Chapter 12 — Quiz
Twenty questions. Attempt before opening.
Multiple Choice
1. Ethanol provides how many calories per gram?
- a) 4
- b) 7
- c) 9
- d) 0
Answer
**b.** Between carbohydrate/protein (4) and fat (9) — and unlike all three, **there is no storage form and no meaningful excretion route.** It has to be metabolized.2. The toxic intermediate in ethanol metabolism, responsible for its carcinogenicity, is:
- a) Acetate
- b) Acetaldehyde
- c) Methanol
- d) Lactate
Answer
**b.** It damages DNA and impairs repair. It's also responsible for flushing, nausea, and much of a hangover — and it's cleared by **ALDH2**.3. Alcohol contributes to fat gain primarily by:
- a) Being converted directly into body fat
- b) Suppressing fat oxidation while it's being metabolized, sparing fat that would otherwise be burned
- c) Damaging the pancreas
- d) It doesn't contribute at all
Answer
**b.** Very little ethanol becomes fat directly — that fact is true and is the basis of a misleading claim. The mechanism is **sparing**, plus zero satiety return, plus evidence it increases subsequent eating.4. "Sick-quitter bias" means:
- a) People underreport how much they drink
- b) The abstainer comparison group is enriched with former drinkers who stopped because they were ill
- c) Sick people drink more
- d) Researchers exclude ill participants
Answer
**b.** Push the reference group's risk up and the drinkers below them look protected. **That's the dip in the J.**5. Which is NOT one of the three problems with the J-curve?
- a) Sick-quitter bias
- b) Healthy-user bias
- c) Exposure misclassification
- d) Alcohol not being measurable in blood
Answer
**d.** The three are sick-quitter bias, healthy-user bias (moderate drinkers are wealthier, better educated, better connected), and misclassification from underreporting plus weekly averaging.6. The ALDH2 variant is useful for Mendelian randomization because it:
- a) Is very rare
- b) Is allocated at conception, doesn't change with lifestyle, and affects mortality mainly through alcohol intake
- c) Causes cancer directly
- d) Only occurs in heavy drinkers
Answer
**b.** A natural randomized trial running for a lifetime in millions of people, **immune to sick-quitter bias and healthy-user bias by construction.**7. Mendelian randomization studies of alcohol and cardiovascular outcomes generally find:
- a) The J-curve confirmed
- b) No cardioprotection, with roughly monotonic relationships
- c) Alcohol is protective at all doses
- d) No relationship at all
Answer
**b.** Less is better, including at the low end. **Cohorts and MR have non-overlapping weaknesses and they disagree** — exactly the signal Chapter 2 §2.10 said to take seriously.8. Why is the resveratrol claim rejected?
- a) Resveratrol doesn't exist
- b) Wine's resveratrol content is very low; matching the animal-study doses would require implausible quantities, and human supplementation trials have been underwhelming
- c) Red wine contains no polyphenols
- d) Resveratrol is toxic
Answer
**b.** And the decisive point: **if resveratrol were the active ingredient, you'd take it without the ethanol** — people have, and it didn't work.9. Which cancer shows a dose-response beginning at low alcohol intakes?
- a) Lung
- b) Prostate
- c) Female breast
- d) Pancreatic
Answer
**c.** Which is why "moderate" stops being reassuring, and a major driver of the guideline changes in §12.9.10. "No level of alcohol consumption is safe for health" means:
- a) Any amount will harm you significantly
- b) There is no identified threshold below which risk is zero
- c) Alcohol should be banned
- d) All drinkers develop cancer
Answer
**b.** Technically defensible and easily misread. It does **not** mean any amount is dangerous enough to dominate your decisions — **those are different claims and the headlines merged them.**11. A US standard drink, a UK unit, and an Australian standard drink contain, respectively:
- a) 10 g, 10 g, 10 g
- b) 14 g, 8 g, 10 g
- c) 8 g, 14 g, 12 g
- d) 20 g, 15 g, 10 g
Answer
**b.** Which is why "two drinks a day" means meaningfully different things in different countries. **Count grams of ethanol if you want to compare anything to anything.**12. Which effect of alcohol reduction do people most commonly notice within days?
- a) Reduced cancer risk
- b) Improved sleep quality
- c) Lower cholesterol
- d) Weight loss
Answer
**b.** Alcohol reduces sleep latency — which is why it feels helpful — then suppresses REM and fragments the second half of the night. This was probably the largest single component of why Theo's juice cleanse made him feel wonderful (Chapter 3, Case Study 1).13. Canada's 2023 guidance is notable for:
- a) Recommending complete abstinence
- b) Framing risk as a continuum — 1–2 drinks/week low risk, 3–6 moderate, 7+ increasingly high
- c) Raising previous limits
- d) Being identical to US guidance
Answer
**b.** A substantial reduction from previous Canadian guidance, and part of a general convergence toward **continuum-of-risk framing** rather than a "safe limit" model. **Note that none of the four guidelines in §12.9 says don't drink.**True / False
One-line justification.
14. Moderate drinking protects against heart disease.
Answer
**Probably false.** The J-curve is substantially explained by sick-quitter bias, healthy-user bias, and misclassification; analyses restricted to lifelong abstainers attenuate the dip; and Mendelian randomization — immune to all three — finds no cardioprotection. **The confident claim no longer has evidence proportionate to how often it's repeated.**15. Alcohol calories don't count because ethanol isn't stored as fat.
Answer
**False.** Direct conversion was never the mechanism. Alcohol contributes by **suppressing fat oxidation** while being metabolized, with no satiety return. The thermic discount is real and modest — 190 kcal becomes perhaps 140–170, not zero.16. Statistical adjustment can correct for sick-quitter bias.
Answer
**False.** Many cohorts never asked about former drinking; where asked, the reason is unreliable; and **the illness may precede the diagnosis by years**, so no adjustment can capture a reason the participant themselves doesn't know. Excluding former drinkers helps and doesn't solve it.17. Someone who drinks heavily every day should stop immediately.
Answer
**False, and this is a genuine safety point.** ⚠️ Alcohol withdrawal can be dangerous and in some cases life-threatening, and is managed medically. **This is one of very few places in this book where "just stop" is the wrong advice.**18. Alcohol is Group 1 like tobacco, so a glass of wine is comparably dangerous to a cigarette.
Answer
**False.** Group 1 describes **confidence in causation**, not magnitude (Chapter 2 §2.6). Tobacco shifts lung cancer risk by more than an order of magnitude; one drink a day shifts several cancer risks by a much smaller relative amount on small absolute baselines. **Overstatement is how accurate warnings get discarded.**Short Answer
19. Explain why Mendelian randomization is such powerful evidence here, and name one thing that could weaken it.
Answer
**Why it's powerful:** the *ALDH2* variant is allocated essentially at random at conception, doesn't change with income, education, diet, or health status, and affects mortality primarily through alcohol intake. It is therefore **immune to sick-quitter bias, healthy-user bias, and self-report error** — the three problems that dominate the observational literature. It functions as a lifelong natural randomized trial in very large numbers. Crucially, **its weaknesses don't overlap with the cohorts' weaknesses**, so when the two disagree, something real is going on (Chapter 2 §2.10). **What could weaken it:** MR assumes the variant affects the outcome *only* through the exposure — pleiotropy. If *ALDH2* influenced cardiovascular risk through some pathway other than alcohol intake, the inference would be compromised. There are also population-specific considerations, since much of the *ALDH2* work is in East Asian cohorts, and social factors around drinking differ across populations.20. A friend says: "I've read the headlines but people have been drinking wine for thousands of years and my grandmother had a glass every night and lived to 94." Respond.
Answer
**Take both parts seriously, because both contain something true.** **The grandmother is rung 3 evidence** (Chapter 2) — one person, no denominator, and survivorship selection: we hear about the grandmothers who reached 94, not the ones who didn't. It tells you nothing about her risk, only about her outcome, and those are different things when the effect size is roughly one extra case per 75 people. **The thousands-of-years point is better than it sounds and still doesn't work.** Long use tells you something about acute tolerability and nothing about lifetime cancer risk — which requires large populations, long follow-up, and controls, none of which existed. Tobacco was also used for centuries. **What I'd actually say:** *"Nobody's telling you it'll kill you — the numbers are small. What's changed is that the 'it's good for your heart' part has fallen apart, so the trade-off no longer has a freebie in it. You're now trading pleasure against a small risk, rather than getting a bonus on top. That's a perfectly reasonable trade to make; it's just a different one than you thought you were making."* **And I would not push further than that**, because a lecture is the fastest way to make someone stop listening — which is §12.10's whole posture.Scoring
| Score | Reading |
|---|---|
| 18–20 | Strong. And Part II is done — the honest summary is that almost nothing that earned a strong verdict was a macronutrient ratio. |
| 14–17 | Good. Reread §12.4 (the three problems) and §12.5 (MR). |
| 10–13 | Reread §12.4–§12.5 together. The J-curve's collapse is the chapter's argument. |
| Under 10 | Reread the chapter. This one contradicts a widely-held belief and takes a second pass for most readers. |
And check yourself on the §12.9b calibration: did you find the fiber arithmetic (Chapter 11) persuasive and the alcohol arithmetic dismissible, or the reverse? They have the same shape. Any difference is coming from you.