| Effect | None |
| Values | Duration of symptoms per episode, median (25th percentile). Placebo: 12 (7). Vitamin D: 12 (8) |
| Trial Design | Randomized trial |
| Trial Length | 6+ Months |
| Number of Subjects | 322 |
| Sex | Both Genders |
In a randomized, double-blind, placebo-controlled trial, 322 healthy adults were given 200,000 IU of vitamin D on the first and second months, or placebo, and 100,000IU monthly afterward for 18 months.
There were no statistically significant differences between groups for the number of upper respiratory tract episodes, infections per person, number of days of work missed, duration of symptoms, or rated severity. The mean levels of vitamin D at baseline were 29 (9) and 28 (9) ng/mL at baseline and increased to roughly 50 in the intervention group, and didn't change notably in the placebo group.
