[dghughes]

My choice was the regular Rockstar energy drink at my worst I was up to the large 750ml cans per day, then suddenly I developed back spasms for the first time in my life I thought it was a kidney stone. I could not straighten up I was curved to my right as if I was made of stone, the only thing that helped were strong muscle relaxers.

I stopped for awhile and drank just the normal ("double" is normal) Rockstar. I felt tingly all over mostly extremities. Now I have a fatty liver I am sure caused by energy drinks, I haven't had one in at least three years.

Coffee and tea are no comparison to energy drinks even a four or six shot espresso is mild in comparison. Although I believe espresso has less caffeine than regular coffee even for equal volumes.

What's odd is I never drank any caffeine until I was about 34 since even a sip affected me making my heart race from just a sip.

I've now left the stupid energy drink drinkers club!

[jamesli]

I suspect there are something else in energy drinks that could have dramatic effects on one's brain.

I usually drink one or two cups of coffee per day. I could drink more. After 7~8 cups of espresso, my hands start uncontrollably shaking, and I feel a little agitated. Those are all the symptoms I feel. Energy drinks is a completely different story. After two cans, I would have a big headache. I experimented a few times [call me crazy :)]. Every time, the headache came. So it was not a fluke, and most probably it was not caused by other factors.

[vsync]

> My choice was the regular Rockstar energy drink[...] fatty liver

Should've gone with the Rockstar Recovery. It's got milk thistle :)

Not to mention no sugar, which I suspect is the worst thing most people can get out of just grabbing a standard energy drink.

[dugditches]

//Although I believe espresso has less caffeine than regular coffee even for equal volumes. //

This is a common confusion. Espresso has more caffeine by volume.

Looking at ~8oz/236ml cup of 'regular' coffee versus ~1oz/29ml shot of espresso.

[lemonberry]

Check your math:

That's 236ml of caffeine for 8oz of coffee and 232ml of caffeine for espresso. That's less caffeine in espresso than coffee by volume.

[dugditches]

My math's fine. I think you misunderstood my post. I was just considering metric and imperial sizes thus included both sets of units.

The first reply to your post shows the math.

Even the 'increased' 240mg in the energy drink is just equivalent to 'regular' coffee due to it being 16oz/473mL can.

As I said though. Much easier to gulp down half a litre of sugary soda than half a litre of oily thick espresso.

[lemonberry]

I did misunderstand it, my apologies.

[maxerickson]

According to Google (which cites USDA) for "espresso caffeine" and "coffee caffeine", there is 64 mg of caffeine in 1 fl oz of espresso and 94 mg of caffeine in 8 fl oz of coffee.

So per unit volume, the espresso has several times the caffeine (and you would already expect a double espresso to have more total caffeine than a modest sized drip coffee).