water soluble vitamins - B12 (cobalamin)

Question 1

what are the coenzyme forms used in body

Answer 1

5-deoxyadenosylcobalamin

methylcobalamin

Question 2

what are functions of these coenzyme forms

Answer 2

methylcobalamin - folate pathway and homocysteine removal; heme synthesis; MYELINATION

5deoxyadenosylcobalmin - threonine and isoleucine metabolism or metabolsim of odd chain fatty acids

Question 3

who may need b12 supplements

Answer 3

anyone over 50 years of age

Question 4

how is b12 digested and absorbed

Answer 4

Intrinsic factor secreted from parietal cells of the stomach

IF receptor in ileum binds B12IF complex and absorbs by receptor mediated endocytosis

Question 5

who is at risk for b12 deficiency

Answer 5

zollinger-ellison syndrome
medications (H2 blockers, metformin)
pancreatic insufficiency
malabsorptive syndromes
strict vegans
elderly
achlorhydria (dec Hcl)
pregnant women
pernicious anemia gastritis(impaired IF release)

Question 6

what is pernicious anemia

Answer 6

type of megaloblastic anemia

autoimmune condition where antibodies attack gastric parietal and mucosal cells

Question 7

can b12 be toxic

Answer 7

no toxicity reported

Question 8

what are dietary sources of b12

Answer 8

shellfish, meats, poultry, fish, dairy, fortified cereals