Although the study showed that vitamin D supplements do not prevent common colds, they may be of benefit for bone health and could help prevent other conditions.
Some studies have suggested the vitamin from sunshine boosts the immune system and helps prevents colds, some cancers and heart disease.
However there is still a lack of clear scientific evidence to support many of these claims.
Researchers from the University of Otago, Christchurch, are engaged in a large scale study of vitamin D (called the Vitamin D and Acute Respiratory Infection Study or VIDARIS) and have published a new paper on its effect on the common cold.
The study, published in the latest edition of the prestigious Journal of the American Medical Association (JAMA), found that taking vitamin D supplements did not result in participants having fewer or less severe episodes of upper respiratory tract infections.
Adult participants (more than 300 Cantabrians) took either a placebo pill or a vitamin D pill every month for a year and half.
Researchers measured the number and severity of participants’ colds during this time.
They found no statistical difference between those taking the placebo pills and those given vitamin D supplements.
VIDARIS principal investigator Professor David Murdoch says there has been considerable speculation about the potential role of vitamin D in preventing a variety of infections, including the common cold.
“Up to now we have lacked evidence to support any benefit from well-designed studies, despite so much money being spent on supplements.”
“VIDARIS is the first study to convincingly show that vitamin D does not prevent colds in healthy adults. However, it is important to note that very few people in our study had extremely low levels of vitamin D at the beginning. So, our findings may not apply to these people and to children who should now be the focus of further research.’’
Vitamin D supplements may still be of benefit for bone health and for the prevention of other conditions, Professor Murdoch says.
The VIDARIS study is also looking at whether vitamin D prevents other infections, including carriage in the nose of staphylococcal bacteria.
Editor's Note: Original news release can be found here.