Glossary term
In vitro
An experiment done in a dish or test tube, outside a living organism.
Why it matters
In-vitro results are the weakest level of evidence for whether something helps people. We flag in-vitro findings clearly so they are not mistaken for human results.
In vitro means “in glass.” It covers studies on isolated cells or tissues in the lab. A result in vitro is a starting point, not proof that the same thing happens in an animal, let alone a person.