It’s always interesting to reverse the direction of causality in these kinds of articles and see if it’s plausible. Could it simply be that people with heart problems drink less coffee?
I don't have numbers on this, but I have the impression that many people drink coffee on weekdays in order to be awake for their job—and they probably wouldn't make it a daily thing if they didn't have a job—and therefore daily coffee drinkers will contain a much higher proportion of people who are healthy enough to hold down a job.
I believe coffee drinkers are less likely to commit suicide too, which definitely would align with the purpose a job gives you (fwiw).
After about ten days of drinking {an amount} of coffee, your tolerance adjusts, and you're aligned to someone who does not drink coffee at all. You're effectively just maintaining a new baseline, but have developed a regular expenditure / tactile ceremony.
The 'make themselves more productive' claim would need some citations to back that up, as I suspect most is self-reporting anecdata.
Is that really true? I'm speaking from a position of ignorance here, but then that's a very strong statement with non-obvious validity to me. I know that substance tolerance exists (at least it's a very common idea), but is it so generic that it applies to a) all effects and each of those effects in its entirety, and b) to all effective substances that make up coffee?
And as a more specific example, I don't think I've ever taken something like "heroin addicts need to take heroin just to feel normal again, and more to feel a high" so literally that I thought they would function "normally" as in exactly like a non-heroin user would when taking an exact dosage to counteract their tolerance.
Good question.
There was a spectacular long-form article, I'm sure I read via HN, about 7 years ago, that included a delightfully lurid dive into the chemical and biological effects of caffeine, on humans, over a period of a few weeks, and that fond but slightly hazy memory is where I'm getting that figure from.
Regrettably I've not been able to find that particular article again.
I did find this, however:
https://betterhumans.pub/how-to-quit-caffeine-in-one-week-e0...
.. and in the Addictive Potential section they cite this:
https://pubmed.ncbi.nlm.nih.gov/27762662/
.. which, if I'm reading that precis right, blows it out to 4 weeks (but it sounds like they were testing the presence of the dependency / tolerance / baseline effect, not trying to determine minimum timeframe to achieve).
The list of Similar Articles at the bottom of that second link suggests there's some body of research out there to back these styles of claims up. The considered wisdom, as far as I can intuit, is to use caffeine strategically rather than frequently, if you want to enjoy the advertised 'energy' and 'focus' benefits. Of course, if you just like the flavour or the ceremony, knock yourself out.
Another example is caffeine is widely used as a pre-workout supplement. In high doses, without tolerance, it actually does demonstrably improve top-level strength. But the way most people use it results in tolerance and doesn't actually help. Nonetheless, the sheer fact that they're working out all the time already results in better heart health, even if the caffeine isn't doing anything on top of that.
I dunno, I guess you could be interested in learning to classify people. If they do X, then that increases your estimate of their current healthiness regardless of the underlying causation. If you're an insurance company, an actuary, etc., then maybe that's all you need to know.
Wet streets do not cause rain (directly).