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Comment by TaupeRanger | Hacker News Reader

People are talking about dental hygiene in this thread, but it’s only mentioned once in the article, and only to suggest that a small portion of the microbes associated with cancer were also associated with dental disease. We literally don’t know if using mouthwash or brushing for 30 seconds longer (the main differences in dental hygiene habits among people reading this) has any effect on cancer risk, so what’s the point of even posting this?

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Actually, research implies the opposite conclusion may be true and overcleaning your mouth may increase disease risk.

I’m guessing it might be explained by the hygiene hypothesis.

The oral microbiome needs balance, not sterilization.

[0] Mouthwash ≥2x/day → 55% increased diabetes risk Nitric Oxide journal, 2017

[1] Mouthwash ≥2x/day → 117% increased hypertension risk Blood Pressure Journal, 2020

[2] 7 days chlorhexidine mouthwash → 90% reduction in oral nitrite, BP increased 2-3.5 mmHg Free Radical Biology & Medicine, 2013

[3] Daily mouthwash → OR 1.31 for head/neck cancer European Journal of Cancer Prevention, 2016

[4] Listerine Cool Mint increased Fusobacterium nucleatum and Streptococcus anginosus (bacteria linked to colorectal cancer) Journal of Medical Microbiology, 2024

People lie about smoking and drinking also use mouthwash to help conceal their secret(s). Plausible?

Yes, thats plausible and the INHANCE consortium even suggested this. However the mechanism for the effect on BP can be explained by antiseptic rinses impairing the nitrate‑nitrite‑NO axis

They might also use mouthwash after another activity that involves possible HPV transmission.

Kissing a middle age woman (or other high risk person)? Very true, but it antecedes as often as it succeeds kissing, depending on whether it antecedes or succeeds marriage vows. Ever smell a husband’s breath?

The research doesn’t really imply any conclusion. You can’t cherry pick 4 studies that show an association (not causal connection) and use it as a plausible argument.

Fair point about association vs causation. To clarify, these studies don’t prove mouthwash causes these conditions, but the pattern across multiple independent studies in different populations suggests we shouldn’t assume ‘more cleaning = automatically better.

I wonder how many mouthwash users do so because they are trying to compensate for another issue.

What if we helped everybody look better and smell better and it turned out it was all for nothing?

If “for nothing” includes an increase in disease from eradicating an otherwise healthy oral microbiome by over-cleaning/washing, well I don’t think I need to answer that. Since we don’t know either way, best avoid drawing a conclusion.

Because keeping your mouth clean is both cheap and easy. If there’s a minuscule chance that it will reduce any risk in cancer, why not? Besides, who wants bad breath?

Because we don’t know either way. There’s also a minuscule chance that doing extra cleaning might lead to the opposite effect, as evidenced by another reply here. We don’t know. This article mentions nothing about halitosis.

Yes, but it’s so cheap and easy to do both time-wise and cost wise that it’s a completely moot point.

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