FRIDAY, Aug. 3, 2012 (HealthDay News) -- Older adults with low vitamin D levels -- especially those who are frail -- have an increased risk of death.
That's the finding of Oregon State University researchers who analyzed data from a survey of more than 4,300 U.S. adults older than 60.
Those with low vitamin D levels had a 30 percent greater risk of death during the study period than those with higher levels. Frail people had more than double the risk of death than those who were not frail. And those who were both frail and had low vitamin D levels were three times more likely to die than those who were not frail and had higher vitamin D levels.
The study was published online recently in the European Journal of Clinical Nutrition.
"What this really means is that it is important to assess vitamin D levels in older adults, and especially among people who are frail," lead author and nutritional epidemiologist Ellen Smit said in a university news release. "Older adults need to be screened for vitamin D."
The researchers could not determine whether low vitamin D levels contributed to frailty or if frail people had low vitamin D levels due to health problems, but that may not be important, the researchers said.
"If you have both, it may not really matter which came first because you are worse off and at greater risk of dying than other older people who are frail and who don't have low vitamin D," Smit said.
"This is an important finding because we already know there is a biological basis for this," she concluded. "Vitamin D impacts muscle function and bones, so it makes sense that it plays a big role in frailty."
According to the news release, about 70 percent of Americans and up to 1 billion people worldwide have insufficient levels of vitamin D, which the body produces in response to sun exposure. Other sources of vitamin D include certain foods and supplements.
Although the study found an association between vitamin D levels and death risk in older adults, it did not prove a cause-and-effect relationship.
The Harvard School of Public Health has more about vitamin D and health.