Exam 2 Flashcards
How were vitamins first discovered
While searching for cures for common diseases
What vitamin micronutrients are measured in micrograms
RDA’s measured in mcg: vit. A, B12, D, K, folate and biotin
What are the functions of vitamins
Membrane stabilizer, hormones, coenzymes, H+and e- donor/acceptors (antioxidants)
What are identifiers of vitamin clinical deficiency
Pellagra, burning feet syndrome, keshan’s disease
What is subclinical deficiency (insufficiency) associated with
Increased risk of chronic diseases such as HTN, CA, and atherosclerosis
Which vitamin metabolism is associated with being absorbed as part of micelles
Fat soluble vitamins
Which vitamin metabolism is associated with being transported in the portal vein
Water soluble
Which vitamin metabolism absorption is enhanced with fat intake
Fat soluble
How are fat soluble vitamins transported
In lipoproteins in lymphatic system
Why are water soluble vitamins less likely to be toxic
Most are not stored in appreciable quantities
Why is fat soluble vitamins more likely to be toxic
Its stored in liver/adipose
What do water soluble vitamins rely on to meet requirements
Daily intake
What are fat soluble vitamins
ADEK
Which vitamin A retinoid is associated with reproduction and growth
Retinol
Which vitamin A retinoid is associated with vision
Retinal
Which vitamin A retinoid is associated with cell differentiation
Retinoic acid
Which type of vitamin A is preformed plant or animal
Animal
Where is preformed (active) vitamin A found
Animal products
What is a retinol ester
Retinol with fatty acid attachment
What is one type of retinal ester and also a storage form of Vitamin A
Reinyl Palmitate (vit A palmitate)
What are proformed vitamin A
Plant products (orange, yellow, red colors)
What are precursors to vitamin A
Carotenoids (antioxidants)
Which type of vitamin A is used only when we don’t get enough preformed in the diet
Proformed
How many carotenoids are known and how many can be converted to retinol
> 600 known carotenoids; <10% can be converted to retinol
What are the structures of carotenoids
B-carotene and lycopene
Where is vitamin a highly concentrated
In the rods of the retina
What is important for vision in dim light
Rhodopsin
How do you get rhodopsin
Retinol converts to retinal and added with opsin
What will a decrease in vitamin a produce in regards to rhodopsin
Decrease in rhodopsin = night blindness
A decrease in vitamin A does what to keratin producing cells
Keratin producing cells replace mucus secreting cells in respiratory, GI, and urinary tracts
What causes hyperkeratinization
Vitamin a deficiency
What do keratinocytes along with vitamin A (retinoic acid) become
Mature epidermal cells
What are 2 carotinoid funx
Antioxidant and cell growth/differentiation
What do carotenoid antioxidants do
Quench reactive oxygen species
What carotenoid antioxidants are concentrated in the macula and what is their funx
Lutein and xeaxanthin that prevent UV induced eye damage
What do carotenoids have to do with cell growth/differentiation
Specific carotenoids may inhibit growth and proliferation of several cancer lines
Supplemental carotenoids can cause what
Increased risk of several cancers due to cell growth and differentiation
What do carotenoids consist of
Carotenes (no oxygen) and xanthophylls (contain oxygen; ex lutein)
What is vitamin A RDA measured as
Retinol activity equivalents (RAE)
What is the RAE for men
900
What is the RAE for women
700
What stores 70% of the body’s vitamin A
The liver
What can toxicity of vit A affect
Can cause liver damage
What is the primary cause of vitamin a deficiency
Inadequate intake
What is the secondary cause of vit a deficiency
Fatty malabsorption
What is the leading cause of preventable blindness in children
Vit a deficiency
What are two common vit a deficiency symptoms besides vision problems
Depressed immune system, skin problems
What does vit a deficiency cause in the immune system
Depressed system, more infx with higher mortality rates
What type of skin problems come from vit a deficiency
Follicular hyperkeratosis caused by plugs of keratin
What causes hypervitaminosis A
Due to preformed only (not carotenoids)
What happens when someone takes in excessive vitamin A during pregnancy
It becomes teratogenic
What is the TUL for carotenoids
No TUL set, considered low toxicity
Chronic carotenoid consumption can lead to what
Yellow/orange skin
Supplements of carotenoids promote what
Oxidative damage, cell division and destruction of other forms of vitamin A
What are good sources of vit a preformed
Liver, fish, fortified dairy, eggs
What are good sources of proformed vit a
Carrots, dark green leafy veggies, sweet potatoes, tomatoes, cantaloupe
When does vit a become unstable
When exposed to heat and oxygen
What does vitamin a absorption require in order to be absorbed
Emulsification by bile salts
What is the bioavailability of preformed vitamin a
75-100%
What is the bioavailability of proformed carotenoids
3-90%(cooking increases)
What type of absorption takes place with vitamin A
Absorbed via passive diffusion
Where is vitamin a absorbed
Duodenum and jejunum as part of micelles
What is retinol bound by during vitamin A absorption
Cellular retinol binding protein (CRBP)
Retinol is reesterified to a ____ in _____ by ____
RE (retinol ester), enterocyte, lecithin and retinol acyl transferase (LRAT)
How much of RE is absorbed
80%
RE are incorporated into what and transported in what
Incorporated into chylomicrons and transported in the lymphatic system
What handles and stores vit A
Liver
What circulates in the blood bound to thyroxine T4
RBP-retinol-TTR
How much cellular vit a is stored in the liver
50-80%
What is the retinol ester (storage) for vit a
CRBP retinol by LRAT, retinol by ARAT
What is the animal form of vitamin D
Cholecalciferol (vit D3)
Where is cholecalciferol made from
Made from cholesterol
What is the plant form of vitamin D
Ergocalciferol (vitamin D2)
What is the half life of cholecalciferol
82 days
What is the half life of ergocalciferol
33 days
Is vitamin D a vitamin
Technically a prohormone, rather than a vitamin
What are problems of vitamin D insufficiency
Soft/spongy bones, rickets, osteomalacia
How does hypovitaminosis D present itself in children
Rickets = bowed legs, bilateral knee pain
What does hypovitaminosis D look like in adults
Osteomalacia = muscle weakness, bone pain
Hypovitaminosis D can present itself in osteoporosis, osteomalacia, rickets what can happen as a result
Stress fractures, low back pain
What is the best biomarker for vitamin D assessment
25- hydroxyvitamin D (calcidol)
What is vitamin d deficiency considered
<20 ng/mL
How many americans are vitamin D deficient
50% of americans
When does vitamin D toxicity happen
Arise with daily doses of 10,000 IU or more for more than 6 months
What happens when someone has vitamin D toxicity
Calcification of soft tissues. Hypercalcemia, hyperphosphatemia
Where does vitamin D regulation take place
Found in high concentration in the kidneys
Vitamin D regulation limits the amount of what
Active calcitriol
What gene mutation can lead to hypercalcemia
Gene coding from 24-hydroxylase
Whee is 24-hydroxylase found
In all cells
What conditions where vitamin D supplementation should be cautioned
Hyperparathyroidsim, granulomatous disorders (sarcoidosis, TB), some lymphomas
Where do most vitamin D sources come from
Fish, fortified dairy, egg yolk
What are poor sources of vit d
Breast milk, unfortified dairy
When is vitamin d stable
Heat, age, storage
How was vit E originally discovered
Discovered it was necessary for animal reproduction
Vit E donates H to what to protect what in membrane
Donates H to free radicals to protect PUFA in membrane
Dietary intakes of vitamin E has been shown to decrease risk of what
Heart disease, cancer, age related macular degeneration
What is the ratio of vitamin E to unsaturated FA in cell membrane
9:1000-2000
What is important for vitamin E functions
Regeneration
What is vit E main funx
Antioxidants
What does hypovitaminosis E produce
Tocopherols producing symptoms like hemolytic anemia (infants), neuropathy, retinopathy
Why does vitamin E deficiency produce neuropathy
Due to disturbance in myelin production
Is hypovitaminosis E rare
Yes
Who is most at risk for hypovitaminosis E
Patients with fat malabsorption, and premature infants
What do vitamin E supplements inhibit
Vitamin K activity
Vitamin E inhibiting vitamin K activity produces what
Increase bleeding and iimpaired bone mineralization
What is the overall best source of vitamin E
Plant oils
What is only present in natural vitamin E
Only biologically active isomers
What is synthetic vitamin e composed as
FA attached, racemic mixture of isomers
What is natural vitamin e a mixture of
Tocopherols and tocotrienols
What are vitamin E supplements made of
Alphatocopherols only
Vitamin E supplements do not have what benefits of naturals
Do not prevent cancer, heart disease, all cause mortality
When is vitamin E instable
With heat and basic pH
What age should one consume B12 fortified foods/supplements
Anyone over 50
What is the primary cause of vitamin B12 deficiency
Poor absorption
What does vitamin B12 need for absorption
Requires intrinsic factor
Where is intrinsic factor secreted
From parietal cells of stomach
What is vitamin B12 bound to in food
R proteins
Where are R proteins secreted
Saliva and stomach
What removes R protein in B12 digestion
Proteases in SI
Where does intrinsic factor bind B12
In ileum
How does intrinsic factor complex and absorb B 12
Receptor mediated endocytosis
Where is vitamin B12 released by intrinsic factor
In the enterocyte
What condition decreases vitamin B12 digestion/absorption due to too much HCL
Zollinger ellison syndrome
What medication cause decreases vitamin B12 digestion/absorption
Histamin blockers glucophage and protein pump inhibitors
What condition decreases vitamin B12 digestion/absorption that deals with not enough proteases to release B12 from R proteins
Pancreatic insufficiency
What malabsorption syndromes decrease vitamin B12 digestion/absorption
Celiac’s, crohn’s, IBS, cystic fibrosis
What causes vitamin B12 deficiency megaloblastic macrocytic anemia
Due to decreased DNA synthesis
What are symptoms of vitamin b12 deficiency megaloblastic macrocytic anemia
Fatique, ha, difficulty concentrating, shortness of breath, peripheral neuropathy
What type of megaloblastic anemia is an autoimmune condition where antibodies attack gastric parietal and mucosal cells
Pernicious anemia
What causes decrease in HCL secreation, impaired IF secreation, and needs treating with B12 injections
Pernicious anemia
How long can it be till vegans may not develp b12 deficiency
5-10 years
What do vegans do to combat vitamin b12 deficiency
15% deficient take by IM injection or nasal spray
Is there a toxicity issue with vitamin b12
No
Is there a TUL set for b12
No
What are vitamin b 12 sources
Bound to protein in food, shellfish, meat, poultry, fish, dairy, fortified cereal
What is a vitamin b12 supplement name
Cyanocobalamin
What causes b12 instability
Water during cooking
What are pantothenic acid (B5) a part of
Coenzyme A and acyl carrier protein
What is a funx of coA pantothenic acid
Metabolism of macros and synthesis of FA, cholesterol, heme
What carrier protein contains pantothenic acid
Fatty acid synthase acyl carrier protein
When can pantothenic acid sources become unstable
May be lost while thawing frozen meats, otherwise stable
What syndrome indicates pantothenic acid deficiency
Burning feet syndrome
What are symptoms of burning feet syndrome
Numb toes, burning feet, depression, fatigue, insomnia, weakness
What are two biotin functions
Coenzyme and non coenzyme roles
Which biotin function is bound to several carbodylases
Coenzyme biotin
What biotin function deals with FA synthesis, gluconeogenesis, metabolism of propionate and leucine
Coenzyme biotin funcion
What biotin functions as transcription of several enzymes/genes
Noncoenzyme roles
When is biotin extracted
Easily in water
What is a biotin chelator in raw egg whites that will bind and prevent absorption
Avidin
Biotin defieciency can occur if a person consumes excessive amounts of what
Raw egg whites
What is the rare genetic condition of inborn error of metabolism of biotin
Biotinidase deficiency
What condition expresses in dermatitis, anorexia, depression, alopecia, muscle pain, lethargy, hallucinations
Biotin deficiency
What makes up 50% of all of the phospholipids in the human body
Lecithin (phosphatidylcholine)
What choline function deals with cell membrane integrity and lipid transport
Lecithin
What choline funx is a part of acetylcholine
Cholines
What are good sources of choline
Soy, eggs, liver, meats
What is choline easily extracted in
Water
How does choline deficiency present
Fatty liver disease, cancer, CVD, neural tube defect, dementia
Choline toxicity is presented by
Low bp, fishy body odor, excessive sweat/saliva, decreased growth
What are 4 phytochemical funx
Antioxidants, hormonal activity, DNA replication, antibacterial
Diets high in what are protective against CVD, cancer, and other chronic diseases
Phytochemicals
What is a life cycle nutritional need of pregnancy and lactation
Folate
What is a life cycle nutritional need of infants, children, adolescents
Vitamin D
What is a life cycle nutritional need of older adults
B12, vitamin D
What lifestyle habit makes one need more vitamin C
Smoking
What lifestyle habit makes one need more vitamin b 12 supplements
Vegans
What lifestyle habit makes one need more supplements
Restrictive diets
What lifestyle habit makes a person need more thiamin, folate, B6
Chronic alcohol intake
What vitamin is named for dutch word koagulation
Vitamin K
What is the majority of vitamin K and is found in green plants
Phylloquinone (K1)
What vitamin K is made by bacteria
Menaquinone (K2)
What is vitmain K main function as
Coenzyme
What is vitamin K funx
Coenzyme that adds carboxylic acid to glutamate residues in proteins to make carboxylglutate
What are the carbodylglutamates from vitamin K used for
Calcium binding sites
Where are carboxylglutamates from vitamin K found
Found on clotting factors (7, 9 ,10), prothrombin and osteocalcin (secreted by osteoblasts)
What is carbodylglutamate required for
Clotting and bone formation
How does vitamin K funx in bone formation
Osteocalcin synthesis is stimulate by vit D and carboxylated by vit K to facilitate calcium binding
Most of our requirements for vitamin K is met through synthesis where
In the gut
Who is most at risk for vit K deficiency
Newborns, patients with fat malabsorption disorders, patients chronically treated with antibiotics
What are the symptoms of vitamin K deficiency
Increased bleeding, poor bone growth
What are 3 functions that vitamin C is required for
Connective tissue, coenzyme, antioxidants
Why is vitamin C required for connective tissue
For collagen synthesis and necessary for hydroxylation of proline/lysine
Who needs the most vitamin C
Smokers
What are the 4 H’s of scurvy
Hemorhaggic signs, hyperkeratosis of hair follicles, hypochondriasis, hematologic
Who would we most likely find scurvy in now days
Poor diet of alcoholics or drug abusers
What are some physiological anomalies caused by scurvy
Corkscrew hairs and bleeding gums
Why would unabsorbed vitamin C cause diarrhea
From LI fermentation
What would high does of vitamin C cause in the kidneys
Kidney stones
Why would vitamin C toxicity cause iron toxicity
Impaired iron metabolism b/c vit c helps with non heme iron absorption
What makes vit c unstable
Oxygen, heat, basic pH
What cooking affects impact vitamin c
Easily extracted water, veggies kept in fridge, frozen contain more than fresh
Why is vitamin c one of the most unstable vitamins
Due to oxidation
Which energy production of thiamin is used by dehydrogenases
Energy production pyruvat e to acetyl coA
What coenzyme thiaminn funx uses NADPH and pentos synthesis
Part of transketolase
What is the noncoenzyme funx of thiamin (TTP)
Regulates sodium channels and chloride transport in nerve transduction in the nervous system
What are the major targets of thiamin deficiency
Peripheral nerves, heart, brain
What is chronic thiamin deficiency
Beriberi common where diet is polished rice
Which beriberi is categorized by low thiamin + high carb intake creating muscle weakness, cacexia, periph neuropathy, tender calf muscles
Dry beriberi
What type of beriberi creates an enlarged heart, rapid heart beat, peripheral edema, and high BP
Wet beriberi
What beriberi is a chronic infant deficiency, breastfed mothers with low thiamin intake, anorexia, nausea, vomit, lactic acidosis
Acute beriberit
What is the name for chronic thiamin deficiency in alcoholics
Wernicke korsakoff syndrome
What is the most common nutritional deficiency in alcoholics
Thiamin
When do issues arise such as HA, convulsions, cardiac arrythmia, shock for thiamin
100x RDA given by IV
What contains thiaminases and what does it do
In raw fish/shellfish, thiamin destroyed by sulfits
How does thiamin become unstable
Neutral/basic pH, water during cooking
What are coenzymes from riboflavin
FAD and FMN
FAD and FMN are coenzymes for what
Dehydrogenase
What does riboflaviin have to do with retinal
FAD/FMN convert retinal to retinoic acid
The flavin ring in FAD/FMN is important for what rxn
Redox
Initially what are symptoms of riboflavin deficiency
Photophobia, burning/itching of eyes, soreness of mouth
Severe riboflavin deficiency inhibits what
Vitamin B6 and NAD synthesis (also vit B deficiency signs)
What riboflavin deficiency symptom causes cheilosis and is also found with other B vitamin deficiencies
Ariboflavinosis
What are other symptoms of ariboflavinosis
Cheilosis, angular stomatitis, glossitis/magenta tongue,photophobia/ corneal vascularization, anemia, peripheral neuropathy, seborheic dermatitis
What dose of riboflavin is useful for treating migraines
400 mg
What causes riboflavin instability
Light, water during cooking (milk cooked with water)
What does niacin mainly funx as
Coenzyme
What are niacins funx in redox rxn
H acceptors
What is NAD used in as a coenzyme from niacin
Glycolysis, krebs, b oxidation, ethanol metab
What is NADPH used in as a coenzyme from niacin
Used in FA synthesis, cholesterol synthesis, folate synthesis
Where does most of our niacin requirement come from
Tryptophan
How does tryptophan become NAD
In the liver
Who discovered the condition pellagra from niacin deficiencys
Dr joseph goldberger
Whatt are the 3(4) D’s of pellagra
Dermatitis, dementia, diarrhea, death
What causes pellagra
Niacin or tryptophan deficiency
Where is pellagra common
Where corn is the staple
What deficiencies are found together
Pellagara(niacin) and ariboflavinosis (riboflavin)
Gram doses of nicotinic acid have been used for what
Lower triglycerides/LDL and raise HDL
What are side affects of nicotinic acid
Flushing (histomine) heartburn, liver damage, gout, impaired blood glucose
What causes niacin instability,
Basic pH and water during cooking
What does vitamin B 6 function as
Coenzyme PLP
What is vitamin B6 coenzyme required for
Amino acid metabolism
Vitamin b6 coenzyme is needed for synthesis of what
Heme, sphingolipids in myelin sheath, steroids, niacin
Needs of vitamin b6 will depend on what
Protein intake, more protein = more b6 required
What are the main problems from vit b6 deficiency
Rare but peripheral neuropathy hypochromic microcytic anemia
Vitamin b 6 is the only one with deficiency and toxicity that causes what
The nervous system
There is a higher bioavalability of vit b6 in what
From animal rather than plant
What causes vit b 6 instabiity
Basic pH, light, water during cookiing
Why is the most stable form of folic acid special
Does not require digestion it is 100% absorbed
What is folate also called
B9
What is the oxidized form of folate in supplements
Folic acid
Folate contains what which are removed by conjugase in brush border
Glutamic acid residues
What are some conjugase inhibitors
Legume, orange, cabbage, chronic alcohol consumption
When is folate important in embryogenesis
Donor and acceptor in 1 carbon metabolism
When else is coenzyme folate funnx in
DNA synthsis/repair, formation of RBC/WBC, AA metabolism
Without b12 THF cannot be regenerated and folate is trapped as
5-methyl THF (called methyl folate trap)
What is folate important for
Preventing neural tube defects
What can occur with folate deficiency
Megaloblastic macrocytic anemia - large RBC due to inadequate DNA synthesis
Who is most likely to experiency polymorphism in MTHFR gene
Mexicans
High supplemental doses of folate can mask what
B12 deficiency, bind with zinc in GI causing zinc deficiency
What is instability in folate caused by
Heat and water during cooking
What vitamin comes in several forms that our body can convert into the active coenzyme
Vit b 12
Vitamin b 12 main function
Myelination, folate pathway, homocysteine remove, heme synthesis
How does vitamin b 12 function as a coenzyme
Threonin/isoleucine metabolism. Or metabolism of odd chain FA
What life cycle needs pregnancy and lactation
Folate
What life cycle needs vitamin D
Infants children and adolescents
What life cycle needs b12 and vitamin d
Older adults
What are megadoses
More than 10 times the RDA of a micronutrient
How do high doses of supplements act
More like drugs (liver damage, pregnancy prob)
Large doses of supplements can cause what
Deficiency in other micronutrients (absorption/increased excretion)
What is a deficiency that can also occur whenn a person suddenly stops overdosing
Rebound effect
What is another name for ascorbic acid
Vitamin C
What are the fat soluble vitamins
ADEK
What is vitamin K instability caused by
Light, irradiation
What is toxic, causes jaundice in infants and was banned in the 1960’s
Synthetic menadione (vit K)
In babies which is more likely to experience atresia from vitamin K deficiency oral or IM groups
Oral
