Chapter 19 — Exercises

Three tiers. 🪞 marks reflection; 🔄 marks retrieval.

Tier 1 — Recall and Comprehension

R1. Name the eight oils usually included in the "seed oils" category. ⚠️ Then explain why the category is defined by provenance rather than composition, using canola, peanut and high-oleic sunflower as your examples.

R2. State the four numbered claims from §19.2 with their verdicts. Which one is factually uncontested?

R3. What are the three documented facts in §19.3? ⚠️ Which one is measured in tissue rather than estimated from surveys, and why does that matter?

R4. Draw the mechanistic chain from §19.4: LA → ? → ? → ? → disease. Name the shared enzyme that makes the ratio argument work.

R5. State the two testable predictions the mechanism generates, and what happened when each was tested.

R6. What is essential fatty acid deficiency? Name three clinical features and the settings in which it has been documented. ⚠️ Why does its existence constrain the "seed oils are toxic" framing?

R7. Why does "improving your omega-6:omega-3 ratio" hide more than it reveals? Use Person A and Person B from §19.5.

R8. Describe the two recovered trials in §19.6 — what they tested, what they found, and three reasons their findings are contested.

R9. ⚠️ Under what condition does the alarming oxidation research actually apply? Give the four-row table from §19.8.

R10. Rank these by smoke point, highest first: butter · refined canola · extra virgin olive oil · refined avocado · ghee. ⚠️ Then explain why smoke point is not the same as oxidative stability.

R11. Give the three processing objections in §19.10 and their separate verdicts.

R12. State §19.11's confounding problem in one sentence. ⚠️ Why is it symmetric?

Tier 2 — Application

A1. 🔄 Fill the five slots. §19.12 says four of five are empty in the standard claim. Do it yourself for this statement, then compare:

"Seed oils are driving the chronic disease epidemic."

⚠️ Then rewrite it as a claim that could be tested. How much narrower did it get?

A2. The comparator matrix. "Should I stop using canola oil?" has different answers depending on the replacement. Give the honest verdict for each:

a) Canola → extra virgin olive oil b) Canola → beef tallow c) Canola → butter d) Canola → not eating the fried food at all e) Canola in a bottle → canola in restaurant deep-fried food (i.e. no kitchen change)

A3. Read a label. Find three packaged foods containing seed oils. For each, record: which oil, where in the ingredient list, and what else is in the product. ⚠️ Then ask §19.11's question — if you removed this product, how many things would change?

A4. The broken link. §19.5 identifies a broken link in a mechanistic chain. Find the equivalent broken link in two other claims from earlier chapters:

a) Antioxidant supplements prevent disease (Ch 13) b) "Fat-burning mode" (Ch 6) c) Sugar feeds cancer (Ch 18)

For each, state which arrow fails and why.

A5. Smoke point audit. List every cooking method you used in the last week and the temperature it roughly reaches. ⚠️ How many exceeded 190°C? For most home cooks the answer is "almost none" — which determines how much §19.9 should change your behaviour.

A6. Grade the trials. §19.6 gives three counter-arguments to the recovered trials.

a) Which is the strongest, and why? b) ⚠️ Which one would a seed oil sceptic find easiest to rebut? c) The trials went unreported for decades. Does that strengthen or weaken the sceptic's overall position? Argue both.

Tier 3 — Analysis and Synthesis

S1. 🔄 The mechanism graveyard. This book now contains at least four cases of an elegant mechanism that failed testing: antioxidants (Ch 13), fat-burning mode (Ch 6), the omega-6 ratio (Ch 19), and arguably the fructose-toxicity chain (Ch 18).

a) What do they have in common structurally? b) Is there a way to predict, before testing, which mechanisms will hold up? c) ⚠️ Name a mechanism in this book that DID hold up under testing. What was different about it?

S2. Symmetric confounding. §19.11 argues the seed-oil/UPF confounding prevents indictment and exoneration equally.

a) Is that true, or does it favour one side? Argue the case that it favours the sceptics. Then argue that it favours the mainstream. b) Design a study that separates them. State your design, your sample, and your duration. c) ⚠️ Why won't your study be funded? Be specific.

S3. The tells versus the truth. §19.11's closing box argues that Chapter 17's tells identify how a claim is sold, not whether it's right.

a) ⚠️ If that's true, what is the tells' actual epistemic value? Defend Chapter 17 against the charge that it taught a heuristic that misfires on true claims. b) Construct a true claim that fires on five or more of the eight tells. c) Construct a false claim that fires on none. d) What does the existence of both do to the ten-minute check (§17.14)?

S4. The documented-episode test, applied. Chapter 18 §18.12 gave a test: year, journal, authors, sponsor, archive.

a) Apply it to the seed oil industry-influence claims you've encountered. What do you find? b) ⚠️ §19.11 says absence of a documented episode "isn't proof of nothing." Is that a reasonable position or a loophole? Where does it stop being reasonable? c) How should a reader treat a suspicion that is plausible and undocumented?

S5. Essentiality and dose. §19.4's subsection argues that LA's essentiality forces the sceptical argument to be about dose rather than toxicity.

a) Name two other nutrients where the same structure applies — essential, and plausibly harmful in excess. Give the dose ranges. b) ⚠️ Is there any nutrient for which "toxic at any dose above zero" is a defensible position? c) What does your answer imply about Chapter 18's threshold?

S6. Write the honest headline. A study is published finding that adipose linoleic acid content correlates with a marker of cardiometabolic risk in a large cohort.

a) Write the headline a sceptical outlet would run. b) Write the headline a debunking outlet would run. c) ⚠️ Write the accurate one. Then explain why nobody would click on it, and what that implies for Chapter 1's pipeline.

🪞 Reflection

M1. ⚠️ Go back to your Learning Check-In answers. You wrote down what would change your mind before reading the verdicts. Did the evidence in §19.5 meet your stated criterion?

If it did and you updated — good, and notice how that felt. If it did and you didn't — name the additional condition you added afterwards. That's the finding. If it didn't meet your criterion — is your criterion meetable by any evidence that could exist?

M2. Theo spent $82 in an afternoon on a mechanism that failed testing. Have you ever done the equivalent? Not necessarily with food. What was the trigger — and was it a fact, or a feeling that something needed doing?

M3. §19.13 says don't throw away oil you've already bought; change when the bottle is empty. ⚠️ Why is that advice psychologically difficult, and what does the difficulty tell you about how dietary change actually gets motivated?

M4. This chapter has more low-confidence verdicts than any other, and §19.13 lists them explicitly. Did that increase or decrease your trust in the chapter? ⚠️ Be honest — and consider what your answer implies about what you actually want from a source.