Week 3 (2) Micronutrient Lectrues Flashcards by Kyle McAtee

what are micronutrients?

nutrients that are only required in SMALL (micro) amounts

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can we take make micronutrients in sufficient quantitiies?

no, we cannot make them in sufficient quantities

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what is the major difference between micronutrients and macronutrients?

micronutrients are not metabolized directly to provide energy

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what are the two large classes of micronutrients?

fat soluble (ADEK) and water soluble (C and B complex)

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what is another word for micronutrients? 2

vitamins and minerals

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what is unique about vitamin A? what is the purpose?

highly conjugated, able to absorb visible light

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like any lipid soluble molecule, the lipid soluble vitamins (ADEK) have to be transported how in blood?

via lipoproteins/carrier proteins (chylomicrons, VDL, HDL), but they can easily diffuse across plasma membranes

chylomicrons–>liver–>VLDL(LDL)–>Tissue

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where do lipid soluble vitamins accumulate?

in body tissues/organs/fat

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what is the danger of lipid soluble vitamin accumulation?

mega-doses (100x RDA), can lead to metabolic consequences

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Vitamin D deficiency is linked to which bone disorder?

rickets

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Vitamin D is derived from what?

sterols

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what is a pro-vitamin?

a vitamin that is not yet in its active form

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how is the vitamin D3 pro-vitamin activated?

UV light

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Vitamin D3 is the precursor for what active endgoenous metabolite?

calcitriol

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in order for vitamin D3 to be converted/activated to calcitriol what must occur

pro-vitamin is activated by UV light to form vitamin D3

2. D3 must be hydroxylated twice (in liver and then in kidney) to form the active calcitriol

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the formation of calcitriol is regulated at what level?

in the kidney/bone during the second hydroxylation event

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what is the function of calcitriol?

maintains plasma calcium homeostasis in conjunction with PTH (promotes transcription of genes associated with calcium uptake from duodenum)

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a decrease in plasma Ca will cause what?

an increase in parathyroid hormone–>an increase in calcitriol–>increase in Ca absorption in intestines

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vitamin D deficiency can lead to what in adults?

osteoporosis. a decrease in bone mass and fragile bones

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what are some conditions associated with vitamin D toxicicty (>10X RDA)

hypercalcemia, calcium deposits in kidney and heart

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when we say that vitamins are a family of molecules what does that mean?

A mixture of forms all of which have some activity. Ex. Vitamin A comprises a family of molecules containing a 20 carbon structure….retinal and retinoic acid

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what is the biologic function of vitamin A? 2

vision: retinol binds rhodopsin and when light hits it, it is converted to the all trans form

gene expression: retinoic acid binds receptor and regulates expression of genes associated with proliferation and differentiation (integrity of epithelial cells, maintain immune function, embryonic development)

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what is the active from of Vitamin A? (2)

retinol (eyes), retinoic acid (gene expression)

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Vit A deficiency causes? 2

night blindness, skin lesions

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vitamin E has how many naturally occurring forms?

8, all hydrophobic in nature

what is fxn of Vit E?

anti-oxidant (non-specific) protect poly-unsaturated FAs from becoming oxidized. a specific metabolic fxn has yet to be found

where do you find Vit E most commonly?

found in commercially produced oils and lotions to preserve them

Vitamin K is acquired how?

diet and intestinal bacteria

what is the role of Vit K? 2

cofactor in carboxylation reactions (plays role in calcium binding). carboxylated products important in coagulation and stimulation of bone and mineral maturation

if you are def in VIt K?

bleeding, lack of clotting

is vit K def common?

rare in adults but more common in infants due to sterile guts

what is vitamin E def?

none discovered

compared to the fat soluble vitamins, the water soluble vitamins are much more

polar (O, N, charged)

which water soluble vitamin is conjugated?

Vitamin B (light sensitive, store in dark to prevent degradation)

how are water soluble micronutrients absorbed

CANT diffuse across membranes, need membrane transporters

are water soluble micronutrients easy to overdose on?

no, they are more easily excreted than the lipid soluble ones AND they saturate membrane transport proteins (M-M kinetics)

in general, the water soluble vitamins and minerals play an important role in...

once processed, serve as co-factors for different metabolic (energy producing) pathways. NAD, FAD, CoA

Thiamin is also called

what is the active form of B1

TPP

what is the fxn of thiamin?

important co-factor for metabolic enzymes. Ex: pyruvate dehydrogenase complex

what is the fxn of thiamin?

important co-factor for metabolic enzymes. Ex: pyruvate dehydrogenase complex...others

what is the source of thiamin? 3

whole grains, enriched flour, meats

factors that destroy thiamin? 3

heat, thiaminase (raw fish), tannins

thiamin deficiency**

Beriberi (be able to associate beriberi and thiamin deficiency)

vitamin B2 is also called

riboflavin

what is riboflavin converted to?

FAD (succinate dehydrogense requires this)

where can we get riboflavin? 5

milk, grains, meat, poultry, fish

another name for B3 is

niacin

niacin is converted to?

NAD and NADP

Niacin can be made from...

Tryptophan

niacin deficiency disease***

the 3 D's Dermatitis, Dementia, Diarrhea

B5 is aprecursor for

CoA (TCA cycle!, beta oxidation)

B6 is a family of

a group of 6 pyrimidine derivatives

are vitamin B deficencies commonq

no, they are in abundance in our diets

are vitamin B deficencies commonq

no, they are in abundance in our diets

B6 fxn?

a coenzyme for >100 enzymes. w/o B6 all AA become essential

Vitamin B7 AKA

biotin

role of biotin

coenzyme in carboxylation reactions (pyruvate carboxylase)

B9 aka

Folic acid

folic acid role

carbon metabolism (AA, purine and thymidine synthesis)

B12 family role

involved in methionine synthesis (coenzyme for methionine synthetase)

what is unique about B12 absorption?

unlike other water soluble vitamins, it requires a protien (intrinsic factor) to be absorbed in the intestines

Vitamin C aka

ascorbic acid

role of Vit C (2)

anti-oxidant, aids hydroxylation (important in collagen formation)

Vit C deficiency

Scurvy: failure to cross-link collagen (weak bones)

important Minerals

Fe (Hb), I (thyroid), Zn, Se

Keshan disease associated with what mineral def?

Selenium role?

forms selenoproteins that play a role in defending against oxidative damage, disulfide bond homeostasis, thyroid hormone metabolism

Zn fxn

essential in fxn of many enzymes and TFs