Does vitamin C prevent the common cold?

We looked at two key findings. The first, drawn from 39 studies, indicates that taking at least 200 mg of vitamin C daily does not meaningfully reduce cold incidence compared to a placebo ¹. The second, based on 53 studies, similarly shows that daily doses of 0.2 grams or more produce no significant reduction in how often people catch a cold ^[2]. Both sets of evidence agree: routine supplementation does not appear to prevent colds.

It is important to note that this is our current analysis. While the evidence we have is strong and consistent, we are always open to new findings. The question of whether vitamin C might shorten a cold once it starts is separate and not covered here.

Practically, if you are hoping to avoid catching a cold, our review suggests that taking vitamin C daily probably will not help. Instead, focus on proven strategies like hand washing, adequate sleep, and a balanced diet.