I have to speak to the contributor that can't find a Vitamin C source that doesn't make him sick. All Vitamin C isn't from the same source.
I had to see a good allergist to find out that the Vitamin C I was taking was made from CORN! It left me shakey and unable to sleep for 3 days, and I had cut a 100 mg tablet in half so all I got was 50 mg!
Since finding that I am allergic to corn, I now take Vitamin C in the Palmitate form, as labeled on the bottle. And, I'm taking about 10 grams a day.
I take TwinLabs Allergy C, it is buffered w/calcium and magnesium. An aside, Vitamin C helps you to absorb the cal/mag for your bones. It's a win-win!