Good drinks for the voice:Part7 Coffee

I will now review how the voice relates to specific kinds of drinks, in a series.
This is part 7: “Coffee”.
There are so many people who like a coffee. I personally also like coffee, and I used to only drink coffee from my personal coffee maker. Nowadays, I sometimes drink coffee in a Starbucks or a restaurant.
I’ve tested whether coffee affects the voice or not.
The test subjects are people who are really sensitive about how their voice sounds. I did not disclose to them any details whatsoever of this test, and let them drink only a coffee and a water before singing. I then asked them, after singing a few songs, “How is your voice doing?”
They responded, “yeah, so/so, fine, or, not very good today.” I then asked them, “what do you think is the reason to cause you problems with your voice?”
No one stated that the ‘coffee’ had caused the issue.
I’m not sure this result was completely accurate, because the test subjects were a select few. Based on the results, I don’t think that coffee significantly negatively affected the voice. Or that these results were at all related to the amount caffeine in the coffee.
There are two effects of caffeine in relation to singing.
The first effect being that the caffeine activates the sympathetic, and your singing is going to be aggressive. Which may be good for singing ‘Hard Rock or Heavy Metal.’ The second effect is that the caffeine is a diuretic, and will make you more likely to need to use the restroom shortly after drinking it.
In conclusion, if you don’t drink coffee too often or excessively, it will not have a negative affect on your voice.