Although vitamin D boosts the immune system, taking large doses
of the nutrient does not appear to ward off colds, a new study
from New Zealand says. In the study, participants who took high
doses of vitamin D supplements every month for more than a year
were just as likely to catch colds as those who took a placebo.
Taking vitamin D supplements also did not reduce the length of
time participants were sick, the severity of their illness or
the number of workdays they missed. The findings suggest vitamin
D should join the list of therapies that researchers have deemed
"ineffective for preventing or treating upper respiratory tract
infections in healthy adults," Dr. Jeffrey Linder, of Brigham
and Women’s Hospital in Boston, wrote in an editorial
accompanying the study. However, the study researchers noted
that even the participants in their study who took a placebo had
sufficient levels of the nutrient. People with a vitamin D
deficiency may see more of a benefit from taking the vitamin, in
terms of a reduced r