Vitamin C intakes above the Recommended Dietary Allowance (RDA) for oral vitamin C are generally well-tolerated and safe for most people, despite the 2,000mg upper limit.

“so if you look at that ratio I don't think it's out of the realm of possibility that humans can consume a couple grams of vitamin C and not have side effects and the tolerable upper limit is two grams and the only reason why they set it at two grams is because some people get diarrhea from it”

“vitamins intakes at doses above the RDA for oral vitamin C are well tolerated and safe”

“it's interesting however that there really isn't any scientific evidence that by see administered in doses up to 10 grams per day in adults is toxic or detrimental to health a person's overall health or lifestyle factors influences how much they need”

“at the other end of the recommendations is the tolerable upper intake limit 2000 milligrams per day the amount that experts believe reduces the risk of these GI problems”