Vitamin D won't keep the doctor away - study

The researchers found there was no statistical difference between those taking the placebo pills and those given vitamin D supplements. Photo / Thinkstock

There is a lack of scientific evidence vitamin D can help prevent colds, Otago University researchers say.

Previous studies have suggested the vitamin from sunshine boosts the immune system and helps prevent colds, some cancers and heart disease, however the university's Vitamin D and Acute Respiratory Infection Study (VIDARIS) counters those claims.

The study, undertaken by researchers from the University of Otago, Christchurch, and 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.

More than 300 Cantabrians took part in the study, taking either a placebo pill or a vitamin D pill every month for a year and half. The researchers then measured the number and severity of participants' colds during this period.

The researchers found there was no statistical difference between those taking the placebo pills and those given vitamin D supplements.

The study's principal investigator Professor David Murdoch said there has been 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," Dr Murdoch said.

"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."

Dr Murdoch said vitamin D supplements may still be of benefit for bone health and for the prevention of other conditions.

The VIDARIS study, which is funded by the Health Research Council of New Zealand, is also looking at whether vitamin D prevents other infections, including carriage in the nose of staphylococcal bacteria.