Drinking 2 to 3 cups of coffee and the same amount of tea per day was linked to an approximately 30 percent lower risk of stroke and dementia compared with having none. In a recent study 2 or 3 cups of either cut stroke risk 12 to 16 percent. Drinking both may supply a wider range of brain cell protecting plant compounds. Note: more than 400 mg daily of caffeine (about 3 to 5 cups of coffee) exceeds guidelines.

Sources:

PLOS One. Nov 16, 2021, and Consumer Reports on Health Vol 34, Issue 3 March 2022