Boiling water can turn a supposedly healthy cup of tea into a drink with reduced antioxidant power. When water temperature climbs well above the optimal range, the same heat that speeds extraction also accelerates breakdown of key compounds.
Tea’s health reputation rests largely on catechins and other polyphenols, which act as antioxidants by donating electrons to neutralize reactive oxygen species. At excessive temperatures, these molecules undergo oxidation and structural degradation, a form of thermal denaturation that reduces their concentration and changes their chemical profile. Instead of increasing benefits, pushing temperature too high shifts the balance toward loss, leaving a brew with lower total antioxidant capacity than tea made with carefully controlled heat.
Different tea types have different thermal tolerance, but the chemistry is consistent: more heat means faster reaction kinetics, including unwanted oxidation and polymerization. Overheated infusions can also increase extraction of caffeine and some bitter tannins, altering flavor while contributing little to antioxidant activity. For drinkers chasing maximum health value, respecting recommended brewing temperatures functions as a simple quality control step, preserving more of the compounds that made tea attractive in the first place.
