Well, I have taken CLA for over a year, and it reduced my insulin resistance...or something, because I lost 15 pounds by taking it and making no other lifestyle changes at all (before Atkins.)
My mother says it kills her middle of the night fridge raids.
A friend says she hasn't had to take her allergy medication since she started taking CLA.
Another friend swears she gets more from her workouts now that she is taking it.
And I got more muscle definition without working out!

I haven't seen any studies that show anything bad about CLA. Please post them, anyone, if you can find it.

CLA used to be in our food, for as long as we ate and milked grass eating animals. It's a natural substance, for what that's worth.