FOOD20003 Lecture Notes - Lecture 23: Semen Analysis, Diarrhea, Nyctalopia
28 Jun 2018
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TRACE MINERALS:
• Food sources = unpredictable b/c depend on water & soil content and processing methods
• Need to consider extent of absorption (bioavailability) due to competing factors and binding agents
• Deficiency = poor growth
• Most are toxic even slightly above recommended intake
o Excessive from diet = unlikely but possible from supplementation
• Excess/deficiency of one can affect absorption of another
1. Outline the forms of iron and where they are found in the body.
• Fe2+ (ferrous) & Fe3+ (ferric) à oxidising agents so BAD in excess
• Iron is a cofactor to enzymes (i.e. in TCA/ETC) à deficiency in iron = cause problems for body
energy
• Iron = conserved in the body (recycled from one form to another, minor losses)
2. Discuss iron absorption with reference to heme and non-heme iron.
• Absorbed and stored in intestinal wall cells bound to mucosal ferritin
• Mucosal transferrin carries iron from intestinal mucosal cells into blood
o BUT these cells = short lifespan so needs to be released into blood before storage dies
• Transferrin transports iron to rest of body
o Most end up in bone marrow for RBC production
• Excess iron = stored in proteins (ferritin & hemosiderin)
o Hemosiderin protects DNA/lipids/proteins from oxidation effect of free iron
• Bodily iron status à measured by blood ferritin levels
• 25% heme iron, 5% non-heme iron absorbed
o Absorption inhibitors: phytates, oxalic acid, fibres etc
