Final exam (first unit) Flashcards
Vitamin C history, why was Britain successful?
-napoleon lost waterloo because of lack of food, especially citrus fruit
-Britain = limeys because they took lime juice for scurvy prevention
-Dutch used sauerkraut
-Magellan troops were fed quince preserved and only lost 11% of their crew
5 functions of vitamin C
- antioxidant
- hydoxylator of co-enzyme
- enhances nonheme iron absorption
- resistance to infection/ stress
- protective of cancer/cardiovascular and eye health?
how is vitamin C a powerful antioxidant? who does it work with?
-vitamin E donates electron to stabilize free radical
-vitamin C regenerates vitamin E by donating e- to restore oxidized form to antioxidant form, maintaining its protective role in lipid environment
how does vitamin C relate to collagen
works as a cofactor for enzymes that form collagen
which of the following vitamins can be provided to the body ONLY by diet
vitamin E
scientifically, why is the initial symptom of scurvy fatigue?
-vitamin C deficiency -> impairs synthesis of carnitine -> necessary to carry LCFA to mitochondria to be oxidized for energy
-low vitamin C = low energy
how does ascorbic acid interact with iron in different oxidation states, in terms of intestinal absorption and enzyme activity?
-AA reduces iron from Fe 3+ nonheme form in foods to Fe2+ (reduced) state for absorption into intestine
-Fe becomes oxidized itself (Fe 2+ to 3+) to regenerate enzymes and activate them after metabolic activity
which population is NOT at risk for AA deficiency? a. Elderly
b. Teenagers
c. Infants fed evaporated or boiled milk
d. Smokers
e.Those with low socio-economic status
teenagers
A standard serving of which of the following has the most vitamin C?
broccoli
what deficiencies cause rachitic rosary?
Vitamin C, Calcium, Copper, Vitamin D
common denominator for synthesis of collagen, carnitine, tyrosine and numerous neurotransmitters?
they all need vitamin C to function as a co-enzyme in the hydroxylation (-OH added) of their synthesis
what is the DRI for men and women for vitamin C?
90 mg Men
75 mg Women
dietary level of vitamin c to prevent scurvy?
10 mg
approximate level of vitamin C that is maximally absorbed?
200 mg/ day is the maximum absorption
does taking vitamin c help prevent the occurrence of a cold? why?
no, it doesn’t help diminish the # of colds but it helps decrease the intensity. destroys histamine and promotes the proliferation of immune cells
who is an important historical figure in the history of vitamin C and why?
Linus Pauling, nobel peace prize, book on vitamin C and cold, his research discovered it’s powerful role and he promoted vitamin C for health
what is rachitic rosary of a child? what deficiency leads to its formation?
vitamin C, copper, calcium and vitamin D.
-it is a series of bumps along the ribcage caused by THE COMPRESSION OF BONES while child is sleeping
-bone base is collagen that is later hardened by Ca deposits
-deficiency in C and Cu = impaired creation of collagen
-deficiency in Ca = impaired strengthening of bone
-deficiency in D = probable deficiency of Ca (D is needed for Ca absorption)
what are visual symptoms of scurvy
coily hair, bleeding gums, petachiae (red skin caused by rupture of small vessels)
which form of vitamin A can be toxic
retinoic acid (remember acid = bad)
how does vitamin A deficiency cause night blindness, include scientific and common names involved
-Nyctalopia = inability of eye to readapt easily to darkness
-vitamin A needed to make retinal
-retinal combines with opsin to = rhodopsin (visual purple)
-rhodopsin is a light sensitive pigment to help see in the dark
-SO, no vitamin A = no rhodopsin = can’t see in low light = night blindness
-need retinal / more vitamin A from diet
describe absorption of various forms of vitamin A form lumen of SI to blood.
-vit A enters enterocyte within a micelle (can contain retinal/ol, free carotenoids, fatty acids, phospholipids, monacylglycerol, cholesterol and bile
-retinal -> retinoic acid -> excreted into blood, be bound by albumin
-retinal -> retinol -> re-esterified to package in chylomicron -> exit eneterocyte to lymph -> blood via subclavian vein
What is not a function of vitamin A?
a. Bone development
b. Blood clotting
c. Gene expression
d. Vision
e. Immune system
blood cotting (this is vitamin K)
how does vitamin A affect gene expression
retinoic acid acts as signaling molecules and activates retinoid receptors and regulation of gene transcription
what is a carotenoid? where are these present in nature? how abundant are these in the human body? what is their significance in nutrition? can they be toxic?
-naturally ocurring pigment in plants that are antioxidants and can be precursors of vitamin A
-30% absorbed as pigments in human body
-foods like leafy greens, peppers, carrots, etc.
-600 carotenoids but only 60 have potential vitamin A activity
-almost impossible to get toxicity from carotenoids but high amounts can cause yellowing of the skin “xanthosis cutis”
who was elmer mccollum
discovered fat-souble factor A
highlighted importance of dietary fat
-by feeding rats a vitamin A containing diet (ex: egg yolks) vs. deficient (ex: lard), he found effects of deficiency like eye problems and growth issues
what are 4 symptoms of vitamin A deficiency
-nyctalopia: night blindness
-bitot’s spots: foamy spots of sloughed cells o cornea and conjunctiva
-xeropthalmia: dryness of cornea and conjunctiva, keratinization of epithelia cells (white thing on the eye)
-toad skin
relationship between vitamin A and carotenoids
-carotenoids serve as precursors to vitamin A
-there are also non provitamin A carotenoids like LUTEIN and LYCOPENE but are still antioxidants
which is the most effective of the antioxidants? why? the most commonly used in metabolism and why?
-lycopene: because it neutralizes free radicals (especially singlet oxygen types, the most powerful ones), stabilizes reactive molecules better than other antioxidants
-most common= beta carotene: major source of provitamin A for vision, immune system, cellular differentiation
what is xeropthalmia? where does it occur? where is it most prevalent?
dryness and hardening of cornea + conjunctiva caused by vit. A deficiency, happens im eye, most prevalent in populations with poor healthcare and malnutrition
What is one of the most common breakfast foods in the world? Explain a possible scientific reason for the significance of this food.
complete “package”: not only contributes protein but also micronutrients like vitamin A and carotenoids, heme iron, healthy fats, choline for brain and memory
what is a consequence of vitamin D deficiency?
osteomalacia
Which of the following is a scientifically proven fact about vitamin D?
a. Reduces the incidence of cancer
b. Reduces the risk of cardiovascular disease
c. Promotes weight loss
d. Maintains bone integrity
e. Decreases the progression of prediabetes to Type 2 diabetes
d. maintains bone integrity
how would kidney removal affect vitamin D levels in the body?
deficiency because kidneys needed to hydroxylate calciDiol into Triol (active form). so no kidney would cause vitamin D-resistant rickets
Which mineral causes itai-itai disease and how does it manifest? Explain. Where has this occurred and what is the reason?
Cadmium! replaces Ca and produces soft bone that can’t sustain weight of the body.
China + India from pollution due to industrial waste
can one develop vitamin D toxicity from too much exposure to the sun? why/not?
no, inactive metabolites like lumisterol and tachysterol prevent excess production of vitamin D. vitamin D binding proteins have low affinity for lumisterol and tachysterol, preventing ciruclation into the blood. they remain on skin and eventually sloughed off.
Explain the synthesis and stages of activation of Vitamin D in the human body. Include the
organs and specific names involved.
7 dehydrocholesterol found in skin, UV light from sun forms PRE-vitamin D3. heat from body somerized to form D3 (calciol) -> liver hydroxylates (calcidiol) -> kidneys hydroxylates (calcitriol) active form
what happens to humans with vit D toxicity and how much does it take?
pregnant women only 2x RDI and regularly 25x more RDI. it would increase Ca deposition -> kidney stones, calcification of arteries and mental confusion. possible heart damage, renal failure and death.
Should one be taking a vitamin D supplement if not prescribed by a physician? Explain your
answer.
no. 30-48 ng/mL are associated with all cause mortality, increased risk of prostate cancer and CVD + number of falls and fractures in elderly.
how did they discover UV radiation could prevent rickets in puppies?
-Elmer McCollum’s vitamin D research
-puppies exposed to UV light had better bone development and no rickets + synthesis of vit D on their skin
what effect does vitamin D have on muscle physiology?
+ Ca absorption, needed for muscle contraction and also regulates gene expression involved in muscle protein synthesis and repair
which is the primary function of vitamin K (apart from clotting)
bone formation through Ca deposition
which is the most biologically active form of vitamin E?
a-tocopherol
1st and 2nd most abundant proteins in bone?
collagen and osteocalcin
Describe how Vitamin E interacts with Vitamin C in the antioxidant cycle. Explain the
importance of this interaction
-vit. E donates e- to free radicals to neutralize them, oxidizing itself in the process
-vit. C regenerates E, maintaining its antioxidant effect
-interaction helps sustain antioxidant activity of vit. E, protecting cells from oxidative stress
If a newborn baby has vitamin K toxicity, what are the symptoms? What is the likely
cause of the toxicity and why?
-cause: overdose of synthetic K1 that is given at birth (no UL for vit. K from foods)
-effect: jaundice, liver damage, hemolytic anemia
Describe the experiments of Henrick Dam in 1929 which led to the discovery of vitamin K.
-fed chicks low fat/ cholesterol free diets -> led to hemorrhage
-added cholesterol, no effect
-added fat, cured hemorrhage
-realized vit. K is coagulation factor + fat soluble
Describe the role of vitamin K in bone formation in detail. What specific protein is made to strengthen bones? Can this specific protein have other biological roles under changing situations? Explain. **
-vitamin k carboxylates (adds CO2) to glutamyl residues in osteocalcin
-this gives osteocalcin a gamma-carboxyglutamyl residue (have extra -COO)
-extra carboxyl group allows Ca to bind to the osteocalcin and deposit in the bone, strengthening it
-if osteocalcin is not carboxylated, changes into a hormone that works in brain, pancreas, muscle and testes
what is the efficiency of carotenoids vs. vit. E
carotenoids like lycopene and B-carotene are a lot more efficient but there is more vit. E in diet
vitamin E and heart disease, what is the relationship?
vitamin E supplements DO NOT lower the incidence of heart attacks, strokes or death from CVD and it does not offer protection either
what are animal deficiencies of vitamin E? lambs, chicks, ducks, rats
lamb: muscular dystrophy
chick: exudative diathesis and encephalomalacia (inflammation of brain)
ducks: anemia
rats: reporduction
what can happen in human deficiency of vit E?
increased hemolysis of red blood cells (destruction) = membrane fragility
RDI for vitamin E + toxicity causes ___
15 mg (NO supplementation recommended)
toxicity= impaired blood clotting
mains source of vit E in diet
sunflower seeds, almonds, red chili powder, wheat germ
which is NOT a function of vitamin E: a. Improves immune function in the elderly
b. Strengthens bone
c. Prolongs clotting time
d. Antioxidant
e. Protects against aging and lipofuscin pigments.
doesn’t strengthen bone (that’s K)
Explain how the storage of vitamin E in cell membranes can affect metabolism.
works as antioxidant, stops free radicals from destroying fatty acid tails in lipoprotein membrane
What could be a reason why the elderly may develop cancer, arthritis, cataracts and diabetes as they age?
ox stress, natural AND environmental
defense and repair systems are not 100% effective and get less effective with age
supplement with vit E for heart disease?
no, no evidence it works and actually increases risk o stroke in healthy adults
what is mechanism shared by blood clotting and bone protein activation
both need gamma carboxylating glutamic acid residue proteins that allow binding of Ca
what is used to asses vitamin K levels
prothrombin (whole blood clotting times)
food sources + requirements for vit. K
M: 120 ug/ day
F: 90 ug/ day
food: cabbage family, fermented soybeans
