> Too much other stuff is changing in a single persons life that could account for all observed side effects.
> You also have latent side effect issues. A person could smoke for 10 years, not smoke for another 10, and then conclude that smoking doesn’t cause cancer. Then they get lung cancer 20 years later.
But that's not the actual experiment here. Your criticism is invalid. The author randomised every day which supplement to take.
> You also have latent side effect issues. A person could smoke for 10 years, not smoke for another 10, and then conclude that smoking doesn’t cause cancer. Then they get lung cancer 20 years later.
But that's not the actual experiment here. Your criticism is invalid. The author randomised every day which supplement to take.
That's pretty close to a blocked design.