Logical Reasoning

PT138 · S3 · Q6 Medical columnist: Some doctors

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Medical columnist: Some doctors recommend taking vitamin C to help maintain overall health because vitamin C is an antioxidant, a substance that protects the body from certain types of oxygen particles that can trigger disease.

Paradox

Generally, doctors recommend vitamin C to maintain health (it's an antioxidant that protects from disease). They especially recommend it to people who already have ailments and want to avoid more health problems. But for some cancer patients — even those whose treatments are physically harmful — doctors discourage vitamin C.

Evaluate

Why would the recommendation flip for cancer patients specifically? The general logic of "antioxidants are protective" should make vitamin C more appealing to people facing harsh therapy, not less. The explanation must give cancer patients a unique reason vitamin C becomes harmful in their case — most likely because it interferes with the cancer therapy itself.

Goal

Find the answer that explains why vitamin C is bad specifically for cancer patients undergoing therapy — a reason unique to them that overrides the general benefit.

Which one of the following, if true, most helps to explain why the doctors' recommendation to some cancer patients differs from the general recommendation regarding vitamin C?

Correct
Some kinds of cancer cells
Why this is right
This resolves the paradox cleanly. Cancer cells absorb large amounts of vitamin C, and that absorption interferes with the oxidation mechanism many cancer therapies use to kill cancer cells. So for cancer patients undergoing therapy, vitamin C actively undermines the treatment — it protects the cancer cells from the very mechanism that's supposed to kill them. That's a unique downside that doesn't apply to people taking vitamin C for general health, and it explains why doctors flip their recommendation specifically for this group.
Skill tested: Paradox · how this choice captures the argument's function is the move to repeat next time.
97% picked this
Vitamin C has not been
No Impact
This says vitamin C hasn't been shown to prevent cancer. But doctors are discouraging it from people who already have cancer — preventive efficacy is a separate question. Whether vitamin C prevents cancer or not doesn't explain why doctors actively discourage cancer patients in treatment from taking it.
1% picked this
Cancer cells that are susceptible
No Impact
This says cancer cells susceptible to certain therapies aren't affected by vitamin C. If vitamin C neither helps nor hurts the cancer cells, then it's neutral with respect to therapy — which would not explain why doctors actively discourage patients from taking it. We need a reason vitamin C is bad for cancer patients in therapy, and this gives a reason it's not bad.
1% picked this
The better the overall health
Cheats Paradox
This deepens the puzzle rather than resolving it. If patients with better overall health during therapy are more likely to recover, then anything that improves overall health (like vitamin C, an antioxidant) should be encouraged. This makes the doctors' recommendation against vitamin C even more puzzling, not less.
0% picked this
Certain side effects of cancer
No Impact
This tells us vitamin C doesn't help with certain side effects. If vitamin C is just unhelpful in this specific way, doctors might be neutral about it — but they're actively discouraging it. We need a reason vitamin C is harmful, not just unhelpful. Failing to address some side effects doesn't explain why patients are warned away from taking it.
1% picked this

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