Every caffeine fiend knows the feeling of going overboard. That sense that you’re teetering on the edge of disaster, but you’re not quite sure why. Or worse, heart palpitations.
Although you know it when you feel it, figuring out how many coffees are too many coffees in advance isn’t always that easy. So The Glow decided to enlist the help of two local health experts: Dr Ian Musgrave, a senior lecturer in the University of Adelaide’s pharmacology department; and Professor Chris Semsarian, a cardiologist from Sydney’s Royal Prince Alfred Hospital.
First, the good news: unless you’re throwing back a short black every two minutes, you’re very unlikely to ingest a lethal amount of caffeine in a day. “Generally, caffeine itself is not very toxic, so you’d have to drink something on the order of 130 or so cups of espresso in order to kill yourself from that,” says Dr Ian Musgrave. Even the most ardent coffee fan would admit that’s a little excessive.
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On an individual level, determining how much coffee is too much is tricky, as the body’s reaction to caffeine differs from one person to the next. While you may find a late afternoon latte keeps you up all night, your best friend might sleep soundly even after a 9pm coffee hit. Interestingly, a study of 120,000 people released last week indicates your coffee consumption is determined, in part, by your DNA; while a new book by Cambridge psychologist Brian Little suggests coffee affects the work performance of extroverts and introverts differently.
There are a number of variables that can determine how you respond to coffee. For instance, if you’re a regular coffee drinker, your body’s likely to accommodate and be more tolerant of caffeine than someone who is “coffee naive”, Dr Musgrave says. “If you’ve never had coffee before and you slam down, say, ten espressos in a row you’re going to have very exaggerated effects. You may even show signs of caffeine intoxication where you get the tremors, the heart palpitations.”
Similarly, some people have heart and liver conditions that impact how caffeine is metabolised. “If you are someone who has a mutant form of the enzyme that breaks down coffee in your body, or if you’ve got liver disease that damages your body’s ability to break down caffeine, or if you have some forms of heart disease, then you’ll be more likely to have the toxic effects of caffeine than the normal population,” Dr Musgrave explains.