Vitamins Flashcards
Three characteristics of a vitamin?
- ) Organic compound
- ) Cannot be synthesized in sufficient amounts in the body
- ) Essential function that in absence it causes physical symptoms that disappear with administration
Water soluble vitamins:
C: ascorbic acid B1: thiamine B2: riboflavin B3: niacin B5: pantothenic acid B6: pyridoxine B7: biotin B9: folate B12: cobalamin
Fat-soluble vitamins:
A: retinol
D: calcitriol
E: a, b, g-tocopherol
K: K1, K2, K3
What are fat soluble vitamins associated with?
Bound to proteins and lipids in food
What releases FS vitamins from lipids and proteins in food?
HCl denaturation and pepsin
How do FS vitamins make it across plasma membrane?
Complexed to FA, complexed with TAGs and removed from chylomicrons by lipoprotein lipase
What activates lipoprotein lipase to cleave TAGs?
Apo C2
What is beta-carotene?
Vitamin A pro-drug
How does rhodopsin change in conformation in sunlight?
11-cis to 11-trans
What can vitamin A deficiency result in?
Night blindness
What affect does Vitamin A have on 1st trimester and children respectively?
1st trimester: too much defects
Children: too little reduced growth
What does too much retinol cause?
Bone resorption and osteoporosis
What is vitamin D a product of?
Cholesterol
Vitamin D deficiency causes:
Rickets
Osteomalacia
What does low calcium cause?
Parathyroid hormone release (takes Ca2+ from bones) stimulating Vitamin D activation in kidney
What does Vitamin D do?
Increased absorption of calcium and phosphate
Vitamin D affect on immune?
Binds to TLRs causing expression of 1alpha-hydroxylase and synth of calcitriol inhibiting proliferation and autoimmunity; also anti-inflammatory cytokines made
Most active form of Vitamin E?
Alpha-tocopherol
What is high in vitamin E?
Seed oils; destroyed commercially so most are synthetic
Vitamin E affects:
Antioxidant
Inhibit platelet clumping
Reduce plaque buildup
How is excess vitamin K excreted?
Bile
What clotting factors need vitamin K?
VII, IX, X, C and S
Cofactor for gamma-glutamyl carboxylase
How does Coumadin work?
Blocks vitamin K recharging
What happens once vitamin K is digested?
It gets converted by colon flora
Why is vitamin K administered to infants at birth?
It doesn’t cross the placenta and no gut bacteria for vitamin K production and no vitamin K in breast milk
Two proteins dependent on vitamin K:
Osteocalcin: secreted by bone-forming osteoblasts
Matric Gla Protein: binds Ca2+ and assists calcium binding to bone matrix and inhibits vascular mineralization
Effect of vitamin K on vessels?
Stops Ca2+ plaque buildup
How is reduced and oxidized vitamin C absorbed respectively?
Oxidized: passive GLUT1/3
Reduced: active Na+-dependent transporters
Effect of vitamin C on iron?
Increase absorbance
What needs vitamin C for formation?
Collagen
What does a deficiency in vitamin C cause?
Scurvy
What is vitamin B1 important as?
A cofactor for multiple reactions
What does vitamin B1 defect cause?
Wet beriberi: edema CHF
Dry beriberi: muscle wasting
What does excess riboflavin (B2) cause?
Bright yellow urine
B2 needed for:
Cofactor for radical and polar redox reactions
B2 deficiency:
Irritated mouth, tongue, cracked lips
When is B2 stable and not stable?
Stable during cooking not in UV light
What can vitamin B3 be made from?
Tryptophan
What is niacin B3 converted to?
NAD+ and NADP+
What can niacin do to cholesterol?
Lower LDL
Elevate HDL
Excess niacin:
Reddish skin
Deficiency in niacin (3 D’s)
Pellagra: dermatitis, dementia, diarrhea
B6 found in foods?
Pyridoxine
Active form of B6?
PLP
Excess B6:
Nerve damage
Deficiency in B6:
Microcytic hypochromic anemia (small and pale RBC’s)
What is hydroxycobalamin (activated charcoal) used to treat (B12)?
Cyanide poisoning
How does hydroxycobalamin treat CN- poisoning?
Take CN- into the molecule taking OH- place
How is methylcobalamin absorbed?
Haptocorrin (R factor) binds to B12 protecting it from stomach acid; IF binds and allows absorption
What is biotin (B7) used for?
Carboxylase enzyme reactions (addition of CO2)
What is pantothenic acid (B5) used for?
Essential part of CoA needed in catabolic and anabolic reactions
Where is CoQ10 found?
ETC Complex I
What is CoQ10 a step of?
Downstream of cholesterol synthesis
