BIOL 380 Lecture Notes - Lecture 11: Vitamin K Deficiency, Chymotrypsin, Trypsin
19 Jun 2018
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BIOL 380 – Lecture 11 (he called it lecture 10) Chapter 13 – Nutrients involved in bone health, energy
metabolism and blood health (part 2)
IRON
- Two forms of iron are present in foods
oHeme iron – found only in animal-based foods and more absorbable
oNon-heme iron – not as easly absorbed (bind to phytates)
More difficult to absorb .. binds strongly to phytates and not all phytates get
absorbed
- Exists in Fe2+ (ferrous – reduced form) and Fe3+ (ferric – oxidized form)
- Factors that promote non-heme iron absorption
oMeat factor (component of muscle tissue)
oStomach acids
oVitamin C
- Factors that impair iron absorption
oPhytate (legumes, rice, and whoel grains)
oPolyphenols (benzene containing compounds) (oregano, red wine, tea and coffee)
oVegetable proteins
oFiber
oCalcium
- Recommended intake
oRDA varies based on age and gender
oWomen need double then men because of loss of blood during period
o8 mg/day men
o18 mg/day for adult women 19-50 y/o
o27 mg/day for pregnant women
- Sources of iron
oMeat, poultry, fish, clams, oysters, liver, enriched or
fortified cereals and breads
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- Hephaestin and ceruloplasmin are copper containing plasma
proteins capable of oxidizing iron (basal membrane and blood)
- Vit C reduces ferric to ferrous in small intestine
- Heme (ferrous – 2+) iron is more absorbable than non-heme iron
- Heme released from iron in small intestine, it gets bound to a
specific receptor on the intestinal lumen and taken into the
enterocyte by endocytosis.
- Iron pool in the enterocyte can be stored or it can be
transported across the membrane of the enterocytes by
ferroportin
- Iron crossing into the interstitial fluid is in the ferrous form (2+)
but it is quickly converted to ferric iron (3+) by either hephaestin
in the intestinal basal cell membrane or ceruloplasmin in the
blood
- Fe(3+) rapidly bound to transferrin,
which transports it to the cells of the
body
Too much iron
- Accidental iron overdose: most
common cause of poisioning deaths in
children
oNo homeostatic mechanism for
high iron
- Symtpoms: nausea, vomiting, diarrhea
-Hemochromatosis: excessive absorption of dietary iron and altered iron storage (release) –
genetic for the most part
- Treatment: reduce dietary iron, avoid high vitamin C intake, blood removal
Not enough iron
- Most common nutrient deficiency
in the world
- High risk: infants, young children,
adolescent girls, premenopausal
and pregnant women
- Reasons
oPoor dietary intakes
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oDiets high in fiber or phytates that bind iron
oLow stomach acid (peptic ulcer)
oPoor iron absorption (poor gut health or dietary supplements with high mineral levels,
e.g. calcium)
Stages of iron deficiency
Functions of ZINC
- Zinc is a trace mineral
- Functions of zinc
oComponent of enzymes (involved in
the assembly of hemoglobin and myoglobin)
oMaintains structural integrity and shape of proteins
Ex. Zinc fingers which
Stabilize DNA binding proteins
Stabilize vitamin A receptors in the retina
oDevelopment and activation of certain immune cells
oRegulation of gene expression
- metalliothionein:
oIn enterocytes
oUnlike Fe, no evidence suggesting that Ca
affects absorption
- Zinc absorption increases during times of growth
- Once inside the enterocytes, zinc can be released into
the interstitial fluid or bound to metalliothionein,
which prevents zinc from moving out of the enterocyte
into the system (regulate zinc pool)
- Zinc is absorbed from the lumen of the intestine and
moves into the enterocyte. It then crosses the
basolateral enterocyte membrane via active transport.
Upon reaching interstitial fluid, zinc is picked up by
albumin, a transport protein in the plasma, and carried
via the portal vein to the liver
3
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Document Summary
Biol 380 lecture 11 (he called it lecture 10) chapter 13 nutrients involved in bone health, energy metabolism and blood health (part 2) Two forms of iron are present in foods: heme iron found only in animal-based foods and more absorbable, non-heme iron not as easly absorbed (bind to phytates) More difficult to absorb binds strongly to phytates and not all phytates get absorbed. Exists in fe2+ (ferrous reduced form) and fe3+ (ferric oxidized form) Factors that promote non-heme iron absorption: meat factor (component of muscle tissue, stomach acids, vitamin c. Factors that impair iron absorption: phytate (legumes, rice, and whoel grains, polyphenols (benzene containing compounds) (oregano, red wine, tea and coffee, vegetable proteins, fiber, calcium. Recommended intake: rda varies based on age and gender, women need double then men because of loss of blood during period, 8 mg/day men, 18 mg/day for adult women 19-50 y/o, 27 mg/day for pregnant women.
