October 3, 2012
New, Extensive Study Finds Vitamin D Ineffectual On Common Cold
John Neumann for redOrbit.com - Your Universe Online
Despite years of common lore and claims to the contrary, scientists say they can find no convincing evidence to show that taking vitamin D supplements will fend off the common cold.
An extensive series of randomized placebo-controlled tests, called VIDARIS, for Vitamin D and Acute Respiratory Infection Study, were conducted by a team of researchers in New Zealand, to fully investigate what, if any, impact the supplements might have, reports Michelle Roberts, health editor for BBC News.
One-hundred sixty-one people in the study took daily vitamin D for 18 months and caught as many colds as the same number of people who took a placebo.
The researchers found that there was no statistically significant differences in the number of upper respiratory tract infections (URTIs) per participant (average, 3.7 per person in the vitamin D group and 3.8 per person in the placebo group) or duration of symptoms per episode (average, 12 days in each group).
“The main finding from this study is that a monthly dose of 100,000 IU of vitamin D3 in healthy adults did not significantly reduce the incidence or severity of URTIs. This result remained unchanged when the analysis included winter season or baseline 25-OHD levels,” the authors write.
“Further research is required to clarify whether there is benefit from supplementation in other populations and with other dosing regimens.”
Muddying the results however, was a leading UK cold expert saying that vitamin D was useful, writes Jon Bardin LA Times. Professor Ronald Eccles, of the Common Cold Centre at Cardiff University, said it can give the immune system a much-needed boost during winter when vitamin D reserves may be low.
He said he takes it every year as a precaution. “There is sufficient information to indicate that vitamin D is a vital vitamin for the immune system. Supplementation might help to support the immune system over the winter when we are short of vitamin D.”
Eccles said Echinacea supplements may also help ward off coughs and colds, but added, “Supplements do not work for everybody because people´s immune systems are different. It´s not a case of one size fits all. They are pointless unless you are deficient.”
Dr. Jeffrey Linder of Harvard Medical School, in an accompanying editorial, claims the study is well-conducted and its results should be trusted.
“The VIDARIS trial, which assessed upper respiratory tract infections as they actually occur in the real world, demonstrated that vitamin D supplementation does not reduce the incidence of respiratory tract infections in adults,” he wrote.
Most of our vitamin D comes from sunlight on our skin, but it is also found in certain foods such as oily fish, eggs and breakfast cereals. Most people should be able to get all the vitamin D they need by eating a healthy balanced diet and by getting some summer sun.
Results of this study are published in the October 3 issue of JAMA and can be found here.