MODULE 2: B6, B9, B12 Flashcards
Folate is?
B9
Cobalamin is?
B12
Pyridoxine is?
B6
Pantothenic acid is?
B5
Thiamin is?
B1
Riboflavin is?
B2
Niacin is?
B3
** Know what the 4 D’s stand for? Vitamin Associated
Dementia
Dermatitis
Diarrhea
Death
Niacin! (B3)
Biotin is?
B7
** Know what pellegra is; what B vitamins might be associated
Pellegra is SEVERE B3 deficiency - presents as 4 D’s
B6 deficiency might also present with Pellegra
** Fate of homocysteine in methylation pathway (what vitamins involved?)
B6! = Homocysteine —> Cystathionine —> Cysteine
B12! = Homocysteine —> Methionine (using methionine synthase) + folate
Zinc and folate absorption
Zinc deficiency INHIBITS folate (B9) absorption
** Regulation of sodium channels and ACH receptors involves what B vit?
Thiamin/B1
** T/F there is more folate in RBCs than is plasma
T
**FUNCTION OF FOLATE
Facilitates the transfer of one carbon-groups from one bio molecule to another
** Why is SAMe important? (Function)
Important methylating compound (produced by methionine in methylation pathway)
** PRINCIPAL BIOLOGICAL METHYL DONOR
** Cysteine, glutamine, and glycine are used to produce?? (Hint: antioxidant)
GLUTATHIONE
** Vitamin B12 & Intrinsic Factor relationship
B12 must BIND with IF in order to be absorbed in the small intestine
(Forms a complex and complex binds to receptors in intestinal enterocytes)
** Describe absorption of B12/where it takes place
- B12 released from food
- Binds to R proteins (found in gastric juice)
- R protein brings B12 to small intestine
- B12 binds with INTRINSIC FACTOR (in upper intestine)
- B12-IF complex binds to enterocyte receptors and B12 is absorbed in **DISTAL small intestine
** Know B vitamin involved in Pernicious Anemia
B12
** Where is B12 primarily stored in the body?
LIVER
** Conversion of homocysteine to methionine requires ?
B12
** Metabolism of vitamin B6 to the primary coenzyme form, PLP (pyridoxal phosphate), requires ??
RIBOFLAVIN
** Lethargy, depression, hallucinations, muscle pain, scaly/red dermatitis is seen with deficiency in?
BIOTIN (B7)
** Fatty acid and cholesterol synthesis - know B vitamin involved
NIACIN
** What 3 B vitamins are needed to synthesize fatty acids?
Niacin (B3)
Riboflavin (B2)
Pantothenic Acid (B5)
** B vitamin involved in pernicious anemia?
B12 (caused by not enough IF)
** Niacin & toxicity?
Tolerable Upper Limit because of VASODILATORY EFFECTS
Those with HYPERLIPIDEMIA should avoid/be careful
** Niacin toxicity includes
SKIN FLUSHING Rapid heart beat Dizziness GI distress (nausea, abdominal pain) Itching Headache
** Niacin can be synthesized in the body from?
Tryptophan
** Niacin’s use in cholesterol treatment? Blood sugar? Metabolic syndrome?
Niacin: Used to treat high cholesterol (Lower LDL, raise HDL, lower triglycerides)
May not be useful as it is also associated with inducing insulin resistance/affecting glucose homeostasis and therefore exacerbating metabolic syndrome
** Niacin function in fatty acid/cholesterol synthesis?
Niacin AS NADPH acts as a reducing agent in F.A./cholesterol synthesis
** Hexose Monophosphate shunt is????
Pentose Phosphate pathway
** Niacin’s relationship to Hexose Monophosphate shunt?
NADPH (Niacin/nicotinamide) produced via the Hexose Monophosphate shunt/Pentose-Phosphate pathway
** B12 testing?
Serum B12
** Methylmalonic acid urine test (If MMA high, B12 low)
** B12 deficiency symptoms include:
- Megaloblastic, macrocytic anemia
- Fatigue, pale skin
- Shortness of breath
- Heart palpitations
Neurological
- Numbness in extremities
- Poor coordination
- Abnormal gait
- Memory loss
- Psychosis
- Dementia
** RDA for folic acid in women of childbearing age
400 micrograms
** Relationship between folic acid and B12 deficiency
Consuming high amounts of folate can MASK B12 deficiency
** Digestive enzymes relationship to FOLATE
Folic acid digestion requires CONJUGASE and other enzymes in order to be broken down and absorbed
** Go from poluglutamate form in food —> monoglutamate (to be absorbed)
** Best way for accessing long term folate levels?
FIGLU excretion
Homocysteine levels! (Elevated H means low B9/12)
** What enzyme is the drug methotrexate designed to inhibit?
Inhibits DIHYDROFOLATE REDUCTASE which converts DHF to Tetra hydrofolate
** Methyl-Folate Trap hypothesis
Involves SYNERGISTIC RELATIONSHIP b/t B9 & B12
(During synthesis of methionine from homocysteine) adequate B12 is require to transfer methyl group to folate
If not enough B12, folate gets “trapped” in unusually form/form needed for DNA synthesis THEREFORE DNA synthesis cannot be accomplished
** What vitamin is required to activate B6?
Riboflavin (B2)
** Elevated homocysteine means what for B6/9/12?
Elevated H = deficiency B6/9/12
** Folate’s function in dividing cells during growth
THF (tetrahydrofolate) involved in DNA synthesis/cell division —> promotes proliferation of all cells (good and bad)
** Tetrahydrofolate and cancer/dividing cells
THF involved in cells division/proliferation/DNA synthesis —> THF sometimes blocked in anti-cancer drugs because THF PROMOTES CELLS PROLIFERATION/GROWTH
** Absorption of folate from green (leafy) vegetables (eg. FOLATE IN FOOD)
Dietary folate (veggies) require digestion in order to be absorbed
Digestion occurs via ENZYMES (Conjugases/carboxypeptidases in brush border)
- Brush border enzymes require ZINC & ADEQUATE pH
