A new national U.S. poll has found that around half of parents still give their children vitamins and supplements to help prevent a cold despite no scientific evidence that they actually work.

Carried out by researchers at University of Michigan, the C.S. Mott Children's Hospital National Poll on Children's Health asked a national sample of 1,119 of parents with children age 5 to 12 about which methods they used for cold prevention.

Despite minimal or even a complete lack of scientific evidence, 51 percent of parents still gave their kids vitamin or supplements to prevent a cold, and even more (71 percent) believed in old-fashioned ways of cold prevention such as not going outside with wet hair or staying indoors.

The most popular product given to children was vitamin C, used by 47 percent of parents, followed by zinc (15%) or Echinacea (11%). Around 25 percent of parents had also given their child a product advertised to boost their immune system.

However, the good news is a huge 99 percent of parents included in the survey reported encouraging good personal hygiene to prevent a cold, including teaching children to wash hands frequently, teaching them not to put their hands near their mouth or nose, and discouraging them from sharing utensils or drinks with others, all methods backed up by science.

Moreover, 84 percent of parents also practice good cleanliness to prevent a cold, such as keeping household surfaces clean and sanitized and cleaning toys.

In addition, 87 percent of parents keep their children away from people who are already sick, with 64 percent reporting that they ask relatives with colds not to hug or kiss their child and 60 percent skip playdates or other similar activities if children with colds are attending.

"The positive news is that the majority of parents do follow evidence-based recommendations to avoid catching or spreading the common cold and other illnesses," says Gary Freed, M.D., M.P.H., co-director of the poll and a pediatrician at Mott.

"However, many parents are also using supplements and vitamins not proven to be effective in preventing colds and that are not regulated by the U.S. Food and Drug Administration. These are products that may be heavily advertised and commonly used but none have been independently shown to have any definitive effect on cold prevention."

The researchers add that colds are caused by viruses and most often spread from one person to person, not through going outdoors with wet hair or other commonly believed causes.

According to the researchers, school kids catch three to six colds a year on average, and some can last as long as two weeks.

"When children are sick with a cold, it affects the whole family," Freed says. "Colds can lead to lack of sleep, being uncomfortable and missing school and other obligations. All parents want to keep families as healthy as possible."

"It's important for parents to understand which cold prevention strategies are evidence-based. While some methods are very effective in preventing children from catching the cold, others have not been shown to actually make any difference."