The latest episode from Mitchell Moffat and Gregory Brown of AsapSCIENCE is on the brain-boosting effects of coffee and the mechanisms of caffeine addiction. Plus, Moffatt and Brown take a crack at the age old question (no, not that one): how much caffeine is too much?
https://gizmodo.com/why-does-coffee-make-you-poop-1538746609
https://gizmodo.com/how-much-caffeine-is-too-much-5982468