Micronutrients

Question 1

Define trace minerals

Answer 1

Mineral for which daily intake is

Question 2

What are the trace minerals?

Answer 2

• iron
• Iodine
• Zinc
• Copper
• Selenium
• Molybdenum
• Chromium
• Fluoride
• Manganese

Question 3

Are trace minerals more or less bioavailable than macronutrients?

Answer 3

Less; they are susceptible to interference w/absorption

Question 4

Iron - what does it do and how much of it is there?

Answer 4

• Total body iron = 5g
• 50% as hemoglobn iron
• storage Fe: 300-1500 mg

Function:

• O2 transport in blood and muscle
• Electron transport
• Enzymes for activation of O2
• Enzymes, dopamine synthesis, CNS myelination

Question 5

Where do we get iron from?

Answer 5

Food:
Heme: meats/flesh, liver (all milks = poor source)
Non-heme: plant sources and Fe-fortified foods

Question 6

Factors affecting absorption/bioavailability

Answer 6

Heme Fe&raquo_space; non-heme

Insoluble complexes in plats inhibit absorption : phytate, oxalate, polyphenols, phosphate, fiber

Question 7

Phytic acid

Answer 7

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

Question 8

more on absorption of iron

Answer 8

Oxidation state:
Fe3+ –> Fe2+ better absorbed;
- ascorbic acid reduces Fe, forms complex

Host factors

• deficiency –> inc absorption
• inflammation –> dec. absorption

Key factors: form of Fe & host status for absorption

Question 9

Iron Homeostasis

Answer 9

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”

Question 10

At risk populations for iron

Answer 10

• BF infant (at birth use Fe in RBCs, but in 4-6 months, have to make their own RBCs so they need Fe from diet)
• Premies
• Young children
• Adolescent girls
• Pregnant women
• Blood loss
• Obese & s/p bariatric surgery