Bioavailability describes how much of a compound your body can actually absorb and use, as opposed to how much is simply present in what you drink. It’s a genuinely different question from how much of something a tea “contains.”
Catechins, the antioxidant compounds concentrated in green tea, are the most common example in tea research. A cup can be measurably rich in catechins on paper, but how much of that actually gets absorbed depends on real variables: how the tea was steeped, how hot the water was, and even what else is in your system at the same time.
An active research question, not a settled one
This is genuinely an ongoing area of nutrition research, not a fully resolved topic, and it’s worth treating it that way rather than as a guarantee. Some studies suggest vitamin C may help the body absorb catechins more effectively, which is part of why tea with citrus shows up in some traditional pairings. Steeping time and temperature also affect how many catechins actually make it into the water in the first place, separate from how well your body then absorbs them.
The honest takeaway is that “high in antioxidants” and “your body absorbs a lot of those antioxidants” aren’t automatically the same claim, and the research connecting the two is still developing.
