Dear Lifehacker, I'd love a clear explanation of caffeine and how much is good/healthy/safe for a typical adult. I love coffee and tea but have moderated my intake for concern of its affect on my health. From davo10101
Caffeine is indeed a stimulant, psychoactive drug (just like MDMA or methamphetamines) and like any other drug it has been proven to be highly addictive. As the saying goes, however, the dose makes the poison, so it is worthwhile to question just how much caffeine someone can consume in a day without experiencing adverse health effects.
Most health professionals recommend somewhere between 300mg and 400mg, depending on your body weight and personal tolerance to caffeine. So how many cups of coffee can you drink within this limit? ABC's Fact File on caffeine quotes the following average caffeine amounts for some of the most popular consumables containing the substance:
•Tea (black, green or white) -- 30 to 100mg (depending on type and strength of brew) •Coffee (instant) 150ml cup -- 60 to 100mg •Coffee (espresso) 150ml cup -- 40 to 90mg (depending on the beans used and the strength of the brew) •Coffee (drip-percolated) 150ml cup -- 100 to 150mg (depending on the beans used and the strength of the brew) •Coffee (decaffeinated) 150ml cup -- 3mg •Cocoa and hot chocolate drink 150ml -- 10 to 70mg (depending on type of chocolate used and the strength of the drink) •Chocolate bar - 30g -- 20 to 60mg •Cola drink 375ml -- 35mg •Energy drink -- 80mg (on average but there are some with up to 300mg)
Indeed, some studies have suggested that caffeine is not necessarily bad for you in the right doses. Indeed it can have a number of beneficial effects as most coffee-drinkers would already know. One 1987 study tested the effect of a low dose of caffeine (in a range of 32, 64, 128 and 256 mg) on people's performance and mood and found that even the smallest dose, equating to less than the amount of caffeine in an average cup of coffee, improved both these factors. Even at the highest dose of 256mg, no adverse effects -- such as anxiety or impaired physical functioning -- were detected. From this study you could say that a few cups of coffee a day would be fine for your health -- which is true, as long as you're not consuming caffeine on a regular basis. The matter of caffeine dependence and tolerance from extended consumption still has to be taken into account.
One study on caffeine dependence identified 16 people suffering from caffeine dependence out of a sample size of 99. However, their median daily caffeine intake sat around 357mg -- well within the recommended 300 to 400mg dosage as listed above. In the second part of the study where they tested the subjects for caffeine withdrawal, eight of 11 showed functional impairment without their daily dose of caffeine. Studies have shown that as little as a single cup of coffee can be enough to get you dependent on coffee, with withdrawal symptoms like headaches, muscle pain and stiffness, lethargy, nausea, vomiting, depressed mood, and marked irritability a distinct possibility.
For more info, check out this video that gets into the nitty gritty of what caffeine is doing to your body. According to the video, caffeine doesn't become toxic unless you've had around 75 cups of coffee -- but that doesn't mean that any more than three cups is highly recommended for daily consumption.
The verdict? A couple of cups of coffee a day won't kill you, but taking a break now and then will probably benefit your overall health. Try swapping coffee for tea on the weekends when mental alertness isn't as important, or check out a few of the ways you can keep yourself awake and aware without relying on caffeine.