Study leader Ellen Smit of Oregon State University in Corvallis and colleagues used data from the National Health and Nutrition Examination Survey of adults age 60 and older.
The study, involving 4,700, found almost 50 percent were either frail, or "pre-frail," meaning that they were at risk for decreased physical functioning.
Food-insufficient older adults have been shown to have poor dietary intake, nutritional status and health status, Smit said.
"We can do something to try and prevent pre-frailty from becoming frail and people who are not frail from being pre-frail, perhaps some kind of an intervention through exercise as well as nutrition," Smit said in a statement.
Frail adults might have difficulty leaving the house and accessing fresh fruits and vegetables. Smit said communities could work on identifying programs or non-profit organizations that can deliver nutritious meals or fresh produce to older frail adults.
The findings were published in the British Journal of Nutrition.