I had been taking 1g three times a day when I went in for a GI appointment with associated lab work recently. They checked my creatinine level and it had gone up since my last lab test six months earlier and was as the max normal range value.
I did a search and found out that Vitamin C can elevate the creatinine level.
www.livestrong.com/article/491226-vitamin-c-creatinine/I'm now taking 1g twice a day and have to go back to get another lab test in a few weeks. Hopefully it is back to a lower value to pacify my doctor.
I would like to continue increasing how much I take so I can find my tolerance level. I had no negative effects even at three grams and the one positive effect I noticed is that my left knee experiences less discomfort (nearly none now) when flexing it to its limit.