If someone gets sick on one diet (or not), it is not possible to say
it should have been better/worse on another diet. You can not test
this, as the next occasion is a new one with other circumstance apart
from the diet.
So if a person changes to paleo, and gets sick, no one can know if
paleodiet is to blame or credit for the sickness not getting even worse.
Such comparisons can only be made statistically on a large group, and
even this is hard, as compensations has to be done for diverse not
relevant factors.

- Hans