Key takeaways
- In vitro studies test cells in the lab; animal studies test living animals.
- Only human studies can show what happens in people.
- Randomised controlled trials are the most reliable single studies.
- Systematic reviews combine studies but depend on their quality.
“Studies show…” can mean very different things. A result in a dish of cells, a result in mice and a result in people are not equivalent. This article explains the main types of study and what each can and can’t tell us.
In vitro studies
In vitro means “in glass”. These studies test compounds or extracts on cells or tissues in the laboratory. They are quick and useful for exploring how something might work, but cells in a dish behave very differently from a whole body, and the concentrations used are often far higher than anything reached by eating or taking a supplement.
Animal studies
Animal studies, usually in rodents, test effects in a living organism with digestion, metabolism and circulation. They are closer to real life than cells, but animals differ from people, and doses and preparations often don’t reflect human use. Many results in animals are never reproduced in people.
Human studies
- Observational studies look at patterns in populations but can’t prove cause and effect.
- Pilot studies are small, often without a control group, and help plan larger trials.
- Randomised controlled trials compare a treatment with a placebo or control, with participants randomly assigned; blinded trials are the most reliable single studies.
Systematic reviews
Systematic reviews and meta-analyses gather all the available studies on a question and assess them together. They sit near the top of the evidence hierarchy, although their conclusions depend on the quality of the studies they include.
Why the distinction matters
When you read about mushroom research, the first question to ask is always: what kind of study was it? See How to Read Mushroom Research and How to Judge the Quality of a Mushroom Study.