vitamins and minerals -Squier Flashcards
What is a vitamin?
small organic molecules that cannot be synthesized
ex: enzyme cofactors, antioxidants and other functions
fat soluble: vitamin A, D, E, K
- -> stored in liver and adipose tissue
- difficult to absorb and excrete
- excess intake can cause toxicity
water soluble: thiamine, riboflavin, vitamin B’s folate, vitamin C, biotin, pantothenic acid, choline
What can lead to megaloblastic anemia?
thiamine or B12 deficiencies
there is an inability to synthesize DNA resulting in an inability of cells to divide
-vit B12 is needed to maintain FH4 –> needed for methyl transfer reactions important in DNA synthesis
a deficiency in vit B12 can cause a deficiency in FH4
What is the function of folic acid (B9)?
What can a deficiency of Folic acid lead to?
folic acid is responsible for 1 C transfers in the synthesis of AAs, purines and thymidine
-forms tetrahydrofolate (TH4) that is critical for DNA synthesis (movement of 1C groups)
- folic acid deficiency can lead to megaloblastic anemia —> large immature RBC precursors
- rapidly dividing cells are affected (bone marrow and gut)
What can a Vitamin B12 deficiency lead to?
accumulation of odd-numbered fatty acids
which may be incorporated into cell membranes of nerves
Neurological abnormalities (dementia) & degeneration of
spinal cord
Glossitis, diarrhea, weight loss
Causes secondary folate deficiency leading to
megaloblastic anemia
causes:
insufficient dietary intake
pernicious anemia
pancreatic insufficiency
What are the two enzymes that Vitamin B12 are cofactors for?
- methylmalonyl CoA mutase
- -> critical for the breakdown of odd-numbered FA’s - homocysteine methyltransferase necessary for methionine synthesis
What carries vitamin B12 in circulation?
dietary B12 is released from food in the stomach and then binds IF (intrinsic factor) is the carrier of B12 in the lumen to the endothelial cells there it can be taken up into the blood and then stored in the liver
What is the function of Vitamin C?
Vitamin C plays an important role in collagen synthesis
–> important in normal connective tissue and wound healing
-binds to collagen to carry it into the cell –> facilities in the absorption of dietary iron
Vitamin C maintains VItamin E in a reduced state –> important in maintaining membranes
–> vit C is a reducing factor –> an tx e-s to keep metals reduced
What can vitamin C deficiency cause?
Scurvy (symptoms due to decrease in collagen synthesis)
- swollen, sore & spongy gums with bleeding & loose teeth - anemia - spontaneous bruising - poor wound healing - swollen joints & muscle pain
What are the two components of collagen that vitamin C is important in maintaining? And how?
hydroxyproline and hydroxylysine
–> vit C keeps the iron in the Fe2+ state (reduced)
vit c prevents the auto-oxidation of active site metals needed for the oxidation of proline and collagen cross linking .
Proline hydroxylase (iron active sites) and lysyl oxidase (copper active sites) are critical for collage cross-linking
What is the significance of vitamin B6?
-precursor to PLP (pyridoxyl phosphate)
required for glycogen phosphorylase (breakdown of glycogen) –> used in transamination, deamination, decarboxylation, condensation
-required for heme synthesis (ALA synthase)
-required for amino acid metabolism (ex: histamine formation)
-*conversion of tryptophan to niacin
What are the symptoms of B6 deficiency?
Symptoms of Deficiency (Rare):
Abnormal amino acid metabolism
Secondary pellagra (due to inability to synthesize niacin)
Microcytic anemia
Deficiencies Have Been Observed For: Women on oral contraceptives Alcoholics & elderly Newborns on certain types of formula Treatment with isoniazid (for tuberculosis infection) inactivates PLP & causes B6 deficiency
What are the functions of thiamine (vitamin B1)?
cofactor for enzymes (thiamine pyrophosphate, TPP) important in 1. pyruvate dehydrogenase complex 2. alpha-ketoglutarate dehydrogenase 3. transketolase 4. branched chain AA --> alpha-ketoacid dehydrogenase
TPP breaks C bonds (ex: 3C private –> 2 C acetyl CoA)
What can thiamine deficiency cause?
Decreased ATP production which affects nervous system activity
Accumulation of lactate & pyruvate (lactic acidosis)
Decreased NADPH formation via HMP & affects fatty acid synthesis
(myelin synthesis affected & peripheral neuropathy)
Causes Beri-beri
- dry skin
- irritability
- progressive paralysis
Causes Wernicke’s encephalopathy
- confusion, ataxia
- nystagmus & eye paralysis
- peripheral neuropathy
If untreated, may progress into Korsakoff ‘s psychosis
- irreversible syndrome
- amnesia & deficits in learning & memory
Causes of Deficiency: Alcoholism Systemic disease (cancer , AIDS) Insufficient dietary intake Severe liver disease
What is the function of Niacin (vitamin B3) and what does a deficiency lead to?
Functions:
Cofactor for oxidase & dehydrogenase enzymes (active forms are NAD+ & NADP+)
Repair of UV light damage in DNA in skin
Treatment of hyperlipidemia in high doses
(nicotinic acid inhibits lipolysis & leads to decrease in VLDL synthesis)
Deficiency:
Causes pellagra (skin, GI & nervous system symptoms)
- photosensitive dermatitis
- diarrhea
- dementia (apathy, confusion, disorientation, lethargy)
- can lead to death
What is the function of vitamin B2 (riboflavin)?
what does a deficiency cause?
cofactors for oxidase and dehydrogenase enzymes (active forms are FAD and FMN)
Deficiency: Causes ariboflavinosis - glossitis - cheilosis (fissures at corners of mouth) - dermatitis - angular stomatitis - cataracts
