Minerals

Question 1

What ionic state is iron better absorbed in

Answer 1

ferrous ion (FE2+) - reduced state

Question 2

Explain digestion and absorption of iron

Answer 2

heme iron (ferrous, from animals):
protease (in stomach and small int) release heme iron from globin portion
–> absorbed (intact) in mucosal cells (25%, most efficient in duodenum)
–> heme oxygenase hydrolyzze heme porphyrin ring to inorganic ferrous ion and protoporphyrin
–> IF BODY NEEDS: absorbed iron bound to ferritin released to mucosal transferrin to blood transferrin, IF BODY DOESNT NEED: excess stored as ferritin in mucosal cells, some lost through shedding of intestinal cells

non-heme iron (ferric, from veggies + animals):
gastric secretion (HCl + pepsin) liberates iron -> reduced to ferrous
–> absorbed in intestines (1-50%), oxidized back to ferric, may form ferric hydroxide complex
–> IF BODY NEEDS: absored iron bound to ferritin released to mucosal transferrin -> blood transferrin, IF BODY DOESN’T NEED: excess stored as ferritin in mucosal cells, some lost in shedding of intestinal cells

Question 3

most abundant trace mineral

Answer 3

iron

Question 4

iron stored in body as

how much iron for hemoglobin synthesis

Answer 4

ferritin and hemosiderin (200-1500 mg) in liver (30%), bone marrow (30%), and rest in spleen muscles

<50 mg

Question 5

iron functions (2)

Answer 5

• role in blood, respiratory transport of Oxygen and CO2: hemoglobin, myoglobin

Question 6

Factors to enhance iron absorption

Answer 6

Meat protein factor (MPF) enhances heme and non-heme absorption

vit C reduces non-heme iron (ferric), forms chelates

citric, lactic acids, HCl

sugars

Question 7

factors inhibiting iron absorption

Answer 7

phytates, oxalates, fibers

EDTA (food additives)

calcium and phosphorus (milk)

tahnic acid (tea, coffee, nuts, some fruits and vegetables), other polyphenols