I've heard and read the same thing. I did not do well on ascorbic acid C. Anything over 1,000mg. gave me tummy problems and loose bowels.
I also did some research and found that the purer the vitamin C, the better. That is when it comes more from a "whole food source."
A super C I now take is actually called " Super C" by TwinLab. It is a powder to be mixed with water.
One teaspoon contains 2,000mg. of C :
Rose Hips 1,450mg.
Acerola ( from cherry ) 1,000mg.
Rutin 25 mg.
Hesperidin 25 mg.
Lemon Bionflavonoids 500mg.
I mix 3 tsps. in to a large 16 ounce glass and sip on it throughout the entire day. It is so much more gentle on my stomach and bowels.
Paulette