Chapter 14 — Quiz

Twenty questions. Attempt before opening.

Multiple Choice

1. The main reason minerals behave differently from vitamins is that:

  • a) They are needed in larger amounts
  • b) They are elements and cannot be destroyed — so absorption, not degradation, is where the action is
  • c) They are only found in animal foods
  • d) They have no upper limits
Answer **b.** Boiling doesn't destroy iron; it leaches it into the water. Which is why absorption regulation, mineral-mineral competition, and narrower toxicity windows all follow.

2. Non-heme iron absorption is most strongly inhibited by:

  • a) Vitamin C
  • b) Meat
  • c) Tea and coffee polyphenols, phytate, and calcium
  • d) Cooking
Answer **c.** And the tea/coffee effect is large — which makes "move your tea away from meals" one of the highest-yield free interventions in the chapter.

3. Ferritin measures __ and hemoglobin measures ____.

  • a) Iron stores; the consequence of exhausting them
  • b) The consequence; the stores
  • c) Both measure the same thing
  • d) Dietary intake; absorption
Answer **a.** Depletion runs **stores → ferritin falls → *(long interval)* → hemoglobin falls**. A normal hemoglobin excludes anemia and says almost nothing about iron status.

4. Devi's hemoglobin was 12.6 and her ferritin was 11. This means she was:

  • a) Perfectly fine
  • b) Anemic
  • c) Iron-deficient without anemia
  • d) Iron-overloaded
Answer **c.** Step two of the staircase, for at least two years — with three clinicians correctly telling her the bell at the bottom hadn't rung.

5. Ferritin can be misleadingly normal or high when:

  • a) The person is dehydrated
  • b) There is inflammation, infection, or liver disease — ferritin is an acute phase reactant
  • c) The person is vegetarian
  • d) The sample was taken in the morning
Answer **b.** Which is why CRP is measured alongside it, and why transferrin saturation or soluble transferrin receptor may be needed. **A genuine trap.**

6. Hepcidin does what during inflammation?

  • a) Falls, increasing iron absorption
  • b) Rises, suppressing iron absorption and sequestering iron
  • c) Has no relationship to inflammation
  • d) Converts ferritin to hemoglobin
Answer **b.** Producing the **anemia of chronic disease**, which looks like iron deficiency and is not treated the same way. It also means hard training transiently suppresses iron absorption.

7. Unexplained iron deficiency in a man or a post-menopausal woman requires:

  • a) An iron supplement
  • b) Investigation for a source of blood loss
  • c) Dietary advice only
  • d) Nothing — it's common
Answer **b.** ⚠️ **Iron deficiency is a finding, not a diagnosis.** In these groups it may be the presenting sign of gastrointestinal bleeding.

8. Calcium supplementation in healthy community-dwelling adults:

  • a) Substantially reduces fractures
  • b) Improves bone density slightly, with small or no reduction in fractures
  • c) Has never been studied
  • d) Increases fractures
Answer **b.** Another surrogate-endpoint gap. **Better evidence** exists for calcium plus vitamin D in frail or institutionalized older adults, and in those with genuinely low intake.

9. Serum magnesium is a poor marker of magnesium status because:

  • a) It fluctuates hourly
  • b) Only ~1% of body magnesium is in blood, and levels are maintained by drawing from bone and tissue
  • c) It cannot be measured accurately
  • d) Magnesium isn't essential
Answer **b.** So a normal serum magnesium doesn't exclude inadequacy — which means we can't easily identify who would benefit, which dilutes every supplementation trial with non-responders.

10. The UL for zinc is approximately 40 mg/day. Chronically exceeding it causes:

  • a) Kidney stones
  • b) Copper deficiency — anemia, neutropenia, potentially irreversible neurological damage
  • c) Hair loss only
  • d) Nothing
Answer **b.** Zinc and copper compete, and high zinc induces intestinal metallothionein which traps copper. **Walt was taking 50 mg indefinitely with nobody monitoring copper** — one of two genuinely dangerous items in his cabinet.

11. Selenium is notable because:

  • a) It's the most abundant trace mineral
  • b) It has one of the narrowest windows between requirement (~55 µg) and UL (~400 µg)
  • c) It cannot be obtained from food
  • d) Deficiency is common in Western diets
Answer **b.** A factor of roughly seven. And **Brazil nuts are extraordinarily and variably high** — a few a day can approach or exceed the UL, which makes them the one food in this book where a daily handful is genuinely inadvisable.

12. Iodine deficiency in pregnancy is important primarily because it:

  • a) Causes maternal fatigue
  • b) Impairs fetal neurodevelopment — severe deficiency causes cretinism
  • c) Increases birth weight
  • d) Affects only the mother's thyroid
Answer **b.** Described as the world's leading preventable cause of intellectual disability. Requirements rise in pregnancy (~220 µg vs 150 µg), and ⚠️ the risk concentrates in women who avoid dairy, use non-iodized specialty salt, or eat plant-based.

13. Roughly what proportion of dietary sodium comes from processed and restaurant food?

  • a) ~20%
  • b) ~40%
  • c) ~70–75%
  • d) ~95%
Answer **c.** Which is why **cooking your own food reduces sodium substantially without anyone tasting less salt**, and why shaker discipline is close to irrelevant.

True / False

One-line justification.

14. A normal full blood count rules out iron deficiency.

Answer **False, and this is the chapter's central point.** It rules out *anemia* — the bell at the bottom of the staircase. Ferritin is the only test that tells you which step you're on, and depletion can sit at step two for years.

15. You should take an iron supplement if you feel tired.

Answer **False.** ⚠️ Test first. Iron has no excretion route, hereditary hemochromatosis is actively worsened by supplementation, iron overdose is a leading cause of poisoning death in young children, and without a baseline you can't tell whether a lack of response means "not deficient" or "wrong dose."

16. Most people get enough potassium.

Answer **False.** Most Western populations get roughly half to two-thirds of the AI (~2,600–3,400 mg). It lowers blood pressure, promotes sodium excretion, and **may matter as much as sodium reduction** — ⚠️ but supplements and potassium-based salt substitutes are dangerous in kidney disease or on ACE inhibitors/ARBs.

17. Sea salt and pink Himalayan salt are nutritionally superior to table salt.

Answer **False, and often worse.** The trace mineral differences are nutritionally trivial, and specialty salts are **generally not iodized** — which is a genuine and re-emerging problem, concentrated in women of childbearing age.

18. Modern soil depletion means our food no longer contains adequate minerals.

Answer **Probably false as a general claim.** Plants can't grow without the minerals *they* need — depleted soil gives you less wheat, not low-iron wheat. **The exceptions are selenium and iodine**, which plants don't require, which is exactly why those two are geographically variable and why iodized salt exists.

Short Answer

19. Explain the iron depletion staircase and why the standard test is described as "a floor sensor, not an early warning system."

Answer **Step one:** stores full, ferritin normal, hemoglobin normal. **Step two:** intake below losses, body draws on stores, **ferritin falls while hemoglobin stays normal** — this step can last months or years, with worsening fatigue and declining performance, and every hemoglobin test comes back normal. **Step three:** stores exhausted, red cell production becomes limited, hemoglobin drifts down but may still sit inside a wide reference range. **Then the bell: anemia.** **Hemoglobin is mounted at the bottom.** It tells you that you have already descended three steps. **Only ferritin tells you which step you're on** — and since repletion takes months while depletion can happen in a season, catching it at step two rather than at the bell is worth a great deal.

20. Someone asks whether they should cut salt. Give the honest answer.

Answer **"It depends on your blood pressure, and the population advice is more confident than the evidence."** **What isn't disputed:** sodium raises blood pressure, reducing it lowers blood pressure (DASH-Sodium is clear and dose-dependent), and blood pressure causes cardiovascular disease. **So if you have hypertension or elevated blood pressure, reduce sodium — that's well supported.** **What is disputed:** whether population-level reduction in normotensive people reduces *events*, and whether there's a lower bound. Some large observational studies (PURE) report **J-shaped** associations — but they rest substantially on **spot urine estimation**, which critics argue is systematically biased, and they face **reverse causation** (sick people eat less), which is structurally identical to Chapter 12's sick-quitter bias. **And two things worth adding regardless of where you land:** ~70–75% of sodium comes from processed and restaurant food, so **cooking more does more than the shaker** — and **raising potassium may matter as much as lowering sodium.**

Applied Scenario

21. A 23-year-old competitive cyclist, vegetarian, female, presents with two seasons of declining performance, persistent fatigue, and a "normal" blood test from six months ago. Her periods stopped around eight months ago. She trains 15 hours a week and eats "really cleanly."

What do you do, in what order, and what would you not do?

Answer **This is Devi with a different bike, and the ordering matters enormously.** **First — and before any mineral question — calculate energy availability.** Amenorrhea plus declining performance plus 15 hours of training is **RED-S until proven otherwise** (Chapter 4, Chapter 6 Case Study 1). If EA is low, **that is the primary diagnosis**, and every micronutrient is under-supplied downstream of it. Treating the iron while leaving the energy deficit would be treating a symptom. **Second — get the right bloods.** ⚠️ **Ferritin with CRP**, not just a full blood count. Also hemoglobin, B12 and folate (vegetarian), vitamin D, and thyroid function. The previous "normal" test almost certainly didn't include ferritin. **Third — ⚠️ refer.** Amenorrhea in an athlete is not a sign of fitness and is not something to train through. This needs a **sports physician and a sports dietitian**, and bone health assessment should be considered given the duration. **Fourth — the absorption fixes**, which are free: vitamin C with iron-containing meals, tea and coffee **away from** meals, soaking legumes, and — if she supplements — **timing it away from hard training**, because exercise-induced inflammation raises hepcidin and suppresses absorption for hours. **What I would NOT do:** - Start iron without testing (⚠️ §14.2) - Treat "eats really cleanly" as reassuring — **diet quality and diet quantity are different problems**, and the second one is what ends careers (Chapter 4, Case Study 2) - Accept the six-month-old "normal" result as excluding anything - Address nutrition without addressing training load, which is the other half of the energy equation

Scoring

Score Reading
18–21 Strong. You'd catch what three clinicians missed in Devi.
14–17 Good. Reread §14.2 (iron) — it carries most of the chapter.
10–13 Reread the staircase diagram and §14.2's two-test problem.
Under 10 Reread the chapter. Chapters 23, 25 and 29 build on it.

And do Exercise C1 regardless. Two boxes ticked → ask for ferritin. One sentence, at your next appointment.