High doses of vitamin C had no adverse clinical impact. For
example, these doses did not cause diarrhea or abdominal
cramps (11). At the nadir of depletion, mild but consistent
feelings of fatigue and/or irritability were elicited from six of
seven volunteers. These symptoms resolved in three volunteers
within 1 week after the 30-mg daily dose was begun, and in the
other three volunteers within 1 week after the 60-mg daily dose
was begun. At the lowest and highest vitamin C doses, there
were no differences in psychometric testing for each volunteer
(data not shown). At the nadir of depletion, one volunteer had
gum pain but no gingival signs of scurvy; another volunteer
developed dry eyes and hyperkeratosis that was distinct from
hair follicles. Both volunteers were immediately begun on the
repletion part of the study with disappearance of signs and
symptoms in 2-3 days. No volunteer developed scurvy.