Research into the benefits of vitamin D is a burgeoning area.

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.

The VIDARIS study is funded by the Health Research Council of New Zealand.

Health Canal