Under extreme physical stress, colds fell by about half
Pooling five trials in marathon runners, skiers and soldiers, 598 people in all, daily vitamin C roughly halved the chance of a cold. In the wider community, no change.
What the study found
In marathon runners, skiers and soldiers, vitamin C halved colds
The one group where prevention does show up is not the general public. Pooling five trials in marathon runners, skiers and soldiers on subarctic exercises, 598 people in all, daily vitamin C roughly halved the chance of catching a cold, against no change at all in the wider community.
The caveat · No ordinary gym-goers tested
Five small trials and 598 people between them, in settings almost nobody lives in: a subarctic military exercise, a 90 kilometre race, an Alpine ski camp. None of them tested ordinary gym-goers. The underlying trials date from the 1960s to the early 1990s and counted colds largely by asking people.
What we don't know
Five small trials and 598 people between them, in settings almost nobody lives in: a subarctic military exercise, a 90 kilometre race, an Alpine ski camp. None of them tested ordinary gym-goers. The underlying trials date from the 1960s to the early 1990s and counted colds largely by asking people.