Version May 29, 2012
Trial | Free of illness during the trial / Persons in group | Proportion of participants getting benefit (95% CI) |
P (1-tail) 1 | |
---|---|---|---|---|
Vitamin C | Placebo | |||
Coulehan-1974 | ||||
641 Navajo schoolchildren Duration 3 months Alternative allocation, double-blind |
||||
All children 2 | 143/321 (44%) | 93/320 (29%) | 16% (8%, 23%) | 0.000,03 |
Low grades (1 g/d vitamin C) | ||||
Boys | 31/81 (38%) | 18/87 (21%) | 18% /4%, 31%) | 0.007 |
Girls | 30/109 (28%) | 12/105 (11%) | 16% (5%, 26%) | 0.002 |
High grades (2 g/d vitamin C) | ||||
Boys | 40/69 (64%) | 34/61 (56%) | 9% (-8%, 26%) | 0.2 |
Girls | 42/69 (61%) | 29/67 (43%) | 18% (1%, 34%) | 0.021 |
Anderson-1972 | ||||
818 adults in Canada with colds usually in winter Duration 3 months Randomized, double-blind, 1 g/d vitamin C |
||||
Free of any illness during the trial | 105/407 (26%) | 76/411 (18%) | 7.3% (1.6%, 13%) | 0.006 |
No 'days confined to house' | 232/407 (57%) | 195/411 (47%) | 9.5% (2.7%, 17%) | 0.003 |
No 'days off work' | 275/407 (67%) | 243/411 (59%) | 8.4% (1.8%, 15%) | 0.006 |