We identified three prophylactic trials which recorded 37 cases of community-acquired pneumonia in 2335 people. Only one was
satisfactorily randomised, double-blind and placebo-controlled. Two trials examined military recruits and the third studied boys from
“lower wage-earning classes” attending a boarding school in the UK during World War II. Each of these three trials found a statistically
significant (80% or greater) reduction in pneumonia incidence in the vitamin C group. We identified two therapeutic trials involving
197 community-acquired pneumonia patients. Only one was satisfactorily randomised, double-blind and placebo-controlled. That
trial studied elderly patients in the UK and found lower mortality and reduced severity in the vitamin C group; however, the benefit
was restricted to the most ill patients. The other therapeutic trial studied adults with a wide age range in the former Soviet Union
and found a dose-dependent reduction in the duration of pneumonia with two vitamin C doses. We identified one prophylactic trial
recording 13 cases of hospital-acquired pneumonia in 37 severely burned patients; one-day administration of vitamin C had no effect
on pneumonia incidence. The identified studies are clinically heterogeneous which limits their comparability. The included studies did
not find adverse effects of vitamin C