Seniors who take a large daily dose of vitamin D may be significantly less likely to suffer from falls, according to a study conducted by researchers from the Center on Aging and Mobility at the University of Zurich, Switzerland, and published in the British Medical Journal.

"Falls are important events to prevent," said researcher Heike A. Bischoff-Ferrari, "and 700 to 1000 IU of vitamin D per day is safe and inexpensive."

Approximately one-third of all adults over the age of 64 and 50 percent of those over the age of 49 fall at least once per year. In 9 percent of these cases, a visit to the emergency room is required. In 6 percent of cases, a fracture results. Falls are often one of the primary events resulting in admission to a nursing home.

Researchers analyzed the results of eight different studies on a total of 2,400 people over the age of 64. All the studies looked at whether vitamin D supplementation could reduce the risk of falls in the elderly.

The researchers found that at doses below 700 IU per day, there was no reduction in the risk of falls. Above this level, however, the risk of falls was reduced by as much as one in four.

"It takes 700 to 1000 international units (IU) of vitamin D per day and nothing less will work," Bischoff-Ferrari said. "At the higher dose of 700 to 1000 IU vitamin D, the benefit on fall prevention is significant -- at least 19 percent, 26 percent with vitamin D3."

Although vitamin D2 is the form most commonly found in supplements, the body absorbs vitamin D3 more effectively.

The researchers found no difference in effectiveness between supplements marketed as "active" and those that were simply unmodified D2. "Active" supplements, however, are significantly more likely to lead to high calcium levels, which may cause hormone problems and cancer.