I wonder if they took fast vs slow metabolizers into account. It seems to be healthy only with the fast metabolizers gene:

https://drwillcole.com/caffeine-one-thing-standing-optimal-h...

If you’re a slow caffeine metabolizer:

1. Increased risk of high blood pressure (hypertension).

2. Increased risk of heart attack.

3. Higher chance of digestive disorders.

4. More stress and measurable cortisol spikes.

If you're a fast metobolizer:

1. Longer life.

2. Faster metabolism.

3. Better memory and mood.

4. Lower cancer risk.

5. Better blood sugar + insulin balance.

I'm most assuredly a slow metabolizer since caffeine makes me feel terrible.