Can vitamin D help prevent colds? New study casts doubt
Like vitamin C, large doses of vitamin D are touted by some as helping prevent or reduce the severity of colds, though research studies remain inconclusive. Now, another study involving 25-hydroxyvitamin D, or 25-OHD, the form of vitamin D available as a nutritional supplement, suggests large doses of the supplement are of no value in preventing upper respiratory infections.
The October 3, 2012 Journal of the American Medical Association (JAMA) reports 322 healthy adults took part in a randomized control trial at the University of Otago in Christchurch, New Zealand. It was funded by the Health Research Council of New Zealand.
David R. Murdoch, M.D., and colleagues conducted a randomized trial to examine the effect of vitamin D supplementation on the incidence and severity of upper respiratory tract infections (URTIs) in healthy adults. The study took place between February 2010 and November 2011. One group received an initial dose of 200,000 IU of oral 25-hydroxyvitamin D, then the same dose a month later, followed by 100,000 IU monthly for a total of 18 months. Others received a placebo.
The study results shows "no statistically significant differences in the number of colds and URTIs per participant (3.7 per person in the vitamin D group and 3.8 per person in the placebo group on average), duration of symptoms per episode, severity of episodes or number of work days missed." Researchers added that further research is needed "to clarify whether there is benefit from supplementation in other populations and with other dosing regimens."
If you consider taking nutritional supplements, always check first with your doctor.