What is a meta-analysis?
A meta-analysis is a study that combines the results of many earlier studies on the same question to get a bigger, more reliable answer.
Asking one friend for a restaurant recommendation gives you one opinion. Collecting every review from hundreds of diners gives you a far better picture, as long as the reviews themselves are honest.
Why it matters for aging
Single studies are often too small to give a clear answer. By pooling data from many, a meta-analysis can detect smaller effects and smooth out flukes. That's why it sits near the top of the evidence pyramid.
When we cite one, we also look at what went into it: how many trials, how many people, how long, and who paid. A meta-analysis of large, well-run randomized trials is strong evidence. One built on small, short or industry-funded studies deserves more caution.
A common myth
If a meta-analysis says something works, it's settled.
A meta-analysis is only as good as the studies it combines. If those studies are small, biased or very different from each other, the pooled answer can mislead. Two meta-analyses on the same question sometimes disagree, as they do for CoQ10 and statin muscle aches.
Go deeper
Deep dives
- CoQ10: who actually needs it?
- Berberine vs metformin: what the evidence actually says
- Why am I always tired after 40? The upstream answer
Related terms
Updated Nov 9, 2026 · All terms