Flashcards in Micronutrients Deck (10):
Define trace minerals
Mineral for which daily intake is
What are the trace minerals?
Are trace minerals more or less bioavailable than macronutrients?
Less; they are susceptible to interference w/absorption
Iron - what does it do and how much of it is there?
- Total body iron = 5g
- 50% as hemoglobn iron
- storage Fe: 300-1500 mg
- O2 transport in blood and muscle
- Electron transport
- Enzymes for activation of O2
- Enzymes, dopamine synthesis, CNS myelination
Where do we get iron from?
Heme: meats/flesh, liver (all milks = poor source)
Non-heme: plant sources and Fe-fortified foods
Factors affecting absorption/bioavailability
Heme Fe >> non-heme
Insoluble complexes in plats inhibit absorption : phytate, oxalate, polyphenols, phosphate, fiber
Binds cations in gut luman
Storage form of phosphorous in plants
Humans don't have phytases
Serves fxn as anti-oxidant
High in grains & legumes
Maize/wheat > legumes > rice
Likely the major cause of dietary deficiencies
more on absorption of iron
Fe3+ --> Fe2+ better absorbed;
- ascorbic acid reduces Fe, forms complex
- deficiency --> inc absorption
- inflammation --> dec. absorption
Key factors: form of Fe & host status for absorption
1. Absorption = main point of regulation
- deficiency --> dec. hepcidin --> inc. uptake
- inflammation --> inc. hepcididn --> dec. uptake
2. Loss: bleeding, cell sloughing
3. Stores: ferritin - liver, bone marrow, spleen
4. Transferrin: transports Fe in body; no "free Fe"