In vitro (Latin for “within the glass”) refers to studies that are performed in an artificial environment outside of a living organism. In scientific research, this often involves performing experiments on isolated bacterial, animal, or human cells growing in lab culture dishes.

In vitro experiments provide a controlled environment in which to obtain mechanistic data on biological processes that can inform us about how, for example, certain nutrients impact health or whether they’re safe for consumption. However, in vitro experiments don’t provide the same level of evidence as in vivo (“within the body”) studies from clinical trials in humans — it’s quite common for a promising in vitro effect to not pan out in vivo.