Coffee vs. Tea: Polyphenol Powerhouses

Note: this is a short launch draft. It's being expanded into a full comparison, and every figure in it gets read back against the source before that happens.

People ask which is healthier, coffee or tea, as if the answer would change what they drink. It won't. But the polyphenol comparison is still interesting, because the two drinks carry completely different compounds.

What's in coffee

Coffee's polyphenols are mostly chlorogenic acids, a family of compounds that survive roasting only partly. Lighter roasts keep more. According to the Phenol-Explorer database, a cup of filter coffee carries somewhere in the range of 100 to 300 mg of chlorogenic acids, which makes coffee the single largest source of polyphenols in many Western diets. Not because coffee is unusually rich, but because people drink so much of it.

What's in tea

Green tea's polyphenols are catechins, with EGCG the most studied. Black tea has had most of its catechins converted into theaflavins and thearubigins during oxidation, which are polyphenols too, just different ones. A cup of green tea typically supplies tens to a couple of hundred milligrams of catechins depending on how much leaf you use and how long it steeps. Milk doesn't destroy them, though it may bind some.

Why the head-to-head is the wrong question

Total polyphenol content is a crude number. Chlorogenic acids and catechins are absorbed differently, metabolized differently, and studied in different contexts. The large observational studies of coffee drinkers and tea drinkers both show associations with better health outcomes, and both are confounded by everything else those people do.

What I'd do

Drink the one you like. If you want more polyphenols from coffee, go lighter on the roast. If you want more from tea, use more leaf and steep it longer. Two or three cups of either a day is where the observational evidence sits, and neither is a reason to start if you don't already.