water soluble vitamins - B12 (cobalamin) Flashcards Preview

Nutrition Exam 3 > water soluble vitamins - B12 (cobalamin) > Flashcards

Flashcards in water soluble vitamins - B12 (cobalamin) Deck (8)
Loading flashcards...
1
Q

what are the coenzyme forms used in body

A

5-deoxyadenosylcobalamin

methylcobalamin

2
Q

what are functions of these coenzyme forms

A

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

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

3
Q

who may need b12 supplements

A

anyone over 50 years of age

4
Q

how is b12 digested and absorbed

A

Intrinsic factor secreted from parietal cells of the stomach

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

5
Q

who is at risk for b12 deficiency

A
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)
6
Q

what is pernicious anemia

A

type of megaloblastic anemia

autoimmune condition where antibodies attack gastric parietal and mucosal cells

7
Q

can b12 be toxic

A

no toxicity reported

8
Q

what are dietary sources of b12

A

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