Here's a followup: Carnitine did not help my own constipation problem. I do not know if the other person on this thread was helped by taking Carnitine.
I tried 1900 mg of Carnitine daily on an empty stomach for 2 weeks.
The only thing it did is maybe give me a little more energy for an hour or so after taking it, but even that was so subtle I can't be sure of that.
But, no help with constipation problems.