Quiz
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1. What makes a mineral a trace mineral?
You need it in amounts under about 20 mg a day (Figure 1).
2. What are the two charges iron switches between?
Fe²⁺ (ferrous) and Fe³⁺ (ferric) (Figure 2).
3. What holds the iron in heme?
Four nitrogens of a porphyrin ring (Figure 2).
4. Which foods supply heme iron?
Animal foods: meat, poultry and fish (Figure 2).
5. How does the body get rid of extra iron?
It has no active way; it controls how much it absorbs and recycles iron from old red cells (Figure 3).
6. Why do women 19–50 need more iron than men?
To replace menstrual losses (Figure 3).
7. What can long-term high-dose zinc supplements cause?
Copper deficiency (Figure 4).
8. Which food is by far the richest in zinc?
Oysters (Figure 4).
9. What is selenocysteine?
Cysteine with selenium in place of sulfur, the 21st amino acid (Figure 5).
10. Why eat Brazil nuts only occasionally?
One nut can exceed a day’s selenium needs; too much causes selenosis (Figure 5).
11. How many iodine atoms are in thyroxine (T4)? In T3?
Four; three (Figure 6).
12. Name one thing that helps and one that hinders nonheme iron absorption.
Helps: vitamin C or meat in the meal. Hinders: phytate, tea or coffee polyphenols, calcium (Figure 8).