If it is pure citric acid , it does not matter where it came from, e.g. the astronauts all drink water derived from their own and their fellow astronauts urine. H2O is H2O.
You mentioned that you "don't remember getting any reactions by" vitamin C. First off, was it ascorbic acid? If not, e.g. a mineral ascorbate like sodium or calcium ascorbate, you were ingesting only ONE-HALF the antioxidant potency [gram-for-gram] of the hydrogen, i.e. acid, form.
Secondly, if you were not ingesting enough to reach Bowel Tolerance regularly, you were not ingesting enough. Consider: If a doctor prescribed a dose of Antibiotic to a patient, it would come with both an amount and frequency of dosage. Hypothetically, if that patient decided to cut that prescribed Antibiotic dosage in half, and/or ingest it at one-half the prescribed frequency, and then did not get the results expected, could we really/honestly say that they tried the Antibiotic out and it did not work? And so it is with ascorbic acid. Dr. Cathcart, MD, has written that he did NOT see significant results in his patients UNTIL they approached Bowel Tolerance: "The clinical symptoms of these diseases and other conditions previously described, are markedly ameliorated ONLY as bowel tolerance dose levels (the amount that almost, but not quite, causes diarrhea) are approached." And Dr. Thomas Levy, MD, wrote, "...the three most important considerations in effective vitamin C therapy are "dose, dose, and dose." If you don't take enough, you won't get the desired effects. Period!...you will rarely ever fail to observe a dramatic response to a wide variety of medical conditions if you take a large enough dose for a long enough time..."
I am just trying to help, Faccio, and offering this "as grist for your mill."