin E
Antioxidant (regeneration of vitamin E has shown to decrease risk of heart disease, cancer, age-related macular degeneration, etc.)
81
What part of the cell uses vitamin E to donate H+?
Plasma membrane (protects PUFA's from free radicals)
82
T/F The ratio of vitamin E to unsaturated fats in the cell is about 1:10
FALSE.
| Closer to 9:1,000-2,000
83
Overall, what is the best source of vitamin E?
Plant oils
84
Who is at risk most of developing hypovitaminosis E?
1) Patients with fat malabsorption disorders (CF, pancreatic cancer, bile disorders)
2) Premature infants
85
Symptoms of hypervitaminosis E
Bleeding
Nausea
Diarrhea
Fatigue
86
Majority of Vitamin K found in plants
Phylloquinone (K1)
87
Majority of vitamin K found in bacteria
Menaquinone (K2)
88
K1 and K2 (phylloquinone and menaquinone, respectively) are absorbed by __________ in the small intestine (mostly _______)
Passive diffusion
| Jejunum
89
K1 and K2 are absorbed and sent to the ______ packaged as ________. From there they can be incorporated in ________
Liver
Chylomicrons
VLDL
90
Where most vitamin K is stored
Liver (others include heart, lungs, kidneys)
91
Functions of vitamin K
1) Coenzyme for Blood clotting (makes calcium binding sites found on clotting factors, prothrombin, and osteocalcin)
2) Coenzyme for Bone formation (makes calcium binding sites on osteocalcin)
92
Carboxylated by vitamin K to facilitate calcium binding (when synthesis is stimulated by vitamin D)
Osteocalcin
93
Vitamin K adds a carboxylic acid group to _______ residues in specific proteins to make __________ (also known as calcium binding sites)
Glutamate
| Carboxylglutamates
94
Food sources for K1 and K2
K1 (Phylloquinones) = plants
| K2 (Menaquinones) = meat, cheese, yogurt, egg yolks
95
People at risk for Vitamin K deficiency
1) Newborns
2) Patients with fat malabsorption
3) Patients chronically treated with antibiotics
96
T/F Oral vitamin K has the highest efficacy
FALSE.
| Intramuscular injection vitamin K has the highest efficacy
97
Symptoms of vitamin K toxicity
None (no established safe upper limit)
