Exam 2: Vitamins Flashcards
Vitamins were first discovered while
Searching for cures for common diseases
What happened in 1906
Found that a diet of synthetic protein, fat, and carbs killed all rats that were fed it but adding milk was enough to maintain normal growth
In 1911
A chemist found an amine that he thought might be a common characteristic of all tiny required compounds
- called it a “Vital Amine”
All Vitamins are
- Organic compounds different than Carbs, lipids, and proteins
- natural components found in food
- Essential (required for normal function)
- Specific deficiency caused by lack of adequate amounts
Vitamins are required in
Small amounts; milligram or micrograms
All vitamins function as
- Membrane stabilizers
- Proton and electron donor and acceptors
- Hormones
- Coenzymes
Diseases caused by clinical deficiency
- Pellagra
- Burning feet syndrome
- Keshan’s disease
Subclinical deficiency is associated with
Increased risk of chronic diseases
HTN, atherosclerosis, CA
Fat soluble vitamins are absorbed as
Part of micelles
What enhances fat-soluble vit. Absorption
Fat intake
Vitamins more likely to be toxic
Fat-soluble vitamins (stored in liver and adipose)
Fat soluble vitamins are transported
In lipoproteins in the lymphatic system
Water soluble vitamins are transported by
Portal vein
Vitamins that are not stored in large quantities
Water-soluble
- less likely to become toxic bc they aren’t stored
- must rely on daily intake to meet requirements
Vitamin A is a ______ vitamin
Fat-soluble
Main function of retinol
Reproduction and growth
Main function of Retinal
Vision
Main function of retinoic acid
Cell differentiation (*Most important function of vitamin A)
Preformed Vit A is found in
- Liver, fish, and added to dairy
- Retinol esters (retinol with a FA attached)
Retinol Palmitate is a ____ ______ that functions as
Retinol ester; storage form of vit A
Proformed versions of Vit A
Orange, yellow, and red colored plants
Carotenoids are found in
Plant sources; only used when we don’t get enough from preformed sources
Preformed to Proformed ratio of Vitamin A
12X as much proformed to equal preformed activity
There are _______ known carotenoids; but only ______ can be converted to ______
> 600, <10%, retinol
Beta-carotene requires ______ as much to get to the RDA of retinol
12X
Lycopene requires _____ as much to get to appropriate level of retinol
24X
Retinal is part of _____ and functions in ____
Rhodopsin; vision
Forms of vitamin A that function in protein synthesis and cell differentiation
Retinoic acid
Retinoic acid and retinol both function to
Maintain epithelial tissue
A deficiency in what vitamin leads to night blindness?
Retinol leads to decrease in rhodopsin
Vit highly concentrated in rods of the retina
Retinal
Retinal + ________= Rhodpsin
Opsin
Vitamin A turns keritinizing cells into
Mucus-secreting cells in the eye, mouth, intestine, lungs, kidneys and reproductive tract
Hyperkeratinization
When vit a is decreased keratin-producing cells replace mucus-secreting cells in the respiratory, GI, and Urinary tracts
Keratinocytes are _____ ____ _____ until they interact with Vit A and then they are ______
Immature skin cells; mature epidermal cells
Carotenoids are the only form of Vit A to act as
Antioxidants
Antioxidants
- quench ROS
- Prevents UV- induced eye damage
Antioxidants prevent UV-induced eye damage because
Lutein and xeaxxanthin are concentrated in the macula
Carotenoid Function in cell growth and differentiation
- specific ones may inhibit growth and proliferation of several CAs
- Supplements increase the risk of several CAs
What form of Vit A do we get mostly from animal products?
Retinol
Carotenoids are found in
Yellow, orange, and dark green plants
Carotenoids consist of 2 things
carotenes (no oxygen) and xanthophylls (contain oxygen; Lutein)
Vit A’s RDDA is measured as
Retinol Activity Equivalents (RAE)
Storage of vit a
Liver stores 70% of the body’s total
- toxicity may cause liver damage
Vit A is toxic if
We don’t bind it
Vit A Deficiency AKA
Hypovitaminosis A
Primary and secondary causes of vit A def.
- Inadequate intake (in the world, not US)
2. Fatty malabsorption (problem in US)
Causes of fatty malabsorption
- inadequate fat intake
- bile or pan created enzyme insufficiency
- liver disease
- zinc deficiency
- protein-energy malnutrition
Vision problems caused by vit A deficiency
- Night blindness
- Xerosis
- Xerophthalmia
- Bitot’s spots
- Permanent blindness (in developing countries)
Xerosis
Itching, burning of eyelid
Xerophthalmia
Dry eye from inadequate mucus production
Bitot’s spots are
Keratin deposition in the eye
Leading cause of preventable blindness in children
Vit A deficiency
Vit A deficiency leads to a _____ immune system and ______ on skin
Depressed; follicular hyperkeratosis caused by plugs of keratin (looks like goosebumps)
Hypervitaminosis A
Vitamin A toxicity
Only ____ vitamin A can cause toxicity
Preformed (not carotenoids)
Vit A toxicity can cause
Bone pain (fractures), dry skin, hair loss, fatigue, anorexia, and liver damage
Excessive Vit A intake during pregnancy is ______ and _____ should not be used during or soon before pregnancy
Teratogenic, accutane
Carotenoids are considered _____ toxicity and have ______ TUL set
Low, no TUL set
Carotenoids are safe in _____ but in supplements they can promote:
Safe in plant based foods; in supplements they promote oxidative damage, cell division and destruction of other forms of vit A
Supplementation of carotenoids
Not recommended
- increased risk of lung cancer, heart disease, and death in smokers and former smokers
Examples of proformed vit A
- Carrots
- Dark green leafy veggies
- Sweet potatoes
- tomatoes
- Cantaloupe
Vit A is unstable when ___________, it’s best to cook it ________
Unstable when exposed to heat and oxygen, best to cook quickly with little water
Requirements for vitamin A absorption
Emulsification by bile salts
Vit A is absorbed via _____ in the ____ and _____
Passive diffusion, in duodenum and jejunum
Bioavailability of Vit A
Preformed: 75-100%
Proformed: 3-90% (increased by cooking)
Which vitamin has the greatest bioavailability
Vitamin A
Retinol is bound by _______ and resertfied to a RE in the enterocyte by ______
Cellular-retinol binding protein (CRBP); lecithin (LRAT)
The RE is incorporated into
Chylomicrons and transported in the lymphatic system
A vitamin is a _____ nutrient
Organic
What is the minimum amount of fat required for Vit A to be absorbed?
5-10g
Which hormone causes the gallbladder to contract?
Cholecystokinin
How much proformed Vit A is required compared to preformed vitamin A?
12
Deficiency of what mineral will not lead to a vitamin A deficiency?
Copper
What form of Vit A is part of Rhodopsin?
Retinal
Does Preformed vit A have antioxidant activity?
No
What is the primary cause of hypovitaminosis A?
Inadequate vitamin A intake
Animal form of vitamin D
Cholecalciferol (D3)
Plant form of Vit D
Ergocalciferol (D2)
Cholecalciferol is made from _____ and has a half life of
Cholesterol; 82 days
Ergocalciferol has a half life of
33 days
Vitamin D is a ______ not a vitamin
Prohormone
What biomarker should be used to check vitamin D levels?
25-hydroxyvitamin D3 (inactive)
Vitamin Ds main function
Maintain blood calcium levels
Vitamin D acts like a _____ hormone and affects gene expression
Steroid
Vit D ________ absorption in the small intestine and _____ renal reabsorption
Increases; increases
Vit D stimulates ___________
Mobilization from trabecular bone if needed (bone mineralization)
Vitamin D ____________ influence PTH release
Does NOT
Vit D recommendations for infants (lesss than 1 year)
400 IU
Vit D recommendations for kids/adults (1-70 years)
600 IU
Vit D. Recommendation for older adults (>70)
800 IU
Steps from Ca to PTH to Vit D to Proteins
- Low blood calcium causes PTH to be secreted
- PTH induces hydroxylase in kidneys
- Hydroxylase activates calcitriol
- Calcitriol stimulates synthesis of Ca-binding proteins
- Ca-binding proteins increase Ca absorption and decrease Ca excretion
Vit D Reequirements Vary due to:
- Season (inadequate October-April)
- Latitude (less made above 35-40 degrees)
- Skin color (Melanin prevents synthesis)
- Sunscreen
- Age (70 year olds synthesize 75% less)
- Malabsorptive conditions
- Obesity
Hypovitaminosis D causes _________ bones that results in _____ in children and ______ in adults
Soft, spongy
Rickets, osteomalacia
Hypovitaminosis D causes
- bone weakness
- autoimmune conditions (RA, MS, IBD)
- Myopathy
- Diabetes
- Depression, Alzheimer’s Schizophrenia, anxiety
- Solid cancers (prostate, colon, stomach, breast, liver, kidney)
- HTN, atherosclerosis, metabolic syndrome
- Respiratory tract infections
- Loss of balance
Deficiency of Vitamin D is considered a serum level
Less than 20 ng/mL
It is estimated that ________of Americans are deficient in vitamin D
50%
Issues don’t arise with vitamin D toxicity until a daily dose of _______ IU has been taken for more than _____
10,000 IU; more than 6 months
Vit D toxicity causes
Hypercalcemia and hyperphosphatemia
-calcification of soft tissues (kidney, lungs, heart)
There have been ______ documented cases of toxicity from excessive sunlight
No
Vit D found in all cells
24-hydroxylase
Vit D is found in high concentration in the
Kidneys
Vit D limits amount of
Active calcitriol
Vid D forms
1,24,25- (OH)3D
Mutations in gene coding for __________ leads to hypercalcemia
24-hydroxylase
Vit D supplementation should be cautioned in people with
- Hyperparathyroidism
- Granulomatous disorders (sarcoidosis, tuberculosis)
- Some lymphomas
Good sources of vitamin D
fish liver oils, salmon, mackerel, tuna, fortified dairy, egg yolk
Poor sources of vit D
Breast milk, unfortified dairy
Vitamins D is most stable with
Heat, age, and storage
Precursor for endogenously produced vitamin D
Cholesterol
What organ does enzyme alpha-1-hydroxylase convert hydroxylase vitamin D3 to its fully active form
Kidney
How does vit D increase calcium absorption?
Induces synthesis of calcium-binding protein
Who could end up with vit D toxicity?
Supplement users
Vitamin discovered necessary for animal reproduction (especially in rats)
Vitamin E
Vitamin E is a potent antioxidant because
Of donating hydrogens
Most common vit E
Alpha tocopherol
Vitamin E functions as an _______ found in ____ ______
Antioxidant; plasma membranes
How does vit. E function as an antioxidant?
Donates H to free radicals to protect PUFA in membrane
_________ of vit E is important because we don’t get enough of it
Regeneration
“Vitamin _____ is the key to vitamin _____”
C is the key to E
Only the _____ form of vitamin E acts an an antioxidant
Reduced
Hypovitaminosis E is
Rare
Vitamin E deficiency is a deficiency of ______ and symptoms include:
Tocopherols
Hemolytic anemia (in infants), neuropathy, retinopathy
People at risk for hypovitaminosis E
Patients with fat malabsorption disorders and premature infants
Too much vitamin E can ____ blood and cause ____ _____
Thin blood; nose bleeds
-inhibits vit. K activity and increases bleeding and impaired bone mineralization
Vitamin E toxicity
- No known toxicity from food
- Supplements of vit. E inhibit Vitamin K activity
Best source of vitamin E
Plant oils
High alpha tocopherol sources:
Olive oil, sunflower oil, safflower oil, cottonseed oil, almonds, peanuts
High gamma-tocopherol sources
Canola oil, soybean oil, corn oil, seasame oil, walnuts
*midwestern oils
High tocotrienol sources
Oats, rye, barley, rice bran oil, wheat germ, palm oil
- found in the germ (oil) of whole grains
Natural vitamin. E is
Only biologically active isomers present
Synthetic vit E has a ________ attached and is a _______ mixture of ______
Fatty acid attached
Race is mixture of isomers
Vitamin E supplements
Alpha-tocopherol only
Natural vitamin E is a mixture of
Tocopherols and tocotrienols
Vit E supplements _____ _____ prevent cancer, heart disease, all cause-mortality, etc.
Do not
Vitamin E is made unstable with _____ and _____
Heat and basic pH
What is the function of vitamin E?
Antioxidant
Which is a good source of Vit E? A. Milk B. Ground Beef C. Almonds D. Dark leafy greens
C. Almonds
Vitamin K AKAs
Phylloquinone (K1)= green plants
Menaquinone (K2)= bacteria/ animal products
Vit K functions in
Clotting and bone formation
Vit K function
Coenzyme
Vit K adds a carboxylic acid group to ________ residues in specific proteins to make _______
Glutamate; carboxyglutamates (for bone synthesis)
Caboxyglutamates are ____ _____ sites
Calcium-binding
Vit K coenzyme is found on
Clotting factors (VII, IX, and X)
Prothrombin
Osteocalcin (secreted by osteoblasts)
Vit K function in bone formation
Osteoclacin synthesis is stimulated by vitamin D and carboxylated by vit K to facilitate calcium binding
Risk for vit K deficiency
- Newborns (w/o shot at birth)
- Patients with fat malabsorption disorders
- Patients chronically treated with antibiotics
Vit K deficiency causes
Increased bleeding (brain bleed in babies), poor bone growth
Synthetic ______ is toxic in infants and can cause jaundice
Menadione (banned in the 60s)
Vit K toxicity
No toxicity symptoms from food or current supplements
Sources of phylloquinones
Broccoli, dark green leafy veggies, kiwi, peas, beans, oils (rapeseed, soybean, olive), margarine
Vit K is made unstable by
Light and irradiation
Which fat-soluble vitamins require digestion prior to absorption?
A and E
Vit K is a coenzyme for formation of
Carboxygluatmates
Carboxyglutamates facilitate binding of
Calcium
Calcium-bound carboxyglutamates are important for ______ and _____
Clotting; bone formation
Which vitamins are required for normal bone formation?
Calcitriol and phylloquinone
Which vitamins act as antioxidants in Vivo?
Beta-carotene and alpha-tocopherol
Know Fat soluble vitamin summary
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