It’s safe to say that caffeinated drinks are pretty popular – the world drank about 7 million tonnes of coffee in 2016, which is nearly the mass of water contained within Loch Ness! If humans were as dedicated to cryptid hunting as we are to some African bean, we would have found Nessie by now. Caffeine is the world’s most widely consumed drug, offices run on it, and many of us even feel that we need it just to function correctly. Aside from its ability to keep us awake, there is some evidence that caffeine has anti-ageing benefits, as do some of the plant compounds that accompany it in tea and coffee. But how much caffeine is too much? There’s certainly a point at which caffeine does more harm than good, but can you ever reach that point by accident?
There’s no straightforward answer to this question because like most drugs, tolerance varies from one person to the next, depending in part on overall health. Some people will experience negative effects like spikes in blood pressure, sleep disturbance and nervousness after a single cup of coffee, while others can drink many cups in a day without any such effects. However, most safety agencies agree that for healthy adults, 400mg a day shouldn’t raise any general health concerns. That doesn’t mean you can’t drink more – just that 400mg is what is tolerated for most healthy individuals. Here’s a handy guide as to how much you would need to drink to reach 400mg:
Caffeine can raise blood pressure for 3–4 hours, but this doesn’t seem to affect cardiovascular health in healthy adults. However, for people with hypertension or heart conditions, the long-term effects of caffeine intake are uncertain. Caffeine is a stimulant and as such could be unsafe for some people with cardiovascular disease – this is something that needs to be judged on a case-by-case basis by a health professional.
We don’t really know. The safe level of caffeine intake for non-adults is currently given as 2.5 or 3 mg/kg/day. The problem is that these numbers have been estimated based on studies in adults. Until we have better data, it is best to be cautious by limiting children’s caffeine intake.
Not all reviews agree on what is safe for pregnant or breastfeeding women: either 200 or 300 mg of caffeine per day. Since there’s not much evidence, it’s better to err on the side of caution and keep to the lower limit.
Caffeine can be lethal at doses of 150 mg/kg, which is about 10 grams (25 times the daily suggested intake) for someone weighing 68 kg (150 lb). So yes, caffeine can kill you, but you’ll probably be kicked out of the Starbucks long before that happens. You do need to be careful with concentrated forms of caffeine like pills and powders, though, as it is much easier to accidentally overdose this way.
How much caffeine is too much?https://examine.com/nutrition/caffeine-consumption/