Vitamin D, which helps fight a host of diseases, may also keep people mobile in their golden age, a new study has claimed.
The Wake Forest University study found that elderly people with the highest levels of vitamin D had better physical function and mobility than others.
"Those with better vitamin D levels started out better and ended up better on physical performance tests," study author Denise Houston, a professor of internal medicine at the University, was quoted as saying by WebMD.
The study tracked 2,788 seniors with an average age of 75 for four years and assessed vitamin D status by analysing each person's blood for 25-hydroxyvitamin D -- a precursor activated vitamin D.
The researchers looked at how quickly each participant could walk a short distance about, six yards, and rise from a chair five times, as well as balance tests.
They found physical function declined during the study period, but it remained significantly higher among those with the highest vitamin D levels at the beginning of the study.
"Over time, everybody declined in the tasks, as expected," Houston said.
However, those who started out with higher vitamin D did better on the tests than those whose vitamin D levels were lower at the start.
"People who had higher levels started out with better physical functioning and because they started out better, they remained at higher physical functioning," she said.
"Those with adequate or optimal vitamin D status [the highest group] had approximately 5 per cent higher physical performance scores and 5 per cent faster walk speed on the 400-meter walk compared to those with insufficient vitamin D status at the 4-year follow up," she added.
Next, Houston wants to focus on whether vitamin D blood levels can predict disability in older adults and whether supplements can ward off disability and mobility problems.
The findings were presented at the American Society for Nutrition at the Experimental Biology meeting in Anaheim, California.