[habinero]

No, the other way around. It's the combination of two well known effects. Well, three if you're uncharitable.

1. Small studies are more likely to give anomalous results by chance. If I pick three people at random, it's not that surprising if I happened to get three women. It would be a lot different if I sampled 1,000 people.

2. Studies that show any positive result tend to get published, and ones that don't tend to get binned.

Put those together, and you see a lot of tiny studies with small positive results. When you do a proper study, the effect goes away. Exactly as you would expect.

The less charitable effect is "they made it up". It happens.